Screening for antimicrobial and antimalarial activities of longan (Dimocarpus longan Lour) seeds

Abstract

The aims of this study were to evaluate methanolic extract of longan seed for antibacterial, antimalarial (antiplasmodial) activity and conducted with cytotoxicity test by using sulforhodamine B (SRB) assay with Vero cells (African green monkey kidney cell line). The methanolic extract was tested for antimicrobial activity with five strains of pathogenic bacteria including Staphylococcus aureus, Bacillus cereus, Psuedomonas aeruginosa, Enterococcus faecalis, Escherichia coli and one strain of pathogenic yeast, Candida albicans . The antimicrobial activities of each extract were screened by agar diffusion before conducting with broth macrodilution method for determining minimal inhibitory concentration (MIC). The assessment of antimalarial activities of methanolic extract was determined by microculture radioisotope technique. Plasmodium falciparum (K1, multi-drug resistant strain) in vitro culture was used for this test. The extract also was screened for cytotoxicity with Vero cells (African green monkey kidney cell line) by SRB colorimetric assay. The results show that longan seed extract (10 mg/ml) inhibited the growth of S. aureus , P. aeruginosa and C. albicans 17, 12 and 11 mm and MIC values were 3.19, 1.59 and 1.59 mg/ml, respectively. The longan seed extract also possessed preferable antimalarial activity (IC 50 = 2.78 ± 0.44 μg/ml) with no cytotoxic effect to Vero cells.