Investigation of the antioxidant and hypoglycemiant properties of Alibertia edulis (L.C. Rich.) A.C. Rich. leaves

Abstract

Ethnopharmacological relevanceAlibertia edulis (L.C. Rich.) A.C. Rich is a vegetable species used in Brazilian folk medicine due to it is putative hypoglycemiant effect but has never been pharmacologically investigated. It is popularly used for the control of diabetes, especially in the state of Mato Grosso, Brazil. Following confirmation of the antioxidant activity of A. edulis by Aquino et al. (2017), the aim of this study was to evaluate the effects of leaves of A. edulis aqueous extract (AEAE) on some biochemical parameters in mice fed a high-fat fed. Material and methodsLeaves of A. edulis were air-dried in an oven at 40 °C for 10 days and ground into a fine powder by mechanical milling. The AEAE was prepared by decoction (1:10 w/v) at 97 °C for 15 min, and later filtered and lyophilized. Preliminary phytochemical analysis of the AEAE has been already indetified the presence of caffeic acid, quercetin 3-rhamnosyl-(1 → 6)-galactoside and iridois ioxide, ferulic acid and rutin in decocted leaves (Aquino et al., 2017). In one experiment, the acute oral toxicity AEAE was evaluated at 2,000 mg/kg of body weight. The animals were observed periodically for 14 days. In second experiment, the animals were divided into four groups (n = 5): Control, AEAE 200, AEAE 400 mg/kg and positive control (Metformin 100 mg/kg). In a third experiment, animals were divided into: Control RC (standard diet) (n = 24) and Control HFF (high-fat fed) (n = 24) groups for induction of glucose intolerance. After eight weeks, they were further subdivided into six groups (n = 8 each) RC or HFF with or without AEAE at doses of 200 and 400 mg/kg (2-wk) treatments to assess glucose tolerance. Plasma indicators of glucose tolerance and liver damage, skeletal muscle expression of antioxidant enzymes, and expression of the antioxidant proteins of superoxide dismutase (SOD), catalase, glutathione peroxidase (GPx) and phosphorylated IKK were determined. ResultsThe HF-fed animals developed glucose intolerance which the AEAE failed to revert. Meanwhile, the AEAE treatment did lower the glucose levels in the normolipidic cohorts by virtue of its antioxidant property. It was also observed that the treatment with the AEAE reduced food intake negatively interfering weight accretion. Beyond that, the treatment with AEAE interfered in the SOD and catalase expression and inhibited phosphorylation of IKK thus suggesting that the observed hypoglycemiant power may be related to its known antioxidant potential. No sings of toxicity or hemolysis were detectaed at indicating that, at the concentrations evaluated, the extract was not toxic to normal cells. ConclusionThe AEAE showed a hypoglycemiant effect in the normolipidic mice that received the control diet, but not in those that were made glucose-intolerant by consuming a high-fat fed. The extract also exhibited substantial protection against hemolysis and oxidative stress. Moreover, no signs of toxicity were evident at 2000 mg/kg of body weight.