Lanostane-type triterpenoid and steroid from the stem bark of Klainedoxa gabonensis

Natural compounds with xanthine oxidase inhibitory activity: A review

Hyperuricemia (HUA), a disease due to an elevation of body uric acid level and responsible for various diseases such as gout, cardiovascular disorders, and renal failure, is a major ground debate for the medical science these days. Considering the risk factors linked with allopathic drugs for the treatment of this disease, the debate has now become a special issue. Previously, we critically discussed the role of dietary polyphenols in the treatment of HUA. Besides dietary food plants, many researchers figure out the tremendous effects of medicinal plants-derived phytochemicals against HUA. Keeping in mind all these aspects, we reviewed all possible managerial studies related to HUA through medicinal plants (isolated compounds). In the current review article, we comprehensively discussed various bioactive compounds, chemical structures, and structure-activity relationship with responsible key enzyme xanthine oxidase.

Triterpenoids

Covering: 2013. Previous review: Nat. Prod. Rep., 2015, 29, 1028-1065This review covers the isolation and structure determination of triterpenoids reported during 2013 including squalene derivatives, lanostanes, holostanes, cycloartanes, cucurbitanes, dammaranes, euphanes, tirucallanes, tetranortriterpenoids, quassinoids, lupanes, oleananes, friedelanes, ursanes, hopanes, serratanes, isomalabaricanes and saponins; 350 references are cited.

Potential anti-gout constituents as xanthine oxidase inhibitor from the fruits of Stauntonia brachyanthera

With the aim of finding a better xanthine oxidase inhibitor with potential anti-gout properties, the studies on the fruit of Stauntonia brachyanthera were carried out, which led to the isolation of 12 glycosides, including 4 new nor-oleanane triterpenoids. Their structures were determined by comprehensive spectroscopic (NMR and HR MS) analysis. Two compounds (4 and 11) exhibited significant inhibitory activities on xanthine oxidase with IC₅₀ values of 5.22 and 1.60µM, respectively. Another five compounds (1, 2, 3, 8 and 10) showed qualified activities. The results suggested that the existences of nor-oleanane triterpenoids and flavonoids in the fruits were responsible for the inhibitory activity on xanthine oxidase that could cut off the production of uric acid. Nor-oleanane triterpenoids, a new leading XO inhibitor, is worthy of further studies on molecular biology level for its mechanisms.

Effects of extracts of leaves from Sparattosperma leucanthum on hyperuricemia and gouty arthritis

ETHNOPHARMACOLOGICAL RELEVANCE

The species Sparattosperma leucanthum (Vell.) K. Schum is used in Brazilian folk medicine to treat rheumatism, throat ulcers, stomatitis, syphilis, bladder stones and as blood cleanser. The aim of this study was to evaluate the potential, in vitro and in vivo, of the extracts of leaves from Sparattosperma leucanthum to treat hyperuricemia and inflammation in the gouty arthritis model.

MATERIALS AND METHODS

Ethyl acetate extract (SLE), methanolic extract (SLM) and aqueous extract (SLW) were evaluated in vitro on XO inhibitory activity and in vivo in an experimental model with oxonate-induced hyperuricemia in mice which was used to evaluate anti-hyperuricemic activity and liver xanthine oxidase (XOD) inhibition. Anti-inflammatory activity was also investigated on MSU crystal-induced paw edema model.

RESULTS

Sparattosperma leucanthum crude extracts showed expressive results on urate-lowering activity in blood. SLW at the dose of 125 mg/kg has proved to be active in reducing hyperuricemia and was capable to inhibit the hepatic xanthine oxidase enzyme (XOD). SLM showed anti-hyperuricemic activity on all doses tested; however, this extract showed activity on the XOD only at the dose of 500 mg/kg. SLE, at the three evaluated doses, has proved to be active in reducing hyperuricemia in vivo and was able to inhibit XO activity in vitro at the concentration of 100 µg/mL. This extract was also able to inhibit XOD activity in vivo at the doses of 250 mg/kg and 500 mg/kg. SLE (125 and 250 mg/kg) and SLW (500 mg/kg) showed significant anti-inflammatory activity on monosodium urate crystal-induced paw edema model.

CONCLUSIONS

The ethyl acetate, methanolic and aqueous extracts of Sparattosperma leucanthum showed significant results on evaluated models and therefore may be important agents for the treatment of gouty arthritis and hyperuricemia.

AfroDb: a select highly potent and diverse natural product library from African medicinal plants

Computer-aided drug design (CADD) often involves virtual screening (VS) of large compound datasets and the availability of such is vital for drug discovery protocols. We assess the bioactivity and "drug-likeness" of a relatively small but structurally diverse dataset (containing >1,000 compounds) from African medicinal plants, which have been tested and proven a wide range of biological activities. The geographical regions of collection of the medicinal plants cover the entire continent of Africa, based on data from literature sources and information from traditional healers. For each isolated compound, the three dimensional (3D) structure has been used to calculate physico-chemical properties used in the prediction of oral bioavailability on the basis of Lipinski's "Rule of Five". A comparative analysis has been carried out with the "drug-like", "lead-like", and "fragment-like" subsets, as well as with the Dictionary of Natural Products. A diversity analysis has been carried out in comparison with the ChemBridge diverse database. Furthermore, descriptors related to absorption, distribution, metabolism, excretion and toxicity (ADMET) have been used to predict the pharmacokinetic profile of the compounds within the dataset. Our results prove that drug discovery, beginning with natural products from the African flora, could be highly promising. The 3D structures are available and could be useful for virtual screening and natural product lead generation programs.

Bioactive natural products derived from the Central African flora against neglected tropical diseases and HIV

This review discusses the medicinal potential of bioactive metabolites isolated from medicinal plants in Central Africa for the treatment of neglected tropical diseases and HIV. A correlation is established between the biological activities of the isolated compounds and the uses of the plants in traditional medicine. Insight is provided on how secondary metabolites from medicinal plants in Central Africa could be exploited for drug discovery.