Inhibition of Proteolytic and Hemorrhagic Activities by Ethyl Acetate Extract ofEclipta prostrata. Against Malayan Pit Viper Venom

The ethyl acetate extract of Eclipta prostrata. L. (Asteraceae) was evaluated for its antivenom potential against Calloselasma rhodostoma. Kuhl (Viperidae) (Malayan pit viper; MPV) venom. The partially purified ethyl acetate extract (PEE) was found to contain 47% wedelolactone as its major constituent. PEE and wedelolactone demonstrated strong antiproteolytic and antihemorrhagic activities against MPV venom in a dose-dependent manner. The extract, at 5 mg/mL, could inhibit proteolytic activity of 100 µg of the venom and hemorrhagic activity of 3 minimum hemorrhagic doses (MHD) to 95% and 68%, respectively. At the same concentration, wedelolactone could neutralize the proteolytic activity at around 76% and, at doses of 0.25–1 mg/mL, offered protection against hemorrhagic activity of the venom in the range 3–35%. Both PEE and wedelolactone displayed partial anti–phospholipase A2 activity (21% for PEE and 7% for wedelolactone) and could not neutralize the lethal effect of either 2LD50 or 4LD50 of MPV venom.