Physicochemical properties and antimicrobial activities of soap formulations containing Senna alata and Eugenia uniflora leaf preparations

Abstract

Senna alata leaf extract demonstrates antimicrobial properties that promise utility for treatment of topical infections. Its combination with similarly bioactive Eugenia uniflora leaf extract in soap formulation could enhance anti-infective efficacy. The objective of this study was to develop potent antiseptic herbal soap formulations (HSFs) with the combined leaf extracts of the two plants. A soap base having suitable physicochemical properties (emolliency, foaming potential, and pH) was selected from a series of trial formulations produced from basic soap ingredients. Into this was incorporated three different preparations (namely, the methanolic fresh leaf extract (FLE), methanolic dry leaf extract (DLE), and the pulverized dry leaf sample (DLP) of S. alata and E. uniflora, respectively, singly or combined in 1:1 (w/w) ratio; to produce HSFs containing 5, 9, or 11%w/w concentrations of the leaf preparations. The physicochemical properties of the HSFs were determined as well as their antimicrobial activities by hole-in-plate agar diffusion assay against Staphylococcus aureus, Bacillus subtilis and Candida albicans. The selected soap base exhibited highest-rank emolliency, satisfactory stable froth production, and pH value. The physicochemical properties of the resulting HSFs were similar. The HSFs containing combinations of the DLEs at 9 and 11% concentrations demonstrated antimicrobial activities against S. aureus and C. albicans comparable (p>0.05) to those of the comparator commercial antiseptic soap containing 0.30% triclosan. B. subtilis was less sensitive (p<0.05) to the HSFs. On the other hand, when used singly, the DLEs as well as the FLEs and DLPs were significantly less potent (p<0.05) than the DLEs combined in the soap formulations. In conclusion, the HSFs containing S. alata and E. uniflora DLEs combined (1:1 w/w) at 9 and 11% concentrations exhibited satisfactory physicochemical properties and potent antimicrobial activities similar to the comparator commercial antiseptic soap employed in the study. Key words: Senna alata, Eugenia uniflora, leaf extracts, herbal soap formulation.