The inhibitory kinetics and mechanism of quercetin-3-O-rhamnoside and chlorogenic acid derived from Smilax china L. EtOAc fraction on xanthine oxidase

Pathology, target discovery, and the evolution of XO inhibitors from the first discovery to recent advances (2020-2023)

Hyperuricemia, a disease characterized by elevation of serum uric acid level beyond 6 mg/dL. This elevation led to appearance of symptoms from joint pain to gout and from gout to difficulty in mobility of the patient. So, in this review, we have summarized the pathology of hyperuricemia, discovery of target and discovery of first XO inhibitor. At last, this review provides in-sights about the recently discovered as natural XO inhibitors, followed by design, structure activity relationship and biological activity of synthetic compounds as XO inhibitors discovered between 2020 and 2023 years. At last, the pharmacophores generated in this study will guide new researchers to design and modify the structure of novel XO inhibitors.

Inhibition mechanism of cordycepin and ergosterol from Cordyceps militaris Link. against xanthine oxidase and cyclooxygenase-2

Cordyceps militaris Link. (C. militaris) is an entomopathogenic fungus that parasitizes the pupa or cocoon of lepidopteran insect larvae, with various bioactive compounds. Cordycepin and ergosterol are the two active components in C. militaris. This study aimed to evaluate the inhibitory activity of cordycepin and ergosterol against xanthine oxidase (XO) and cyclooxygenase-2 (COX-2), as well as investigate the inhibition mechanism. Cordycepin could better inhibit XO (IC50 = 0.014 mg/mL) and COX-2 (IC50 = 0.055 mg/mL) than ergosterol. Additionally, surface hydrophobicity and circular dichroism (CD) spectra results confirmed the conformational changes in enzymes induced by cordycepin and ergosterol. Finally, cordycepin and ergosterol significantly decreased uric acid (UA) and inflammatory factors to normal level in mice with gouty nephropathy (GN). This study could provide theoretical evidence for utilization of C. militaris in hyperuricemia-management functional foods.

Ferulic acid ameliorates hyperuricemia by regulating xanthine oxidase

Hyperuricemia is characterized by elevated uric acid (UA) level in the body. The xanthine oxidase (XO) inhibitory ability is an important way to evaluate the anti-hyperuricemia effect of natural products. Ferulic acid (FA) is a phenolic acid compound, and it is a free radical scavenger with many physiological functions. The aim of this study was to investigate the structure-activity relationship, potential mechanism and interaction of FA as XO's inhibitor. In the cell experiment, using 1.25 mM adenosine to incubate for 24 h under the optimal conditions (37 °C, pH = 7.2) can increase the UA production by 1.34 folds. PCR analysis showed that FA could reduce the mRNA expression level of XO. FA inhibited XO in a mixed mode (IC50 = 13.25 μM). The fluorescence quenching of XO by FA occurs through a static mechanism, with an inhibition constant of Ki = 9.527 × 10-5 mol L-1 and an apparent coefficient of α = 1.768. The enthalpy and entropy changes were found as -267.79 KJ mol-1 and - 860.85 KJ mol-1, indicating that both hydrogen binding and hydrophobic are involved in the interaction of this polyphenolic natural compound with XO. Thus, FA supplementation may be a potential therapeutic strategy to improve hyperuricemia by reducing UA production.

Hepatoprotective effects of a chemically-characterized extract from artichoke (Cynara scolymus L.) against AFB1-induced toxicity in rats

This study was conducted to investigate the protective potential of a pharmaceutically formulated capsule of artichoke leaf powder (ArLP) against aflatoxin B1 (AFB1)-induced hepatotoxicity in male albino rats. In the 42-day experiment, rats were divided into five equal groups: (i) control, treated with sterile water, (ii) treated with 4% DMSO as AFB1 vehicle, (iii) ArLP of 100 mg kg-1 bw, (iv) AFB1 of 72 µg kg-1 bw, and (v) AFB1 plus ArLP. Exposure of rats to AFB1 resulted in hepatotoxicity as manifested by the intensification of oxidative stress, production of free radicals and significant increase in the activity levels of liver function enzymes relative to the control. Significant reductions in both the enzymatic and non-enzymatic antioxidant markers as well as histopathological abnormalities in liver tissues were also observed. Notably, the combined administration of ArLP with AFB1 clearly reduced AFB1-mediated adverse effects leading to the normalization of most of these parameters back to control levels. These findings clearly highlight the potential benefits of artichoke dietary supplements as a safe and natural solution in counteracting the adverse hepatotoxic effects conferred by AFB1 exposure. Further research is warranted to fully dissect the biochemical and molecular mechanism of action of the observed artichoke-mediated hepatoprotection.

Phytochemical and Bioactivity Studies on Hedera helix L. (Ivy) Flower Pollen and Ivy Bee Pollen

Bee pollen, known as a 'life-giving dust', is a product of honeybees using flower pollen grains and combining them with their saliva secretions. Thus, flower pollen could be an indicator of the bee pollen botanical source. Identification of bee pollen sources is a highly crucial process for the evaluation of its health benefits, as chemical composition is directly related to its pharmacological activity. In this study, the chemical profiles, contents of phenolic marker compounds and pharmacological activities of Hedera helix L. (ivy) bee pollen samples from Türkiye and Slovenia, as well as ivy flower pollen grains, were compared. High-performance thin-layer chromatography (HPTLC) analyses revealed that pollen samples, regardless of where they were collected, have similar chemical profiles due to the fact that they have the same botanical origins. Marker compounds afzelin, platanoside and quercetin-3-O-β-glucopyranosyl-(1→2)-β-galactopyranoside, common to both bee pollen and flower pollen, were isolated from bee pollen, and their structures were elucidated by nuclear magnetic resonance (NMR) and mass spectrometry (MS). These three compounds, as well as chlorogenic acid and 3,5-dicaffeoylquinic acid (found in flower pollen), were quantified using high-performance liquid chromatography (HPLC) analyses. In vitro tests and effect-directed analyses were used to evaluate the xanthine oxidase inhibition and antioxidant activity of the marker compounds and extracts from flower pollen and bee pollen. This is the first report comparing chemical profiles and related bioactivities of the flower pollen and bee pollen of the same botanical origin, as well as the first report of the chemical profile and related bioactivities of ivy flower pollen.

Smilax china L. Polysaccharide Alleviates Dextran Sulphate Sodium-Induced Colitis and Modulates the Gut Microbiota in Mice

This work aimed to investigate the preventive effect of Smilax china L. polysaccharide (SCP) on dextran sulfate sodium (DSS)-induced ulcerative colitis (UC) in mice. Smilax china L. polysaccharide was isolated by hot water extraction, ethanol precipitation, deproteinization, and purification using DEAE-cellulose column chromatography to yield three polysaccharides: SCP_C, SCP_A, and SCP_N. Acute colitis was induced by administering 3% (w/v) DSS in drinking water for 7 days. Sulfasalazine, SCP_C, SCP_A, and SCP_N were administered by gavage for 9 days. SCP_C, SCP_A, and SCP_N could significantly improve symptoms, as evidenced by the declining disease activity index (DAI), decreased spleen weight, increased length of the colon, and improved colonic histology. Moreover, SCP_C, SCP_A, and SCP_N increased serum glutathione and decreased the levels of pro-inflammatory cytokines, malondialdehyde, nitric oxide, and myeloperoxidase in colon tissues. Additionally, SCP_C, SCP_A, and SCP_N modulated gut microbiota via ascending the growth of Lachnospiraceae, Muribaculaceae, Blautia, and Mucispirillum and descending the abundance of Akkermansiaceae, Deferribacteraceae, and Oscillibacter in mice with UC. The results suggested that Smilax china L. polysaccharide ameliorates oxidative stress, balances inflammatory cytokines, and modulates gut microbiota, providing an effective therapeutic strategy for UC in mice.

Anti-Inflammatory and Hypouricemic Effect of Bioactive Compounds: Molecular Evidence and Potential Application in the Management of Gout

Gout is caused by the deposition of monosodium urate crystals in the joint and represents the most common form of inflammatory arthritis in men. Its prevalence is rising worldwide mainly due to the increase of risk factors associated with the disease, in particular hyperuricemia. Besides gout, hyperuricemia leads to an increased inflammatory state of the body with consequent increased risk of comorbidities such as cardiovascular diseases. Increasing evidence shows that bioactive compounds have a significant role in fighting inflammatory and immune chronic conditions. In gout and hyperuricemia, these molecules can exert their effects at two levels. They can either decrease serum uric acid concentrations or fight inflammation associated with monosodium urate crystals deposits and hyperuricemia. In this view, they might be considered valuable support to the pharmacological therapy and prevention of the disease. This review aims to provide an overview of the beneficial role of bioactive compounds in hyperuricemia, gout development, and inflammatory pathways of the disease.