Effect of bioactive compounds from Moringa oleifera leaf extract against ethanol toxicity in Saccharomyces cerevisiae

Abstract

During fermentation, increased concentration of ethanol is a major stress that causes yeast cell
damage and finally reduces ethanol production. Therefore, the reduction of ethanol toxicity may be a
key step to improve ethanol production. Previously, the protective effect of Moringa oleifera leaf
extract against ethanol toxicity has been reported. This study aims to investigate the effect MOLE and
its bioactive compounds on reducing ethanol toxicity in Saccharomyces cerevisiae. Since the cell wall
is one of major cellular targets of ethanol, we examined the effect of MOLE on protecting yeast cell
wall against ethanol by using Zymolyase sensitivity assay. However, our result showed that MOLE
has no effect on yeast cell wall during ethanol stress. Since it has been reported that the generation of
intracellular reactive oxygen species is induced during ethanol stress and MOLE is rich in
antioxidants, it is possible that the major antioxidants in MOLE such as quercetin and gallic acid may
have ability to reduce ethanol toxicity. To test this hypothesis, we determined the yeast growth under
ethanol stress conditions in the presence and absence of quercetin or gallic acid by using spot
susceptibility assay. Our results revealed that quercetin and gallic acid did not promote the yeast
growth during ethanol stress. Further study is therefore needed to clarify the cellular mechanism of
MOLE on reducing ethanol toxicity.