Evaluation of antimicrobial activity of essential oil of Pogostemon heyneanus benth (f. lamiaceae) leaves and formulation of an emulgel dosage form

Abstract

Pogostemon heyneanus Benth is an important medicinal plant belonging to family Lamiaceae. This study investigates the antimicrobial properties of the essential oil obtained from the leaves of P. heyneanus and formulation of an emulgel, The oil was extracted by hydro-distillation. Antimicrobial activity was evaluated against Staphylococcus aureus, Pseudomonas aeruginosa, and Candida albicans using agar disk diffusion method. Gentamicin and fluconazole served as positive controls for bacteria and fungi respectively. As negative control, 10% v/v DMSO was used. An emulgel was prepared using the above essential oil, Tween 20 (the surfactant), and Carbopol 940 (gelling agent). Agar well-diffusion method was used to test the antimicrobial activity of the emulgel. IC50 of the oil and the emulgel was obtained by performing the broth microdilution test. The yield of the essential oil was 1.36 % w/w. The results revealed that the essential oil exhibited significant (p<0.001) antimicrobial activity compared to positive control, with IC 50 values of 8.29 mg/mL for P. aeruginosa, 14.92 mg/mL for S. aureus, and 22.11 mg/mL for C. albicans. However, the IC50 of the emulgel, was slightly higher; 61.7 mg/dL for S. aureus, 56.82 mg/dL for P. aeruginosa, and 61.29 mg/dL for C. albicans. The pH of the emulgel was pH 6.2. There was no any phase separation or colour change of the emulgel up to three months under room temperature. In conclusion, the efficacy of the formulated emulgel, suggesting its potential as a promising topical antimicrobial properties. Further development of emulgel as a value added product would be beneficial.