Pharmacogn Mag. Aug 2014; 10(Suppl 3): S501–S505.
New steroidal saponin from Antigonon leptopus Hook. and Arn.
Antigonon leptopus Hook. and Arn., Polygonaceae (cadena de amor), is a herbal remedy for pain and gout-like symptoms in the Philippines. The methanol extract of A. leptopus have shown strong inhibitory action against xanthine oxidase.
To isolate and identify the compound responsible for the xanthine oxidase inhibitory action.
Materials and Methods:
A bioassay-guided isolation scheme using an in vitro assay for the inhibition of xanthine oxidase was employed. The structure was established using spectroscopic analysis and chemical methods.
The isolated compound was determined to be a noncompetitive inhibitor of xanthine with an IC50 of 1.79 μg/mL.
The isolated compound may represent a new class of xanthine oxidase inhibitors.
Keywords: Gout, medicinal plants, saponin, uric acid, xanthine oxidase
Antigonon leptopus Hook. and Arn. is a woody, perennial member of the buckwheat (Polygonaceae) family commonly found in tropical Asia, Africa, the Caribbean and the Americas. Its common names include cadena de amor, flores kadena, bride's tears, chain-of-love and confederate vine. It is propagated by seeds or cuttings and is mostly used as an ornament. The bark, fruit, leaves, and seeds of this plant also have widespread applications in folkloric medicine. In the Philippines, the aerial parts of the plant are used as an anti-inflammatory agent and for wound healing.[1,2] In Trinidad and Tobago, the leaves are used for diabetes, urinary problems and low blood pressure. Preliminary studies on the activity of crude extracts of A. leptopus in inhibiting the action of xanthine oxidase (XO) had been done. Results of phytochemical profiling included cardiac glycosides, steroids, tanins and terpenoids among possible types of compound responsible for this bioactivity. Being a traditional medication used for inflammation and pain, these compounds may potentially find application as new XO inhibitors.
The only commercially available XO inhibitor to date is allopurinol (1,5-dihydro-4H-pyrazolo[3,4-d] pyrimidin-4-one), a purine analog in clinical use for >30 years. Despite generally acceptable efficacy and safety profiles, very rare but serious adverse reactions of allopurinol administration occur including interstitial nephritis, renal failure, hepatotoxicity, vasculitis, and an array of skin rashes varying from mild to very severe and life-threatening allopurinol hypersensitivity syndrome.[6,7] The recurrence and severity of gout has been reportedly increasing over the last decades and it continues to be a major health problem due to shifts in diets and lifestyles.
As part of our effort to search for new biologically active compounds from local herbal remedies, a new saponin, with a steroidal backbone was isolated from A. leptopus. In this paper, we present the result of the isolation, structure elucidation and XO inhibitory activity of this new compound.
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