Study on developmental biochemical characteristics of Leishmania donovani promastigote and inhibitory effect of Achyranthes aspera Linn plant extract on it

Leishmania donovani is an obligatory intracellular digenetic parasite transmitted by insects, causing serious global health problems as it is endemic to most developing countries. Extensive use of antimony compounds as drugs poses high toxicity and cost; therefore, herbal medicine has identified a position. This study explored the developmental and biochemical characteristics of L. donovani promastigote and the effect of ethanolic extract of Achyranthes aspera Linn (Amaranthaceae) plant on it. The parasites were incubated at 2.5×106 cells/well for 72 h at 23 °C in the presence of various concentrations of extract (µg/mL) dissolved in 1% dimethyl sulfoxide (DMSO) with sterile phosphate-buffered saline and 1% DMSO as negative controls and meglumine antimoniate as positive control. Friedman’s repeated measures analysis showed that 96hr of development is the junction point in promastigotes ontogeny. Post 96hr, it grows with a long stationary phase with higher enzymatic activities of acid phosphatase, superoxide dismutase and glutathione (oxidized and reduced). Total protein estimated showed a linear relationship (R2 = 0.999). Phytochemical screening of the plant extract showed the presence of alkaloid, ﬂavonoid, fixed oil and fats, saponin, tannin and phenolic compounds. It showed an effectual free radical scavenging in the 2,2-diphenyl-1-picrylhydrazyl (DPPH) assay with an inhibitory concentration IC50 value of 61.70 µg/ml. At a concentration of 250 µg/mL, the plant extract completely inhibited the promastigotes in vitro while at 50 µg/mL and 100 µg/mL, the survival level declined by 25-50%. These findings corroborate the ethnopharmacological use of this plant for the treatment of leishmaniasis caused by L. donovani.