Synergistic Effect of Garcinia Mangostana Combined With Chlorhexidine on Acanthamoeba Triangularis Trophozoites and Cysts

Background: Various parts of Garcinia mangostana Linn, including its pericarp have been traditionally used to treat different types of diseases. This study was carried out to determine the anti- Acanthamoeba activity of G. mangostana pericarp extract against Acanthamoeba triangularis . Methods: : The G. mangostana ethanolic pericarp extract was screened for the anti- Acanthamoeba activity and determined its minimal inhibition concentrations (MICs) by the microdilution method. Then, the time-kill kinetic assay of the extract was determined. The synergistic effect of G. mangostana extract and chlorhexidine was performed using the checkerboard method. Parasite morphology was detected by scanning electron microscopy (SEM). Results: : The MICs of extract were assessed on trophozoites and cysts with 250 and 4000 µg/mL, respectively. More so, at 2×MIC of extract exhibited inhibitory activity against trophozoites and cyst of A. triangularis for up to 7 days. Checkerboard assays showed synergistic activity of extract (500-1000 μg/mL) plus chlorhexidine (3.90-15.62 μg/mL) at a fractional inhibitory concentration index (FICI) of 0.18-0.37. The lowest FICI (0.18) displayed good synergism resulting in up to 16-fold reduction of drug MIC and reducing to 8-fold of extract MIC. The viability of cysts decreased to 12.28±3.03 cells/mL. FICI interpretation equal to 1 is considered an additive effect on Acanthamoeba trophpzoites. The SEM results clearly showed that Acanthamoeba cells treated with a single drug of chlorhexidine and its combination with G. mangostana extract caused cell membrane damage and irregular cell shapes comparing with the control. Conclusion: A good combinatorial relationship displayed by G. mangostana extract and chlorhexidine suggest a more reliable evidenced based therapeutic strategy. Therefore, this approach is promising and could be employed as an alternative treatment method for the management of Acanthamoeba infection.