Browsing by Author "Soares, Andreimar M."

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Structural, enzymatic and pharmacological profiles of AplTX-II - A basic sPLA2 (D49) isolated from the Agkistrodon piscivorus leucostoma snake venom
(2021) Ramos, Maria Joäo
A basic sPLA2 (D49) from the venom of snake Agkistrodon piscivorus leucostoma (AplTX-II) was isolated, purified and characterized. We determined the enzymatic and pharmacological profiles of this toxin. AplTX-II was isolated with a high level of purity through reverse phase chromatography and molecular exclusion. The enzyme showed pI 9.48 and molecular weight of 14,003 Da. The enzymatic activity of the AplTX-II depended on Ca2+ pH and temperature. The comparison of the primary structure with other sPLA2s revealed that AplTX-II presented all the structural reasons expected for a basic sPLA2s. Additionally, we have resolved its structure with the docked synthetic substrate NOBA (4-nitro-3-octanoyloxy benzoic acid) by homology modeling, and performed MD simulations with explicit solvent. Structural similarities were found between the enzyme's modeled structure and other snake sPLA2 X-Ray structures, available in the PDB database. NOBA and active-site water molecules spontaneously adopted stable positions and established interactions in full agreement with the reaction mechanism, proposed for the physiological substrate, suggesting that NOBA hydrolysis is an excellent model to study phospholipid hydrolysis.
Synergism of in vitro plasmodicidal activity of phospholipase A2 isoforms isolated from panamanian Bothrops asper venom
(2021) Silva, Simoes R.; Alfonso Ruiz Díaz, Jorge Javier; Gómez Garay, Ana Fidelina; Sobrinho, Juliana C.; Kayano, Anderson Makoto; Medeiros, Daniel Sol de; Teles, Carolina Bioni Garcia; Quintero Rueda, Aristides; Fuly, Andre; Gómez, Celeste Vega; Pereira, Soraya S.; Da Silva, Saulo Luis; Stábeli, Rodrigo Guerino; Soares, Andreimar M.
Bothrops asper is one of the most important snake species in Central America, mainly because of its medical importance in countries like Ecuador, Panama and Costa Rica, where this species causes a high number of snakebite accidents. Several basic phospholipases A2 (PLA2s) have been previously characterized from B. asper venom, but few studies have been carried out with its acidic isoforms. In addition, since snake venom is a rich source of bioactive substances, it is necessary to investigate the biotechnological potential of its components. In this context, this study aimed to carry out the biochemical characterization of PLA2 isoforms isolated from B. asper venom and to evaluate the antiparasitic potential of these toxins. The venom and key fractions were subjected to different chromatographic steps, obtaining nine PLA2s, four acidic ones (BaspAc-I, BaspAc-II, BaspAc-III and BaspAc-IV) and five basic ones (BaspB-I, BaspB-II, BaspB-III, BaspB-IV and BaspB-V). The isoelectric points of the acidic PLA2s were also determined, which presented values ranging between 4.5 and 5. The findings indicated the isolation of five unpublished isoforms, four Asp49-PLA, corresponding to the group of acidic isoforms, and one Lys49-PLA2-like. Acidic PLA2s catalyzed the degradation of all substrates evaluated; however, for the basic PLA2s, there was a preference for phosphatidylglycerol and phosphatidic acid. The antiparasitic potential of the toxins was evaluated, and the acidic PLA2s demonstrated action against the epimastigote forms of T. cruzi and promastigote forms of L. infantum, while the basic PLA2s BaspB-II and BaspB-IV showed activity against P. falciparum. The results indicated an increase of up to 10 times in antiplasmodial activity, when the Asp49-PLA2 and Lys49-PLA2 were associated with one another, denoting synergistic action between these PLA2 isoforms. These findings correspond to the first report of synergistic antiplasmodial action for svPLA2s, demonstrating that these molecules may be important targets in the search for new antiparasitic agents
Viperidae snakebites in Ecuador: a review of epidemiological and ecological aspects
(2020) Arias Peláez, María Cristina; Da Silva, Saulo Luis; Celorio Carvajal, Cristopher Andrew; Zaruma Torres, Fausto Leonardo; Soares, Andreimar M.; Alves da Silva Caldeira, Cleópatra; Ochoa Avilés, Angélica María; Heredia Andino, Odalys Stefania; Escandón Dután, Samuel Adrián
Snakebite envenoming is a neglected disease of public health concern. Most snakebite accidents occur in developing countries. In Ecuador, 17 viper species are responsible for 99% of official accidents, and ten species are in critical conservation states. This report analyzes the snakebite incident cases and mortality rates in Ecuador between 2014 and 2019. The data obtained from the national surveillance system suggests that the incidence and mortality rates remained constant. The geographic region with the highest incidence rates is the Amazonian region. National policies are urgently needed to prevent snakebite accidents and to protect snakes in danger of extinction.