Antioxidant activity and molecular docking study of Erythrina × 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.