Polyphenolic profile of callistemon viminalis aerial parts: Antioxidant, anticancer and in silico 5-lox inhibitory evaluations

Abstract

Five new compounds viz kaempferol 3-O-(4′′-galloyl)-β-D-glucopyranosyl-(1′′′ →6′′ )-O-β-D-glucopyranoside (1), kaempferol 3-O-β-D-mann-uronopyranoside (2), kaempferol 3-O-β-D-mannopyranoside (3), quercetin 3-O-β-D-mannuronopyranoside (4), 2, 3 (S)-hexahydroxydiphenoyl]-D-glucose (5) along with fifteen known compounds were isolated from 80% aqueous methanol extract (AME) of C. viminalis. AME and compounds exerted similar or better antioxidant activity to ascorbic acid using DPPH, O2−, and NO inhibition methods. In addition, compounds 16, 4, and 7 showed cytotoxic activity against MCF-7 cell lines while 3, 7 and 16 exhibited strong activity against HepG2. An in silico analysis using molecular docking for polyphenolic compounds 2, 3, 7, 16 and 17 against human stable 5-LOX was performed and compared to that of ascorbic acid and quercetin. The binding mode as well as the enzyme-inhibitor interactions were evaluated. All compounds occupied the 5-LOX active site and showed binding affinity greater than ascorbic acid or quercetin. The data herein suggest that AME, a source of polyphenols, could be used against oxidative-stress-related disorders.