Antioxidant Activity and Toxicity of Stem Bark Extracts of Hancornia speciosa Gomes (Apocynaceae)

Hancornia speciosa Gomes, popularly known as mangabeira, is a species from the Apocynaceae family widely distributed in Brazil and used in traditional medicine due to its therapeutic properties. This study aimed to evaluate the antioxidant activity and toxicity of stem bark extracts from this species. The extracts were obtained through sequential extractions using n-hexane, ethyl ether, and methanol. Antioxidant activity was assessed using the DPPH radical scavenging assay, while toxicity was evaluated through the Artemia salina bioassay. The results showed that the extracts exhibited significant antioxidant capacity, with emphasis on the ethereal extract (EEHS), which presented an IC₅₀ of 7.35 μg/mL, a value close to that of the positive control, ascorbic acid (IC₅₀ of 4.31 μg/mL). In the toxicity assay, EEHS showed higher toxicity, with an LC₅₀ of 67.35 μg/mL, comparable to potassium dichromate, while the methanolic extract (EMHS) exhibited an LC₅₀ of 561.7 μg/mL, indicating lower toxicity. These findings highlight the potential of the species as a source of bioactive compounds with antioxidant properties, while also emphasizing the need for further studies to structurally characterize the involved metabolites, elucidate their mechanisms of action, and evaluate the safety of these extracts for possible therapeutic applications. Additional assays using more complex biological models are essential to determine their viability in the development of new antioxidant agents and natural product-based drugs.