Correlation between antibacterial activity and yeast extract of <i>Orthosiphon stamineus</i> extract

Abstract

This paper investigates the boosting antibacterial effect of O. stamineus extracts supplemented with 1.0, 2.0, 3.0, 4.0 and 5.0 mg/ml concentration of yeast extracts. Leaves and stems of O. stamineus were extracted with methanol to assess their different antibacterial potential against Staphylococcus aureus, Escherichia coli and Pseudomonas aeruginosa through disc diffusion assay. Post-hoc comparisons using Tukey HSD test indicated the mean zone of inhibition for leaves extract (M = 8.67, SD = 0.58) was different compared to stems extract (M = 10.33, SD = 0.58) towards S. aureus. Zone of inhibition produced by the leaves extract (M = 6.67, SD = 0.58) was different compared to the stems extract (M = 7.00, SD = 0.00) towards E. coli. O. stamineus have no antibacterial potential against P. aeruginosa. This study showed the addition of yeast extract have no enhancing or reducing effect towards antibacterial potential. The Pearson correlation coefficient ranging from r(6) = -0.003 to -0.594, p < 0.212 to 0.996.

Keywords: correlation; antibacterial activity; yeast extract; Orthosiphon staminues