Trypanocidal Activity of Methanolic Extracts (50 and 100%) of Emblica officinalis (Phyllanthus emblica Linn) Dried Fruits against Trypanosoma evansi

Abstract

Trypanosomosis is on the increase in the endemic regions of the world and resistant strains of trypanosomes had defiled few limited classes of readily available trypanocides. There is a need to search for new drug. Because of this, Emblica officinalis dried fruits were extracted with methanolic solvent (50 and 100%). The test extracts of E. officinalis dried fruits at different concentrations ((250-1000 µg ml-1) were screened against Trypanosoma evansi on Alsever’s medium. Trypanosomes were suspended in Alsever’s solution with inactivated bovine serum at 58oC for 1 h.  Trypanosomes concentration was 1x10⁶ parasites/ml. 180 µl of the medium was added to the test extract of E. officinalis (20 µl) and incubated at 37oC with 5% carbon dioxide for 5 h. On hourly basis, drops of the incubated mixture were observed under inverted microscope for antitrypanosomal activity. In vitro cytotoxicity test of methanolic plant extract (MPE) of E. officinalis at concentrations (1.56-100 µg ml-1) was done on Vero cells grown in Dulbecco's Modified Eagle Medium (DMEM) but without fetal calf serum at appropriate conditions. Marked trypanocidal activity was observed at 250 µg ml-1 of MPE (100%) of E. officinalis and trypanosomes were not detected after 5 h of incubation, which was statistically equivalent to diminazine aceturate (50µg/ml) standard drug at 4 h. For 250 µg ml-1 of MPE of E. officinalis (50%), there was drastic reduction at the end of 5 h incubation but not complete killing of trypanosomes. However, at 500 µg ml-1, trypanosomes were not detectable at 4 h of incubation.  Extract of E. officinalis and diminazine aceturate were cytotoxic to Vero cells in all concentrations except at 1.56-6. 25 µg ml-1. MPE of E. officinalis exhibited marked trypanocidal activity with significant difference ((P ≤ 0.05 to 0. 01).). These results pave way for further research (e.g. bioassay-guided purification) for isolation of trypanocidal compound(s), which will give a lead for development of new trypanocide.