title: Pharmacological characterization of venoms from three theraphosid spiders: Poecilotheria regalis, Ceratogyrus darlingi and Brachypelma epicureanum.
abstract: BACKGROUND
  Tarantulas (Theraphosidae) represent an important source of novel biologically active compounds that target a variety of ion channels and cell receptors in both insects and mammals. In this study, we evaluate and compare the pharmacological activity of venoms from three taxonomically different theraphosid spiders bred in captivity: Poecilotheria regalis, an aggressive arboreal tarantula from southeastern India; Ceratogyrus darlingi, an aggressive tarantula from southern Africa; and Brachypelma epicureanum, a docile tarantula from the Yucatan dry forest of Mexico. Prior to this study, no research had been conducted with regard to the composition and pharmacological activity of these venoms.
  
  
  METHODS
  The pharmacological characterization of the venoms was described for the first time by the assessment of their toxicity in crickets (LD50) along with their nociceptive (by using the formalin test), hyaluronidase, phospholipase A2, edematogenic and caseinolytic activity.
  
  
  RESULTS
  P. regalis and B. epicureanum venoms induced a similar lethal effect on crickets (LD50 = 5.23 ± 3.1 and 14.4 ± 5.0 μg protein/g 48 h post-injection, respectively), whereas C. darlingi venom (119.4 ± 29.5 μg protein/g 48 h post-injection) was significantly less lethal than the other two venoms. All three venoms induced similar edematogenic activity on rats but did not induce nociceptive behavior. The assessment of enzymatic activity indicated that P. regalis venom induces significantly higher hyaluronidase activity (27.6 ± 0.9 TRU/mg) than both C. darlingi (99.7 ± 1.9 TRU/mg) and B. epicureanum (99.6 ± 1.6 TRU/mg); these latter venoms did not display phospholipase A2 or caseinolytic activity.
  
  
  CONCLUSIONS
  This study demonstrates that these theraphosid spiders of different habitats produce venoms with different activities. P. regalis venom displays a high level of hyaluronidase activity, which may be associated with its potentially medically significant bite.
authors.affiliation: Laboratory of Chemical and Pharmacological Natural Product Research, School of Chemistry, Autonomous University of Querétaro (UAQ), Santiago de Querétaro, Querétaro Mexico.
authors.forename: Alejandro
authors.initials: A
authors.lastname: García-Arredondo
authors.affiliation: Laboratory of Chemical and Pharmacological Natural Product Research, School of Chemistry, Autonomous University of Querétaro (UAQ), Santiago de Querétaro, Querétaro Mexico.
authors.forename: Luis
authors.initials: L
authors.lastname: Rodríguez-Rios
authors.affiliation: Laboratory of Chemical and Pharmacological Natural Product Research, School of Chemistry, Autonomous University of Querétaro (UAQ), Santiago de Querétaro, Querétaro Mexico.
authors.forename: Luis Fernando
authors.initials: LF
authors.lastname: Díaz-Peña
authors.affiliation: Laboratory of Chemical and Pharmacological Natural Product Research, School of Chemistry, Autonomous University of Querétaro (UAQ), Santiago de Querétaro, Querétaro Mexico.
authors.forename: Ricardo
authors.initials: R
authors.lastname: Vega-Ángeles
keywords: Brachypelma epicureanum; Ceratogyrus darlingi; Poecilotheria regalis; Tarantula; Toxicity; Venom