GC/MS analysis, in vitro antioxidant and enzyme inhibitory activities of the n-hexane extract of Gmelina philippensis CHAM and in silico molecular docking of its major bioactive compounds

Gmelina philippensis is a decorative plant distributed in South Asia and the Mediterranean region. The n-hexane extract from G. philippensis leaves has been investigated for its chemical composition, antioxidant activity, and enzyme inhibition against six enzymes – acetylcholinesterase (AChE), butyrylcholinesterase (BChE), tyrosinase, amylase, and glucosidase. The main components were fatty acids, esters, and hydrocarbons, with glycidyl palmitoleate (22.11%) and 2-methyl hexacosane (10.75%) dominating in the GC/MS analysis. The extract exhibited higher Cu + + and Fe + + + reducing capacity and chelating with values of 60.18 ± 0.58 mg TE/g, 31.48 ± 0.72 mg TE/g, and 31.11 ± 0.52 mg EDTAE/g. It also displays anti-DPPH (13.46 mg TE/g) and anti-ABTS (23.50 mg TE/g) activities. Enzyme inhibition tests showed that the n-hexane extract has the best anti-tyrosinase activity (39.97 mg KAE/g) and recorded high anti-BChE activity (3.54 mg GALAE/g). The α-amylase and α-glucosidase inhibitory activity of the n-hexane extract recorded values of 0.57 and 1.62 mmol ACAE/g. In addition, the in-silico study demonstrated that the major compounds had satisfactory binding scores when docked with the enzymes under study. Hence, the n-hexane extract of G. philippensis shows great potential as a candidate for the advancement of new therapeutic approaches for oxidative stress, neurodegeneration, and diabetes mellitus.