Inhibitory activity against α-amylase and α-glucosidase by phenolic compounds of quinoa (Chenopodium quinoa Willd.) and cañihua (Chenopodium pallidicaule Aellen) from the Andean region of Peru

Background: Chenopodium quinoa Willd. and Chenopodium pallidicaule Aellen are grains from the Andean region of Peru, which in addition to having a high nutritional value, have health-promoting properties related to the prevention of chronic diseases such as diabetes. Objetive: The present study aimed to identify phenolic compounds associated with an inhibition of carbohydrate hydrolyzing enzymes associated with type 2 diabetes. Material and Methods: Two varieties of quinoa and two varieties of cañihua from the Puno Region in Peru, were evaluated. Total phenolics, total flavonoids, identification of phenolic compounds and antioxidant activity in vitro were measured by Folin-Ciocalteu assay, aluminum chloride colorimetric method, HPLC-DAD and DPPH radical scavenging assay, respectively. In vitro hypoglycemic activity was evaluated through the inhibition of the α-amylase and α-glucosidase enzymes. Results: Gallic acid, rutin and chlorogenic acid were identified by HPLC-DAD in the varieties of quinoa and cañihua. The latter showed significantly higher levels of chlorogenic acid compared to quinoa varieties (p<0.05). Both Andean grains exhibited inhibition of key-enzymes linked to type 2 diabetes, presenting IC₅₀ values of 7.99 to 34.05 and of 8.07 to 1158 μg/mL for α-amylase and α-glucosidase, respectively. Total phenolics, total flavonoids, DPPH radical scavenging assay, gallic acid and chlorogenic acid showed the greatest contribution to the inhibitory activity of the α-glucosidase enzyme (p<0.05). Conclusion: Our findings suggest that the phenolic compounds present in the varieties of quinoa and cañihua could modulate the inhibition of carbohydrate hydrolyzing enzymes associated with type 2 diabetes.