Antibacterial Activity of Rhinacanthus nasutus (L.) Kurz Extract Against Bacteria with Dermatologic Relevance

Abstract

Rhinacanthus nasutus has been traditionally used for skin treatment. From
previous reports, the extracts of this traditional plant possess antibacterial activity. This
study entailed macerating Rhinacanthus nasutus leaves in methanol, analyzed
compounds of this extract by thin layer chromatography (TLC) and testing the antibacterial
activity of this extract by using disc diffusion and broth dilution techniques against four
bacteria strains, including Staphylococcus aureus, Staphylococcus epidermidis, Escherichia
coli and Pseudomonas aeruginosa.
The results showed that umbelliferone and lupeol are two compounds in this
extract. By disc diffusion technique, 50 and 500 mg/ml of methanolic Rhinacanthus
nasutus extract could inhibit growth of S. aureus, S. epidermidis, and E. coli but did not
inhibit growth of P. aeruginosa. By broth dilution technique, the results of antibacterial
activity were reported as minimum bactericidal concentration (MBC) and minimum
inhibitory concentration at 90 % (MIC90) and 50 % (MIC50). We found that MIC90 of
Rhinacanthus nasutus extract were 9.5±0.12, 9.65±0.11 and 9.8±0.10 mg/ml, and MIC50
were 6.4±0.05, 6.5±0.06 and 6.8±0.04 mg/ml to S. aureus, S. epidermidis, and E. coli,
respectively, and the MBC of extracts to these three bacteria was 25 mg/ml. This study
showed that Rhinacanthus nasutus extracts could inhibit growth of skin bacteria. The
extract will be used to develop skin cleansing products, leading to increased value of
Rhinacanthus nasutus.