Antimicrobial Activities of Extracts and Flavonoid Glycosides of Corn Silk (Zea mays L)

Abstract

Corn silk refers to the stigmas of Zea mays L. (Gramineae) from the female flowers of maize.Based on its flavonoid contents, it is medicinally used in the treatment of a number of diseases.Screening of plants against pathogenic bacteria is an important step to validate its medicinal properties.Therefore, the aim of this study was to investigate the antimicrobial activities of different solvent extracts, flavonoids of corn silk and compare the activities with standard antibiotic gentamycin.The petroleum ether (PECS), chloroform (CECS) and methanol (MECS) extracts (25 mg/mL) of corn silk were tested for their antimicrobial activity.Twelve pathogenic bacteria: Bacillus cereus, Bacillus subtilis, Staphylococcus aureus, Pseudomonas aeruginosa, Enterobacter aerogenes, Salmonella typhi, Salmonella paratyphi, Escherichia coli, Shigella sonnei, Shigella flexneri, Proteus vulgaris, Proteus mirabilis and one yeast Candida albicans were used to investigate the antimicrobial activities of the extracts.Gentamycin (50 µg/mL) was used as reference antibiotic.Two isolated flavonoid glycosides (2.0 mg/mL) of corn silk were tested for their antimicrobial activity.The microbial growth inhibitory potential was determined by using the agar hole-plate diffusion method.PECS, MECS and flavonoids were active against eleven bacteria out of twelve bacteria.CECS was active only against five bacteria.No extracts and flavonoids were sensitive against Escherichia coli and Candid albicans.The results were compared with gentamycin, which was active against all the bacteria tested.Extracts and flavonoids showed significantly (p<0.05)higher sensitivity against a number of bacteria than gentamycin.