Investigation of Extraction Methods, Antioxidant and Antibacterial Activities of Crude Extracts of Eurycoma longifolia (Pla Lai Phueak Yai) Root

Abstract

Pla Lai Phueak Yai (Eurycoma longifolia) root is a valuable source for phytochemicals, which is an important ingredient in drugs and dietary supplement products in Thailand and other countries in Southeast Asia.  There are various biological properties, including antioxidant, antibacteria and sexual stimulation. The objectives of this study were to investigate the effective method, antioxidant and antimicrobial activity. The result showed that many factors, including ethanol concentrations, type of solvent, temperature and period of extraction affected on antioxidant activity. Extraction by using distill water at 60°C for 6 hours and 30% ethanol at 30°C for 4 hours were the most effective method. The antioxidant inhibition, amount of antioxidant and total phenolic compounds of these two methods were 71.22%, 0.302±0.004 mg vitamin C/g DM, 353.07±20.53 mg Gallic acid/g DM and 72.27%, 0.3063±0.003 mg vitamin C/g DM, 330.40±16.00 mg Gallic acid/g DM, respectively. In addition, the ethanol crude extract showed potential inhibitory effect on Escherichia coli, Listeria monocytogenes and Samonella typhinurium and showed bactericidal effect against Bacillus cereus, Staphylococcus aureus and Vibrio parahaemolyticus. While, water extract showed a little antibacterial activity and no potential against was observed. Therefore, the level of ethanol concentration, temperature and duration of the herbal extraction were direct and combined factors on type and amount of the phytochemicals in the crude extracts, resulting in the different antioxidant and antibacterial activity.