Gerardo Magela Vieira Júnior

magela@ufpi.edu.br

Laboratório de Produtos Naturais – Departamento de Química, Universidade Federal do Piauí, Piauí, Brazil

Toad poison is a fascinating source of bioactive secondary metabolites, such as alkaloids, arginine derivatives, biogenic amines, bufotoxins and bufadienolides, among others like peptides and proteins. Over fourteen years researching toad poison, our group has worked with toad species from Amazon, Cerrado and Caatinga Brazilian biomes. Anurans of the Bufonidae family have a pair of parotid glands, present in the dorsolateral region of the body, which store biological secretions of high toxicity and varied chemical composition, having the function of defense against infections, microorganisms, and predators. In my research, approximately 70 compounds were identified and/or isolated from toad poison species of Bufonidae family (Rhinella marina, R. jimi, R. diptchya, R. granulosa, Rhaebo guttatus), mainly bufadienolides and alkaloids. A large number of biological activities of extracts and/or isolated compounds were evaluated, such as cytotoxic, antiplasmodial, antimutagenic, antitumor, Na, K-ATPase inhibition, phytoalexin induction, antibacterial, antifungal, acetylcholinesterase inhibition and larvicidal, where the extracts and/or compounds presented promising potential in many of these activities. The metabolomic and ionomic profiles of Rhinella jimi were investigated in different biomes in the state of Piauí – Brazil, where it was observed that PCA revealed that abiotic factors such as biome and seasonality influence in the ionome but did not show significantly differences in their secondary metabolites. A comprehensive approach combining analytical and chemometric techniques was developed to investigate the venomic profile (peptides and proteins). Two quantification methods for bufadienolides were established: one using HPLC-UV for specific bufadienolides and another using UV-Vis for total bufadienolides found in toad poison. Currently, some bufadienolides are being submitted to reactions to obtain acylated and amino-ester derivatives, aiming to enhance their cytotoxic and antiplasmodial activities.

Keywords: Toad poison, secondary metabolites, biological activities, environmental interaction, development methods, structural modification

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