Novel fatty acid esters of apocynin oxime exhibit antimicrobial and antioxidant activities

Apocynin (4-hydroxy-3-methoxy acetophenone), a well known phytochemical, was converted to its oxime and further esterified with fatty acids of different chain lengths (C4-C18) to obtain the oxime esters in about 80% yields. The structures of the oxime esters were confirmed using NMR, IR and mass spectroscopy. The prepared oxime esters of fatty acids and apocynin were evaluated for their in vitro antimicrobial and antioxidant activities. It was observed that the oxime ester of undecenoic acid was the most active apocynin oxime ester that exhibited both antibacterial and antifungal activities. From a mechanistic perspective, it was found that the oxime ester of undecenoic acid acted as an ergosterol biosynthesis inhibitor, confirming its antifungal property. All the compounds exhibited moderate antioxidant activity based on different assays such as DPPH radical scavenging, superoxide free radical scavenging and inhibition of lipid peroxidation.