The present study was undertaken to investigate the isolated compounds from the stem bark of Garcinia atroviridis as potential cholinesterase inhibitors and the ligand-enzyme interactions of selected bioactive compounds in silico. The in vitro cholinesterase results showed that quercetin (3) was the most active AChE inhibitor (12.65 ± 1.57 µg/ml) while garcinexanthone G (6) was the most active BChE inhibitor (18.86 ± 2.41 µg/ml). It is noteworthy to note that compound 6 was a selective inhibitor with the selectivity index of 11.82. Molecular insight from docking interaction further substantiate that orientation of compound 6 in the catalytic site which enhanced its binding affinity as compared to other xanthones. The nature of protein-ligand interactions of compound 6 is mainly hydrogen bonding, and the hydroxyl group of compound 6 at C-10 is vital in BChE inhibition activity. Therefore, compound 6 is a notable lead for further drug design and development of BChE selective inhibitor.
Butyrylcholinesterase ; Catalytic Domain ; Cholinesterase Inhibitors ; Cholinesterases ; Computer Simulation ; Drug Design ; Garcinia ; Hydrogen Bonding ; In Vitro Techniques ; Quercetin ; Xanthones

Carica papaya is a medicinal and fruit plant owing biological activities including antioxidant, antiviral, antibacterial and anticancer. The present study aims to investigate the acetyl (AChE) and butyryl (BChE) cholinesterase inhibitory potentials of C. papaya extracts as well as their chemical compositions. The chemical composition of the active extract was identified using a gas chromatography-mass spectrometry (GCMS). Ellman enzyme inhibition assay showed that the alkaloid-enriched leaf extract of C. papaya possessed significant anti-BChE activity with an enzyme inhibition of 75.9%. GC-MS analysis showed that the alkaloid extract composed mainly the carpaine (64.9%) – a major papaya alkaloid, and some minor constituents such as aliphatic hydrocarbons, terpenes and phenolics. Molecular docking of carpaine revealed that this molecule formed hydrogen bond and hydrophobic interactions with choline binding site and acyl pocket. This study provides some preliminary findings on the potential use of C. papaya leaf as an herbal supplement for the prevention and treatment of Alzheimer’s disease.