Evaluation of Alcoholic Extracts of Mucuna pruriens (L.) DC. Var. utilis for Antibacterial, Antioxidant and Cytotoxic Activities toward Human Cancer Cell Lines

Abstract

Mucuna pruriens L. DC. Var. utilis (velvet bean), a medicinal Indian plant that has been longterm applied for the treatment of some neurological disorders including Parkinson’s disease. This plant is rich in phytochemical compounds and considered to provide more pharmaceutical medication but those details especially for the velvet bean seeds of the Thai cultivar are still unclear. In this study, the velvet bean seeds extracts were evaluated for their antimicrobial, antioxidant and cytotoxic activities towards three human cancer cell lines. The extractions were performed by ethanol 70% (EVBS70) and 95% (EVBS95), methanol with 70% (MVBS70) and 95% (MVBS95) and hydrochloric acid (HVBS). The quantitative analysis revealed that the highest total phenolic compounds were obtained in MVBS70 with 1,186.37 mg/g gallic acid equivalent. Levodopa (L-Dopa), a major phytochemical in Mucuna seed, was found in EVBS70, MVBS70, MVBS95 and HVBS but not in EVBS95. Since the extraction by EVBS95 appeared an oil-liked substance (EVBS95oil), four fatty acids including palmitic acid, linoleic acid, oleic acid and stearic acid were detected by Gas Chromatography-Mass Spectrometry. The fractions of EVBS70, EVBS95, and MVBS95 exhibited an antibacterial activity for Bacillus cereus, Staphylococcus aureus, Escherichia coli, Pseudomonas aeruginosa, Klebsiella pneumoniae and Salmonella typhi. Furthermore, the radical scavenging assay using 1,1-diphenyl-2-picrylhydrazyl as a free radical demonstrated that all extracts presented a higher activity against DPPH than that of the commercially available as L-Dopa, gallic acid, quercetin and catechin. Additionally, all extracts exhibited a dosedependent cytotoxic effect towards A549, HepG2 and SW480 cell lines, while EVBS70 showed the most potent cytotoxic effect. All extracts except HVBS showed the greatest effect on SW480 with IC50 values ranging from 105-205 μg/ml. This study provides additional effects of the alcoholic extracts on various pharmaceutical activities, in which velvet bean in Thailand is a promising economic plant for medical applications and industrial purposes.