PHYTOCHEMICAL SCREENING AND BIOLOGICAL EVALUATION OF DYPSIS LEPTOCHEILOS LEAVES EXTRACT AND MOLECULAR DOCKING STUDY OF THE ISOLATED COMPOUNDS

Objective: phytochemical investigation of the ethyl acetate fraction (EAF) of 80% aqueous methanol extract (AME) of Dypsis leptocheilos leaves, in addition to evaluation of the antioxidant, cytotoxic and antimicrobial activities of the AME and EAF. Docking was used to predict and understand cytotoxicity of the isolated compounds. Methods: The ethyl acetate fraction (EAF) of Dypsis leptocheilos leaves was subjected to different chromatographic separation techniques. Structures of the isolated compounds were established by different spectroscopic techniques (1H/13C NMR). Antioxidant activity was evaluated by DPPH assay, while cytotoxicity was evaluated by MTT cell viability assay. Antimicrobial activity was evaluated by agar diffusion method. The docking study was conducted using Auto Dock Vina; the estrogen receptor (PDB 5t92) was used as a receptor for the docking. Results: Chromatographic separation techniques were led to the isolation of five phenolic compounds; these compounds were identified to be apigenin 8-C-β-D-glucopyranoside (Vitexin) (1), apigenin 6-C-β-D-glucopyranoside (Isovitexin) (2), luteolin 7-O-β-D-glucopyranoside (3), luteolin 8-C-β-D-glucopyranoside (Orientin) (4), luteolin 6-C-β-D-glucopyranoside (Isoorientin) (5). They were isolated and identified for the first time from this plant species. The AME and EAF showed moderate activity against Gram positive and Gram negatvie bacteria, while both of them showed similar and powerful antioxidant activity with SC50 = 12.8±0.56 µg/ml and SC50 = 17±0.77 µg/ml respectively, compared to ascorbic (reference drug) SC50 = 14.2±0.35 µg/ml. The EAF showed higher cytotoxic activity on the MCF-7 cells (human breast cancer cell line), with IC50 = 12.3 ± 1.82 µg/ml, compared to Vinblastine Sulfate (reference drug). All isolated compounds showed good binding affinity to the estrogen receptors existed in the MCF-7 cell. Conclusion: Five phenolic compounds were isolated for the first time from the EAF of Dypsis leptocheilos leaves. The AME and EAF extracts showed variable antioxidant, antimicrobial and cytotoxic activities