Antimicrobial Activity Of The Aqueous Leaf Extracts Of Amaranthus hybridus Linn., Amaranthus spinosus Linn., Caladium bicolor Vent and Colocasia esculenta (Linn.) Schott.:- Iwuoha, Dorathy C

ABSTRACT

The antimicrobial properties of the aqueous leaf extracts of A. spinosus, A. hybridus, C. esculenta, C. bicolor on four human pathogens, Staphylococcus aureus, Escherichia coli, Salmonella typhi and Candida albicans were studied using paper disc diffusion techniques. The minimum inhibitory concentration (MIC) was evaluated for each of the plant extracts on the test organisms. Result showed that there were significant variations in the levels of activity against the test organisms. Findings showed that the inhibition of staphylococcus aureus was in the range of 18.3 mm in C. bicolorto 11.67 mm in A. hybridus while the activity against Escherichia coli was 16.67 mm in C. bicolorto 10.33 mm in A. hybridus. Salmonella typhi was inhibited within the range of 14.00 mm in C. bicolor to 10.33 mm in A. hybridus and the inhibition was between 21 mm in C. bicolor to 11.07 mm in A. hybridus. Candida albicans was in the range of 11.67 mm in C. esculenta to 21.00 mm in C. bicolor. The results showed that the aqueous extract of C. bicolor was the most potent while A. hybridus extract was the least potent. All the test extracts had activities lower than that ofstandard antibiotics. The minimum inhibitory concentration (MIC) revealed that the extracts possess antimicrobial properties at concentrations ranging from > 12.50 mg/ml to > 200 mg/ml respectively. The result obtained in this study suggested that the aqueous leaf extracts of the plants possessed antimicrobial activities against the bacterial isolates at different concentrations. The MIC against Escherichia coli was between 12.5 mg/ml and 50 mg/ml and against Salmonella typhi it was between 12.3 mg/ml and 50 mg/ml. There were variations in the lowest concentrations ofthe different plant extracts that caused inhibition against the different test organisms.