In vivo antibacterial activity of Garcinia mangostana pericarp extract against methicillin-resistant Staphylococcus aureus in a mouse superficial skin infection model.

Context: Garcinia mangostana Linn. (Guttiferae) (GM) pericarp has been shown to exhibit good in vitro antibacterial activity against methicillin-resistant Staphylococcus aureus (MRSA); however, there is currently no available information regarding its in vivo antibacterial activity.
Objective: To examine in vivo antibacterial activity of G. mangostana extract against MRSA.
Materials and Methods: GM pericarp was extracted by ethanol (GM-EtOH) and methanol (GM-MeOH). The crude extracts were examined for in vitro antibacterial activity against MRSA using broth microdilution assay. The in vivo antibacterial activity of 10% GM-EtOH against MRSA was determined in a tape stripping mouse model of superficial skin infection for 9 days by evaluating transepidermal water loss (TEWL) and performing colony counts from cultured swabs.
Results: GM-EtOH showed greater in vitro activity against MRSA than GM-MeOH in broth microdilution assay with minimum inhibitory concentration 17 versus 20 μg/mL and minimum bactericidal concentration 30 versus 35 μg/mL, respectively. The GM-EtOH (13.20 ± 0.49%) contained α-mangostin more than the GM-MeOH (9.83 ± 0.30%). In the tape stripping mouse model, 10% GM-EtOH reduced the number of MRSA colonies (0-1) recovered from infected wounds (>100 colonies) on the first day of treatment, restored TEWL to normal levels on the fourth day, and had completely healed the wounds by day 9.
Conclusion: GM-EtOH showed promising in vivo antibacterial activity against MRSA in a superficial skin infection model in mice. It is of interest to develop a topical formulation of GM-EtOH to further study its potential as a novel antibacterial agent.