Chemical composition and biological activities of essential oils from fresh and dried leaves of Microcos tomentosa Sm.

Microcos tomentosa, a member of the family Malvaceae, is traditionally recognised for its medicinal properties. This study analysed the chemical composition of essential oils (EOs) from fresh and dried leaves of M. tomentosa and evaluated their cholinesterase inhibitory and cytotoxic activities. Gas chromatography (GC) and gas chromatography-mass spectrometry (GC-MS) analyses identified 19 constituents in the fresh leaf EO and 20 constituents in the dried leaf EO, with fatty acids as the predominant constituents. The fresh leaf EO was rich in hexadecanoic acid and (Z,Z,Z)-9,12,15-octadecatrienoic acid, while drying increased the relative abundance of hexadecanoic acid and altered the profile of minor terpenoids. Cholinesterase inhibition assays demonstrated that the fresh leaf EO exhibited higher acetylcholinesterase (AChE; 41.19%) and butyrylcholinesterase (BChE; 39.26%) inhibitory activities than the dried leaf EO. The fresh leaf EO exhibited IC50 values of 119.79±5.89 µg/mL against AChE and 179.77±14.96 µg/mL against BChE. Cytotoxicity evaluation using Hs27 fibroblasts, SH-SY5Y neuroblastoma cells, and MCF-7 breast cancer cells showed no significant reduction in cell viability at concentrations up to 100 µg/mL, indicating low risk of cellular toxicity. These findings suggest that fresh leaf EO of M. tomentosa exhibited cholinesterase inhibitory activity with low cytotoxicity, indicating its potential as a bioactive agent that warrants further investigation.