Lonicerae Japonicae Flos and Lonicerae Flos: A Systematic Pharmacology Review

Lonicerae japonicae flos, a widely used traditional Chinese medicine (TCM), has been used for several thousand years in China. Chinese Pharmacopeia once included Lonicerae japonicae flos of Caprifoliaceae family and plants of the same species named Lonicerae flos in general in the same group. Chinese Pharmacopeia (2005 Edition) lists Lonicerae japonicae flos and Lonicerae flos under different categories, although they have the similar history of efficacy. In this study, we research ancient books of TCM, 4 main databases of Chinese academic journals, and MEDLINE/PubMed to verify the origins and effects of Lonicerae japonicae flos and Lonicerae flos in traditional medicine and systematically summarized the research data in light of modern pharmacology and toxicology. Our results show that Lonicerae japonicae flos and Lonicerae flos are similar pharmacologically, but they also differ significantly in certain aspects. A comprehensive systematic review and a standard comparative pharmacological study of Lonicerae japonicae flos and Lonicerae flos as well as other species of Lonicerae flos support their clinical safety and application. Our study provides evidence supporting separate listing of Lonicerae japonicae flos and Lonicerae flos in Chinese Pharmacopeia as well as references for revision of relevant pharmacopeial records dealing with traditional efficacy of Lonicerae japonicae flos and Lonicerae flos.


Introduction
Lonicerae japonicae flos (also Jinyinhua in Chinese), a plant species in traditional Chinese medicine (TCM), has been widely used as a drug for several millennia with confirmed curative effects. It has been recorded in the Chinese Pharmacopeia (1963 Edition), limiting the therapeutic use of Lonicerae japonicae flos to the dried flower buds of Lonicera japonica Thunb., which belongs to Caprifoliaceae. In the 1977,1985,1990,1995 Compared with other commonly seen antibacterial drugs, Lonicerae japonicae flos exhibits a broader antimicrobial spectrum, more powerful antibacterial activity, and inhibition of drug-resistant bacteria. The antibacterial activities of Lonicerae japonicae flos were detailed in Table 1.
The components of Lonicerae japonicae flos including water-soluble polysaccharides have remarkable inhibitory   [16][17][18]. Current clinical antimicrobial treatments are associated with a high frequency of multidrug resistance and widespread plasmid resistance. Studies suggest that Lonicerae japonicae flos extracts not only potently inhibit common pathogens but also significantly suppress drug-resistant bacteria. In addition, the water decoction effectively inhibits drug-resistant R plasmid of Pseudomonas aeruginosa and sensitizes Pseudomonas aeruginosa to single antibiotic. Mice administered with extracts of Lonicerae japonicae flos show improved multiantibiotic sensitivities [19][20][21]. Lonicerae japonicae flos kills several clinically common drug-resistant bacteria such as methicillin-resistant Staphylococcus aureus (MRSA), methicillin-resistant Staphylococcus haemolyticus (MRSH), methicillin-resistant Staphylococcus epidermidis (MRSE), and high-level aminoglycoside resistant (HLAR) bacteria to varying degrees, and the antibiotic effects are positively correlated with drug concentration [22]. These experimental results further enrich our understanding of the antibacterial activity of Lonicerae japonicae flos and provide scientific data of therapeutic efficacy against drug-resistant pathogens.

Lonicerae Flos.
Reports of efficacy and pharmacology of Lonicerae flos suggest several effective antifungal and antibacterial extracts (see Table 1).
Lonicerae flos shows various antibacterial activities. The water extracts of Lonicera macranthoides Hand.-Mazz. are the most effective against Staphylococcus aureus and group B Streptococcus and effective against Salmonella Typhi, Escherichia coli, and Shigella dysenteriae but poorly effective against Proteus vulgaris [27]. Lonicerae flos (Lonicera macranthoides Hand.-Mazz., Lonicera hypoglauca Miq.) from Sichuan has inhibitory effects against Staphylococcus aureus, Streptococcus haemolyticus, Escherichia coli, Shigella flexneri, Salmonella Typhimurium, and Streptococcus pneumoniae, but not against Streptococcus haemolyticus and Salmonella Typhimurium [28]. Although reports of antibacterial activity of Lonicerae flos vary, they still clearly indicate that the antibacterial pharmacologic activity of Lonicerae flos is markedly different depending on bacteriostatic effect.
The antibacterial effects of Lonicerae flos extracts vary with the different types and methods of preparation. For example, Lonicera macranthoides Hand.-Mazz. contains phenolic acids (total chlorogenic acids), glycosides, flavonoids (total flavones), and volatile oil that inhibit Escherichia coli, Staphylococcus aureus, and Pseudomonas aeruginosa to different degrees, with greater inhibition of Staphylococcus aureus than Escherichia coli. Further, phenolic acids have significantly better antibacterial effects than others [29].
The flavone extracts of Lonicerae flos (Lonicera macranthoides Hand.-Mazz.) significantly inhibit and inactivate pseudorabies virus (PRV) infection of Vero cells [42]. The active components called chlorogenic acids significantly suppress the Newcastle disease virus (NDV) infection in Vero cells [48] and chlorogenic acids significantly inhibit the proliferation of NDV in Vero cells [49].
The water extracts of Lonicerae japonicae flos inhibit the production of histamine and the expression of L-histamine decarboxylase by cultured human keratinocytes [59]. Further, it inhibits the production of nitric oxide and secretion of tumor necrosis factor-alpha (TNF-) by Raw264.7 cells with dose-dependent effects [60] and prevents the trypsininduced mast cell activation by suppressing the extracellular 6 Evidence-Based Complementary and Alternative Medicine Alcohol extract 30% Croton oil-induced inflammatory model [55] Alcohol extract 57% Egg white-induced paw swelling model, dimethylbenzene-induced inflammatory model [51,53] Alcohol extract 70% LPS-induced Raw264.7 cell activation model [62] Alcohol extract 95% Resection wound model, H1N1-infected human bronchial epithelial cell line A549 model [57,156] Alcohol extract Ovalbumin-induced asthma model [58] Supercritical carbon dioxide extract Dimethylbenzene-induced inflammatory model [51] Lonicerae flos Dimethylbenzene-induced inflammation model, carrageenan-induced paw swelling model, cotton ball granulomatous hyperplasia model [64] signal-regulated kinase (ERK) phosphorylation [61]. The polyphenols of Lonicera japonica Thunb. downregulate proinflammatory mediators and counter the lipopolysaccharidesinduced inflammatory response of Raw264.7 cells by inhibiting NF-B p65 nuclear translocation and p38 MAPK phosphorylation [62]. According to the Min Jiang research, it is clear that the anti-inflammatory activity of Flos Lonicerae Japonicae (FLJ) has profound material basis. By using UPLC-Q/TOF-MS and dual luciferase reporter gene assay, they revealed the potent NF-B inhibition influence of the extract from FLJ, which could be classified into 2 types: chlorogenic acid and iridoid glycosides, including swertiamarin. More importantly, as reported in this study, the anti-inflammatory activity decreased during the flowering phases progression. This result suggested that the intensity of anti-inflammatory efficacy of FLJ is dynamically changed in distinct flowering phases, indicating that the effective components temporally affect the clinical application. Taken together, the molecular based quality control (including chlorogenic acid, swertiamarin, and sweroside) and the optimized pharmacological practice are extremely needed and urgent for FLJ [63].

Lonicerae Flos.
Water and alcohol extracts of the leaves and flowers of Lonicerae flos have anti-inflammatory effects on dimethylbenzene-induced mouse ear edema, carrageenan-induced rat swelling, and cotton ball granulomatous hyperplasia model [23,64]. The volatile organic compounds of Lonicerae flos (Lonicera macranthoides Hand.-Mazz.) have some inhibitory effects on acetic acid-induced abdominal capillary permeability increase in mice, mouse ear edema, rat pleuritis, and cotton ball granulomatous hyperplasia, significantly lower the concentrations of prostaglandin E 2 (PGE 2 ) and malondialdehyde of the carrageenan-induced paw swelling in norepinephrine animals, and decrease the contents of PGE 2 and NO in acute pleural effusion of rat [23,65,66]. Moreover, the water extracts of Lonicerae flos (Lonicera macranthoides Hand.-Mazz.) have significant antiinflammatory effects by inhibiting the increased capillary permeability in mice, rat paw swelling, and cotton ball granulomatous hyperplasia [25]. The anti-inflammatory effects of both Lonicerae japonicae and Lonicerae flos were listed in Table 2.
The alcohol extracts of Lonicerae japonicae flos have antioxidative effects on edible rapeseed oil, peanut oil, ghee, Evidence-Based Complementary and Alternative Medicine 7 salad oil, mutton tallow [69], linoleic acid, and lard [70]. The crude extracts of chlorogenic acid and total flavones have an inhibitory effect on the antioxidative reaction of oil and prevent the autoxidation of linoleic acid and lard. Further, their redox capacities are 2.0-and 2.8-fold higher than that of synthetic antioxidant butylated hydroxyanisole (BHA) [71,72]. The antioxidative effects of water and alcohol extracts of Lonicerae japonicae flos on oil may be closely related to the clearance of 2,2-diphenyl-1-picrylhydrazyl (DPPH) and the inhibition of oxygen free radical chain reaction in oil [73,74].
The ultrasonic-treated extracts and decoction of Lonicerae japonicae flos can both scavenge hydrogen peroxide (H 2 O 2 ), hydroxyl radical ( ⋅ OH), and superoxide radical (O −2 ) [75]. The reducing power and the clearance of ⋅ OH are positively correlated with the chlorogenic acid content of Lonicerae japonicae flos. Though the alcohol extracts and methanol extracts have better reducing power and higher clearance rates of ⋅ OH than water extracts, the water extracts still have a higher clearance rate of DPPH radicals and a stronger chelating ability with Fe 2+ [76]. In addition, the direct clearance of H 2 O 2 by water extracts effectively reduces tissue injuries in scalded mice [77]. Analysis of antioxidative effects in vitro reveals that the fermented and alcohol extracts of Lonicerae japonicae flos inhibit tyrosinase in mushroom (ED 50 4.07 mg/mL and 6.93 mg/mL, resp.). Compared with alcohol extracts, fermented extracts are more effective in promoting the clearance of DPPH (ED 50 0.207 mg/mL) and superoxide [78].
Lonicerae japonicae flos significantly upregulates the antioxidant enzyme system of human liver rat basophilic leukemia cell and downregulates NF-B signal transduction pathway [79,80]. Moreover, it significantly increases the antioxidant enzyme activities of D-galactose-induced aging model in mice, inhibits lipid peroxidation of liver and kidney tissues, and reduces the oxidative damage in human body [81].

Antipyretic Effects
3.5.1. Lonicerae Japonicae Flos. Lonicerae japonicae flos has antipyretic effects in dry yeast-induced rat fever model [82] and the IL-1 -induced fever model in New Zealand rabbits [83], possibly due to the expression of prostaglandin E2 receptor EP3 at the preoptic area of hypothalamus (POAH) neurons [82]. Further, it reduces injuries caused by free radicals and improves human immunity [84].  [89]. Saponins of Lonicera fulvotomentosa Hsu et S. C. Cheng resolve AAPinduced liver injuries by lowering the cytochrome P450 concentration in liver cells of mouse [90][91][92]. The total saponins of Lonicera fulvotomentosa Hsu et S. C. Cheng significantly alleviate CCl 4 -induced liver injuries, reduce liver injuries of the patient, and effectively lower the incidence of liver necrotizing changes and the total amount of spotty necrosis. Chlorogenic acid has potent choleretic action that not only significantly increases bile secretion volume but also alleviates chromium-induced liver injuries [93,94].

Immunoregulation
3.7.1. Lonicerae Japonicae Flos. Lonicerae japonicae flos decoction effectively improves human immunity, increases macrophage count, elevates phagocytic ratio and lymphocyte transformation rate [82], and enhances the secretion function of Th1 cells [95]. Lonicerae japonicae flos also promotes the phagocytic function of leucocytes. It decreases T-cellnaphthyl acetate percentage of guinea pig and in vitro secretion of neutrophils and remarkably increases the production of IL-2 [96]. The water extracting-alcohol precipitating solution or the flavones of Lonicerae japonicae flos significantly elevate the organ index of immunosuppressed mice [97]. Lonicerae japonicae flos polysaccharides improve mouse splenocyte proliferation [98], markedly enhance immunity, and resolve delayed-type hypersensitivity. Serum hemolysin test shows that Lonicerae japonicae flos polysaccharides enhance humoral immune activities and raise the organ index of immunocompromised animal models, correlated with dosage [99]. Moreover, the water extracts of Lonicerae japonicae flos have significantly regulated immune response in scald-induced immunosuppressive model [100].
The water extracts of Lonicerae japonicae flos effectively substitute the highly toxic immunosuppressants such as cyclosporin A for the induction of immune tolerance. Lonicerae japonicae flos extracts combined with Con A significantly reduce the active degree of T lymphocytes [101] and avoided acute immunological rejection, hence effective in treating graft rejection.

Lonicerae Japonicae Flos. Intraperitoneal injection of
Lonicerae japonicae flos polysaccharides 30 mg/kg and 90 mg/kg inhibited 23.95% and 30.02% of sarcoma S180, respectively, upregulated the expression level of Bax protein in mouse sarcoma S180, and increased Bax/Bcl-2 ratio and serum TNF-concentration of tumor-bearing mice, indicating an antitumor effect that does not affect the normal growth and immune functions of tumor-bearing mice [103]. The polyphenolic extracts of Lonicerae japonicae flos inhibit proliferation of human hepatoma HepG2 cell line in a dose-dependent manner, decrease the expression of CDK1, CDC25C, cyclin B1, procaspases 3 and 8, and PARP, and promote the phosphorylation of ERK1/2, JNK, and MAPKs and the dephosphorylation of Akt, resulting in G2/M arrest and apoptosis [104].  [107]. Studies using highthroughput screening models indicate that the ethyl acetate extracts of Lonicera macranthoides Hand.-Mazz. suppress epidermal growth factor receptor (EGFR) kinase, with IC 50 of 2.027 g/mL. In addition, the phenolic acids and flavones in the extract may play a major role in inhibiting EGFR kinase [108].

Effects on Glucose and Lipid Metabolism.
The water extracts of Lonicerae japonicae flos inhibit the alloxan-induced blood glucose elevation in mice [109]. The results of iodinestarch colorimetry and p-nitrophenyl -D-glucopyranoside (PNPG) assay show that the water extracts dose dependently inhibit activities of -amylase and -glycosidase [110]. Another study indicates that Lonicerae japonicae flos extracts lower the triglyceride levels in serum and liver tissues of hyperlipidemia animal model without significantly affecting serum cholesterol, low-density lipoprotein, high-density lipoprotein, and liver tissue cholesterol [111].

Antiatherosclerotic (As) Effects. The intragastric administration of Lonicera macranthoides
Hand.-Mazz. decreases the area of atherosclerotic plaque and plaque-to-wall area ratio and alleviates atherosclerotic changes in apolipoprotein E (ApoE) gene knockout mice and reduces lipid droplets and cholesterol concentrations of lipid-loaded THP-1 macrophages [112].

Antiallergic Effects
3.11.1. Lonicerae Japonicae Flos. The caudal vein of egg white lysozyme-sensitized mice with increased blood supply is reduced by 35% alcohol extracts of Lonicerae japonicae flos. This phenomenon indicates that 35% alcohol extracts have antiallergic effects, and the effective components include chlorogenic acid, iridoid, loganin, and sweroside [113].  [114,115]. Subcutaneous injection of Lonicerae flos total saponins alleviates diarrhea in mice to varying degrees, decreases mast cell aggregation and degranulation, lowers OVA-specific Ig E level, relieves OVAmediated footpad edema, and resolves small intestinal villi inflammation, indicating that total saponins attenuate mouse Ig E-and immunocyte-mediated hypersensitive response [116,117]. The volatile organic compounds of Lonicera macranthoides Hand.-Mazz. also inhibit heterologous passive cutaneous anaphylaxis of ear and dextran-induced pruritus in mice [118].

Antipregnancy Effects.
Intraperitoneal injection of alcohol extracts of Lonicerae japonicae flos has inhibited early pregnancy in mice. Intravenous drip also shows good antipregnancy effects in dogs as early as days 20-22 at a dosedependent manner [119].

Modulating Gut Microbiota.
The water extracts of Lonicera fulvotomentosa Hsu et S. C. Cheng significantly improve intestinal folate deficiency and reduce Gram-negative bacterial resistance and intestinal flora imbalance in rat obstructive jaundice model [120]. The water extracts also promote the growth of bifidobacteria and lactobacilli in vitro, but they inhibit the growth at high concentration [121].
3.14. Antiultraviolet Radiation. Administration of water extracting-alcohol precipitating solution of Lonicerae japonicae flos reduces the breakage of wavy elastic fibers in the skin and the coiling degree of mouse model with ultraviolet radiationaged skin injuries, possibly due to the antioxidant effects [122].
Evidence-Based Complementary and Alternative Medicine 9 3.16. Spasmolytic Effects. The decoction of Lonicerae japonicae flos inhibits the motility of isolated small intestine from rabbit and significantly reduces rabbit small intestinal smooth muscle contraction, electrical activity range (IC 50 , 6.30 mg/mL), frequency, and area under curve in dosedependent manner. Propranolol, L-NAME, and glibenclamide partly block the inhibitory effects of Lonicerae japonicae flos on rabbit small intestinal smooth muscle contraction [124]. The water extracting-alcohol precipitating solution of Lonicerae japonicae flos also inhibits the motility of rabbit isolated small intestine [125]. The decoction of Lonicerae japonicae flos significantly inhibits acetylcholine-induced intra-and extracellular calcium-mediated smooth muscle contraction [124].

Neuroprotective Effect.
The water extracts of Lonicerae japonicae flos have potential antiparkinsonian activities and reduce 6-hydroxydopamine-induced SH-SY5Y cytotoxicity. The protective mechanism is closely related to the inhibition of cellular apoptosis and oxidative stress and the activation of MAPKs, PI3K/Akt, and NF-B pathways [129]. Further, the water extracts neutralize the H 2 O 2 -induced SH-SY5Y neuroblastoma cytotoxicity, apoptosis, and ROS production to protect the nerves, possibly via inhibition of Akt, JNK, p38 MAPK, and ERK1/2 phosphorylation [130]. The fluorescence spectrum analysis using thioflavin-T fluorometric assay and atomic force microscopy reveals that the dextran derived from Lonicerae japonicae flos inhibits A 42 deposition with dose-dependent effects and reduces the neurotoxicity of A 42 for SH-SY5Y cells, suggesting potential therapeutic value for Alzheimer's disease [131].

Toxicity and Adverse Effects.
Intragastric administration of aqueous extracts of Lonicerae japonicae flos is not significantly toxic and does not affect the respiration, blood pressure, or urine volume in experimental animals. The LD 50 of subcutaneous injection of Lonicerae japonicae flos concrete is 53 g/kg for mice [132]. The LD 50 of oral administration of Lonicerae japonicae flos is larger than 15 g/kg and thus innocuous. The micronucleus test on bone marrow polychromatic erythrocytes of mice and Ames Salmonella/ microsome mutagenicity assay do not reveal any mutagenicity of Lonicerae japonicae flos. Sperm shape abnormality tests in mice reveal no genotoxicity of Lonicerae japonicae flos for germ cells of male animals. The anti-early pregnancy assay of SD rat (oral administration) indicates no adverse effects of Lonicerae japonicae flos on the reproductive function of female animals during pregnancy [133].
After intragastric administration of Lonicera macranthoides Hand.-Mazz. decoction, the mice show significantly decreased spontaneous activities and some degree of sleepiness and prone position, which were restored in 24 hours. Most death occurred in 24 hours, before any convulsions or seizure. However, subsequent anatomical observation indicates no lesions in major organs and the LD 50 was 73.95 (69.80-78.34) g/kg [134]. The maximum dosage of Lonicera macranthoides Hand.-Mazz. buds for mice is 15 g/kg, and subacute toxicity test shows no dose-related differences in weight, hematology, blood biochemistry, or organ index with normal control group [135].

Comparative Pharmacology and Toxicology of Lonicerae Japonicae Flos and Lonicerae Flos
According to pharmacopoeia, Lonicerae japonicae flos and Lonicerae flos have similar efficacy, but researchers still compare the pharmacology and toxicity experimentally since the drugs have different origin and geographic distribution.  [137]. Compared with Lonicerae japonicae flos, it has better bactericidal effects on Shigella dysenteriae [44,137], Sarcina, and Bacillus subtilis [44] and poorer effects on Salmonella Typhi [44] and Escherichia coli [138] while having similar effects on Pseudomonas aeruginosa [138]. Lonicera confusa DC. exhibits inhibitory effect against Staphylococcus aureus and Salmonella Typhi, equivalent to that of Lonicerae japonicae flos, but better than that of Lonicera hypoglauca Miq. Moreover, it has more significant inhibitory effects on Streptococcus haemolyticus than Lonicerae japonicae flos and Lonicera hypoglauca Miq. [139]. Lonicera macranthoides Hand.-Mazz. decoction 40 g/kg is protective in Staphylococcus aureus-infected mice, with a significantly longer survival time than Lonicerae japonicae flos [140]. In conclusion, all species of Lonicerae flos are more antibacterial and bacteriostatic.

Comparison of Anti-Inflammatory Effects. Lonicera macranthoides
Hand.-Mazz. and Lonicerae japonicae flos used at 1 and 10 g/kg significantly inhibit the abdominal capillary permeability in mice and suppress carrageenan-induced paw swelling, with no significant differences. Lonicerae japonicae flos 10 g/kg inhibits dimethylbenzene-induced ear edema in mice but Lonicera macranthoides Hand.-Mazz. only shows inhibitory trends and the comparison between them reveals significant difference [44,138].

Comparison of Antipyretic Effects. Lonicera macranthoides
Hand.-Mazz. and Lonicerae japonicae flos 20 g/kg equally inhibit the fever induced by subcutaneous injection of Saccharomyces cerevisiae in mice, although the latter is effective for a longer time [140]. Lonicera macranthoides Hand.-Mazz., 10 g/kg, shows inhibitory trend against yeast powderinduced fever in mice and the antipyretic effect is slightly weaker than Lonicerae japonicae flos at the same dose [138,140].

Comparison of Immunoregulatory Effects. Lonicera macranthoides
Hand.-Mazz. and the water extracting-alcohol precipitating concentrated concretes of Lonicerae japonicae flos (main components: total flavones and chlorogenic acid) 1 g/kg and 10 g/kg significantly increase spleen index, thymus index, carbon clearance index, and phagocytic index in mice, but not significantly differently [44,138]. Lonicerae japonicae flos 10 g/kg significantly elevates the white cell count in normal and immunocompromised mice unlike Lonicera macranthoides Hand.-Mazz. [138]. The water extracts of Lonicera fulvotomentosa Hsu et S. C. Cheng alleviate small intestinal villi inflammation in sensitized mice, reduce mast cell aggregation and cell degranulation, increase the whole-mast cell ratio in LP, decrease intestinal histamine release of sensitized mice, lower the levels of IL-4 and OVA-specific Ig E levels in sensitized mice, and resolved OVA-mediated delayed-type hypersensitivity of footpad in mice [143].

Comparison of Toxicity and Adverse Effects.
According to a comparative study, the LD 50 values of Lonicera macranthoides Hand.-Mazz. and Lonicerae japonicae flos are 84.14 g/ kg and 72.95 g/kg, respectively, with no significant difference [27].
The water extracts of sun-cured Lonicera macranthoides Hand.-Mazz. are hemolytic. However, the water extracts of steaming sun-cured Lonicera macranthoides Hand.-Mazz. and Lonicerae japonicae flos show hemolytic reaction only after 3 hours [144]. Total saponins of Lonicera fulvotomentosa Hsu et S. C. Cheng also result in mild hemolysis [139].
In active systemic anaphylaxis test using crude water extracting-alcohol precipitating solution of Lonicera macranthoides Hand.-Mazz., four out of six sensitized guinea pigs show dyspnea, gait instability, and Cheyne-Stokes respiration and die in 40 s to 5 min after excitation by intravenous injection of chlorogenic acid 15 mg/kg. Two out of six guinea pigs show agitation, rapid respiration, and gait instability in 30 s. In 10 to 15 min, these symptoms disappear and the mice recover. The allergic reaction intensity is graded as strongly positive. After intravenous injection of crude extracts 15 mg/kg, the nonsensitized guinea pigs manifest agitation, gait instability, rapid respiration, spasm, urination, and defecation in 10 s to 2.5 min and recover in 20-30 min. The strength of anaphylactic reaction is strongly positive [145].
Some researchers have compared the hypersensitive and anaphylactic reactions of Lonicerae japonicae flos and Lonicerae flos. The intraperitoneal injection of the water extracts and water extracting-alcohol precipitating solution of Lonicerae japonicae flos or Lonicera macranthoides Hand.-Mazz. on alternate days for 3 times may lead to hypersensitive reaction in guinea pigs, with possible death. A further study reveals that the degranulation rate (based on -hexosaminidase release assay) of rat basophilic leukemia Evidence-Based Complementary and Alternative Medicine 11 cells (RBL-2H) induced by the water extracting-alcohol precipitating solution of Lonicera macranthoides Hand.-Mazz. is significantly higher than that of Lonicerae japonicae flos (11.33% ± 0.78 versus 8.52% ± 0.44), but with similar activation and proliferation inhibition on peripheral blood mononuclear cells [146]. Therefore, compared with Lonicerae japonicae flos, Lonicerae flos may be potentially dangerous. Our results confirm similar pharmacological activities of Lonicerae japonicae flos and Lonicerae flos, but the former is more widely studied pharmacologically. Lonicerae japonicae flos has glucose-lowering, antiearly pregnancy, antiultraviolet radiation, antiendotoxin, antiulcer, antiplatelet aggregation, antifertility, and neuroprotective activities that are not reported in Lonicerae flos. Lonicera macranthoides Hand.-Mazz. and Lonicerae japonicae flos have similar antibacterial, antiviral, antiinflammatory, antioxidative, antifebrile, hepatoprotective, immunoregulatory, and antitumor activities. However, the pharmacological effects involving balancing intestinal flora and antiatherosclerotic effects have not been reported in Lonicerae japonicae flos. Antioxidation is the common pharmacological activity of Lonicera hypoglauca Miq., Lonicera confusa DC., and Lonicera fulvotomentosa Hsu et S. C. Cheng. In addition, Lonicera hypoglauca Miq. also has antibacterial, anti-inflammatory, and antipyretic effects; Lonicera confusa DC. has antibacterial and hemostatic effects; Lonicera fulvotomentosa Hsu et S. C. Cheng has hepatoprotective and antiallergic effects and saponins have mild hemolytic effect.

Summary
Further analysis reveals twenty plus studies comparing the pharmacological activities between Lonicerae japonicae flos and Lonicerae flos. Lonicerae flos has certain advantages in terms of antibacterial and other effects. Some studies report better antibacterial and bacteriostatic activities with Lonicera macranthoides Hand.-Mazz. and Lonicera confusa DC. than Lonicerae japonicae flos and more antioxidant activities of Lonicera macranthoides Hand.-Mazz. than Lonicerae japonicae flos. Lonicera macranthoides Hand.-Mazz. and Lonicerae japonicae flos do not differ significantly in antiviral effects. Lonicera confusa DC. and Lonicerae japonicae flos do not differ significantly in hemostatic effect but both are better than Lonicera hypoglauca Miq. Lonicerae japonicae flos is slightly better than Lonicera macranthoides Hand.-Mazz. in anti-inflammatory, antipyretic, and immunoregulatory effects, but no significant difference in toxicity. Some studies have reported adverse events such as hypersensitive/anaphylactic and hemolytic reaction in Lonicera macranthoides Hand.-Mazz. and Lonicera fulvotomentosa Hsu et S. C. Cheng. Therefore, meticulous screening and identification of the different species are essential to avoid the risk of adverse and toxic effects during the production and clinical use.
In conclusion, modern pharmacological effects of Lonicerae japonicae flos and Lonicerae flos are similar, although a few significant differences should not be neglected. Since a systematic and standard comparative study has not been developed so far, it is difficult to scientifically evaluate their advantages/disadvantages and differences/similarities. We suggest a comprehensive systematic review and a parallel, crossover study to delineate the mechanisms underlying the comparative pharmacological activities of Lonicerae japonicae flos and Lonicerae flos and different species of Lonicerae flos. A comparative analysis of the clinical efficacy and safety of pharmacologically active ingredients/products in Lonicerae japonicae flos and Lonicerae flos is essential to fully and accurately evaluate their effects and toxic side effects. References for the revision of relevant pharmacopoeial records should be provided along with supporting clinical efficacy and safety data.