Effects of ethanolic extract of cantella asiatica on the expression of superoxide dismutases (SODs) in staphylococcus aureus (ATCC 25923) / Mohamad Zahid Mohd Kasiram

Centella asiatica (C. asiatica) plant is known to possess antimicrobial properties and is widely used in traditional medicine in Asian country. The objectives of this study are to determine the minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of ethanolic extract of C. asiatica against Staphylococcus aureus (S. aureus) through broth rnicrodilution method. Further, killing potential of ethanolic extract of C. asiatica was also determined by performing liquid killing assay of extract against S. aureus in reference to 10 mM methyl viologen (paraquat). Further, the effect of ethanolic extract of C. asiatica on expression of superoxide dismutases (SODs) encoding SodA and SodM in S. aureus were also investigated through SDS-PAGE analysis. The results showed that MIC and MBC of ethanolic extract of C. asiatica are 16 mg/mL and 32 mg/mL respectively. 10 mM methyl viologen does not significantly (p>0.05) affect the killing potential of ethanolic extract of C. asiatica against S. aureus although it reduced percent survival of S. aureus to 2.8% compared to C. asiatica extract alone that reduced cell survival to 4.1 % in 30 minutes. Expression of SodA and SodM may possibly be slightly inhibited as evident by reduction of density of the 23 kDa and 22.7 kDa protein band (comigration) is reduced after being treated with MIC of ethanolic extract of C. asiatica compared to untreated S. aureus. Total protein between untreated and treated S. aureus also showed reduction from 2.62 mg/mLi:o 2.31 mg/mL (1 hour) and 1.88 mg/mL (2 hours) indicating effective treatment with C. asiatica extract. Mechanism of antimicrobial activity of ethanolic extract of C. asiatica against S. aureus is suggested through inhibition of SodA and SodM expression to eliminate its protective role against superoxide radical generated to kill it.