Abstract
Antibacterial active compounds isolated from higher plants appear to be one of the most important alternative approaches to contain antibiotic resistance and the management of disease. The present study was aimed at to investigate the antibacterial activity of some medicinal plant species including seeds namely Centella asiatica, Oxalis corniculata, Phoenix dactylifera, Clitoria ternatea and Nigella sativa. The methanolic and ethanolic extract of Centella asiatica, Oxalis corniculata, Phoenix dactylifera and Clitoria ternatea was investigated for antimicrobial activity at different concentrations by using disc diffusion method against some bacterial strains with standard antibiotic cephachlore (10 μg). The result demonstrated that all the extracts showed antibacterial activities against the isolates, which were dose dependent. The ethanolic extract of Oxalis corniculata at a concentration of 50 μl/disc had the highest effect on the test organism B. subtilis, Salmonella typhi and E. coli with 9.3, 9.7 and 10.8 mm diameter of zone of inhibition respectively while at the same concentration the extract of Clitoria ternatea had a higher antimicrobial activity on Bacillus cereus with 11.3 mm diameter of zone of inhibition. The activities of the plant extracts on the tested pathogens were not as effective as the standard commercial antibacterial disc but was significant. In case of Nigella sativa, Pseudomonas aeruginosa was sensitive to both the ethanolic extract and oils at different concentration. Salmonella typhi shows the same degree of inhibition for ethanolic extract as Bacillus cereus, but greater inhibition for oils. Of all the bacteria, Pseudomonas aeruginosa was the most sensitive bacteria against ethanolic extract and oils, while Bacillus cereus was the most resistant bacteria. Generally, the oils of Nigella sativa sample had higher antibacterial activity against bacteria than ethanolic extract. All the extracts are inhibitory to most common human pathogen S. typhi. The results suggest that the different plant extracts has a significant scope to develop a novel broad spectrum of antibacterial herbal formulations.Asian J. Med. Biol. Res. December 2017, 3(4): 405-411
Highlights
Nature has bestowed on us a very rich botanical wealth and diverse types of plants grow in different parts of the world
Several reports are available on the antimicrobial activity of plant extracts on human pathogenic bacteria (Raghavendra et al, 2006; Babu et al, 2007)
Phytochemical analysis of all the solvent extracts revealed the presence of carbohydrates and glycosides, phytosterols, phenolic compounds/tannins, flavonoids, proteins and aminoacids and volatile oils are present in ethanolic and methanolic extracts of Oxalis corniculata (Raghavendra et al, 2006)
Summary
Nature has bestowed on us a very rich botanical wealth and diverse types of plants grow in different parts of the world. The use of plants and plant products as medicines could be traced as far back as the beginning of human civilization (Ahmed et al, 1998). The development of drug resistance in human pathogens against commonly used antibiotics has necessitated a search for new antimicrobial substances from other sources. Several reports are available on the antimicrobial activity of plant extracts on human pathogenic bacteria (Raghavendra et al, 2006; Babu et al, 2007). Many higher plants accumulate wide array of bioactive molecules that is extractable organic substances in quantities sufficient to be economically useful as antibiotic evolved as chemical defense against predation or infection. Species of higher plants are much less surveyed for antibacterial activity.
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