Pharmacological Basis for Use of Selaginella moellendorffii in Gouty Arthritis: Antihyperuricemic, Anti-Inflammatory, and Xanthine Oxidase Inhibition

Kaempferol Attenuates Gouty Arthritis by Regulating the Balance of Th17/Treg Cells and Secretion of IL-17

Kaempferol is a common flavonoid aglycone widely found in plants. It exhibits beneficial therapeutic effects in the treatment of arthritis. However, the effects of kaempferol on gouty arthritis (GA) have not been verified. This study aimed to explore the potential mechanisms by which kaempferol regulates GA by network pharmacology and experimental validation. Potential drug targets for GA were identified with a protein-protein interaction network. Then, we performed a KEGG pathway analysis to elucidate the major pathway involved in the kaempferol-mediated treatment of GA. In addition, the molecular docking was performed. A rat model of GA was constructed to verify the results of network pharmacology analysis and investigate the mechanism of kaempferol against GA. The network pharmacology study indicated that there were 275 common targets of kaempferol and GA treatment. Kaempferol exerted therapeutic effects on GA, in part, by regulating the IL-17, AGE-RAGE, p53, TNF, and FoxO signaling pathways. Molecular docking results showed that kaempferol stably docked with the core MMP9, ALB, CASP3, TNF, VEGFA, CCL2, CXCL8, AKT1, JUN, and INS. Experimental validation suggested that kaempferol eased MSU-induced mechanical allodynia, ankle edema, and inflammation. It significantly suppressed the expression of IL-1β, IL-6, TNF-α, and TGF-β1 and restored Th17/Treg imbalance in MSU-induced rats and IL-6-induced PBMCs. Kaempferol also affected RORγt and Foxp3 through IL-17 pathway. The present study clarifies the mechanism of kaempferol against GA and provides evidence to support its clinical use.

Three New Benzophenone Derivatives from Selaginella tamariscina

Six compounds including three new benzophenones, selagibenzophenones D-F (1-3), two known selaginellins (4-5) and one known flavonoid (6), were isolated from Selaginella tamariscina. The structures of new compounds were established by 1D-, 2D-NMR and HR-ESI-MS spectral analyses. Compound 1 represents the second example of diarylbenzophenone from natural sources. Compound 2 possesses an unusual biphenyl-bisbenzophenone structure. Their cytotoxicity against human hepatocellular carcinoma HepG2 and SMCC-7721 cells and inhibitory activities on lipopolysaccharide-induced nitric oxide (NO) production in RAW264.7 cells were evaluated. Compound 2 showed moderate inhibitory activity against HepG2 and SMCC-7721 cells, and compounds 4 and 5 showed moderate inhibitory activity to HepG2 cells. Compounds 2 and 5 also exhibited inhibitory activities on lipopolysaccharide-induced nitric oxide (NO) production.

Exploring the Mechanism through which Phyllanthus emblica L. Extract Exerts Protective Effects against Acute Gouty Arthritis: A Network Pharmacology Study and Experimental Validation

Increased uric acid levels and inflammatory reactions are the main factors considered responsible for the development of gouty arthritis. Phyllanthus emblica L. (PEL) has several promising pharmacological properties, including anti-inflammation and antioxidation. However, only a few studies have investigated its use for treating acute gouty arthritis (AGA), and the mechanism of action of PEL has not yet been clarified. The aim of this study was to verify the protective effects of PEL against gout and explore its underlying mechanism through network pharmacology and animal experiments. The main active components of the extract from PEL including mucic acid, mucic acid lactone, gallic acid, ethyl hexyl phthalate, and glucose were identified by UPLC-ESI-qTOF-MS. Network pharmacological analysis results revealed 13 active compounds in PEL and 85 related targets for the treatment of gout. The core mechanism of action of PEL is mainly associated with inflammation-related pathways, including the HIF-1, PI3K-Akt, TNF, and NOD-like receptor signaling pathways. Previous studies revealed that the NOD-like receptor signaling pathway, especially the NLRP3 inflammasome, plays an important role in the pathogenesis of AGA; therefore, we mainly investigated the effect of PEL on the NLRP3/ASC/caspase-1 pathway in gout rats. In the animal experiments, PEL was shown to have a satisfactory antigout effect, as it effectively reduced uric acid (UA) and xanthine oxidase (XOD) levels. In terms of inhibiting AGA-associated inflammatory reactions, our results showed that PEL significantly decreased the expression of NLRP3 and caspase-1 in ankle synoviocytes as well as the levels of downstream inflammatory factors, such as TNF-α, IL-10, and IL-1β in serum. Moreover, the results of our study show that PEL reduced MMP13 expression in the ankle synovium. Overall, the results of this study indicate that PEL exerted a therapeutic effect against AGA. Reducing uric acid levels, inhibiting inflammation, and decreasing the expression of MMP13 may be responsible for the therapeutic effect of PEL, which suggests that PEL can be further developed as a drug for the treatment of gout.

Influence of Pinealectomy and Long-term Melatonin Administration on Inflammation and Oxidative Stress in Experimental Gouty Arthritis

Gout is an inflammatory arthritis characterized by the deposition of monosodium urate (MSU) crystals in the joints or soft tissue. MSU crystals are potent inflammation inducers. Melatonin (MLT) is a powerful endogenous anti-inflammatory agent and effective in reducing cellular damage. In the present study, possible underlying mechanisms associated with anti-inflammatory and antioxidative effects were investigated in rats with gouty arthritis and melatonin deprivation treated with MLT. Fifty-six rats were divided into seven groups: control, sham control, pinealectomy (PNX), MSU (on the 30th day, single-dose 20 mg/ml, intraperitoneal), MSU + MLT (10 mg/kg/day for 30 days, intraperitoneal), MSU + PINX and MSU + PINX + MLT. PNX procedure was performed on the first day of the study. As compared to the controls, the results showed that MSU administration caused significant increases in oxidative stress parameters (malondialdehyde and total oxidant status). Besides, significant decreases in antioxidant defense systems (glutathione, superoxide dismutase and total antioxidant status) were observed. A statistically significant increase was found in the mean histopathological damage score in the groups that received MSU injection. It was found that histopathological changes were significantly reduced in the MSU + MLT group given MLT. In our study, it was determined that many histopathological changes, as well as swelling and temperature increase in the joint, which are markers of inflammation, were significantly reduced with MLT supplementation. These results suggest that melatonin ameliorates MSU-induced gout in the rat through inhibition of oxidative stress and proinflammatory cytokine production.

Integrated in silico - in vitro strategy for the discovery of potential xanthine oxidase inhibitors from Egyptian propolis and their synergistic effect with allopurinol and febuxostat

Xanthine oxidase (XO) has been well-recognized as a validated target for the treatment of hyperuricemia and gout. Currently, there are two drugs in clinical use that shut down XO overactivity, allopurinol and febuxostat; however, detrimental side effects restrict their applications. Propolis is a unique natural adhesive biomass of structurally variable and biologically active metabolites that exert remarkable health benefits. Moreover, combination drug therapy has become a promising pharmacotherapeutic strategy directed for reformulating existing drugs into new combination entities with potentiating therapeutic impacts. In this study, computer-aided molecular docking and MD simulations accompanied by biochemical testing were used for mining novel pharmacologically active chemical entities from Egyptian propolis to combat hyperuricemia. Further, with a view to decrease the potential toxicity of synthetic drugs and enhance efficacy, propolis hits were subjected to combination analysis with each of allopurinol and febuxostat. More specifically, Glide docking was utilized for a structure-based virtual screening of in-house datasets comprising various Egyptian propolis metabolites. Rosmarinic acid, luteolin, techtochrysin and isoferulic acid were the most promising virtual hits. In vitro XO inhibitory assays demonstrated the ability of these hits to significantly inhibit XO in a dose-dependent manner. Molecular docking and MD simulations revealed a cooperative binding mode between the discovered hits and standard XO inhibitors within the active site. Subsequently, the most promising hits were tested in a fixed-ratio combination setting with allopurinol and febuxostat separately to assess their combined effects on XO catalytic inhibition. The binary combination of each techtochrysin and rosmarinic acid with febuxostat displayed maximal synergy at lower effect levels. In contrast, individually, techtochrysin and rosmarinic acid with allopurinol cooperated synergistically at high dose levels. Taken together, the suggested strategy seems imperative to ensure a steady supply of new therapeutic options sourced from Egyptian propolis to regress the development of hyperuricemia.

Xanthine oxidase (XO) has been well-recognized as a validated target for the treatment of hyperuricemia and gout.

The Efficacy and Mechanism of Chinese Herbal Medicines in Lowering Serum Uric Acid Levels: A Systematic Review

Background. Chinese herbal medicines are widely used to lower serum uric acid levels. However, no systemic review summarizes and evaluates their efficacies and the underlying mechanisms of action. Objectives. To evaluate the clinical and experimental evidences for the effectiveness and the potential mechanism of Chinese herbal medicines in lowering serum uric acid levels. Methods. Four electronic databases PubMed, Wed of Science, the Cochrane Library and Embase were used to search for Chinese herbal medicines for their effects in lowering serum uric acid levels, dated from 1 January 2009 to 19 August 2020. For clinical trials, randomized controlled trials (RCTs) were included; and for experimental studies, original articles were included. The methodological quality of RCTs was assessed according to the Cochrane criteria. For clinical trials, a meta-analysis of continuous variables was used to obtain pooled effects. For experimental studies, lists were used to summarize and integrate the mechanisms involved. Results. A total of 10 clinical trials and 184 experimental studies were included. Current data showed that Chinese herbal medicines have promising clinical efficacies in patients with elevated serum uric acid levels (SMD: −1.65, 95% CI: −3.09 to −0.22; p = 0.024). There was no significant difference in serum uric acid levels between Chinese herbal medicine treatments and Western medicine treatments (SMD: −0.13, 95% CI: −0.99 to 0.74; p = 0.772). Experimental studies revealed that the mechanistic signaling pathways involved in the serum uric acid lowering effects include uric acid synthesis, uric acid transport, inflammation, renal fibrosis and oxidative stress. Conclusions. The clinical studies indicate that Chinese herbal medicines lower serum uric acid levels. Further studies with sophisticated research design can further demonstrate the efficacy and safety of these Chinese herbal medicines in lowering serum uric acid levels and reveal a comprehensive picture of the underlying mechanisms of action.

Ameliorative effect of quercetin, catechin, and taxifolin on rotenone-induced testicular and splenic weight gain and oxidative stress in rats

Background The physiological functions of the testis and spleen can be affected through several cellular and molecular mechanisms such as the generation of reactive oxygen species (ROS) that causes oxidative stress. This study aimed at investigating the protective effect of catechin, quercetin, and taxifolin in rotenone-induced testicular and splenetic toxicity. Methods Male Wistar rats were administered with 1.5 mg/kg rotenone (s.c.) for 10 days followed by post-treatment with catechin (5, 10, or 20 mg/kg), quercetin (5, 10, or 20 mg/kg), and taxifolin (0.25, 0.5, or 1.0 mg/kg) for 3 days (s.c.), followed by estimation of biochemical markers of oxidative stress, inflammatory activities, and tissue damage in testes and spleen. Results Exposure of rats to rotenone caused reduced body weight gain, increased organ weight, decreased glutathione level and activities of glutathione transferase and superoxide dismutase, enhanced lipid peroxidation, and increased activities of prooxidant/proinflammatory enzymes and lactate dehydrogenase, which were mitigated by post-treatment with flavonoids. In general, quercetin and taxifolin showed better activity than catechin. Conclusions Catechin, quercetin, and taxifolin ameliorated rotenone-induced weight disturbances and oxidative damage in rats, indicating their potential relevance in toxicant and pesticide-induced tissue injury.

Screening the Best Compatibility of Selaginella moellendorffii Prescription on Hyperuricemia and Gouty Arthritis and Its Mechanism

Objectives

The Selaginella moellendorffii prescription (SMP) consists of S. moellendorffii Herba (SM), Smilacis glabrae Rhizoma (SGR), and Plantaginis Semen (PS). It has been commonly used to treat hyperuricemia and acute gouty arthritis as a hospital preparation. This study was aimed at investigating the best compatibility ratio of SMP on hyperuricemia and gouty arthritis and getting better insight of the possible mechanism. Methods. In vitro, anti-inflammatory activity of SMP was evaluated by lipopolysaccharide (LPS) induced RAW264.7 cells. The release of nitric oxide (NO) was screened by Griess assay, and NF-κB p65 and NLRP3 proteins expression was examined by immunofluorescence assay. Then, the levels of creatinine (Cr), blood urea nitrogen (BUN), and uric acid (UA) were detected in mice induced by potassium oxonate, and the paw oedema, inflammatory mediators, and histological examination were analyzed in rats induced by monosodium urate (MSU). HPLC method was employed to investigate the chemical profile of this preparation. Results. In vitro, SMP-3 (the ratio of SMP:SGR:PS was 3:1:1) exhibited the most potent anti-NO production activity without obvious toxicity. This anti-inflammatory effect was associated with suppression of NF-κB p65 nuclear translocation and NLRP3 protein expression. In animal experiments, the levels of BUN and Cr in SMP-3 group were lower than other extract groups, and the level of UA was also remarkably decreased by SMP-3 in hyperuricemic mice (P<0.01). Besides, SMP-3 extract was able to prevent the paw edema, reduce gouty joint inflammatory features, and decrease the levels IL-1β, PGE-2, IL-8, and NO in gouty arthritis rats. Furthermore, 6-C-β-D-xylopyranosyl-8-C-β-D-glucopyranosyl, apigenin, and astilbin were identified from SMP-3 extract.

Conclusions

In summary, SMP-3 may be a potential therapeutic agent for the prevention of hyperuricemic and gout.

Candidate genes of flavonoid biosynthesis in Selaginella bryopteris (L.) Baker identified by RNA-Seq

In the present study, de novo transcriptome analysis of Selaginella bryopteris in frond and root was performed to understand the regulation of flavonoid (FL) biosynthesis. High-quality data of 5.84 and 5.86 Gb was generated for frond and root, respectively, that assembled into 94,713 and 81,567 transcripts. A total of 87,471 and 73,395 unigenes were obtained from frond and root, respectively. A total of 41,267 and 31,048 CDS of frond and root, respectively, were annotated by BLASTX, which showed maximum hits against S. moellendorffii. Out of 11,285 differentially expressed genes, a total of 5639 genes were found to be down-regulated and 5628 genes up-regulated in frond as compared to those in root. In silico analysis of expression of genes in frond as compared to that in root was done for those related to phenylpropanoid (PP)/FL biosynthesis along with transcription factors (TFs) after DESeq and MapMan-based information. Results showed that genes of PP/FL biosynthesis pathway namely SbCHS, SbCHI, SbF3H, SbF3'H, SbDFR, SbUF3GT, SbCCOAMT, and SbCATOMT and TFs (SbMYB1, SbMYB2, SbMYB3, SbBHLH1, and SbWD40-5) were up-regulated in frond in comparison to those in root. Further, this in silico expression data was validated by RT-PCR analysis which showed predominant expression of most of these genes in frond and indicated their importance in the biosynthesis of flavonoids in S. bryopteris. A total of 9074 simple sequence repeats (SSRs) were also identified for frond and 3811 SSRs for root; these can be used for experimental validation.