Inhibition of Dehydrogenase Activity in pathogenic bacteria Isolates by aqueous extract of Curcuma longa (Turmeric) Rhizome

Abstract

Inhibition of dehydrogenase activity in pathogenic Gram – positive and Gram – negative microorganism exposed to ethanol extract of curcuma longa was used as an index for assessment of its antibacterial activity. Assay of dehydrogenase activity was done in the test organisms (Escherichia Coli, Staphlococcus aureus and Salmonella typhi) using 2, 3, 5- triphenyltetrazolium chloride (TTC) as an artificial electron acceptor which was reduced to the red-coloured triphenyl-formazan. Response of the bacterial isolates varied with extract concentration. Dehydrogenase activity was progressively inhibited in a logistic dose-response fashion. The Gram positive staphylococcus aureus responded more markedly than Gram negative Escherichia Coli and Salmonella typhi inhibitory concentrations (IC50) of ethanol extracts against Escherichia Coli, Staphylococcus aureus and Salmonella typhi were 250.51ug/ml, 55.80ug/ml, and 570.48ug/ml respectively. Preliminary phytochemical screening of the extract gave positive reactions for alkaloids, flavonoids, tannins, 4-hydroxybenzoic acid (phenolic compound) and saponins. These phytochemicals may be responsible for the observed inhibition of total dehydrogenase enzyme activity that translates to anti-bacterial action in these pathogenic organisms.