Modulating Effects of the Hydroethanolic Leaf Extract of Persicaria lanigera R. Br. Soják (Polygonaceae) against Acute Inflammation

Plant species have been used traditionally to treat numerous inflammatory disorders because of their known medicinal properties. This study aimed to assess the anti-inflammatory effect of aqueous ethanolic leaf extract of Persicaria lanigera using acute inflammatory models. The safety profile of the Persicaria lanigera extract was assessed using an acute toxicity model. The anti-inflammatory effect of the Persicaria lanigera leaf extract (100–600 mg·kg−1, p.o.) was studied in carrageenan-induced paw oedema, zymosan-induced knee joint arthritis, and histamine-induced paw oedema in Sprague–Dawley rats (n = 5). It was observed that the Persicaria lanigera leaf extract administered prophylactically significantly inhibited paw oedema from 99.01 ± 12.59 to 59.10 ± 4.94%, 56.08 ± 3.65%, and 48.62 ± 3.27% at 100 mg·kg−1, 300 mg·kg−1, and 600 mg·kg−1, while the standard drug, aspirin, showed 41.84 ± 9.25% in carrageenan-induced paw oedema, respectively. Furthermore, the extract decreased knee joint inflammation significantly from 62.43 ± 5.73% to 32.07 ± 2.98% and 24.33 ± 8.58% at 300 mg·kg−1 and 600 mg·kg−1 in zymosan-induced knee joint inflammation, respectively. In the histamine-induced paw oedema model, the extract significantly inhibited oedema to 61.53 ± 9.17%, 54.21 ± 9.38%, and 54.22 ± 9.37% at the same doses. Aqueous ethanolic leaf extract of Persicaria lanigera is safe and attenuates inflammation in acute inflammation models.


Introduction
Infammation is defned as the body's reaction to damaging stimuli such as infections, toxins, or heat, as well as autoimmune illnesses [1]. Tis is the body's major method for tissue repair following injury, and it entails a sequence of cellular and vascular processes that culminate in the removal of damaged tissues and the regeneration of new ones. Increased vascular permeability, cellular adhesion, cell migration, and oedema production are all part of this chain of events [2]. Although infammation is supposed to be selfregulating, a persistently unregulated infammatory response can lead to chronic infammatory conditions, such as rheumatoid arthritis, gastrointestinal diseases, asthma, or autoimmune disorders, and, as a result, function loss [3,4]. Currently, infammatory diseases are managed with orthodox drugs such as steroidal anti-infammatory drugs, nonsteroidal anti-infammatory drugs (NSAIDs), and disease-modifying antirheumatoid drugs (DMARDs) [5,6]. Usually, the use of these medications is associated with numerous adverse efects including obesity, dyspepsia, gastric ulcers, renal damage, and immunosuppression [7,8].
Medicinal plant species are reported to play a major role in drug discovery and have become essential sources with pharmacological potential for the development of safe and potent drugs [9].
Terefore, the search for new drugs with no or fewer adverse efects for the management of infammatory diseases is very crucial. Persicaria lanigera is a medicinal plant that can be explored to mitigate infammatory conditions. It belongs to the family Polygonaceae which can be located in tropical and subtropical regions [10]. Te Polygonaceae family has been linked to a variety of medical uses, including the treatment of ulcerative colitis, intestinal parasites, asthma, bronchitis, infammatory disorders, and diarrhea [11]. Obese and his colleagues (2021) demonstrated the analgesic properties of this plant; however, there is no scientifc report on its antiinfammatory activities to support its folkloric use in the management of infammatory diseases. Hence, this study aimed to evaluate the anti-infammatory efect of the aqueous ethanolic leaf Persicaria lanigera extract on infammatory models in Sprague-Dawley rats.

Plant Collection and Extraction.
Te leaves of Persicaria lanigera were collected in Efutu along the Jukwa road in Cape Coast, Central Region, between September and November 2018. Te plant was identifed and authenticated subsequently by Mr. Felix Fynn, a botanist at the School of Biological Sciences Herbarium, University of Cape Coast (UCC), and a voucher specimen (no. MAA003) was kept in the herbarium of the School of Biological Sciences, UCC.
To prepare the aqueous ethanolic extract, the leaves of the plant were air-dried at room temperature for 21 days and later pulverized with a heavy-duty blender (3628GL72-430CB2-Waring, USA) into fne powder. Afterwards, 600 g of the powder was extracted by cold maceration using 2.0 L of 70% ethanol for 72 h and the resulting supernatant was decanted and fltered using a Buchner funnel and Whatman flter paper no. 1. Te fltrate was then concentrated under a reduced pressure at a low temperature of 50°C using a rotary evaporator (Model: R-290, BUCHI, Switzerland) to obtain darkgreen liquid which was evaporated to dryness in an oven (Gallenkamp OMToven, Sanyo, Japan) at 50°C for 24 h. Later, the semisolid dried extract was kept in a refrigerator (LG Haiser 220L Freezer, Ningbo Haiser Electronic Appliance Co., Ltd., Zhejiang, China) until use. A fnal yield of 9.3% (w/w) was obtained. Te extract was referred to as Persicaria lanigera extract (PLE) and kept in a desiccator.  [12,13]. Sprague-Dawley rats (100-150 g, n � 5) of both sexes were randomly selected and divided into six (6) groups. Animals were allowed to acclimatize to the laboratory environment for 1 week and fasted overnight with access to water ad libitum. Animals were weighed before oral administration of PLE in doses of 100 mg·kg −1 (Group II), 300 mg·kg −1 (Group III), 1000 mg·kg −1 (Group IV), 3000 mg·kg −1 (Group V), and 5000 mg·kg −1 (Group VI). Te control group (Group I) received 10 ml·kg −1 of distilled water. Individual animals in all treatment groups were critically observed for a period of 24 h for general behaviour changes, alterations in physiological function, and mortality. Animals were monitored at 0, 15, 30, 60, 120, 180, 240 min, and 24 h for convulsions, tremors, excitement, respiratory changes, unusual locomotion, agitation, ataxia, aggression, sedation, salivation, urination, and defaecation after oral PLE (100-5000 mg·kg −1 ) administration. Using the Basante-Romo et al. (2021) scaling method, observations made for all toxicity signs were scored on a scale of 0-3 [14]. Te lethal dose (LD 50 ) of PLE was estimated using the following equation [15]: where D o is the maximum dose that resulted in 0% mortality; D 100 is the minimum dose that resulted in mortality.

Carrageenan-Induced Paw Oedema in Rats.
Paw oedema was induced by subplantar injection of 0.1 ml of 1% (w/v) sterile carrageenan (dissolved in 0.9% saline solution) into the right hind limbs of rats (100-150 g, n � 5) [16,17]. Te initial basal thickness of the animals was measured using an electronic digital Vernier caliper (VC1346i, MP Lab, Equip, USA) before the carrageenan injection. Paw thickness of the injected limb was then measured at an hourly interval for 5 h. Inhibition of oedema was expressed using the following equation: where P o is the paw thickness before carrageenan injection (i.e., time zero). P t is the paw thickness (at various time intervals) after carrageenan injection. Te percentage change in paw thickness for each animal was calculated from the raw scores at time 0 and then averaged. Total oedema was expressed as the area under the time-course curve (AUC), and the percentage inhibition of oedema was calculated using the following equation: In the prophylactic study, PLE (100, 300, 600 mg·kg −1 , p.o) or aspirin (100 mg·kg −1 , p.o) were administered before carrageenan inoculation. In the therapeutic study, drugs were administered 1 h after subplantar injection of carrageenan solution. Te control rats orally received distilled water (10 ml·kg −1 ).

Zymosan-Induced Acute Knee Arthritis in Rats
(1) Induction of Acute Arthritis and Evaluation of Knee Joint Infammation. Using a method earlier described by Mortada and Hussain (2014) [18], Sprague-Dawley rats (100-150 g, n � 5) were randomly selected into six (6) groups (I-VI) and joint infammation was induced by injecting 500 µg of zymosan in 25 µl of normal saline in each knee joint cavity of the right limb. Before induction, hair around the knee joint was carefully shaved to expose the joint and cleaned with 70% alcohol. Te initial right knee joint thickness (transverse diameter, mm) of each rat in all groups (I-VI) was measured using a digital caliper (VC1346i, MP Lab Equip, USA) and recorded. Knee joint swelling was assessed by measuring the knee joint of each rat in all treatment groups at an hourly interval of 5 h. Inhibition of joint swelling was determined using the procedure described in Section 2.2.2.
(2) Determination of Joint Neutrophils and Leukocyte Infltration. Neutrophil and leucocyte infltration into the knee joint cavity was determined after 5 h of intra-articular injection of zymosan. Under light ether anaesthesia, blood samples were collected from each knee joint synovial cavity into EDTA tubes. Blood samples were analyzed for neutrophils and total leucocytes using an automated haematology cell diagnosis analyzer (HP-HEMA6500A, Zhengzhou Hepo International Trading Co. Ltd., Henan, China).
(3) Histopathological Evaluation of the Knee Joint. Knee joint tissues were removed from each rat in the various treatment groups to assess the histopathology of the tissue cavity after arthritic induction. In brief, formalin-fxed tissues were decalcifed, dehydrated, embedded in parafn oil, and sectioned for histopathological studies. Te prepared sections were stained with hematoxylin and eosin (H&E), and histological alterations were examined by light microscopy using a microscope (BS-2040 fb LED, Movel Scientifc Instrument Co. Ltd., Zhejiang, China).
(4) Determination of Mast Cell Proliferation. Tick segmented sections of the knee joint tissues were fxed in Carnoy's fxative and stained with 1% toluidine blue. Using a micrometer grid (0.042 mm 2 ), mast cells were counted in coded sections at ×20 magnifcation.

Histamine-Induced Paw
Oedema. Paw oedema was induced by injecting 0.1 ml of 1% histamine (freshly prepared in normal saline) into the subplantar tissues of the right hind paw of rats [17]. In brief, Sprague-Dawley rats (100-150 g, n � 5) of both sexes were allowed to fast overnight and grouped into fve (5) groups. Te initial paw thickness of both limbs of rats was measured before oedema induction. Paw thickness was measured at 30, 60, 90, 120, and 180 min using Percentage changes in paw thickness and total paw oedema were determined using the formula stated above (in Section 2.2.2).

Data Analysis
All data were presented as the mean ± SEM (n � 5) of the efect of drugs on the maximal and total oedema efects over the period. Data were analyzed statistically through a test of signifcance using both one-way and two-way analysis of variance (ANOVA) followed by Dunnet's post hoc test. All graphs were plotted using GraphPad Prism version 7.0 (GraphPad, San Diego, USA).

Acute Toxicity Profle.
Preliminary acute toxicity evaluation of PLE at doses of 100, 300, 1000, 3000, and 5000 mg·kg −1 showed no critical adverse efects that could lead to death, which is suggestive that the LD 50 value of PLE could exceed 5000 mg·kg −1 , thus indicating that the extract is nontoxic. Terefore, PLE (100-5000 mg·kg −1 , p.o) did not cause any noticeable behavioural, physiological, or clinical signs that may lead to death, and thus, PLE was acutely safe (Table 1). However, 8 h after PLE administration, there were only mild signs of urination and defaecation observed in rats of PLEtreated groups of 3000 and 5000 mg·kg −1 (Table 1), but these signs were of gradually until the 24 th h. Hence, no mortality was recorded during the observation period in all PLE-treated groups (Table 1). Te doses used in the anti-infammatory activity test of PLE were based on the LD 50 value.

Zymosan-Induced Acute Knee Joint Arthritis in Rats
(1) Knee Joint Infammation Assessment. In this study, the induction of acute joint infammation as a result of intraarticular injection of zymosan caused swelling of the knee joint. In the study, the naïve (parafn oil-treated) group showed no swelling of the knee joint when compared to the control (zymosan-treated) group ( Figure 2). However, there was severe swelling of the knee joints of the right limbs of rats in the negative control group that attained a mean maximal knee joint thickness of 62.43 ± 5.73% (Figure 2(a)). Aspirin (100 mg·kg −1 , p.o) signifcantly decreased the mean maximal knee joint swelling attained to 19.28 ± 5.78% relative to the control group (Figure 2(a)). Similarly, PLE (100-600 mg·kg −1 , p.o) showed a signifcant reduction of the mean maximal knee joint thickness attained to 32.07 ± 2.98% and 24.33 ± 8.58% at 300 and 600 mg·kg −1 when compared to the control response, respectively (Figure 2(a)). Te total knee joint swelling attained after 5 h of acute knee joint   Te Scientifc World Journal arthritis induction was suppressed signifcantly by 37.51%, 47.27%, and 60.46% at 100, 300, and 600 mg·kg −1 relative to the control response in a dose-dependent manner, respectively (Figure 2(b)).
(2) Neutrophil and Leucocyte Infltration in the Knee Joint. In the study, there was elevated infltration of neutrophil and leucocyte levels in the knee joint cavity of the control group. Te infux of neutrophils in the synovial joint of the knee increased to 8.51 ± 0.50 in the control group (Figure 3(a)). Aspirin (100 mg·kg −1 , p.o) signifcantly inhibited the neutrophil infltration in the knee cavity to 3.28 ± 0.73 when compared to the control group (Figure 3(a)). PLE (100-600 mg·kg −1 , p.o) similarly inhibited the neutrophil infux in the knee cavity signifcantly to 4.93 ± 0.71 and 3.72 ± 0.54 at 300 and 600 mg·kg −1 when compared to the control group, respectively (Figure 3(a)). Total leucocyte infltration into the knee cavity increased enormously to 10.46 ± 0.39 in the control group (Figure 3(b)). Aspirin (100 mg·kg −1 , p.o) signifcantly inhibited the total leucocyte infltration to 5.29 ± 0.60 when compared to the control group (Figure 3(b)). Similarly, PLE (100-600 mg·kg −1 , p.o) showed a signifcant inhibition of total leucocyte migration into the knee joint cavity to 7.42 ± 0.47, 6.50 ± 0.51, and 5.51 ± 0.49 at 100, 300, and 600 mg·kg −1 when compared to the control group, respectively (Figure 3(b)).  Figure 1: Efect of PLE on carrageenan-induced paw oedema in rats. Te percentage change in paw oedema is shown in the time-course curve (a, c). Total paw oedema was determined as AUC (b, d), and data were presented as the mean ± SEM (n � 5). * * * P < 0.001 compared to the infamed control response (two-way ANOVA followed by Dunnet's post hoc test). Te arrow denotes the time of drug administration. group (Figure 4(a)). Te zymosan-treated (negative control) group exhibited severe disruption of synovial membranes and bone cortex indicative of pathological arthritis characterized by marked increased infammatory cell infltration, decreased chondrocytes, and damaged cartilage (Figure 4(b)). However, aspirin (100 mg·kg −1 , p.o) attenuated pathological arthritis by reducing cartilage and bone destruction, infammatory cell infltration, and synovium hypertrophy relative to the control group (Figure 4(c)). Similarly, PLE (100-600 mg·kg −1 , p.o) ameliorated the histological changes associated with pathological arthritis by decreasing synovium hypertrophy, infammatory cell infltration, and improving knee joint and cartilage architecture at all doses relative to the control group (Figures 4(d)-4(f)).

(4) Mast Cell Proliferation in the Knee Joint Cavity.
In this study, the naïve (parafn oil-treated) control showed no increased infux of mast cells to the joint tissues ( Figure 5(a)) and  Figure 2: Efect of PLE on zymosan-induced acute knee joint arthritis in rats. Joint swelling was observed at 1 h intervals for 5 h as a percentage change in paw thickness (a). Total paw oedema was determined as AUC (b) and data were presented as the mean ± SEM (n � 5). ### P < 0.001; * P < 0.05; * * P < 0.01; * * * P < 0.001 compared to the infamed control response (two-way ANOVA followed by Dunnet's post hoc test).  Figure 3: Efect of PLE on neutrophil (a) and total leukocyte (b) infltration of the knee joint cavity in rats with zymosan-induced acute knee joint arthritis. Data were presented as the mean ± SEM. ### P < 0.001; * P < 0.05; * * P < 0.01 when compared to the control group. Te Scientifc World Journal signifcantly (P < 0.05) recorded a baseline mean total number of mast cells of 6.60 ± 1.33 when compared to the knee joint arthritis (zymosan-treated) control group ( Figure 5(b)). Te knee joint arthritis (zymosan-treated) control group showed elevated infux levels of mast cells to the knee joint tissues ( Figure 6) with a high mean total number of mast cell count of 30.80 ± 3.06 ( Figure 6). However, the aspirin (100 mg·kg −1 )treated groups decreased the proliferation of mast cells in the knee joint tissues ( Figure 5(c)) and signifcantly (P < 0.05) reduced the mean total number of mast cell count to 15.20 ± 1.66 when compared to the arthritic (zymosan-induced) control group (Figure 6). Similarly, the PLE-treated (100-600 mg·kg −1 ) group showed a decreased infux of mast cells to the knee joint tissues (Figures 5(d)-5(f)) with a significant (P < 0.05) reduction in the mean total number of mast cell count to 21.20 ± 3.34, 18.20 ± 2.85, and 17.00 ± 2.00 at 100, 300, and 600 mg·kg −1 when compared to the zymosan-treated (acute knee joint infamed) control group, respectively ( Figure 6).

Discussion
Toxicity screening of medicinal plants using animal models is essential to validate their use in regular therapy [19] because the efects observed in animals as a result of exposure to chemical substances can be related to humans [20]. Based on this assertion, the acute toxicity profle of Persicaria lanigera was assessed to confrm its safety using acute toxicity studies in rats. Te animals used in the study survived in all doses after oral administration of PLE at the end of the observation period. PLE-treated (100-5000 mg·kg −1 , p.o) animals showed no noticeable behavioural, physiological, or clinical alterations or any toxic efect, and there was no death. However, some mild, short-lived signs such as defaecation and Te Scientifc World Journal urination were observed in rats at doses of 3000 mg·kg −1 and 5000 mg·kg −1 , and nevertheless, these signs gradually diminished within a period of 24 h after PLE administration. From the study, the data obtained revealed that the LD 50 of PLE could be estimated to be above 5000 mg·kg −1 , and therefore, it is important to establish that PLE is relatively safe for its usage in traditional medicine, which conforms to the scale based on the Hodge and Steiner toxicity scale [21]. For this reason, the confrmation of the Persicaria lanigera safety profle further supported the assessment of its antiinfammatory activity on infammatory models. To investigate infammation, several experimental models are used to evaluate infammatory responses. Te methods used to assess a substance's anti-infammatory efectiveness are often conducted on test animals, including other biochemical models. Te most common test in the quest for new, complementary, and alternative anti-infammatory medications focuses primarily on evaluating an agent's ability to reduce oedema that is brought on by the injection of phlogistic substances in animals [22]. Tus, to investigate the antiinfammatory efects of PLE on acute infammation, carrageenan-induced paw oedema, histamine-induced paw oedema, and zymosan-induced acute knee joint arthritis in rats were employed.
Carrageenan-induced paw oedema is a typical acute infammatory model used in animal studies to evaluate the antiinfammatory activity of a test compound. It is a sensitive and reproducible model used to assess new compounds. Te model is useful for discovering orally active anti-infammatory compounds that act through acute infammatory mediators [23]. It has also been observed that lipoxygenase (LOX) and cyclooxygenase (COX) inhibitors are useful in combating carrageenan-induced paw oedema [24].
Te injection of carrageenan causes a biphasic induction of oedema over time, and the anti-infammatory efect is normally determined after 6 h due to the depletion of an infammatory cofactor, kininogen, after this period [25]. In the early phase (0-2 h after carrageenan injection), proinfammatory mediators such as histamine, bradykinin, and serotonin (5-HT) are involved. Te late phase, which occurs after 2 h, is mediated by the release of prostaglandins, nitric oxide, TNF-α, free radicals, oxygen species, and leukotrienes [26]. In the study, treatment with PLE showed signifcant inhibition of oedema both in the prophylactic (preemptive, 2 h before carrageenan injection) and curative studies (2 h after carrageenan injection). PLE was a potent inhibitor of the initial phase, which suggests that the anti-infammatory efect of PLE could be attributed to the inhibition of proinfammatory mediators such as histamine, bradykinin, and 5-HT.
Te extract also signifcantly inhibited the late phase, suggesting its high inhibitory efects on the metabolic arachidonic acid pathway. Te potential action of PLE in the late phase also suggests that other proinfammatory mediators, such as nitric oxide and leukotrienes, were inhibited. Furthermore, a proinfammatory mediator such as histamine, which plays a major role in acute infammation [27], was signifcantly inhibited by PLE in the histamine-induced paw oedema model via downregulation of the synthesis as well as its efects.
Te basic understanding of infammatory joint illnesses and the creation of medications with efcient anti-infammatory and antiarthritic activities have both benefted from the use of animal models, despite their many limitations.
Zymosan-induced acute knee joint arthritis is widely used to evaluate the anti-infammatory activities of various compounds [28]. During infammatory responses as a result of zymosan-induced infammation, the actions of phagocytosis, cell migration, and the synthesis of proinfammatory mediators can be studied [18]. Zymosan has been shown to stimulate phagocytic cells, which increases the quantity of lysosomal enzymes secreted, boosts the release of proinfammatory cytokines including TNF-α and IL-6, and increases the leukotriene synthesis of monocytes, chemokines such as chemokine-C-X-C motif (CXCL-1), matrix metalloproteinase-9, and monocyte chemoattractant protein (MCP-1) [29].
When zymosan is injected into joints, it induces biphasic arthritis in rodents. Te early stage is marked by increased lymphocyte and macrophage production, whereas the late stage is mediated by increased vascular permeability, oedema, leukocyte infltration, and the infux of neutrophils [30]. Previous reports have also shown that proinfammatory cytokines such as NF-κB, TNF-α, IL-1β, IL-6, and ROS [31] are involved in zymosan-induced acute knee joint arthritis in rats.
Tis study revealed that oral administration of PLE before the injury dramatically reduced the thickness of the knee joints in the right limbs of rats. As a result, oedema caused by zymosan injection into the articular cavity was signifcantly reduced, which in turn led to the inhibition of proinfammatory mediators that are involved in acute knee joint infammation. Tis antiarthritic action of PLE may be explained by the suppression of several cytokines, enzymes, ROS, and other proinfammatory mediators involved in arthritic infammation. Terefore, it can be said that PLE has antiarthritic action, consistent with past research showing that plants can treat infammatory diseases such as arthritis by reducing infammation [32].
It has been reported that intra-articular injection of zymosan stimulates massive migration of leukocytes, especially neutrophils, into the synovial tissue and fuids of infamed joints [31]. Neutrophils have been shown to play a key role in the pathogenesis of joint arthritis and promote cartilage damage as well as bone resorption in the joints via the production of ROS in association with other proteolytic enzymes [33]. Neutrophils are also reported to induce the release of proinfammatory cytokines such as TNF-α, IL-1β, IL-6, and chemokines including CXCL-1 that cause bone and cartilage damage [31]. Terefore, inhibiting neutrophil infltration or activation is a crucial treatment option for arthritis.
In the study, treatment with PLE signifcantly attenuated the infux of neutrophils and the migration of leukocytes into the synovial cavity of the knee joint and thus potentially inhibited the production of proinfammatory mediators and other proinfammatory cytokines such as TNF-α, IL-1β, and IL-6 that could cause cartilage and bone damage. Te reduction of neutrophil and leukocyte levels by the extract in the knee cavity and fuids of the infamed joints contributed to the management of the arthritic condition. Tis is in consonance with the literature which previously reported that established attenuation of increased neutrophil infltration is relevant in the management of arthritis [34].
According to Babu et al., histopathological changes in an arthritic knee joint are characterized by severe cell infltration, loss of synovial space, cartilage and bone erosion, and distortion of the synovial membrane lining [35]. Hence, these pathological alterations are known to be clinical features of degenerative joint disorders. In addition, it has also been reported that bone and cartilage erosion in the arthritic knee joint is mediated by proinfammatory mediators and cytokines [36]. In the study, PLE showed a signifcant improvement in the histological changes in the knee joint of rats caused by the bone and cartilage tissues, synovial membrane lining, and synovial space. Tis was evident in its inhibitory efects on cartilage and bone degradation, decreased synovial space, increased infammatory cell infltration, and proinfammatory cytokines as well as mediators implicated in knee joint arthritis. Hence, bone remodeling could be upregulated to maintain bone integrity, and therefore, this agrees with earlier literature that reported the established ability of plant extracts to maintain the histopathological architecture of the bone and cartilage during arthritic infammation [35].
Chan et al. reported that mast cells are implicated in the pathogenesis of osteoarthritis and their levels are proliferated in the osteoarthritic bone [37]. Tey are also said to be present in the synovium and synovial fuids of patients with knee osteoarthritis [38]. Mast cells, upon activation, release a series of proinfammatory mediators such as histamine, proinfammatory lipids (prostaglandins), chemokines, and cytokines including TNF-α and and IL-6 [39] that regulate bone metabolism potentiating bone resorption [40]. Based on this assertion, the antiproliferative efect of PLE on mast cell proliferation or activation in this study was very signifcant. PLE remarkably reduced the mast cell levels in the synovium and synovial fuid of the knee joint cavity and consequently inhibited the proinfammatory cytokines and mediators that could be released to modulate bone metabolism, leading to increased bone resorption to cause cartilage and bone erosion. Tis aligns with the literature earlier reported that established the inhibitory efects of medicinal plants to suppress mast cell activation or proliferation in bone tissue as a key mechanism in arthritic therapy [37].

Conclusion
Putting all the above data from the study together, it can be concluded that the aqueous ethanolic leaf extract of Persicaria lanigera is a potent anti-infammatory agent and could be efective against both acute and chronic infammation. Tis study has revealed for the frst time that the Persicaria lanigera leaf extract inhibits oedema, joint infammation, and colonic damage through its inhibitory efects on histamine, mast cells, and infammatory cells such as neutrophils.

Data Availability
Te data used to support this study are available upon request.