Chronic Antihyperglycemic Effect Exerted by Traditional Extracts of Three Mexican Medicinal Plants

Chronic hyperglycemia, the product of uncontrolled diabetes, leads to the appearance of vascular complications that can result in the premature death of diabetic patients. Consequently, pharmacological intervention with hypoglycemic agents could delay these complications and improve the quality of life of patients in the long term. Traditional Mexican medicine provides a great wealth of medicinal plants that are used for the treatment of type 2 diabetes, the most prevalent form of diabetes, accounting for nearly 90-95% of total cases. However, there is still a lack of studies that support their hypoglycemic effects, clarify their mechanisms of action, and report their long-term efficacy. Therefore, the aim of this study was to evaluate the chronic effects of the traditional extracts of some Mexican medicinal plants used by diabetic patients (Ageratina petiolaris (Moc. & Sessé ex DC.) R.M. King & H. Rob. (Asteraceae), Calea urticifolia (Mill.) DC. (Asteraceae), and Eryngium cymosum F.Delaroche (Apiaceae)) on hyperglycemia and hypertriglyceridemia. To achieve this goal, the aqueous extracts of these plants at their traditional doses were administered daily to streptozotocin-nicotinamide (STZ-NA) hyperglycemic Wistar rats for 42 days to assess their effects on nonfasting blood glucose (NFBG), glycated hemoglobin (HbA1c), and blood triglycerides (TG). The results showed that the A. petiolaris extract significantly reduced NFBG by 33% compared to its baseline (p = 0.0281). Besides, it prevented the increase in HbA1c by 2.63% (p = 0.0303) and diminished the AUC of TG (p = 0.0031) compared with the negative control. On the other hand, both C. urticifolia and E. cymosum prevented worsening of hyperglycemia by avoiding the significant increase in glucose levels seen in the negative control and the rise in HbA1c by 2.58% (p = 0.0156). These outcomes provide evidence for the first time of the antihyperglycemic effect of these Mexican medicinal plants, confirming their long-term efficacy in the control of chronic hyperglycemia.