UPREGULATION OF trxB EXPRESSION BY PIPER BETEL LINN ETHANOLIC EXTRACT SUGGESTS INDUCTION OF OXIDATIVE STRESS WHICH POTENTIALLY CONTRIBUTES TO KILLING OF STAPHYLOCOCCUS AUREUS IN VITROUPREGULATION OF TRXB EXPRESSION BY PIPER BETEL LINN ETHANOLIC EXTRACT SU
Objective: In this study, mRNA expressions of thioredoxin reductase B and catalase (encoded by trxB and katA respectively) in S. aureus were quantitated in response to P. betel ethanolic extract to determine its regulatory potential on oxidoreductases that may affect the organismâ€™s ability to survive oxidative damage within the host.
Methods: P. betle ethanolic extract was prepared using the rotary evaporator and predetermined MIC (5mg/ml) for S. aureus (ATCC25923) was used in gene expression analyses that were performed using real-time PCR. Standardized bacterial inoculum (1 x108 cfu/ml) harvested at mid exponential phase were used in all assays. Total cytoplasmic protein concentrations were performed using the Bradford assay as per manufacturerâ€™s instruction.
Results: trxB was expressed 3.95 fold higher in S. aureus cells treated with the extract (p<0.05) whereas expression of katA was only 0.0083 compared to untreated cells. A corresponding increase (87%) in total cytoplasmic protein was observed in cells treated with the extract.
Conclusion: Our observations suggest that P. betle ethanolic extract exerts oxidative stress on S. aureus causing upregulation of trxB. Further, it down regulates expression of katA (catalase) which may contribute to reduced ability of the organism to survive damage caused by phagocytic cells.
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