Design, synthesis and bioactive evaluation of geniposide derivatives for antihyperuricemic and nephroprotective effects

High-throughput discovery of highly selective reversible hMAO-B inhibitors based on at-line nanofractionation

Human monoamine oxidase B (hMAO-B) has emerged as a pivotal therapeutic target for Parkinson's disease. Due to adverse effects and shortage of commercial drugs, there is a need for novel, highly selective, and reversible hMAO-B inhibitors with good blood-brain barrier permeability. In this study, a high-throughput at-line nanofractionation screening platform was established with extracts from Chuanxiong Rhizoma, which resulted in the discovery of 75 active compounds, including phenolic acids, volatile oils, and phthalides, two of which were highly selective novel natural phthalide hMAO-B inhibitors that were potent, selective, reversible and had good blood‒brain permeability. Molecular docking and molecular dynamics simulations elucidated the inhibition mechanism. Sedanolide (IC50 = 103 nmol/L; SI = 645) and neocnidilide (IC50 = 131 nmol/L; SI = 207) demonstrated their excellent potential as hMAO-B inhibitors. They offset the limitations of deactivating enzymes associated with irreversible hMAO-B inhibitors such as rasagiline. In SH-SY5Y cell assays, sedanolide (EC50 = 0.962 μmol/L) and neocnidilide (EC50 = 1.161 μmol/L) exhibited significant neuroprotective effects, comparable to the positive drugs rasagiline (EC50 = 0.896 μmol/L) and safinamide (EC50 = 1.079 μmol/L). These findings underscore the potential of sedanolide as a novel natural hMAO-B inhibitor that warrants further development as a promising drug candidate.

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.

Study on the chemical reactivity difference of primary hydroxyl groups in iridoid glycosides

Iridoid glycoside, which belongs to the polyhydroxy compound, is a kind of active ingredient of traditional Chinese medicine with a wide range of sources, and has many pharmacological effects such as anti-cancer, anti-inflammatory, anti-virus, hypoglycemic and so on. Its structure contains many hydroxyl groups, including two primary hydroxyl groups. The chemical reactivity of primary hydroxyl groups has very little difference, so it is very important to control the selectivity of hydroxyl groups under certain conditions. In this paper, the difference between the two primary hydroxyl groups in iridoid glycoside was calculated based on computer simulation and verified this result through designed experiments. This study will provide an important way for site-directed modification of hydroxyl in iridoid glycoside in the future.

A New Avenue for Enhanced Treatment of Hyperuricemia and Oxidative Stress: Design, Synthesis and Biological Evaluation of Some Novel Mutual Prodrugs Involving Febuxostat Conjugated with Different Antioxidants

Febuxostat (FEB) is the first non-purine xanthine oxidase inhibitor (XOI) used for the treatment of hyperuricemia and gout. The oxidative stress induced by reactive oxygen species (ROS) which accompany purine metabolism by XO, could contribute to cellular damage and several pathological conditions. In this view, the present work addresses the evaluation of combining the hypouricemic effect of FEB and the free radical scavenging potential of various natural antioxidants in a single chemical entity by implementing the "mutual prodrug" strategy. Accordingly, a series of five ester prodrugs containing FEB together with different naturally occurring antioxidants namely, thioctic acid (4), thymol (5), menthol (6), vanillin (7), and guaiacol (8) was synthesized. Prominently, all the chemically conjugated prodrugs (4 - 8) revealed an obvious increase in the hypouricemic and antioxidant potentials when compared with their corresponding promoieties and physical mixtures. Moreover, they showed a potential protective effect against CCl4-induced hepatotoxicity and oxidative stress, together with no cytotoxicity on normal breast cells (MCF10A). Furthermore, the in vitro chemical and enzymatic stability studies of the prodrugs (4 - 8) using a developed HPLC method, verified their stability in different pHs, and rapid hydrolysis in rabbit plasma and liver homogenate to their parent metabolites. Moreover, the prodrugs (4 - 8) showed higher lipophilicity and lower aqueous solubility when compared to the parent drugs. Finally, the obtained merits from the implementation of the mutual prodrug strategy would encourage further application in the development of promising candidates with high therapeutic efficacy and improved safety profiles.

Studies on the interaction mechanism between xanthine oxidase and osmundacetone: Molecular docking, multi-spectroscopy and dynamical simulation

Xanthine oxidase (XO) is a key enzyme in uric acid production, and its molybdopterin (Mo-Pt) domain is an important catalytic center when xanthine and hypoxanthine are oxidated. It is found that the extract of Inonotus obliquus has an inhibitory effect on XO. In this study, five key chemical compounds were initially identified using liquid chromatography-mass spectrometry (LC-MS), and two compounds, osmundacetone ((3E)-4-(3,4-dihydroxyphenyl)-3-buten-2-one) and protocatechuic aldehyde (3,4-dihydroxybenzaldehyde), were screened as the XO inhibitors by ultrafiltration technology. Osmundacetone bound XO strongly and competitively inhibited XO with a half-maximal inhibitory concentration of 129.08 ± 1.71 μM, and its inhibition mechanism, was investigated. Osmundacetone and XO via static quenching and spontaneously bound with XO with high affinity, primarily via hydrophobic interactions and hydrogen bonds. Molecular docking studies showed that osmundacetone was inserted into the Mo-Pt center and interacted with hydrophobic residues of Phe911, Gly913, Phe914, Ser1008, Phe1009, Thr1010, Val1011, and Ala1079 of XO. In summary, these findings suggest that provide theoretical basis for the research and development of XO inhibitors from Inonotus obliquus.

Anti-gout activity and the interaction mechanisms between Sanghuangporus vaninii active components and xanthine oxidase

Xanthine oxidase (XO) plays a critical role in the progression of gout. We showed in a previous study that Sanghuangporus vaninii (S. vaninii), a perennial, medicinal, and edible fungus traditionally used to treat various symptoms, contains XO inhibitors. In the current study, we isolated an active component of S. vaninii using high performance countercurrent chromatography and identified it as davallialactone using mass spectrometry with 97.726 % purity. A microplate reader showed that davallialactone had mixed inhibition of XO activity with a half-inhibitory concentration value of 90.07 ± 2.12 μM. In addition, the collision between davallialactone and XO led to fluorescence quenching and conformational changes in XO, which were mainly driven by hydrophobicity and hydrogen bonding. Molecular simulations further showed that davallialactone was located at the center of the molybdopterin (Mo-Pt) of XO and interacted with amino acid residues Phe798, Arg912, Met1038, Ala1078, Ala1079, Gln1194, and Gly1260, suggesting that entering the enzyme-catalyzed reaction was unfavorable for the substrate. We also observed face-to-face π-π interactions between the aryl ring of davallialactone and Phe914. Cell biology experiments indicated that davallialactone reduced the expression of the inflammatory factors, tumor necrosis factor alpha and interleukin-1 beta (P < 0.05), can effectively alleviate cellular oxidative stress. This study showed that davallialactone significantly inhibits XO and has the potential to be developed into a novel medicine to prevent hyperuricemia and treat gout.

Therapeutic effects of traditional Chinese medicine on gouty nephropathy: Based on NF-κB signalingpathways

As the final product of purine metabolism, excess serum uric acid (SUA) aggravates the process of some metabolic diseases. SUA causes renal tubule damage, interstitial fibrosis, and glomerular hardening, leading to gouty nephropathy (GN). A growing number of investigations have shown that NF-κB mediated inflammation and oxidative stress have been directly involved in the pathogenesis of GN. Traditional Chinese medicine's treatment methods of GN have amassed a wealth of treatment experience. In this review, we first describe the mechanism of NF-κB signaling pathways in GN. Subsequently, we highlight traditional Chinese medicine that can treat GN through NF-κB pathways. Finally, commenting on promising candidate targets of herbal medicine for GN treatment via suppressing NF-κB signaling pathways was summarized.

Anserine beneficial effects in hyperuricemic rats by inhibiting XOD, regulating uric acid transporter and repairing hepatorenal injury

This study aims to investigate the anti-hyperuricemia effect and mechanism of anserine in hyperuricemic rats. Hyperuricemic rats were induced with a combination of 750 mg per kg bw d potassium oxazinate (PO) and 200 mg per kg bw d hypoxanthine for a week, and the rats were separately orally administered anserine (20, 40, 80 mg kg^-1) and allopurinol (10 mg kg^-1) for three weeks. The results show that the content of serum uric acid (SUA) decreased by approximately 40% and 60% after the intervention of anserine and allopurinol, respectively. The activity of superoxide dismutase (SOD) was increased and the levels of malondialdehyde (MDA), alkaline phosphatase (ALP) and alanine aminotransferase (ALT) were significantly decreased in the anserine groups. After the administration of anserine, the contents of blood urea nitrogen (BUN) and creatinine (Cr) were reduced in the kidney, and the levels of the proinflammatory cytokines IL-1β, IL-6β, TNF-α and TGF-β and inflammatory cell infiltration were reduced in both the liver and kidney. Moreover, the gene expressions of xanthine oxidase (XOD), renal urate transporter 1 (URAT1) and glucose transporter type 9 (GLUT9) were downregulated by anserine administration, and the gene expressions of ATP-binding cassette transporter G2 (ABCG2), organic anion transporter 1 (OAT1) and organic anion transporter 3 (OAT3) were upregulated at the same time. These findings suggest that hepatorenal injury was repaired by anserine, which further regulated the expression of hepatic XOD and renal URAT1, GLUT9, ABCG2, OAT1 and OAT3 to relieve hyperuricemia in rats.

A geniposide-phospholipid complex ameliorates posthyperuricemia chronic kidney disease induced by inflammatory reactions and oxidative stress

Hyperuricemia is a common metabolic disease and is one of the factors that could induce chronic kidney disease (CKD). Geniposide (GEN) is a typical natural iridoid glucoside compound with a series of biological activities, but the poor bioavailability of GEN limits its clinical application. In this context, the pharmacological activity of the geniposide-phospholipid complex (GEN-PLC) in ameliorating posthyperuricemia CKD was evaluated by in vitro and in vivo experiments in this study. In vitro cell experiments showed that GEN-PLC treatment markedly decreased inflammatory cytokine levels and reactive oxygen species levels compared with those of GEN in uric acid-treated HKC cells. In vivo research results confirmed that a high concentration of uric acid could cause CKD by increasing inflammatory cytokines and reactive oxygen species in hyperuricemic mice. At the same time, GEN-PLC could regulate the PI3K/AKT/NF-κB and Keap1/Nrf2/HO-1 signaling pathways to effectively inhibit the inflammatory response and oxidative stress, thereby ameliorating posthyperuricemia CKD, and the therapeutic effect was better than that of GEN. In addition, the preparation technology of GEN-PLC was optimized, and the physiochemical analysis explained the intermolecular interactions of the two components. Based on the research results, GEN-PLC could enhance the bioavailability of GEN and become a promising candidate for clinical drug development.

Katsuwonus pelamis Peptide and its Complexes Protect Zebrafish and Mice From Hyperuricemia Through Promoting Kidney Excretion of Uric Acid and Inhibiting Liver Xanthine Oxidase Activity

Katsuwonus pelamis peptide and its complexes have the effect of lowering uric acid (UA)-levels. To identify the effect and possible mechanisms, different concentrations of Katsuwonus pelamis peptide and its complexes were administered to the zebrafish and mice hyperuricemia models, and the UA level was measured. Meanwhile, the hyperuricemic mice were treated orally at 0.83, 1.67, and 5.00 mg/g body weight for 7 days with Katsuwonus pelamis peptide and the complexes groups, separately. The levels of serum UA (SUA), urinary UA (UUA), serum creatinine (SCR), blood urine nitrogen (BUN), and xanthine oxidase (XOD) activities were detected in each group. The results showed that the Katsuwonus pelamis peptide (125 μg/ml) and its complexes (83.3 and 250 μg/ml) effectively reduced UA level in zebrafish with hyperuricemia (p < 0.05). The Katsuwonus pelamis peptide at high concentration (5.00 mg/g) decreased the SUA level, SCR level, BUN level, and hepatic XOD activity, and the complexes (1.67 and 5.00 mg/g) significantly reduced the SUA level and hepatic XOD activity (p < 0.05) in the hyperuricemic mice. In addition, in a hyperuricemic mouse model, the UUA level was increased after treatment with Katsuwonus pelamis peptide and its complexes at high concentrations (p < 0.05). The total therapeutic effects in the Katsuwonus pelamis peptide complex group were better than those in the Katsuwonus pelamis peptide group. Thus, Katsuwonus pelamis peptide and its complexes may possibly be used to prevent hyperuricemia via promoting urate secretion and inhibiting XOD activity production.

Synthesis and biological evaluation of thiazolidine-2-thione derivatives as novel xanthine oxidase inhibitors

Xanthine oxidase (XO) is a key enzyme in the generation and development of hyperuricemia. Thiazolidine-2-thione, a typical heterocyclic compound, have been widely used in the field of drug synthesis. In this study, a series of novel thiazolidine-2-thione derivatives were synthesized as XO inhibitors, and the XO inhibitory potencies of obtained compounds were evaluated by in vitro enzyme catalysis. The result shown that compound 6k behaved the strongest XO inhibitory activity with an IC₅₀ value of 3.56 μmol/L, which was approximately 2.5-fold more potent than allopurinol. The structure-activity relationship revealed that the phenyl-sulfonamide group was indispensable for thiazolidine-2-thione derivatives to produce XO inhibitory activity. The enzyme inhibition kinetics analyses confirmed that compound 6k exerted a mixed-type XO inhibition. Additionally, the molecular docking results suggested that the 4-fluorophenyl-sulfonyl moiety could interact with Gly260 and Ile264 in the innermost part of the active pocket through 2 hydrogen bonds, while the thiazolidinethione moiety could form two hydrogen bonds with Glu263 and Ser347 in hydrophobic pockets. In summary, the results described above suggested that compound 6k could be a valuable lead compound for the treatment of hyperuricemia as a novel XO inhibitor.