Abstract
Dehydrogenase and inhibitions of dehydrogenase activities in Salmonella typhimurium by ethanolic and methanolic leaf extracts of Ocimum gratissimum and Carica papaya were investigated. Dehydrogenase activity assay was carried out using 2, 3, 5-triphenyl tetrazolium chloride (TTC) as the electron acceptor. Pure culture of S. typhimurium was exposed to varied concentrations of ethanolic and methanolic extracts of Ocimum gratissimum and Carica papaya [0-4000 μg/ml]. The ethanolic and methanolic extracts exhibited a concentration dependent response against the tested organism. Results obtained revealed that the ethanolic extracts showed a higher bactericidal effect on the test organism than the methanolic extracts at the threshold and total inhibitory concentrations. The IC50 were 45.349 and 15.697; IC100 were 43.732 and 35.526 for ethanolic extracts of Carica papaya and Ocimum gratissimum respectively while the IC50 were 7.108 and 13.696; IC100 were 40.815 and 31.104 for methanolic extracts of Carica papaya and Ocimum gratissimum respectively. This in-vitro study further revealed that the leaf of Carica papaya was more potent on Salmonella typhimurium than the leaf of Ocimum gratissimum. The findings from this study seem to provide the in-vitro evidence that justifies Carica papaya and Ocimum gratissimum as good candidate medicinal plants for the potential treatment of Salmonella typhimurium infections.
Highlights
Ocimum gratissimum and Carica papaya are valuable multi-purpose medicinal plants which belong to the family Lamiaceae and Caricaceae respectively and are distributed in tropical and warm regions
The results of this study on the effects of different concentrations of ethanolic and methanolic extracts of C. papaya and O. gratissimum on Salmonella typhimurium with respect to the dehydrogenase activity and its inhibition are shown in Figures 1, 3, 5 and 7
Dehydrogenase activities observed in the control samples (0 μg/ml i.e. no plant extract) of ethanolic and methanolic extracts of C. papaya and O. gratissimum indicated that the test organism was able to reduce tetrazolium chloride (TTC) to the red formazan (Figures 1, 3, 5 and 7)
Summary
Ocimum gratissimum and Carica papaya are valuable multi-purpose medicinal plants which belong to the family Lamiaceae and Caricaceae respectively and are distributed in tropical and warm regions. This study carried out in Anthony van Leeuwenhoek Research Laboratory, Nekede in Imo State, Nigeria isolated Salmonella typhimurium from feces of different categories of livestock using selective/differential media and determined the effects of ethanolic and methanolic extracts of O. gratissimum and C. papaya on the dehydrogenase activity of the recovered Salmonella typhimurium. This is because the outcome of this study will contribute to current knowledge on the variations in the effects of ethanolic and methanolic extracts of O. gratissimum and C. papaya on the dehydrogenase activity of Salmonella typhimurium.
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