Background: Polyphenols have been studied for their potential involvement in the prevention of various chronic diseases as well as for their antimicrobial potential. The crude extracts of arecanut have been reported to have antiinfective properties. We aimed to explore the endosperm of Areca catechu (arecanut) for the extraction of polyphenol components and to study the antituberculosis activity of these polyphenol against Mycobacterium tuberculosis H37Rv.
Method: A comparative extraction was performed using microwave and Soxlet apparatus. High performance liquid chromatography (HPLC) technique was used for the estimation of the extracted polyphenols. The minimum inhibitory concentration (MIC) values against M.tuberculosis H37Rv stain, Staphylococcus aureus and Escherichia coli were estimated by resazurin microtiter assay.
Results: There was a 11-fold increase in the total phenolic content by microwave assisted extraction compared to the Soxhlet extraction. The powdered extract was found to be active with MIC value of 0.975 ± 0.02 μg/mL. Fractionation and HPLC-based estimation of the extract revealed catechin, epicatechin, and epigallocatechin gallate to be the polyphenol components in the ethanol fraction.
Conclusions: The bioactivity of these polyphenols confirmed their presence and complementary effect in the extract form. Because the toxic alkaloid arecoline, known to be present in arecanut, did not show any activity individually, the bioactivity of the extract was attributed to the nontoxic polyphenols present. This extract also showed selective inhibition of M. tuberculosis over other gram positive and gram-negative bacteria, thereby establishing that arecanut is an exploitable selective source of polyphenols acting against M. tuberculosis.
Keywords: Anti-tuberculosis activity; arecanut; microwave-assisted extraction; polyphenols.