Type 2 diabetes is a worldwide prevalent disease that is due to a progressive loss of adequate β-cell insulin secretion, frequently against a background of insulin resistance. In Mexican traditional medicine, the therapeutic use of hypoglycemic plants to control the disease is a common practice among type 2 diabetic patients. In the present work, we examined the traditional use of the aerial parts of Eryngium longifolium and the rhizome of Alsophila firma, consumed by people use over the day (in fasting state) to control their blood glucose levels, therefore, we aimed to assess the acute hypoglycemic effect of both plants. First, basic phytochemical profiles of both plants were determined and, subsequently, acute toxicity tests were carried out. Then, in vivo hypoglycemic tests were performed in streptozotocin-nicotinamide (STZ-NA) induced hyperglycemic Wistar rats and finally the effect of the plants on three enzymes involved in glucose metabolism was assayed in vitro. Through HPLC-DAD chromatography, caffeic acid, chlorogenic acid, rosmarinic acid, isoflavones, and glycosylated flavonoids were identified in E. longifolium, while the possible presence of flavanones or dihydroflavonols was reported in A. firma. Both plants exhibited a statistically significant hypoglycemic effect, without a dose-dependent effect. Furthermore, they inhibited glucose 6-phosphatase and fructose 1,6-bisphosphatase in in vitro assays, which could be associated with the hypoglycemic effect in vivo. Thus, this study confirmed for the first time the traditional use of the aerial part of E. longifolium and the rhizome of A. firma as hypoglycemic agents in a hyperglycemic animal model. In addition, it was concluded that their ability to regulate hyperglycemia could involve the inhibition of hepatic glucose output, which mainly controls glucose levels in the fasting state.

The onset of type 2 diabetes (T2D) is a consequence of the progressive loss of adequate β-cell insulin secretion, which frequently occurs under a background of insulin resistance. Currently, nearly 13 million Mexicans are living with diabetes. Moreover, due to poor socioeconomic conditions and the cultural idiosyncrasies of the Mexican population, the use of medicinal plants to treat T2D is a common practice in Mexico. In the Mexican state of Hidalgo, we found the traditional use of Calea urticifolia (CU) to treat this disease. To treat T2D, people drink an infusion made from the aerial part of the plant throughout the day. With the aim of investigating whether the infusion at a traditional dose produces a hypoglycemic effect in either the fasting or postprandial state, we measured the effect of the infusion in a hyperglycemic animal model (rats administered streptozotocin (STZ) and nicotinamide (NZ)) by conducting a glucose tolerance test and constructing a blood-glucose curve. We then analyzed whether the observed effect was related to the inhibition of glucose absorption in the gut or the inhibition of hepatic glucose output (HGO) in vivo and in vitro. Furthermore, we confirmed our findings by identifying the potential targets of the infusion via a network pharmacology analysis. Through high-performance liquid chromatography (HPLC) and thin layer chromatography (TLC), we detected a number of compounds in the extract and identified two of them. The plant extract produced a highly significant hypoglycemic effect under fasting conditions and a weak hypoglycemic effect following glucose or sucrose challenge. Although the plant extract blocked only 20 of the alpha-glucosidase enzyme activity in vitro, in the pyruvate tolerance test (which measures the liberation of hepatic glucose), it significantly reduced glucose levels. Furthermore, in vitro, the extract diminished the activity of the glucose-6-phosphatase complex by 90. In addition, by conducting TLC, we detected the presence of chlorogenic acid and rutin, which have been reported to block HGO. The results presented here provide evidence of the hypoglycemic effect of the traditionally used C. urticifolia extract and demonstrate that this effect is associated with both a reduction in glucose synthesis via gluconeogenesis due to the phytochemical composition of the extract and a slight blockage of glucose absorption in the gut.

In the pursuit of identifying the novel resin glycoside modulators glucose-6-phosphatase and α-glucosidase enzymes, associated with blood sugar regulation, methanol-soluble extracts from the flowers of Ipomoea murucoides (cazahuate, Nahuatl), renowned for its abundance of glycolipids, were employed. The methanol-soluble extracts were fractionated by applying the affinity-directed method with glucose-6-phosphatase enzymes from a rat’s liver and α-glucosidase enzymes from its intestines. Mass spectrometry and nuclear magnetic resonance were employed to identify the high-affinity compound as a free ligand following the release from the enzymatic complex. Gel permeation through a spin size-exclusion column allowed the separated high-affinity molecules to bind to glucose-6-phosphatase and α-glucosidase enzymes in solution, which led to the identification of some previously reported resin glycosides in the flowers of cazahuate, where a glycolipid mainly structurally related to murucoidin XIV was observed. In vitro studies demonstrated the modulating properties of resin glycosides on the glucose-6-phosphatase enzyme. Dynamic light scattering revealed conformational variations induced by resin glycosides on α-glucosidase enzyme, causing them to become more compact, akin to observations with the positive control, acarbose. These findings suggest that resin glycosides may serve as a potential source for phytotherapeutic agents with antihyperglycemic properties.

Background/Objectives: Ethnopharmacological studies indicates that plant-based infusions are usually consumed by some people in advanced stages of diabetes, that is, when poor pancreatic dysfunction coexists with insulin resistance (IR). Current treatments aim to prevent β-cell deterioration by promoting improved insulin function and/or enhancing pancreatic function to avoid the development of hyperglycemia. Therefore, Croton guatemalensis (Cg) and Eryngium cymosum (Ec), two medicinal plants with potential insulin-sensitizing effects described in previous studies, were assessed on parameters related to IR and on the architecture of pancreatic islets in rats exposed to a syrup containing 8.8% glucose and 5.2% fructose in drinking water. Methods: After an 8-week exposure to syrup, plant extracts were orally administered for four weeks at traditional doses (Cg: 30 mg/kg body weight; Ec: 470 mg/kg body weight). Body weight, food intake, and drinking water consumption were monitored. At the end of the study, IR surrogate indices were calculated, metabolic assays were performed, and white adipose tissues, liver, gastrocnemius muscle, and pancreas were extracted in fasting and postprandial state for lipid quantification (liver), measurement of Akt phosphorylation status by western blot (liver and muscle), and determination of insulin content by immunohistochemistry (pancreatic islets). Results: Both species decreased hepatic lipid content without promoting significant changes in visceral adiposity. Although they did not improve surrogate markers of fasting IR, both ameliorated insulin function, glucose tolerance, and restored the glucose-stimulated insulin secretory response in metabolic tests. Cg restored the insulin signaling response in liver and muscle, whereas Ec only did so in muscle. Moreover, both appeared to enhance insulin pancreatic content or restore pancreatic islet population. Conclusions: Cg and Ec can reverse the IR phenotype in a tissue-specific manner and improve pancreatic function.