RADICAL-SCAVENGING ACTIVITIES OF CACTUS CLADODES (OPUNTIA HUMIFUSA RAF.) IN A SUBMERGED CULTURE

Abstract

The aim of this work was to select suitable fermentation treatments for the efficient bioconversion of cactus bioactive components with an improved radical-scavenging activity for use as a nutraceutical. To obtain microorganisms for the microbial conversion of cactus, various fungi including Monascus pilosusKCCM 60029 (ATCC 22080) were used for the fermentation of cactus. DPPH (2,2-diphenyl-2-picrylhydrazyl hydrate) and ABTS [2,2-azinobis(3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt] radical-scavenging activities in M.pilosus fermentation were enhanced by 70 and 50%, respectively, compared with control. In particular, uronic acid levels showed a remarkable increase (approximately over threefold) in fermentation. The polyphenol and quercetin content of the fermented cactus showed a large increase from 180 and 2g/mL to 233.4 and 8.5g/mL, respectively, showing a maximum level at 4 days of fermentation. This result correlated with the increase of the radical-scavenging activity, meaning that polyphenol and quercetin contents are associated with radical-scavenging activity. M.pilosus is a very useful tool in the fermentation of cactus and enhancement of radical-scavenging activity.