Cytotoxic Activity Study Of Crotapotin And Native And Modified Phospholipase A2 Isolated From Crotalus durissus terrificus VenomOn Tumoral Cells

¹Menezes, C.S.R.; ¹Gebrim, L.C.P.C.; ¹Silveira-Lacerda, E.P.; ¹Rodrigues, V.M.; ¹Homsi-Brandeburgo, M. I. and ¹Hamaguchi, A.

1 Instituto de Genética e Bioquímica, Universidade Federal de Uberlândia, Uberlândia-MG, Brasil.

Crotoxin is a B-neurotoxin protein from Crotalus durissus terrificus venom, a heterodimeric protein composed by two subunits: crotactine, a basic protein having phospholipase A2 (PLA2) activity and crotapotin, an acidic protein. The aim of this work was to investigate the cytotoxic activity in vitro induced by PLA2  native and modified and crotapotine on Sarcoma 180 (S180), melanoma (B16F10) and intraperitoneal macrophage murine cells. PLA2 was submitted to chemical modifications of aminoacids residues: His, by using 4-bromophenacyl bromide (BPB); Tyr by 2- nitrobenzenesulphonyl fluoride (NBSF) and Trp by o-nitrophenylsulphenyl (NPSC) that affected several pharmacological, catalytic and toxic activities. The cells were distributed in plates of 96 wells with 5.0 x 10⁵ cells.mL^-1 in each well and were treated with 0.1mg.mL^-1 to 1.0mg.mL^-1 of each toxin, alone or associated. After 24h of treatment exposure, cells were counted and their viability determined by the colorimetric MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium assay. At low concentrations, PLA2 and crotapotin showed high cytotoxic activity on all tumor cells (approximately 70%), however this effect was lower on macrophage (about 12%). The modified PLA2 presented anti-tumoral activity reduced, probably due to modification in its structure resulting in decrease of the cytotoxicity on neoplasic cells. Increased of toxicity was observed when PLA2 and crotapotin were associated. We conclude that these toxins may play a relevant role in the control of cancer cells proliferation.

Financial Support: Capes, CNPq and FAPEMIG.

Correspondence to: casm_br@yahoo.com.br