Avaliação da toxicidade aguda, potenciais genotóxicos, imunomodulatórios e investigação dos efeitos anti-hiperglicêmicos do infuso liofilizado das folhas de Aristolochia triangularis Cham

Abstract

The Brazilian Cerrado is considered a global hotspot. Although many plant species are used in food, prevention, and treatment of various diseases, it is known that empirical use alone is not enough to validate the safety of a plant. Thus, toxicity studies associated with pharmacological studies are necessary to evaluate the possible adverse effects and ensure safety for use. Also, they can elucidate the medicinal and pharmacological potentials of plants from Brazilian biomes, allowing, in the future, the description of phytotherapeutics and the synthesis and prospection of new drugs. Among the plants of popular use, Aristolochia triangularis, popularly known as "cipózinho-prá-diabetes" and a common occurrence in the south and midwest regions, is one of the 92 Aristolochia spp. cataloged in Brazil so far. Its relevance to this study is justified by the considerable history of use of the plant species in folk medicine to treat diabetes. It is also indicated for the treatment of rheumatism, infections, and skin wounds. The plant organ of A. triangularis used to treat diabetes is the leaf, whose consumption is in tea, obtained by the infusion method. And despite such popular use of the species, there are no records of Brazil studies that validate any safe use of the leaf infusion and corroborate its pharmacological properties. In this sense, the research aimed to evaluate the acute toxicity, estimate the median lethal dose (LD50) in rats treated with the lyophilized infusion (Inf-L) of A. triangularis leaves at a dose of (2000 mg/kg). Subsequently, the mutagenic potential of Inf-L at doses of (0.62, 1.25; 2.5; 5mg/mL) was evaluated in Ames test and by Somatic Mutation and Recombination Test (SMART) using Standard (ST) and High Bioactivation (HB) crosses in Drosophila melanogaster wings. For the in vivo genotoxicity and mutagenicity assays, 50 Wistar rats of both sexes were used, subdivided into five experimental groups (5 animals of each sex): the animals in the negative control group were treated with 1 mL of the vehicle via oral (v.o); three Inf-L-At groups were treated by v.o with doses of (62.5, 125, and 250 mg/kg b.w., v.o); and the positive control group received via intraperitoneal (50 mg/kg b.w. of cyclophosphamide). The bioactivity of Inf-L-At was evaluated verifying its effect on the blood glucose levels of 25 male animals, normoglycemic and hyperglycemic in 5 times (0, 15, 30, 60 and 180 minutes), subdivided into five groups respectively: 1- Control (Glucose 4000 mg/kg); 2- ((Glibenclamide (100 mg/kg) + (Glucose 4000 mg/kg)); and 3,4 and 5- ((Groups Inf-L-At 62.5, 125 and 250 mg/kg) + (Glucose 4000 mg/kg)). The glycemic curve and the effects of InfL-At on liver and muscle glycogen content and the activity of intestinal disaccharidases (maltase, lactase, and saccharase) were determined. The LD50 was estimated to be above 2000 mg/kg, and Inf-L-At showed no short-term toxic effects. However, the absolute liver weight and relative kidney weight differed significantly from the negative control. Furthermore, by the Ames test, Inf-L-At at different concentrations was mutagenic in strain TA100 with (S+) in microsomal fraction and indicated positive diagnosis for mutagenic effects at concentrations of 2.5 and 5.0 mg/mL, similarly to the DXR group. In vivo, rats of both sexes exposed to different doses of Inf-L-At were genotoxic, with recruitment of lymphocytes in the spleen, and an exponential increase in splenic phagocytosis. Micronucleus assays in peripheral blood and bone marrow corroborate Inf-L-At's mutagenic potential attributed to Inf-L-At by the Ames test and SMART test. And after 72 hours, the frequencies of micronuclei were decreased. These results may be justified by increasing apoptotic cells in the liver and kidneys of animals treated with the compound at the respective doses. By the TOTG test, the infusion showed a significant reduction in the glycemic curve throughout the evaluation protocol, similarly to glibenclamide. However, despite the antihyperglycemic effects observed by Inf-L-At in the conditions and doses used, there is no correlation with the activity of intestinal disaccharides and muscle glycogen, according to the results for the model. It is concluded that the aqueous extract of the lyophilized infusion of A. triangularis leaves (Inf-L-At) did not exhibit acute toxicity in Wistar rats. However, at the respective doses evaluated, Inf-L-At has potential for mutagenicity in vitro and in vivo, as described by the Ames test, Micronucleus test, and SMART test. In addition, it also has potential hypoglycemic effects, similar to glibenclamide.