Diabetes mellitus (DM) is a metabolic disorder characterized by the deficiency of insulin production and is one of the concerning health problems worldwide, especially in developing countries. Considering the systemic toxicity associated with current antidiabetic medications and their limited efficacy, there is an urgent need to discover new plant-based natural antidiabetics. Since time immemorial, medicinal plants have played an important role in the management of health disorders. In recent years, herbal medicine has experienced exponential growth in popularity worldwide, owing to its natural origin and fewer side effects, appealing to both developing and developed nations. Ecuador has a rich cultural history in ethnobotany that plays a crucial role in their people's lives. Several Ecuadorian medicinal plants have hypoglycemic or an-ti-hyperglycemic properties that are rich with bioactive phytochemicals. These medicinal plants were extensively used in traditional medicine preparation in Ecuador for many decades to treat diabetes because of their cost-effectiveness, available traditional knowledge, and low toxicity. Many Ecuadorian medicinal plants are reported to have antidiabetic properties that reduce blood sugar levels, and oxidative stress, regulate intestinal function, improve insulin resistance, inhibit α-amylase and α-glucosidase, lower gluconeogenic enzymes, stimulate glucose uptake mechanisms, and play an important role in glucose and lipid metabolism, yet there is a substantial lack of integrated approach between the existing ethnomedicinal practice and pharmacological research. Therefore, this review aims to discuss and explore the traditional medicinal plants used in Ecuador for treating DM and their bioactive phytochemicals, which are mainly responsible for their anti-diabetic properties.

Nine components (C1-C9) were isolated from chloroform fraction of fractionated methanol extracts of Vernonia amygdalina leaves (FMEVA) by column chromatography. All the components C1 to C9 were purified and screened for hypoglycaemic activities in type-2 diabetic rats. The most potent hypoglycaemic component was elucidated on the basis of extensive spectroscopic (1D-, 2D-NMR, GC-MS, FTIR) data analysis. The Component C5 was found to be the most potent hypoglycaemic in reducing blood glucose by 12.55 ± 3.55% at 4 h post-oral administration, when compared to the positive (18.07 ± 1.20%) and negative (-1.99 ± 0.43%) controls. The spectroscopic data analysis reveals that the isolated compound has a structure consistent with 11β,13-dihydrovernolide. The isolated compound is part of the hypoglycaemic components present in V. amygdalina leaves that is responsible for the anti-diabetic activities. Further research is needed in the development of this compound or its derivatives for pharmaceutical use.