Rastreio toxicológico do extrato hidroalcoólico de jambolão (Syzygium Cumini (L.) Skeels) em zebrafish (Danio rerio)

Abstract

The jambolan (Syzygium cumini (L.) Skeels) is an important source of phenolic compounds, particularly anthocyanins, substances that contribute to its biological properties. However, beyond its bioactive properties, it is necessary to conduct investigations to certify safe dosages for its use. This study aimed to perform a toxicological screening of the hydroalcoholic extract of jambolan (EJ) administered at different concentrations in the zebrafish (Danio rerio) model at different life stages (embryonic and adult). The EJ was obtained from lyophilized jambolan fruits (pulp+peel) using 70% v/v ethanol through exhaustive cold extraction. The extract characterization was performed using the following analyses: high-performance liquid chromatography (HPLC), total phenolic compounds (TPC), total monomeric anthocyanins (TMA), and antioxidant activity (ABTS and DPPH). Zebrafish were exposed to serial concentrations of EJ (10 – 400 µg/ml) and subjected to acute toxicological screening, cardio and neurotoxicity evaluations, as well as morphological and histological analyses. Fifteen phenolic compounds were identified by HPLC, with anthocyanins being predominant (82%). The EJ showed a TPC content of 21.80 ± 0.01 mg GAE/g of dry fruit and TMA content of 11.39 ± 0.91 mg Cy3-G/g of dry fruit, with DPPH antioxidant activity of 844.70 ± 58.81 mmol Trolox Eq/g and ABTS+ of 323.88 ± 11.05 mmol Trolox Eq/g, with inhibitory activity (IC50) of ABTS+ at 0.606 mg/ml. EJ concentrations above 50 µg/ml were directly proportional to a higher number of malformations and death in both life stages of zebrafish. The estimated median lethal concentration (LC50) for embryos was 118.4 ± 11.7 µg/ml and for adults was 68.86 ± 4.45 µg/ml, with the estimated chronic toxic concentration being 10.22 µg/ml and 5.54 µg/ml, respectively, for these stages. Overall, no cardio or neurotoxicity was observed in larvae exposed to EJ, but those exposed to a concentration of 10 µg/ml exhibited inferior behavioral performance (p < 0.0001). In adults, anxious behavior was noted in the EJ 10 µg/ml group in the novel tank and avoidance tests (p < 0.05 and p ≥ 0.005), and in the EJ 100 µg/ml group in the sociability test (p < 0.05); the EJ 50 µg/ml group showed greater exploratory activity in the open field and aggression tests (p < 0.05). Additionally, histopathological analyses showed that animals from all groups, including the control group, exhibited morphological impairment in the spinal cord, liver, and intestine. However, some animals in the EJ-exposed groups showed preserved intestinal morphology, suggesting a protective effect of EJ on this organ. In light of the above, the results indicate that moderate doses of EJ (around 25 µg/ml) are safe in both life stages of zebrafish. However, further tests addressing aspects not analyzed in the present study need to be conducted to ensure the safety and efficacy of EJ, with a view to advancing research on the bioactive potential of this extract in various health conditions.