ANTIOXIDANT POTENTIAL OF FIVE COMPOUNDS FROM THE MARINE FUNGUS ASPERGILLUS FLOCCULOSUS BY DFT METHOD: HAT AND SET MECHANISM

Abstract

Antioxidant potential of five compounds, ochraceopone F (1), aspertetranone D (2), cycloechinulin (3), wasabidienone E (4) and mactanamide (5) in the extracts from marine fungus Aspergillus flocculosus in Nha Trang was investigated by computational chemistry methods. All calculations were performed at the theoretical level M05-2X/6-31+G(d) in the gas phase. The physicochemical parameters including bond dissociation enthalpy (BDE), ionization potential (IP), electron affinity (EA) which characterize HAT (Hydrogen atom transfer) and SET (Single electronic transfer) antioxidant mechanisms were calculated. As a result, the H-atom donating ability of the studied compounds increases in the descending order of BDE value (1)> (2)> (3)> (4) (5). Wherein the compounds (4) and (5) represent as the most potential antioxidant with the lowest BDE in the gas phase being 73.2 and 74.8 kcal/ mol. Moreover, the electronic donating ability of the compounds increases as function of the descending order of IE value (2)> (1)> (5)> (3)> (4). And the electron accepting ability decreases in descending EA value (4)> (3)> (2)> (5)> (1). Compound (4) (wasabidienone E) has the smallest IE value of 6.50 eV and has the highest EA value of 2.26 eV.