title: The inhibitory potential of the condensed-tannin-rich fraction of Plathymenia reticulata Benth. (Fabaceae) against Bothrops atrox envenomation.
abstract: BACKGROUND
  Ethnobotanical studies have shown that Plathymenia reticulata Benth. (Fabaceae) has been widely used in cases of snake envenomation, particularly in Northern Brazil. In light of this, the aim of this study was to evaluate the inhibitory potential of the condensed-tannin-rich fraction obtained from the bark of P. reticulata against the main biological activities induced by Bothrops atrox venom (BaV).
  
  
  METHODS
  The chemical composition of the aqueous extract of P. reticulata (AEPr) was first investigated by thin-layer chromatography (TLC) and the extract was then fractionated by column chromatography on Sephadex LH-20. This yielded five main fractions (Pr1, Pr2, Pr3, Pr4 and Pr5), which were analyzed by colorimetry to determine their concentrations of total phenolics, total tannins and condensed tannins and to assess their potential for blocking the phospholipase activity of BaV. The Pr5 fraction was defined as the fraction rich in condensed tannins (CTPr), and its inhibitory potential against the activities of the venom was evaluated. CTPr was evaluated in different in vivo and in vitro experimental protocols. The in vivo protocols consisted of (1) pre-incubation (venom:CTPr, w/w), (2) pre-treatment (orally administered) and (3) post-treatment (orally administered) to evaluate the effect on the hemorrhagic and edematogenic activities of BaV; in the in vitro protocol the effect on phospholipase and coagulant activity using pre-incubation in both tests was evaluated.
  
  
  RESULTS
  There was statistically significant inhibition (p<0.05) of hemorrhagic activity by CTPr when the pre-incubation protocol was used [55% (1:5, w/w) and 74% (1:10, w/w)] and when pre-treatment with doses of 50 and 100mg/kg was used (19% and 13%, respectively). However, for the concentrations tested, there was no statistically significant inhibition in the group subjected to post-treatment administered orally. CTPr blocked 100% of phospholipase activity and 63.3% (1:10, w/w) of coagulant activity when it was pre-incubated with BaV. There was a statistically significant reduction (p<0.05) in edema induced by BaV in the oral protocols. Maximum inhibition was 95% (pre-treatment).
  
  
  CONCLUSIONS
  Our findings indicate that CTPr could be a good source of natural inhibitors of the components of snake venom responsible for inducing local inflammation.
authors.affiliation: Programa Multi-institucional de Pós-graduação em Biotecnologia, Laboratório de Imunoquímica, Instituto de Ciências Biológicas, Universidade Federal do Amazonas-UFAM, Av. Rodrigo Octávio Jordão Ramos, 6.200, 69077-000 Manaus, AM, Brazil. Electronic address: mouraovm@yahoo.com.br.
authors.forename: Valéria Mourão
authors.initials: VM
authors.lastname: de Moura
authors.affiliation: Programa de Pós-graduação em Recursos Naturais da Amazônia, Laboratório de Bioprospecção e Biologia Experimental, Universidade Federal do Oeste do Pará-UFOPA, rua Vera Paz, s/n, Salé, Santarém, PA 68035-110, Brazil.
authors.forename: Wania Cristina Rodrigues
authors.initials: WCR
authors.lastname: da Silva
authors.affiliation: Programa de Pós-graduação em Química, Universidade Federal do Pará-UFPA, Rua Augusto Corrêa, 66075-110 Belém, PA, Brazil.
authors.forename: Juliana D A
authors.initials: JDA
authors.lastname: Raposo
authors.affiliation: Programa de Pós-graduação em Toxinologia, Instituto Butantan, Av. Vital Brazil, 1500, 05503-900 São Paulo, SP, Brazil.
authors.forename: Luciana A
authors.initials: LA
authors.lastname: Freitas-de-Sousa
authors.affiliation: Programa Multi-institucional de Pós-graduação em Biotecnologia, Laboratório de Imunoquímica, Instituto de Ciências Biológicas, Universidade Federal do Amazonas-UFAM, Av. Rodrigo Octávio Jordão Ramos, 6.200, 69077-000 Manaus, AM, Brazil.
authors.forename: Maria Cristina
authors.initials: MC
authors.lastname: Dos-Santos
authors.affiliation: Programa de Pós-graduação em Recursos Naturais da Amazônia, Laboratório de Bioprospecção e Biologia Experimental, Universidade Federal do Oeste do Pará-UFOPA, rua Vera Paz, s/n, Salé, Santarém, PA 68035-110, Brazil.
authors.forename: Ricardo Bezerra
authors.initials: RB
authors.lastname: de Oliveira
authors.affiliation: Programa de Pós-graduação em Recursos Naturais da Amazônia, Laboratório de Bioprospecção e Biologia Experimental, Universidade Federal do Oeste do Pará-UFOPA, rua Vera Paz, s/n, Salé, Santarém, PA 68035-110, Brazil.
authors.forename: Rosa Helena
authors.initials: RH
authors.lastname: Veras Mourão
mesh_terms: D000818:Animals; D000997:Antivenins / Q000737:chemistry / Q000494:pharmacology; D017837:Bothrops; D001938:Brazil; D003435:Crotalid Venoms / Q000037:antagonists & inhibitors*; D004487:Edema / Q000188:drug therapy / Q000378:metabolism; D007887:Fabaceae / Q000737:chemistry*; D006470:Hemorrhage / Q000188:drug therapy / Q000378:metabolism; D010740:Phospholipases / Q000378:metabolism; D010936:Plant Extracts / Q000737:chemistry / Q000494:pharmacology*; D044945:Proanthocyanidins / Q000737:chemistry / Q000494:pharmacology*; D012909:Snake Bites / Q000188:drug therapy*
chemical_list: D000997:Antivenins; D003435:Crotalid Venoms; D010936:Plant Extracts; D044945:Proanthocyanidins; D010740:Phospholipases
keywords: Anti-snakebite plants; Condensed tannins; Plathymenia reticulate; Snakebite envenomation