In this study we examined the acute in vivo effect and short- and long-term in vitro effects of samples from native and commercial Ilex paraguariensis on glucose homeostasis. Also, the potential effect of I. paraguariensis on serum insulin secretion was investigated. The chemical identification and quantification of methyl xanthines and polyphenols in CH₂Cl₂, EtOAc and n-BuOH fractions of native I. paraguariensis as well as infusions of green and roasted I. paraguariensis from a commercial source was verified by high-performance liquid chromatography. The results for the serum glucose-lowering indicated that both fractions and both infusions were able to improve significantly the oral glucose tolerance curve. Additionally, both the EtOAc and n-BuOH fractions induced-insulin secretion, but EtOAc induced an early (at 15 min) and late (at 60 min) biphasic peak of insulin secretion similar to glipizide stimulatory effect. Both fractions increased liver glycogen content compared with fasted normal rats. Also, EtOAc and n-BuOH fractions inhibited in vitro disaccharidases activities after an acute treatment. The maximum inhibitory effect of the EtOAc and n-BuOH fractions on maltase activity (at 5 min) was around 35%. The evident reduction of protein glycation by glucose or fructose with EtOAc and n-BuOH fractions increased from 7 to 28 days of in vitro incubation. Inhibition of bovine serum albumin glycation by glucose and fructose, by around 50% and 90%, respectively, was observed. Additionally, the green and roasted mate infusions reduced the formation of AGEs in a characteristic long-term effect. In conclusion, this study shows that I. paraguariensis has an anti-hyperglycemic potential role able to improve the diabetic status and is probably a source of multiple hypoglycemic compounds.

In this study, the in vivo effect of the crude extract and n-butanol and aqueous residual fractions of Baccharis articulata (Lam.) Pers. on serum glucose levels, insulin secretion and liver and muscle glycogen content, as well as in vitro action on serum intestinal disaccharidase activity and albumin glycation were investigated. Oral administration of the extract and fractions reduced glycemia in hyperglycemic rats. Additionally, the n-butanol fraction, which has high flavonoids content, stimulated insulin secretion, exhibiting an insulinogenic index similar to that of glipizide. Also, the n-butanol fraction treatment significantly increased glycogen content in both liver and muscle tissue. In vitro incubation with the crude extract and n-butanol and aqueous residual fractions inhibited maltase activity and the formation of advanced glycation end-products (AGEs). Thus, the results demonstrated that B. articulata exhibits a significant antihyperglycemic and insulin-secretagogue role. These effects on the regulation of glucose homeostasis observed for B. articulata indicate potential anti-diabetic properties.

Background: Epidemiologic studies and clinical trials have suggested a correlation between dietary polyphenols and prevention of chronic diseases such as diabetes. The current study has been limited to the compounds previously studied by in vivo and in vitro experimental model concerned glucose homeostasis. Objective: Some selected compounds as myricitrin, quercetin, catechin, naringenin, caffeic acid, rutin, fukugetin, hispidulin, kaempferitrin and chlorogenic acid were investigated in sodium-glucose co-transporter activity in rat intestine through an in situ approach, compared with phlorizin, a classical competitive inhibitor of Na +-dependent glucose transport. Methods: For the in situ studies the intestine segments were uploaded with glucose solution, phlorizin and/or compounds and after 30 min the glucose was measured into the respective intestinal segment. Results: Among the substances assayed, myricitrin, quercetin, catechin, naringenin, caffeic acid, rutin and fukugetin significantly reduced the glucose uptake by affecting the SGLT1 transporter activity measured in the presence of phlorizin. It worthwhile mentions that myricitrin at 10mM exhibited a per se inhibitory effect around 90% higher than that observed for phlorizin. Quercetin inhibited the glucose uptake in both concentrations used and exhibited an effect on glucose absorption as good as phlorizin at 10 mM. Catechin and caffeic acid (10 mM) in the presence of phlorizin potentiated the inhibitory effect of this compound on glucose uptake. Moreover, 10 mM naringenin showed a similar inhibitory effect of phlorizin. Additionally, rutin and fukugetin (10 mM) alone or in combination with phlorizin slightly reduced the glucose absorption. Conclusion: Based on these results, myricitrin, quercetin, catechin, naringenin, caffeic acid, rutin and fukugetin are able to regulate glucose absorption by acting in an intestinal target, SGLT1, contributing to ameliorate glucose homeostasis.