Abstract
Cordyceps militaris has been used for treating various diseases, as well as maintaining good overall health. The antibacterial properties of the C. militaris fruiting body and substrate, cultured in Chiang Mai (sample A and B) and Chiang Rai (sample C), Thailand, were investigated in this study. The aqueous and ethanolic extracts of C. militaris exhibited antibacterial activities against Staphylococcus aureus, Pseudomonas aeruginosa, Cutibacterium acnes and methicillin-resistant S. aureus (MRSA) with the MIC/MBC ranging from 3.91 to 31.25 mg/mL. The ethanolic extracts of the fruiting body and substrate from sample B also inhibited all bacterial growth within 2-4 h of treatment. Furthermore, ethanolic extract from sample B showed the highest cordycepin content of 57.42 mg/g extract, whereas the highest adenosine content, 3.78 mg/g extract, was observed in the ethanolic extract from the fruiting body of sample A by HPLC. The ethanolic extracts from sample A also demonstrated the highest antioxidant activity and flavonoid content by 9.50 mg GAE/g extract and 10.59 mg QAE/g extract, respectively. However, the highest phenolic content of 49.04 mg GAE/g extract was found in the aqueous extract of sample A. In addition, the ethanolic extract of sample A at 2 and 4 mg/mL could significantly down-regulate the mecA gene expression in MRSA. Our findings reported the potential of C. militaris extract as a new substance for the treatment of skin pathogenic bacteria infections and an antioxidant agent.