Investigation of antibacterial and antifungal activity of Saussurea costus root extracts

Infectious diseases are a serious danger to public health, and plants may be a potential source of novel antimicrobial agents. In this study, the antibacterial and antifungal activity of the essential oil, hexane-chloroform, methanolic, and aqueous extracts of Saussurea costus (S. costus) root were evaluated against Staphylococcus aureus, Pseudomonas aeruginosa, Staphylococcus epidermidis, Enterobacter cloacae, Enterococcus faecalis, Klebsiella pneumonia, Acinetobacter baumannii, Escherichia coli, and Candida albicans. For this evaluation, disc diffusion and micro- dilution susceptibility assays were performed. Chemical analysis was also performed to determine phytochemical constituents of the extracts. Our results showed that the essential oil and methanolic extract of S. costus root exhibited the highest antimicrobial activity, followed by hexane-chloroform extract, with aqueous extract showing the lowest activity. The highest activity with the lowest MIC value was recorded as 3.12 μl/ml for the essential oil (against S. epidermidis and C. albicans), 3.12 mg/ml for the methanolic extract (against S. aureus), and 6.25 mg/ml for both hexane-chloroform and aqueous extracts (against S. aureus). In general, the tested extracts had moderate to good antimicrobial activity against the tested gram-positive bacteria and C. albicans. S. costus root can be considered as a potential natural source of antimicrobial agents to fight pathogen microorganisms.