Phytochemical Characteristics and Anti-Inflammatory, Immunoregulatory, and Antioxidant Effects of Portulaca oleracea L.: A Comprehensive Review

Portulaca oleracea L. (P. oleracea) or purslane is a plant from the Portulacaceae family, which is used as food and traditional medicine for various diseases. This review article provides comprehensive information on the antioxidant, immunomodulatory, and anti-inflammatory properties of P. oleracea and its constituents. The literature survey of the different databases until the end of June 2023 was explored based on the keywords including the “P. oleracea, purslane, anti-inflammatory, immunomodulatory, and antioxidant properties.” The plant contains flavonoids, alkaloids, terpenoids, fatty acids, vitamins, minerals, and some other compounds. The results indicated that P. oleracea and its constituents showed anti-inflammatory and immunomodulatory properties through reduction of inflammatory mediators including interferon gama (IFN-γ), interleukin (IL)-10, IL-4, tumor necrosis factor-alpha (TNF-α), and nitric oxide. Improvement in cytokines' serum levels (IFN-γ, IL-10, and IL-4) and increased IgG and IgM serum levels, as well as reduction of IgE, phospholipase A2, and total protein were demonstrated for P. oleracea. The plant and its constituents also improved oxidative stress by reduction of oxidant and increase of antioxidant markers. P. oleracea could be considered as an effective remedy for various inflammatory and immune diseases.


Introduction
Portulaca oleracea L. (P.oleracea) is a plant with an annual life cycle from the Portulacaceae family.Te Portulacaceae includes 25-30 genera making it the largest genus Portulaca [1].It has a global geographical distribution specifcally in the tropical and subtropical areas including South America, Australia, and Africa [2,3].Tis plant is known as purslane and has thick feshy leaves, yellow fowers, and small black seeds, and its stem may reach 15.30 cm in height [4].
Diferent sections of the plant such as stems, leaves, and fower buds are edible [5,6]; thus, it is used both as a plant food and medicinal herb in the eastern Mediterranean and middle eastern from Italy to China [4].In traditional medicine, P. oleracea was advised for the therapy of several conditions including gastrointestinal and respiratory disorders, infammations, kidney and liver diseases, and headaches [4,[7][8][9][10].In addition, the various pharmacological properties of P. oleracea were investigated and proved efective in analgesia and infammation [11], antioxidation [12], and nephroprotection [13] and as antitussive [14], antimicrobial, anticancer, antidiabetic, antiulcerogenic, neuroprotective, hepatoprotective in wound healing and hypocholesterolemic activities [4,5,15,16], as well as the relaxant efect due to inhibition of muscarinic receptors [12], stimulation of β-adrenoceptors in isolated guinea pigs' tracheal smooth muscles [17], and bronchodilatory efect in asthmatic patients [1,13,18].Hence, pharmaceutical properties of P. oleracea were mentioned in most prominent medical textbooks including Canon of Medicine by Avicenna, Al-Hawi by Rhazes Zakhireh Kharazmshahi by Jorjani, and other Traditional Persian Medicine (TPM) books [4].P. oleracea is also indexed in a number of pharmacopoeias such as the Ayurvedic Pharmacopoeia of India [19] and Pharmacopoeia of PR China [20].
Pharmacokinetics of quercetin, a constituent of P. oleracea, showed that after oral administration of a single dose (10 mg/kg) of quercetin in rats, about 6.7% was absorbed in the form of unchanged quercetin [21].However, high amounts of conjugated quercetin are found in the systemic circulation.93.3% of quercetin was metabolized in the gut and only 3.1% metabolized in the liver [21].Pharmacokinetic of quercetin in humans was also indicated that after the oral administration of quercetin (500 mg three times daily); the clearance (CL/F) was high (3.5 × 10 4 l/h) with an average terminal half-life of 3.5 h for quercetin.Te maximum concentration (C max ) value for the quercetin-conjugated metabolites was 447.8 ng/ml [22].
Oral absorption and disposition of alpha-linolenic acid (another constituent of P. oleracea) after administration of a single dose of 3000 mg enriched goat dairy fat (EDF) containing 31 mg ALA/kg body weight to rats were evaluated.ALA was rapidly absorbed (t 1/2a , 76 h) and slowly eliminated (t1/2β, 16.52 h), for plasma.C max value in plasma was 63.42 μg/mL [23].
Anti-infammatory, antioxidant, immunomodulatory, and antitumor activities of P. oleracea were briefy described in a review paper [1].However, this article is an updated and comprehensive narrative review of the pharmacological properties of P. oleracea based on evidence from animal and human studies.All attempts have been made to make a very detailed literature, surveying and as comprehensive as possible.Assessment of the quality of the individual studies is not included in this review, and it will be performed under quantitative systematic reviews (i.e., meta-analysis) in future studies.

Methods
In this review article, the diferent databases such as Sci-enceDirect, PubMed, and Scopus were searched until the end of June 2023 to identify studies published regarding the anti-infammatory, immunoregulatory, and antioxidant effects of P. oleracea and its constituents.Te keywords used for the search were Portulaca oleracea, purslane, P. oleracea constituents, anti-infammatory, immunomodulatory, and antioxidant.Te studies obtained from the abovementioned databases were screened by two authors separately, the search results were checked and fnally articles, chapters, and thesis copies related to the topic of this review that were available online were included.Te included articles were reviewed by authors, and information from each study was presented.Articles in a language other than English, abstracts, or unpublished articles were excluded.

Phytochemistry
Several constituents have been isolated from P. oleracea including favonoids, alkaloids, terpenoids, carotenoids, fatty acids, sterols, polysaccharides, proteins, vitamins, and minerals [4,10].Compounds isolated from P. oleracea are presented in Table 1.Te main active constituents of the plant are also shown in Figure 1.
3.1.Flavonoids.Te amount of favonoids changes in the various sections of the plant.Tey are the highest amounts in the roots and subsequently in the stems and leaves; apigenin, genistein, genistin, kaempferol, luteolin, myricetin, and quercetin are seven favonoids in this plant.However, in ethanolic extracts of leaves and stems, only apigenin and kaempferol have been found with the levels in the former being higher [10,25,26].Portulacanones A-D are homoisofalvonoids with the same chemical structure, which have been derived from aerial parts of the plant [4,24].

Anti-Inflammatory Properties
Infammation is a defensive reaction of the tissue to injury, which in the acute stage is characterized by accumulation of infammatory cells (leukocytes) and mediators as well as increase in the vascular permeability.Diferent cytokines such as TNF-α, interleukin (IL)-1 (α and β), IL-6, IL-8, and IL-11 play efective roles in acute infammatory responses [48].Infammatory mediators are metabolites of arachidonic acid, chemokines, cytokines, and free radicals which lead to enhanced cell proliferation, angiogenesis, mutagenesis, and oncogene activation [49].Although nonsteroidal and steroidal anti-infammatory agents are currently described for the improvement of acute and chronic infammatory conditions like rheumatoid arthritis (RA), however, they showed considerable side efects in long-term medication [50][51][52].Terefore, new and safe anti-infammatory agents are needed, and medical herbs and their active ingredients are one of the best candidates for new drugs and efective remedies [53].Plants and their active components are potential candidates for ongoing research for this purpose.

4
Evidence-Based Complementary and Alternative Medicine in nonstimulated and stimulated conditions signifcantly increased IL-10, while decreasing IL-4 [54].In nonstimulated cells, the plant extract also signifcantly decreased cell proliferation compared to the nontreated group.In addition, IL-4, IL-10, interferon gama (IFN-c), and nitric oxide (NO) production signifcantly decreased in stimulated lymphocytes following treating with the plant extract compared to nontreated cells [54].In a study by Lee et al., pretreatment of human umbilical vein endothelial cells by various doses of P. oleracea aqueous extract inhibited TNF-α induced intracellular reactive oxygen species (ROS) production [55].In addition, the extracts of the plant suppressed TNF-α-induced overexpression of E-selectin and adhesion molecules dose dependently.Moreover, P. oleracea extract signifcantly inhibited TNF-α-induced degradation of IκB-α (a member of a family of cellular proteins) on TNF-α-induced nuclear factor-kappa B (NF-κB) binding in the vascular endothelial cells [55].Productions of NO, TNF-α, IL-1β, and IL-6 were inhibited by P. oleracea ethanol extract in RAW 264.7 cells (a cell line derived from mice) induced by LPS [56].In addition, the phosphorylation of ERK1/2, c-Jun NH 2 -terminal kinase (JNK), and NF-κB activation in the cells were suppressed by the extract of the plant [56].In another study, treatment with 250 µg/ml of the polysaccharide fraction of P. oleracea (POL-P3b) led to overexpression of cluster of diferentiation-80 (CD80), CD83, and CD86.Productions of IL-12, TNF-α, and to a lesser extent IL-10 were also upregulated by POL-P3b [57].Te increase of the toll-like receptor 4 (TLR-4) expression is caused by treatment with POL-P3b on dendritic cells (DCs).Terefore, DCs maturation may occur by POL-P3b via TLR-4 [57].
In a study conducted by Kim et al., ethanolic extract of P. oleracea reduced NO production and suppressed the mRNA expression of the infammatory parameters such as TNF-α and IL-1-β on LPS-induced infammation in RAW 264.7 cells [58].In addition, incubation of LPS-stimulated human peripheral blood mononuclear cells (PBMCs) with the hydroalcoholic extract from aerial parts of P. oleracea (100 μg/m) decreased the concentrations of TNF-α and IL-6 [59].
Te results of the abovementioned (in vitro) studies indicated that P. oleracea extracts or fractions could inhibit production of cytokines as well as cytokine-induced ROS production.Te plant extracts or fractions also inhibited TNF-α-induced degradation of cellular proteins and/or phosphorylation of some mitogen-activated protein kinases in the cells.P. oleracea extracts also increased the expression of membrane proteins in the immunoglobulin superfamily such as CD80, CD83, and CD86 that enhanced and sustained T-cell activation.Moreover, the plant fractions also increased expression of the conserved receptors (TLR-4) that recognize conserved pathogen-associated molecular patterns (PAMPs), thus representing the frst line of defense against infections.

In Vivo Studies.
It was shown that various concentrations of P. oleracea polysaccharides decreased weight of the spleen and stimulated T and B lymphocytes in Wistar rats as dose dependently [60].
In D-galactose-induced aging mice model, P. oleracea polysaccharide (POP) showed preventive efects as decrease in the weight of the spleen and reduction in the number of spleen T cells at 30 days after D-galactose administration in mice [61].
In ovalbumin (OVA)-induced asthmatic rats, administration of drinking water contains hydroethanolic extract of P. oleracea decreased total protein (TP), phospholipase A2 (PLA2), and immunoglobulin E (IgE) levels in the bronchoalveolar lavage fuid (BALF) dose dependently [62].In another similar study, the extract of P. oleracea and alphalinolenic acid (ALA) signifcantly reduced NO 2 and NO 3 levels and total WBC count in serum.Furthermore, P. oleracea and ALA signifcantly increased lymphocyte percentages, while decreased the neutrophil and eosinophil percentages [63].
Oral administration of P. oleracea in LPS-induced acute lung injury (ALI) rats suppressed lung infammation via the decline of IL-1β, IL-6, TNF-α, prostaglandin E2 (PGE2), and transforming growth factor beta (TGF-β), while increased IL-10 levels in the BALF.Te P. oleracea extract also improved the level of WBC and myeloperoxidase (MPO) compared to the LPS group [64].
Te efects of anti-infammatory of aerial parts of P. oleracea were shown on acute paw edema created by formalin in male mice [67].
In rats with chronic constriction injury (CCI), intraperitoneal use of P. oleracea considerably attenuated pain-related behaviors and contents of TNF-α and IL1β as dose dependently [68].
Pretreatment of rats with P. oleracea (400 mg/kg, p.o.) for 14 days in the LPS-induced neuroinfammation model improved the memory and reduced the level of TNF-α [69].
Infammation was decreased via reducing proinfammatory genes including TNF-α and TGF-β in bile duct ligation-induced rat model of acute liver injury after treatment with 500 mg/kg methanolic extract of P. oleracea for 7 days [70].Pretreatment of mice with 1, 2, and 4 g/kg aqueous extract of P. oleracea in a liver injury model induced by carbon tetrachloride (CCl4) decreased TNF-α, IL-1b, and IL-6 in serum [71].
Te results of in vivo studies indicated that P. oleracea extracts showed anti-infammatory properties due to a reduction in some enzymes and proteins that promote infammation in mammals including total protein, PLA2, and IgE levels.
P. oleracea extracts also improved the levels of WBC and leukocyte-derived enzyme that catalyses the formation of a number of reactive oxidant species (ROS), as well as reduced the proinfammatory cytokines while increasing antiinfammatory mediators.Te plant extracts suppressed overexpression of the superfamily of proteins including VCAM-1, ICAM-1, ET-1, and MMP-2 that controlled a large variety of physiological and pathological processes, including tissue remodelling, DNA replication, cell-cycle progression, and cancer.

Alpha Linolenic Acid
(1) In Vitro Studies.ALA is an essential omega-3 fatty acid [77].ALA is also known as one of the important components of P. oleracea [78].It is demonstrated that ALA regulated the immune system by acting on T lymphocytes [79].
Treatment of LPS-stimulated human corneal epithelial (HCE) cells with ALA (125 μM) signifcantly ameliorated the stimulation-induced increase in mRNA and protein levels of TNF-α, IL-1β, IL-6, and IL-8 [80].Te antiinfammatory activity of ALA on proinfammatory cytokines was similar to that of dexamethasone (10−5 M).Te inhibitory activity of ALA on the proinfammatory cytokines was connected with a reduction in inhibitory factor κBα (I-κBα) [80].
In hypercholesterolemic subjects, the production of proinfammatory cytokine by cultured peripheral blood mononuclear cells (PBMCs) had been reduced after high ALA (6.5% of energy) supplementation [83].ALA also reduced IL-6, IL-1β, and TNF-α by PBMCs.In addition, TNF-α production by PBMC was inversely correlated with ALA use [83].Tese results indicated anti-infammatory efects of ALA by reduction of the production of infammatory cytokines.
(2) In Vivo Studies.In a mice model of neuroinfammation induced by cadmium, oral administration of ALA (60 mg/ kg) for 6 weeks suppressed NF-κB and IL-1β in the brain tissue, which suggests neuroprotective efects of ALA [84].Leung et al. reported a decrease in the levels of infammatory factors such as IL-1β, IL-6, and TNFα following treatment of mice with ALA-enriched diets for 28 days [85].
In a mouse model of OVA-induced allergic rhinitis, treatment of animals with ALA (500 and 2000 mg/kg, daily, for 13 days) reduced expression of IL-6 and IL-1β in nasal mucosa that show anti-infammatory efects of this essential fatty acid [86].

Quercetin
(1) In Vitro Studies.Quercetin is a polyphenolic favonoid with anticancer, antioxidant, and antiviral features which are found in several plants such as P. oleracea [88].Quercetin suppressed TNF-α generation as dose dependently and impaired chemokines and cytokines levels in DCs stimulated by LPS.In addition, quercetin signifcantly reduced production of cytokines and chemokines in LPS-stimulated DCs [89].Also, quercetin suppressed enhanced expressions of CD40, CD80, and CD86 in LPS-stimulated DCs.Te cytokines secreted by activated DCs were downregulated by quercetin, indicating the immunoregulatory function of this agent on DCs [89].
In primary cells, quercetin (40 µM) suppressed generation of IFN-c and IL-2 with T-cell receptor (TCR) stimulation.Quercetin signifcantly inhibited the increase of IL-2Ra expression, when TCR and exogenous recombinant human IL-2 are stimulated [90].
Quercetin (8 and 16 mg/kg/day) administration significantly reduced the BALF level of eosinophils (68.79% and 73.35%, respectively) in mice challenged with OVA [95].Quercetin also decreased IL-4 and IL-5 secretion, as well as MMP-9 and erythropoietin (Epo) mRNA expression but increased the IFN-c concentration in the BALF compared to nontreated animals [95].
Treatment with quercetin (500, 1000, and 1500 mg/day, p.o) or coadministration with azathioprine (100 mg/day) for eight weeks in rheumatoid arthritis patients compared to the placebo was investigated [96].Coadministration of high dose of quercetin signifcantly declined the IL-6 and complement (C3 and C4) but elevated the level of IL-10 compared to the placebo-treated group.Treatment with diferent doses of quercetin signifcantly reduced ICAM-1 compared to the azathioprine alone-treated group [96].
Oral gavage of 50 mg/kg quercetin in mice with infammatory bowel diseases (IBD) led to reduce of T17 cells but increase in the number of Treg cells, resulting in reduction of gut infammation [97].
Tese results indicated that P. oleracea and its components showed anti-infammatory properties and promote subsets of T-cell toward T-helper1 (IFN-c) and Treg secretion (IL-10), which may indicate a therapeutic use of the plant and its constituents for the treatment of infammatory and allergic diseases.In addition, quercetin and ALA (the constituent of the plant) inhibit infammatory cytokine levels and downregulate secretion of cytokines and chemokines.Tus, P. oleracea and its active components could be potentially used for prevention and therapy of infammatory and allergic disorders such as COPD and asthma.Table 2 shows anti-infammatory properties of P. oleracea and its components.In addition, possible mechanisms of the anti-infammatory activity of the plant and its major components are summarized in Figure 2.

Antioxidant Efects of P. oleracea
5.1.1.In Vitro Studies.Antioxidant properties and mineral composition of P. oleracea were evaluated at several growth steps.Te antioxidant capacity was evaluated by 1,1diphenyl-2-picryl-hydrazyl (DPPH) and ferric-reducing antioxidant power (FRAP) assays [115].Mature plants of P. oleracea had more total phenol content (TPC) and antioxidant efects than plants at the immature steps.Particularly, 60-day-old plants had large amounts of TPC and antioxidant capacity as evaluated by the DPPH test and FRAP assay [115].
P. oleracea aqueous extracts obtained from leaves, stems, and fowers were examined for the total phenolic content, antioxidant activity, and ferric-reducing antioxidant power [116].Signifcantly, higher values were observed for stems than in fowers and/or leaves.In the DPPH assay, the 50% inhibition rate is obtained in lesser concentrations for the three plant parts [116].
In vitro and in vivo studies were done to assess antioxidant capacity of P. oleracea leaves' ethanolic extract.Te extract (25, 50, and 100 mg/kg) considerably decreased lipid peroxidation and remade the nonenzymatic and enzymatic antioxidants levels in the liver tissue.Te P. oleracea ethanolic extract at a dose of 100 mg/kg was more efective than doses of 25 and 50 mg/kg [117].
Te in vitro antioxidant efect of P. oleracea methanolic extract was investigated by diferent methods including NO free radical scavenging activity, DPPH free radical scavenging activity, superoxide scavenging activity, reducing power by FeCl, and the alkaline DMSO method.Te in vitro  Evidence-Based Complementary and Alternative Medicine antioxidant activity of P. oleracea methanolic extract was showed to be more than standard antioxidants [118].Te total phenol contents of six cultivars of P. oleracea methanolic extracts had been analyzed by the Folin-Ciocalteu method.Tere was a well relation between the total phenol content value and its ascorbic acid equivalent antioxidant capacity and FRAP values in all of the cultivars [119].Te ascorbic acid content for the cultivars was from 38.5 ± 0.6 to 73.0 ± 17.5 mg/100 g.Te BCB assay demonstrated that all cultivars were able to inhibit lipid peroxidation, and the inhibitory efect did not relate to the total phenol content value [119].

Evidence-Based Complementary and Alternative Medicine
Te in vitro antioxidant efect of leaves of the P. oleracea methanolic extract from Turkey was evaluated by DPPH and β-carotene-linoleic acid assays.Te extract exhibited high levels of free radical scavenging activity [120].
Radical scavenging activities were measured for evaluating the solvent extracts of P. oleracea.Te electrondonating abilities (EDAs) of ethyl acetate and methanolic extracts showed high antioxidant activity.Te SOD-like abilities of ethyl acetate and petroleum ether extracts also showed some activities.However, there was not a signifcant antioxidant activity for the thiobarbituric acid reactive substances [121].
Total antioxidant capacity of fresh and dried hydroalcoholic P. oleracea extracts was measured using radical cation (ABTS) and DPPH tests and the FRAP assay.Fresh hydroalcoholic P. oleracea extract showed the highest radical scavenging power in ABTS and DPPH tests [122].
It was shown that diferent drying methods (microwave drying, hot-air drying, and freeze-drying) may afect the antioxidant capacity of P. oleracea leaves.Te best antioxidant activity was seen for fresh purslane leaves as 147.78 μmol trolox and 53.23% per 100 g dry weight for ABTS and ABTS, respectively [123].Between dried samples, those dehydrated by freeze-drying and diferent hot-air drying temperatures method showed maximum antioxidant capacity and no signifcant diferences was observed between both ABTS and DPPH methods [123].
Total phenolic content and antioxidant capacity of the fractions of P. oleracea crude extract which were obtained using reversed-phase separation method were determined.According to optical absorption, fve fractions were isolated [124].In comparison to crude extract, the quantifed total phenolics amount in fraction 3 was higher.In fraction 3, free phenolic acids including cafeic, chlorogenic, ferulic, p-coumaric, and rosmarinic acids were detected, and also free favonoids (quercetin and kaempferol) were determined too.Trolox equivalent antioxidant capacity (TEAC) of the crude extract was four times lower than fraction 3 TEAC.Te thiobarbituric acid reactive substance (TBARS) assay method showed the highest lipid peroxidation inhibition activity for fraction 3 [124].

In Vivo Studies.
Te antioxidant activity aqueous juice from P. oleracea was determined by measuring reduced GSH, CAT, SOD, GR, GST, and GPx, as well as NO and lipid peroxidation inhibition in the kidney, liver, and testis of rats [114].Aqueous juice of P. oleracea (1.5 ml/kg, orally) administration in rats resulted in marked improvement in parameters related to kidney and liver function [114].Water extract of P. oleracea decreased the serum and lipid peroxidation levels in the liver and increased the antioxidant enzymes activities in the liver and serum in high-fat mice [125].Pretreatment with the P. oleracea aqueous extract (300 mg/kg) prevented the lactate dehydrogenase (LDH), alanine aminotransferase (ALT), and alkaline phosphatase (ALP) increased in the nephrectomized rat model subsequently ischemia-reperfusion (IR) injury in the kidney [126].
Te protective efect of P. oleracea ethanolic extract versus hepatic toxicity induced by carbon tetrachloride (CCl4) was investigated.Intragastric administration of the P. oleracea extract normalized hepatic marker enzymes in rats treated to CCl4.Both liver histopathological alterations and marker of liver function improved after P. oleracea treatment [128].
Te antioxidant activity of P. oleracea (POEE, 4 mg/kg, orally, for 21 days) versus the MeHg-induced neurotoxicity (5 mg/kg for 21 days) was investigated in the cerebellum and  Evidence-Based Complementary and Alternative Medicine cortex of rats [129].Te activities of CAT, SOD, GPx, and the level of GSH were declined but GR and malondialdehyde (MDA) levels were enhanced in cerebellum and cortex by MeHg.All of biochemical changes were reversed after POEE treatment [129].
Treatment with fresh and dried P. oleracea in C57BL/6J diabetic mice signifcantly decreased the MDA level and enhanced SOD activity in the liver relative to untreated diabetic mice [130].
Te efect of P. oleracea on the oxidantantioxidantcondition in hepatic toxicity induced by paracetamol was evaluated in rats.Paracetamol induces toxic efect including depletion in total antioxidant capacity, an increase in the hepatic TBARS content, and reduction in GSH content, catalase, and superoxide dismutase activities.Coadministration of P. oleracea (300 mg/kg, orally) and paracetamol signifcantly prevented the hepatotoxicity of paracetamol [131].
In a study, ameliorative efects of 1, 2, and 4 mg/mL P. oleracea extract on oxidative biomarkers including MDA, SOD, CAT, and thiol were observed in the BALF of asthmatic rats [132].
Saleh et al. showed that administration of ethanolic extract of P. oleracea (100 mg/kg) and Chicory water extract (100 mg/kg) in rats with testicular and autophagy dysfunction synergetically improved testicular toxicity via reducing MDA and enhancing GSH, GST, and GPx activities [133].Similarly, in the rat model of testicular toxicity induced by acrylamide, oral administration of 200 and 400 mg/ kg P. oleracea extract improved testicular toxicity through reduction of oxidative status [134].
Antioxidant efect of the hydroalcoholic extract of P. oleracea (25, 50, and 100 mg/L) on functional parameters of human sperm samples was evaluated.Reduction of intracellular ROS and increase of motility of sperm were observed after treatment [135].
Treatment with hydroalcoholic extract of P. oleracea (400 mg/kg) in a thyrotoxic rat model improved hyperthyroid state by reducing MDA level and increase of thiol, SOD, and CAT activities [136].
Based on the abovementioned experimental studies, P. oleracea-based extracts showed antioxidant efects by increasing antioxidant markers such as CAT, GSH, and SOD and decreasing oxidant parameters including MDA and NO levels.

Alpha Linolenic Acid
(1) In Vitro Studies.Antioxidant activity of plant sterol ester of α-linolenic acid (PS-ALA) was examined using the in vitro model.In this model, HepG2 cells induced by oleic acid treated to 0.1 mM ALA-PS for 24 h.Te results showed reduction of ROS production in oleic acid-loaded HepG2 cells after treatment with PS-ALA [137].
(2) In Vivo Studies.Oxidative stress agents and antioxidative enzymes were evaluated in rats fed with a single lipid source such as sunfower oil, canola oil, rosa mosqueta oil, sacha inchi oil, and chia oil containing diferent amounts of ALA [138].Te results showed that higher supply of ALA improved the antioxidative status (GSH content and GSH/ GSSG ratio as well as the antioxidant enzyme activity such as SOD, CAT, GPx, and GR) [138].
Te antioxidant efect of ALA on oxidative stress induced by amyloid-beta peptide was evaluated in a rat model.Treatment with 150 μg/kg ALA for 2 weeks reduced MDA and NO levels but increased CAT activity and glutathione content in hippocampus [139].

Quercetin
(1) In Vitro Studies.Te cytoprotective efect of quercetin was examined on iron-loaded hepatocyte cultures.In the presence of quercetin, the amount of MDA was decreased as dose dependently [140].Te damaging efect of Fe-NTA on hepatocytes led to increase of LDH in the culture medium and a decrease in intracellular LDH levels.Permeation of enzyme was inhibited using quercetin as dose dependently [140].
Te infuence of the chemical structure on antioxidant capacity of quercetin was evaluated by examining of inhibition of copper-catalysed oxidation of human low density lipoprotein (LDL) in vitro.Quercetin (2.5, 5, and 7.5 µM) inhibited human LDL oxidation in a dose-dependent manner [141].
Erythrocyte membranes versus lipid peroxidation were protected by quercetin through inhibition of hemolysis and GSH depletion [142].
In a study, mouse thymocyte was used to investigate whether quercetin acted as an antioxidant or as a cytotoxic factor.Quercetin protected thymocytes against apoptosis induced by glucose oxidase in mice as dose dependently [143].In addition, electrophoretic mobility shift assays (EMSAs) showed that 50 µM quercetin inhibited the glucose oxidase-mediated DNA-binding activity of redox state sensitive transcription factors, such as NF-kappaB, AP-1, and p53.Tese results indicate antioxidative efects of quercetin on thymocytes [143].Quercetin (10, 20, 50, 100, or 1000 µM) decreased the formation of hydroperoxides from methyl linoleate as concentration dependently [144].
Te quercetin antioxidant efect was assessed by two methods of measuring the ability to scavenge the ABTS radical cation at diferent pH and also FRAP assay.In these tests, the quercetin acts as radical scavenger and decrease compound antioxidant agents as an α-tocopherol [145].It was also shown that antioxidant activity on antisuperoxide formation, DPPH scavenging, antilipid peroxidation, and superoxide anion scavenging was less potent in pure quercetin than the quercetin-loaded nanoparticles [146].
Moreover, the antioxidant capacity of the quercetinnanoparticles in vitro using reducing power test and free radical scavenging activity test showed that quercetin-loaded nanoparticles in the DPPH test reduced the stable radical DPPH, and its reducing power was correlated well with increasing concentration [147].

Evidence-Based Complementary and Alternative Medicine
(2) In Vivo Studies.In rats adapted for 3 weeks to a semipurifed diet riched with 0.2% quercetin, it was shown that the total antioxidant status of plasma in the group fed with the quercetin was signifcantly more than that in the control group [148].Treatment of streptozotocin (STZ)-induced diabetic rats with 15 mg/kg, quercetin reduced MDA and NO levels and also increased the GSH-Px, SOD, and CAT activities [149].Te protective efect of quercetin (75 mg/kg) was also shown in a rat model of cyclophosphamide-induced hepatotoxicity.Treatment of animals with quercetin for 10 days decreased oxidative stress parameters including MDA and protein carbonyl (PCO) [150].In liver injury induced by bile duct ligation, treatment of rats with 50 mg/ kg/day quercetin (for 10 days) reduced oxidative stress through suppressing the oxidation of proteins and activity of the glutathione peroxidase [151].
It was shown that the plasma antioxidant status was markedly upper in animals treated with quercetin (50 mg/kg, intragastrically), [152].Subacute treatment with quercetin treatment (10 mg/kg) in STZ-induced diabetic rats ameliorated the efects of diabetes on hepatic GPx activity and brain oxidized GSH concentration.Tere was 40% decline in GSH concentration of liver, 20% increase in the liver MDA level, and increase in GPx activities of renal (23%) and cardiac (40%), as well as a 65% increase in CAT activity of cardiac tissue.Tese results showed the preventive efects of quercetin in oxidative stress-induced diabetes [153].
Antioxidant and antiulcerogenic efects of quercetin in gastric lesions induced by ethanol in rats showed signifcant decreased gastric injury and MDA level and signifcantly enhanced GSH-Px, SOD, and CAT activities [154].
In a model of tramadol intoxication, rats received 100 mg/kg of quercetin for 14 days.Findings showed improvement of oxidant/antioxidant agents (MDA, SOD, and NOx) in various tissues including the heart, liver, adrenal, and kidney [155].In another study, protective efect of quercetin was shown in a rat model of hepatotoxicity and renal toxicity induced by radiation.Oral administration of 50 mg/kg quercetin before or after radiation led to decrease of MDA level in liver and kidney tissues [156].
Pretreatment of mice exposed to cigarette smoke with quercetin (10 mg/kg/day) improved pulmonary function and emphysema via reduction of infammatory cytokines, increase of SOD and CAT activities, and decline of myeloperoxidase activity which suggest that quercetin may be used as an antioxidant agent [157].In addition, the efect of quercetin on expression of antioxidant genes including CAT, superoxide dismutase 1 (SOD1), glutathione peroxidase 1 (GPX1), and antioxidant capacity (TAC) was evaluated in the dental pulp of diabetic rats induced by streptozotocin.Oral gavage of quercetin (25 mg/kg) for 40 days improved CAT, SOD1, GPX1, and TAC levels [158].

Other Constituents.
Te antioxidant activity of P. oleracea seed oil (PSO) was evaluated using diferent methods in vitro.Te higher concentrations of PSO (4 mg/ ml) elevated hydroxyl free radical scavenging activity.Increase in the oil concentration improved the DPPH scavenging ability [159].Tere was a linear relationship between scavenging ability and PSO concentrations at the range of 3-20 mg/ml.Moreover, antioxidant activity of PSO detected at concentrations ≥3 mg/ml.Moreover, the TBHQ free radical scavenging capacity of PSO was more potent than that of DPPH [159].
Te evaluation of the antioxidant capacity of the various extracts of P. oleracea leaves using two methods of extraction including hot-maceration and rapid solid-liquid dynamic extraction showed a inhibition percentage of 52% and 54%, respectively, while the mixed extraction method showed a high inhibition rate (70%) [160].
Te antioxidant activities of polysaccharide fractions purifed from P. oleracea were examined by cell-free and cell-mediated radical generating systems.Te fractions possessed strong antioxidant activities in both systems [161].
Te antioxidant potential of an oral treatment (3 weeks) of diabetic rats with P. oleracea polysaccharide fraction (PPFt) (25 and 50 mg/kg) dose dependently reduced the serum TBARS and glucose and increased in total GPx activity and GSH levels.PPFt administration also improved SOD and CAT values near to optimal levels [162].
Antioxidant activities of phenolic alkaloids extracted from P. oleracea, such as oleracein A (OA), oleracein B (OB), and oleracein E (OE), were indicated.Te inhibitory efects of these compounds on lipid peroxidation in brain tissue in rats were evaluated [41].Tese phenolic alkaloids exhibited lower DPPH radical scavenging activities than cafeic acid but their DPPH radical scavenging were higher than ascorbic acid and α-tocopherol (OB > OA > OE).OE preventing efects for lipid peroxidation was most potent with an EC50 of 73.13 µM, near to cafeic acid (72.09µM).It was indicated that phenolic alkaloids served as new antioxidant factors in this plant [41].
In a study, the antioxidant efect of P. oleracea was examined in a vitamin A defciency induced-oxidative stress rat model.Feeding rats with pure beta-carotene diet or a diet supplemented with P. oleracea leaves resulted in lower TBARS concentrations in liver and heart tissues compared to vitamin A-defcient diet rats [163].Te liver GSH and heart glutathione disulfde (GSSG) concentrations of the P. oleracea treated group were lower than vitamin Adefcient group [163].
Te antioxidant enzymes, including GPx, GR, GST, SOD, and CAT, have an important role in maintaining glutathione homeostasis in tissues [39].Enhanced levels of GPx, GR, GST, SOD, and CAT were related to increased glutathione level and depressed MDA, NO, and lipid peroxidation in the liver, kidney, heart, and testis of rats, thus indicating the antioxidant activity of P. oleracea.Te reduction of the liver enzymes activity, ALT, AST, c-GT, and ALP in the P. oleracea treatment group indicates its protective role versus liver injury [39].Te antioxidant efects of P. oleracea and its constituents are summarized in Table 3. Figure 3 also shows possible mechanisms of antioxidant efects of P. oleracea and its components.
Abovementioned in vitro and in vivo studies showed that P. oleracea constituents, especially quercetin, have the potential to be used as an antioxidant agent.Tis claim is 12 Evidence-Based Complementary and Alternative Medicine In vitro ↑ DPPH scavenging capacity and FRAP [115] Aqueous extracts of leaves, stems, and fowers

Ethanolic extract of leaves
In vitro ↑ ABTS and DPPH scavenging capacity [117] Methanolic extract

Methanolic extract of leaves
In vitro ↑ DPPH scavenging capacity [120] Inhibition ratio of the linoleic acid oxidation
Evidence-Based Complementary and Alternative Medicine proved by increasing FRAP, ABTS, and DPPH scavenging capacity and decreasing MDA concentration, superoxide and hydroperoxide anions, and lipid peroxidation.However, further clinical studies regarding the efect of P. oleracea and its constituents are needed.

Immunomodulatory Effects
Immunomodulation is the modulation of the function of the immune system or an immune response with use of a drug or herbal compound.Immunomodulatory drugs change immune response by the stimulation (immunostimulators) or inhibition (immunosuppressives) of antibody formation or the white blood cell activity [164,165].Many plants and their bioactive components were studied for their possible use as immunomodulation drug [166,167].
6.1.Immunomodulatory Efects of P. oleracea 6.1.1.In Vitro Studies.Aqueous alcoholic extract of P. oleracea on T helper cells T1/T2 balance in stimulated and nonstimulated human lymphocytes showed that the extract (160, 40, and 10 µg/ml) reduced cell proliferation and serum level of cytokines but enhanced IFN-c/IL-4 ratio and Treg/T2 (IL-10/IL-4) balances in stimulated cells [54].Te results were compared to control and dexamethasone as positive control and showed immunomodulatory efects of plant which were lower than dexamethasone [54].
Treating BALB/c-isolated splenocytes stimulated by concanavalin A (Con A) indicated that ethyl acetate and chloroform extracts of P. werdermannii and P. hirsutissima inhibited the proliferation of cells suggesting immunomodulatory activity of this plant [168].In this study, extracts from aerial parts of Portulaca were tested and more studies to identify the active compounds present in these extracts for the treatment of immune-mediated the disorders are needed [168].
6.1.2.In Vivo Studies.Immunomodulatory evaluation ethyl acetate extract of P. oleracea in cyclophosphamide-treated mice showed increased phagocytosis and elevated proliferation of splenic lymphocytes due treatment with of P. oleracea suggesting immunoactivity property of the plant [169].However, there are no data about the mechanisms by which the active compounds present in the plant could induce immunomodulatory efects.
Immunomodulatory efect of P. oleracea extract on IL-4 and interferon gamma (IFN-c) and IFN-c/IL4 ratio in BALF of asthmatic rats showed an immunomodulatory efect through increase of IFN-c/IL4 ratio [170].Te efect of administration of P. oleracea extract on immune markers in asthmatic rats during sensitization period showed reduction of BALF levels of IgE indicating modulation of immune function [62].
Barakat and Mahmoud reported that purslane/pumpkin seed mixture has immunomodulator efects on hypercholesterolemic rats through improvement of immunoglobulin G (IgG) and immunoglobulin M (IgM) levels, which is probably due to present of ALA in the mixture [171].Oral administration of extract (200 mg/kg) for 7 days in a mice model of acetic acid-induced ulcerative colitis signifcantly reduced IL-1, IL-6, IL-17, TNF-α, IFN-c, and nuclear factorkappa B as well as myeloperoxidase activity.Te fndings suggest immunomodulatory property of the ethanolic extract of P. oleracea [172].
In a cyclophosphamide-induced immunosuppressive rat model both in vivo and in vitro (isolated spleen cells), immunostimulatory efects of P. oleracea L. and Perilla frutescens seed complex extracts (PPCE) were evaluated [173].Te fndings showed that treatment with PPCE led to increase of immune cells and splenic recovery.Te PPCE also enhanced proliferation of splenocyte and infammatory cytokines including IL-2, IL-12, TNF-α, and IFN-c as well as NK cell activity.According to these results, P. oleracea could be used as an immunomodulatory agent [173].
Ethyl acetate and ethanolic extracts of P. oleracea on infammatory responses induced by LPS in RAW264.7 macrophages (in vitro model) and dextran sulphate sodium (DSS)-induced colitis in mice (in vivo model) indicated the inhibition of the serum proinfammatory cytokines (TNF-α, IL-6, and 1L-1β) in both models.According to these fndings, P. oleracea can appropriately regulate immune responses [174].
Administration of 20 mg/ml P. oleracea in mice with atopic dermatitis led to decrease of serum level of Ig E and histamine HIS, reduction of infammatory mediators such as TNF-α, IFN-c and IL-4 as well as mast cell infltration [175].
All in vivo studies were well designed and showed that P. oleracea-based extracts has the potential to be used as  Evidence-Based Complementary and Alternative Medicine a potent immunomodulatory agent.However, more studies should be carried out in future to identify active compounds responsible for immunomodulatory efects of herb and its possible mechanisms.
6.2.Immunomodulatory Efects of the Plant Constituents 6.2.1.Alpha Linolenic Acid (1) In Vivo Studies.Te efect of an fatty acids enriched diet on T1/T2 polarization in lymphocytes of mice showed signifcant increased ratio of IFN-c/IL-4 in mice fed the omega-3 compared to omega-6.Tus, an omega-3 rich diet containing ALA induce a shift in T1/T2 balance and modulates immune function [176].Increased serum IgG and IFN-c as well as reduced IL-4 and PGE2 were observed in cows receiving 0, 100, 200, 300, and 400 g/d ALA by duodenal cannulas [11].Tus, the results suggest immunomodulatory efects of ALA by modifying production of T1/ T2 cytokines and the efect of plant on T-cell-mediated immunity.In this study, the infusion of large quantities of ALA and secretion into milk fat may afect immunity which needs more investigations [11].Jefery et al. [177] showed that feeding rats with a highfat enriched diet (178 g lipid/kg) containing the ratios of palmitic, oleic, linoleic, and ALA for 6 weeks caused modifying the spleen lymphocyte functions [177].Similarly, feeding weanling rats with 4.4 g ALA, c-linolenic, ara-chidonic (ARA), eicosapentaenoic (EPA), or docosahexaenoic acid/100 g total fatty acids afects lymphocyte functions and cell-mediated immunity [178].Te fnding indicated that replacing ALA with EPA in dietary leads to reduction of lymphocyte proliferation and natural killer (NK) cell activity as well as cell-mediated immune response [178].Te efect of ALA (0.2 and 0.4 mg/ml) on immune markers in sensitized rats with OVA also showed increase of IFN-c and IFN-c/IL4 ratio as well as decreased IL-4 indicating an immunoregulatory efect for the ALA [179].
Te efect of alpha-linolenic acid on immune responses was shown in the abovementioned in vitro studies.However, further studies including clinical trials are needed to recommend it as immunoregulator.

Quercetin
(1) In Vitro Studies.Te immunomodulatory activity quercetin on human mesangial cells (HGMCs) showed reduction of nuclear factor-κB p65 and IKKβ expression, increased IκBα expression, and inhibition of the expression of PTX3 antibody through inhibition of NF-κB signalling pathway [180].Further studies are needed to determine whether quercetin has inhibitory efects on PTX3 in vivo.Immunomodulatory activity of quercetin-3-O-α-Lrhamnopyranoside versus infammatory reactions of infuenza infection by propagation of infuenza virus in Madin Darby-Canine kidney (MDCK) cells and incubation of quercetin-3-O-α-L-rhamnopyranoside (150 μg/ml) for 48 h indicated reduction of TNF-α expression and increased IL-27 expression as pro and anti-infammatory cytokines, respectively [181].In model of asthma induced by Blomia tropicalis, treatment of spleen cells with 3.5, 7.5, and 15 μg/ ml quercetin for 48 h led to reduction of IL-4, IL-5, and IL-13 cytokines in spleen cell culture supernatants.Tese results suggest a potential therapeutic role of quercetin as an immunomodulatory agent [182].
In an in vitro model, immunomodulatory efect of incubation of PBMCs incubated with shikimic acid and quercetin at concentrations (10 and 100 nM) for 24 h showed that combination of shikimic acid and quercetin led to marked increase of IL-8 and IL-6 compared to baseline levels whereas incubation of cells with tamifu did not change cytokine levels [183].Te results suggest the modulatory efect of shikimic acid and quercetin combination on innate immunity [183].In mouse dendritic cells (DCs) treated with quercetin in the presence of LPS for 24 h, cytokines and chemokines (MIP-1a, MIP-1b, MCP-1, and RANTES) were reduced [89].In addition, quercetin decreased the expression of CD40, CD80, and CD86 in DCs.Tese results show immunosuppressive property of quercetin on DCs activation and function [89].
Te efect of diferent concentrations of quercetin (1, 10, and 50 µM) on LPS-stimulated bone marrow-derived macrophages (BMDMs) indicated that treatment of cells with quercetin inhibited expression of high levels of TNF-α and IL-1β proteins, IkB-α phosphorylation, and iNOS expression induced by LPS in BMDM [94].Te peripheral blood mononuclear cells (PBMCs) of normal subjects incubated with 0.5-50 µM quercetin for 24-72 h signifcantly enhanced IFN-c gene expression and its secretion in cell supernatant while expression and generation of IL-4 markedly decreased by normal PBMC [91].Terefore, induction of T1-derived cytokines and inhibition of T2 derived cytokines could be the possible mechanisms of immunomodulatory efects of quercetin [91].Sternberg et al. showed that PBMC proliferation, the generation of cytokines, and matrix metallopeptidase 9 (MMP-9)/tissue inhibitor of metalloproteinases-1 (TIMP-1) ratio in the presence or absence of quercetin were evaluated [92].Exposure of cells with 5-200 µM quercetin for 48 h dose dependently reduced PBMC proliferation and cytokine levels in cell culture supernatants.Dose-dependent efect of quercetin on MMP-9/TIMP-1 ratios was also observed which suggest immunomodulatory efects of quercetin [92].
In an in vitro study, CD4+ T cells were derived from Tbet transgenic/defcient mice and incubated with anti-CD3 and anti-CD28 in the presence/absence of quercetin (40 µM) for 24 h.Cytokine levels of IL-2 and IFN-c in supernatants of T cells incubated with quercetin were signifcantly reduced dose dependently but T2 cytokines (IL-4) did not changed [90].
Despite the diferences in the studied cellular model, dose of quercetin and duration of the study, all these studies demonstrated the positive efects of quercetin on cytokine production and cell-mediated immunity that suggests immunomodulatory efects of quercetin.However, more studies to evaluate the molecular mechanisms of quercetin-Evidence-Based Complementary and Alternative Medicine mediated immunomodulatory efects and its use in clinical applications are required.
Al-Rekabi et al. evaluated immunomodulatory efect of quercetin consumption (500, 1000, 1500 mg/day) in combination with azathioprine twice daily for eight weeks in active rheumatoid arthritis patients [96].Oral use of high dose of quercetin decreased IL-6, complement protein 3 (C3) and complement protein 4 (C4) levels as well as increased IL-10 compared to lower doses of quercetin and placebo group.Intercellular adhesion molecule I (ICAM-1) was also decreased after treatment with all three doses of quercetin relative to placebo group [96].Lack of designing of the group treated to quercetin alone and mentioning the type of randomization are some limitations of the study.
Te evaluation of quercetin efect on the T1/T2 immune response in OVA-induced asthma in mice demonstrated that administration of quercetin for 3 days reduced the numbers of infammatory cells in BALF [95].In addition, MMP-9 and GATA-3 mRNA expression in lung tissues of asthmatic mice were inhibited by quercetin.Increased IFN-c concentration but reduction of IL-4 and IL-5 in the BALF was also observed [95].In a murine model of dry eye disease (DED), topical pretreatment of 0.01% quercetin, 0.1% resveratrol, and 0.01% quercetin +0.1% resveratrol decreased infammatory response of the ocular surface, clinical symptoms, IL-1α, and IL-4 levels compared to DS mice treated with vehicle.In addition, quercetin reduced CD4+ T cells [186].
All the abovementioned fndings reported in vivo studies support immunomodulatory property quercetin.However, the efects of the P. oleracea extract and its phytochemical components such as quercetin were studied only in a few clinical studies.Tus, further clinical studies regarding the efect of P. oleracea and its constituents are needed.

Other Constituents.
Tere are few studies about the immunomodulating efects of other constituents of P. oleracea.Efects of isolated three polysaccharide complexes from P. oleracea, silver linden, and lavender were evaluated in the ex vivo model of human white blood cells and the ex vivo murine model of Peyer's patch (PP) cells from the small intestine [187].Tese complexes stimulated phagocytic leukocytes, human blood T-cell populations, and induced IL-6 production obtained from Peyer's patch cells and human white blood cells.Te results demonstrated purslane polysaccharides can play a role in treatment of immune system disorders [187].Te immunomodulatory function of purslane polysaccharides (POL-P3b) was evaluated in dendritic cell (DC) vaccine for breast cancer.Treatment of tumor antigen-sensitized DC with POL-P3b (50 µg/mL) increased immune responses and was efective as an immunomodulatory agent for the maturation and activation of DC [188].
Treatment of rats with ovarian cancer purslane polysaccharides demonstrated an increase of the spleen, thymocyte T, and B lymphocyte proliferation which suggest immunity-modulatory activity of this plant [60].
Assessment of efects of purslane polysaccharides on immune status in rats with N-methyl-N-nitro-Nnitrosoguanidine (MNNG) induced-gastric cancer indicated that administration of diferent concentrations of purslane polysaccharides (200, 400, or 800 mg/kg, as oral gavage) signifcantly raised proliferation of splenocytes in gastric cancer rats [189].In addition, the serum level of cytokines, including IL-2, IL-4, and TNF-α, was increased after treatment with these polysaccharides.Tese results confrm the immunomodulatory activity of the plant that could be therapeutic value in gastric cancer [189].
Immuno-stimulating activity of a polysaccharide from of P. oleracea was examined on in vivo model by accessing the immune organ index and T lymphocyte subsets after administration of polysaccharide [190].Te fndings showed an increase in immune responses through enhancement of white blood cell count, CD4+ T-lymphocytes, and CD4+/ CD8+ ratios [190].
In the DSS-induced colitis mouse model, oral administration of bioactive compounds of P. oleracea extract (portulacanone C, cis-n-feruloyl-3′-methoxytyramine, and trans-n-feruloyltyramine) and 3% DSS led to signifcant reduction of cytokine levels such as TNF-α, IL-6, 1L-1β, IL-4, IL-17, and IFN-c [174].Based on these results, active compounds of P. oleracea have immunomodulatory properties and could be used as a new therapeutic approach in various diseases [174].
P. oleracea and its main constituents such as ALA, quercetin, and polysaccharide showed immunomodulatory efects by modulation of both innate (diferent cells from white blood cells group and NK cells) and adaptive immune (infammatory and anti-infammatory cytokines in the blood and tissue, B lymphocytes, T lymphocytes, antibodies formation, and T1/T2 balance) systems.Terefore, it can play a role in the treatment of immunological based disorders as an immune-modulatory herb.Table 4 demonstrates immunomodulatory efects of P. oleracea and its components.Evidence-Based Complementary and Alternative Medicine  Evidence-Based Complementary and Alternative Medicine Te immunomodulatory efects of this plant and its constituents with possible mechanisms of action are also summarized in Figure 4.

Limitations and Strengths
Despite demonstrating valuable fndings, there were limitations that made data interpretation difcult.Te main limitation of this review article is the low number of clinical studies on anti-infammatory, immunoregulatory, and antioxidant efects of P. oleracea and its constituents in various diseases.Terefore, designing further standard clinical trials with appropriate sample size can help in the better generalizability of the results.In addition, assessment of possible mechanisms related to these efects is recommended in future studies.Te evaluation of the quality of the individual studies did not perform in this review, so design systematic review and meta-analysis studies can be a potential direction of research.

Conclusion
Te efect of P. oleracea and its constituents on infammation, oxidant/antioxidant status, and immune system was reviewed.In vitro and in vivo studies showed that the efects of this plant and its constituents such as polysaccharides and favonoids especially quercetin could be attributed due to their anti-infammatory, antioxidant, and immunomodulatory properties.P. oleracea as an antioxidant plant could be scavenged free radicals and balanced oxidant and antioxidant parameters.Tis herb can also inhibit infammation and modulate the immune system via improvement of T-lymphocytes, and NK cells, and infammatory markers (IL-4, IL-10, IFN-c, and TNF-α) and T1/T2 balance.Reviewed studies suggest the potential therapeutic value of P. oleracea for treatment of disorders related to infammation, oxidant/antioxidant status, and immune system imbalance.

Figure 4 :
Figure 4: Possible mechanisms of immunomodulatory efects of P. oleracea and its constituents.IgM: immunoglobulin M; IgG: immunoglobulin G.

Table 3 :
Antioxidant efects of P. oleracea and its constituents.

Table 4 :
Immunomodulatory efect of P. oleracea and its constituents.