Aim of the study: This experiment studied two extracts of Opuntia streptacantha, a plant used by the Mexican population to treat type 2 diabetes, in different assays to contribute to the understanding of the hypoglycemic mechanism of this plant.
Materials and methods: Two different extracts were prepared and tested: the first extract was a filtrate of the traditional liquefied extract (LE) preparation of the cladode; and the second filtrate extract (FE) is a filtered sample of the first. Both extracts contained a newly identified compound for Opuntia (4-hydroxy)-phenyl acetic acid derivate, they were tested on streptozotocin (STZ)-diabetic rats in a series of two tests. The first test was performed to confirm if STZ-diabetic rats presented a hypoglycemic effect after administration of the extracts (LE 135 mg/kg and FE 27 mg/kg). In the second experiment, the extracts were administered before an oral glucose tolerance test (OGTT) to confirm if they have an anti-hyperglycemic effect (LE 135 mg/kg, FE 12 and 27 mg/kg).
Results: The extracts administered to STZ-diabetic rats did not produce a significant hypoglycemic effect compared to the control group, while the same extracts administered before an OGTT produced an anti-hyperglycemic effect compared to the control group.
Conclusions: The filtered, traditional LE of the cladode of Opuntia streptacantha produces an anti-hyperglycemic effect when administered before a glucose challenge, and this anti-hyperglycemic effect is maintained after filtering the extract. Administration of both plants can improve glycemic control by blocking the hepatic glucose output, especially in the fasting state. These data support the traditional use of the plants as "agua de uso", a cold infusion of the plant consumed over the course of a day.
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