Effect of centella asiatica ethanolic extract on alkyl hydroperoxide reductase c (AhpC) of staphylococcus aureus (ATCC 25923) / Nurul Wajihah Ramezan

Centella asiatica plant has many different properties such as antimicrobial, potential antifungal and antioxidants which is of interested for studies. Staphylococcus aureus is a major problem in the community as it causes a variety of infections and develops resistance towards antibiotics rapidly. The aims of this study is to identify the antimicrobial effect of C. asiatica ethanolic extract against S. aureus (ATCC 25923), to investigate the effect of diamide and C. asiatica ethanolic extract treatment on killing rate of S. aureus (ATCC 25923) and the effect of C. asiatica ethanolic extract on the expression of AhpC protein in S. aureus (ATCC 25923). The antimicrobial effect of C. asiatica ethanolic extract against S. aureus (ATCC 25923) was determined by Minimal Inhibitory Concentration (MIC) and Minimal Bactericidal Concentration (MBC) methods which MIC and MBC value were 16 mg/ml and 32 mg/ml respectively. S. aureus treated with MIC of C. asiatica extract and 10 mM diamide showed decreasing survival to 7.23 % at 30 minutes and almost completely killed at 150 minutes. S. aureus challenged with MIC of C. asiatica extract alone showed slower death rate compared to the treatment of MIC of C. asiatica extract together with 10 mM diamide which only about 70 % of S. aureus killed at first 30 minutes and were killed completely at 150 minutes. 10 mM diamide treatment alone showed slowest killing rate compared with other treatment which only about 37 % S. aureus were killed at 30 minutes and at 180 minutes, 80 % of S. aureus were killed. The expression of AhpC protein in S. aureus (ATCC 25923) was visualized by SDS-PAGE analysis. There was no reduced expression of Ahpc in treated with 1 hour and 2 hour of MIC C. asiatica extract compared to untreated S. aureus. S. aureus treated with 32 μg/ml penicillin also showed same intensity colour band corresponding to Ahpc of untreated S. aureus. Thus, it is found that C. asiatica ethanolic extract has antimicrobial effect against S. aureus (ATCC 25923), and diamide can enhance C. asiatica ethanolic extract killed S. aureus (ATCC 25923) but C. asiatica ethanolic extract alone killed better S. aureus (ATCC 25923). The expression AhpC protein of untreated S. aureus (ATCC 25923) and treated S. aureus (ATCC 25923) with C. asiatica ethanolic extract and penicillin do not showed any reduced expression. It can be concluded AhpC does have oxidative stress resistance alongside with catalase in S. aureus.