Chemical Evaluation, Free Radical Scavenging Activities and Antimicrobial Evaluation of the Methanolic Extracts of Corn Silk (Zea mays)

Corn silk is thought to possess medicinal properties according to Nigerian folklore. This study was undertaken to appraise its phytochemical constituents and anti-microbial activities. Data obtained revealed that alkaloids, flavonoids, tannins, saponins, steroids, glycosides and cardiac glycosides were detected in the fresh mature and dried mature samples (FMCSS and DMCSS). The antioxidant activity of the extracts was determined by the DPPH inhibition method. The crude extract of the FMCSS exhibited a stronger free radical scavenging activity than that of the DMCSS (76.14: 73.54, 75.76: 68.23, 68.18: 61.46 and 64.18: 41.58% for the fresh versus the dried samples at 5, 3, 2 and 1 mg/ml concentrations). Results showed that when tested against Staphylococcus aureus, Pseudomonas aeruginosa, Klebsciella pneumonia, Escherichia coli and Salmonella thypi, the zones of inhibition obtained ranged from 10 to 16 mm for the fresh samples and between 12 to 20 mm for the dried samples. Mineral analysis revealed the presence of calcium (0.1869: 0.0610 mg/g), iron (0.005: 0 mg/g), magnesium (0.1939: 0.0934 mg/g), copper (0.0073: 0.0094 mg/g), manganese (0.0109: 0.0027 mg/g) and zinc (0.0165: 0.0146 mg/g) in the dried immature/mature silk. The results obtained suggested that the DMCSS sample studied plant possess better anti-bacterial activity with the major activity tailored to the phyto-constituents. GCMS analysis of the hexane extract of the silk showed the presences of straight chain alkanes and poly unsaturated methyl esters.