Antioxidant activity and molecular docking study of Erythrin neillii polyphenolics

Abstract

Species of genus Erythrina have a great contribution in folk medicine; various species are utilized as a tranquilizer, to treat insomnia, inflammation and colic. Besides, Erythrina species have reported antioxidant, hepatoprotective and anxiolytic activities. Erythrina neillii is a hybrid obtained through a cross between E. herbacea L. and E. humeana Spreng. It has not been well-studied for its chemical or biological profile; therefore it represents an interesting field of study. In this study, seven phenolic compounds; two hydrolysable tannins (1,3), one phenolic acid (2) and four known flavonoids (4�7) were isolated and characterized for the first time in E neillii and Erythrina genus except for vitexin (7). Isolated compounds were assessed for their antioxidant activities using ORAC assay. 2?-O-galloyl orientin (6) exhibited the highest activity followed by 2?-O-galloyl vitexin (5). Flexible molecular docking on heme oxygenase, an important stress protein that is involved in cellular protection, antioxidant and anti-inflammatory activities, justified the antioxidant activity of the isolated compounds. The best scoring was observed with 2?-O-galloyl orientin forming four binding interactions with residues, Arg 136 (two interactions), Met34 and Gly139. Erythrina neillii offered powerful and available antioxidant beside significantly active phytoconstituents. 2018 South African Association of Botanists