ABSTRACT
The objective of this study was to develop and validate of Structure-Based Virtual Screening (SBVS) protocol which was used to select the best pose of inhibitor-aspartic protease complex interaction in the active sites of HIV-1 protease, plasmepsin I, II, and IV. Retrospective validation was performed on enhanced dataset of ligands and decoys (DUD-E) for HIV-1 protease. The crystal structures 1XL2, 3QS1, 1SME, and 1LS5 were obtained from Protein Data Bank. The protocol was then challenged to re-dock the ligands to its origin places in the active sites by correlating Tanimoto coefficient (Tc) and binding affinity (Ei) with Root Mean Square Deviation (RMSD). Enrichment factor at 1% false positives (EF1%) values for Tc and Ei were 18.26 and 9.03, respectively, while the Area Under Curve (AUC) values for Tc and Ei were 76.84 and 60.95. The SBVS protocol was valid and showed better virtual screening qualities in ligand identification for HIV-1 protease compared to the original protocol accompanying the release of DUD-E and showed its ability to reproduce the co-crystal pose in the HIV-1 protease, plasmepsin I, II, and IV to its origin places in the active sites.
ABSTRACT
A sunscreen active compound has been isolated from the ethanol extract of Garcinia mangostana Linn (Clusiaceae). The ethanol extract was fractionated by liquid liquid extraction with n-hexane, methylene chloride and ethyl acetate, followed by further fractionation and purification using column chromatography on silica gel and gradient elution with combinations of n-hexane and ethyl acetate. Isolation and fractionation was guided by sunscreen activity assay. One of the active compounds was identified as αmangostin based on LC-MS and NMR Spectroscopy. The SPF value of the isolated α –mangostin at 50 and 100 ppm were 21.76 and 37.18, respectively and were much higher than the SPF values of the fractions obtained by liquid-liquid extraction.