Lipoxygenase Inhibitory Activity of Boropinic Acid, Active Principle of Boronia Pinnata

Abstract

Boropinic acid and other natural prenyloxycinnamic and benzoic acids were easily synthesized in high yield by a two-step sequence from the corresponding p-hydroxy aromatic acids and were assayed for radical scavenging activity using the DPPH test and for inhibition of enzymatic lipid peroxidation mediated by soybean 5-lipoxygenase. Compared to other acids and to known antioxidant compounds like BHT, Trolox and ascorbic acid, boropinic acid was far more active in the lipoxygenase test (IC50 = 7.6 ng/mL, p < 0.05). The recorded inhibition value suggested that boropinic acid acted as an enzyme inhibitor rather than a mere radical or peroxide scavenger. This hypothesis was confirmed by studying the interaction between boropinic acid and soybean 5-lipoxygenase by molecular modelling techniques.