Potencial hipoglicemiante do extrato aquoso de quiabo (Abelmoschus esculentus L.) em lipossomas em um modelo de resistência à insulina

Abstract

Given its therapeutic importance as an anti-inflammatory, antiallergic, immunosuppressive agent, among others, glucocorticoids are widely used in clinical medicine; however, the chronic use of this hormone has been associated with the development of peripheral insulin resistance. On the other hand, functional foods such as okra (Abelmoschus esculentus L.) appear as promising bioactive compounds in the fight against metabolic diseases, such as type 2 diabetes mellitus. In this work we aim to characterize (in terms of mean diameter, polydispersity index zeta potential and pH) liposomes containing okra, and to test their hypoglycemic effect in an insulin resistance rat-model. At 60 days-old, male and female Wistar rats underwent a daily injection of dexamethasone (DEX; 1mg/kg body weight, bw, intraperitoneal, i.p.) for 10 days, while control rats received saline solution (NaCl, 0.9% i.p., CONT group). At 65 days-old, a batch of DEX rats were treated, via gavage for five consecutive days, with a liposome containing okra (1.5mg/kg bw, DEX-LipoQ group) or okra extract in the free form (200mg/kg of pc, DEX-ExtrL group), as an negative control, DEX rats received white liposome (liposome without okra, DEX-LipoB group). During treatment, baseline blood glucose, weight, water, and food intake were evaluated. At the end, glycemic homeostasis and biometric parameters were evaluated. The characterization of the developed liposomes shows a structure with an average diameter of 280nm, zeta potential –31.46±1.48 and 6.8 as pH. In relation to CONT rats, DEX rats, in both sexes were hyperglycemic, glucose intolerant and insulin resistant (P<0.05). Similarly, DEX-LipoB rats, in both sexes, were hyperglycemic, glucose intolerant and insulin resistant compared to CONT rats (P<0.05), and not statistically different of the DEX rats (P>0 .05). DEX-LipoQ and DEX-ExtrL rats, in both sexes, presented basal glycemia, glucose tolerance and inulin responsiveness like those observed in CONT rats (P>0.05), but significantly different of those observed in DEX rats (P<0.05). Regarding sexual dimorphism, glycemic homeostasis of males was more vulnerable to the effect of dexamethasone, as well as showing a more prominent improvement against the effect of okra; on the other hand, peripheral insulin sensitivity in females improved with magnitude about of 40-fold greater than in males. In summary, the treatment with okra, even in a smaller concentration, was effective on reversing glucose intolerance and insulin resistance, which was also observed in rats treated with okra in a free form, but only by using a higher okra-extract concentration. Furthermore, considering the applied dose, liposomes containing okra was more effective in promoting glycemic control in hyperglycemic animals, in both sexes, than it was using okra-extract in free form.