In vitro effect of an alkaloid isolated from Amphimedon viridis (Porifera)on promastigots of Leishmania mexicana

The dose dependent antiproliferative effect of an alkaloidal substance extr acted from the sponge Amphimedon viridis was tested on Leishmania mexicana promastigotes. Sponges were collected in Isla Larga, Venezuela (10 degrees 20' 20 " - 10 degrees 24 " N, 64 degrees 19' - 64 degrees 22' W), cut and d ipped in methanol for vacum filtering extraction every 24 hr. The aqueous e xtract was separated by chromatography over silica gel. The parasites were from the Venezuelan NR strain. Their growth rate was reduced by 50 % with a dose of 10 mug/ml in 48 hr, whilst concentrations of 30 and 40 mug/ml indu ce leishmanicidal action after 110 and 20 min, respectively. Lysis is prece ded by an immediate increase in cellular volume associated with progressive damage of cellular content and the destruction of organelles. These findin gs suggest that one important factor associated with the antiproliferative effect of this alkaloidal substance on L, mexicana promastigotes is the los s of the plasma membrane selective permeability.