Aqueous Bark Extract of Ceiba speciosa (A. St.-Hill) Ravenna Protects against Glucose Toxicity in Caenorhabditis elegans

Plants are widely used in folk medicine because of their pharmacological properties. Ceiba speciosa, popularly known as paineira-rosa or tree-of-wool, is a species found in the Northwest of Rio Grande do Sul, being native of the upper Uruguay River, Brazil. The tea obtained from the stem bark is employed in folk medicine to reduce cholesterol, triacylglycerides, and glucose levels. However, there are no studies in the literature proving its efficacy or the safety of its use. For this study, we used Caenorhabditis elegans as an animal model considering its advantages for risk assessment and pharmacological screenings. For the toxicological tests, C. elegans N2 (wild type) was treated with the aqueous extract of the stem bark of C. speciosa (ECE) at the first larval stage (L1) at concentrations of 5, 25, 50, and 250 μg/mL. To evaluate biological activities, we challenged the extract for oxidative stress resistance in the presence of paraquat (0.5 mM), H(2)O(2) (1 mM), and against glucose-induced toxicity. Our results demonstrated that ECE did not alter survival rate, pharyngeal pumping, and reproduction of the nematodes. The extract was not able to protect the nematodes against the toxicity induced by prooxidants. Notably, ECE protected against glucotoxicity by increasing worms' life span and by reducing glucose levels. On the other hand, ECE treatment did not reduce lipid accumulation induced by exogenous glucose feeding, as observed in worms which lipid droplets were tagged with GFP. Based on our results, we believe that the extract is indeed promising for further studies focusing on carbohydrates metabolism; however, it needs to be carefully evaluated since the extract does not seem to modulate lipid accumulation.