Supercritical fluid extraction of drug-like materials from selected Myanmar natural plants and their antimicrobial activity

Supercritical fluid extracts of three Myanmar natural plants, namely, Curcuma aeruginosa, Citrus hystrix, and Azadirachta indica A. Juss were screened for antimicrobial activity against different strains of bacteria and yeast, which are known to cause various types of skin infections. The antimicrobial activity was tested on Bacillus cereus, Bacillus subtilis, Staphylococcus epidermidis, Staphylococcus aureus, Escherichia coli, Propionibacterum acnes, and Malassezia furfur. None of the plants tested produced consistent inhibition of the Gram-negative bacteria E. coli and yeast M. furfur. Three plants consistently inhibited bacterial growth of Bacillus subtilis. The antimicrobial activity profile showed that Bacillus subtilis was the most susceptible bacterial strain. According to the antimicrobial profile, SFE extracts of C. aeruginosa presented no significant difference in inhibitory activity on all Gram-positive bacterial strains. A. indica leaf extracts showed the highest antibacterial activity on P. acness and S. aureus, a moderate activity on B. cereus, B. subtilis, and S. epidermidis. The SFE extracts of C. hystrix ( stem and bark) presented the highest antibacterial activity on B. subtilis, moderate activity on B. cereus and S. epidermidis, and weak activity against S. aureus and P. acness. Therefore, the SFE extracts of C. aeruginosa, C. hystrix, and A. indica have the possibility to be applied as a constituent of cosmetic products and medicines, because they exhibit antimicrobial activities. The most active extracts can be subjected to isolation of the therapeutic antimicrobials using SFE techniques and undergo further pharmacological evaluation.