BIOCHEMICAL AND PHARMACOLOGICAL CHARACTERIZATION OF Vitalius dubius (ARANEAE, THERAPHOSIDAE) VENOM

ROCHA E SILVA T.A.A. (1), FRANCHI JR. G.C.(2), NOWILL A. E. (2), HYSLOP S. (1)

(1) Dept. of Pharmacology and (2) Onco-Hematological Child Research Center,  Faculty of Medical Sciences, State University of Campinas (UNICAMP), Campinas, SP, Brazil.

Tarantula venoms are a rich source of proteins and peptides with novel pharmacological activities. In this work, we examined the composition and some biological activities of venom from the Brazilian tarantula Vitalius dubius. Venom was obtained by electrostimulation and contained high hyaluronidase activity (275±24 turbidity reducing units/mg of protein; mean±SEM, n=4) but no significant proteolytic activity towards casein, collagen or elastin. SDS-PAGE (10% and 20% gels) revealed proteins of 14 to 160kDa and two bands of peptides (2-4kDa and 6-12kDa). Fractionation of the venom by reversed phase chromatography resulted in three major and four minor peaks. The venom reacted in ELISA with affinity purified IgG from arachnidic antivenom (Butantan Institute) raised against spider (Phoneutria nigriventer andLoxosceles gaucho) and scorpion (Tityus serrulatus) venoms. Immunoblots detected proteins of 40 to 100 kDa. Venom dose-dependently increased the vascular permeability in rat skin (53±3, 100±6, 153±8, 165±9 and 202±10 ml of plasma for 1, 3, 10, 30, and 100 mg of venom/site, respectively; n=6) but did not contract isolated guinea-pig ileum (up to 100 mg/ml) or significantly alter the dose-response curves to acetylcholine or serotonin; however, it potentiated the maximum response to bradykinin from 25 to 200% over control.  The venom (up to 200 mg/ml) was not hemolytic to rat erythrocytes but was cytotoxic to the leukemic cell line K562 (maximum mortality of 64±3% after 72h with 300 mg of venom/ml, n=3). Vitalius dubius venom causes edema and cytotoxicity and contains various proteins and peptides, some of which share immunological similarity with other arachnid venoms.

KEY WORDS: hyaluronidase, tarantula, vascular permeability, venom.

FINANCIAL SUPPORT: FAPESP.

CORRESPONDENCE TO: THOMAZ A.A. ROCHA E SILVA, Dept. of Pharmacology, Faculty of Medical Sciences, State University of Campinas (UNICAMP), PO Box 6111, 13083-970, Campinas, SP, Brazil. Fax: +(55) (19) 3289-2968, E-mail: taars@unicamp.br; hyslop@fcm.unicamp.br