Bioactivity of Flavonoid in Ethanol Extract of Annona squamosa L. Fruit as Xanthine Oxidase Inhibitor

Abstract

The global gout prevalence was increased rapidly in recent decades, especially in some developing countries. One of the most commonly used to treat gout is allopurinol, that act as xanthine oxidase inhibitor. However, consuming allopurinol in the long term can cause some unwanted side effects. On the other hand, many kinds of flavonoid compounds identified in some Indonesian grown plants have bioactivity as xanthine oxidase inhibitor. One of that is sugar apple (Annona squamosa L. fruit). Therefore, the aims of this study were to isolate the flavonoid compounds in ethanol extracts of sugar apple and to test the activity as xanthine oxidase inhibitor relative to allopurinol. The study has been carried out in some phases: (1) flavonoid extraction using 70% ethanol, (2) purification of the flavonoid isolate using n-hexane, chloroform and ethyl acetate as solvent, (3) flavonoids identification and (4) inhibitory activity test against xanthine oxidase, relative to allopurinol using spectroscopy methods. The results have shown that: from 275 grams of sugar apple fruit can be isolated 6 grams of flavonoid with the purity of 95.26% (according to HPLC peak) and has xanthine oxidase inhibitory activity was higher (83%) than allopurinol (48%) at the same concentration (100 ppm). Moreover, based on in silico study, there was also confirmed that a flavonoid compound found in Annona squamosa L., has higher binding affinity to the xanthine oxidase than allopurinol. This result thus indicated the flavonoid isolated from Annona squamosa L. might be a promising herbal drug for gout treatment.