In vitro anti-diabetic activity and molecular docking studies of Amaranthus cruentus, Amaranthus hybridus and...

Amaranthus species are traditional leafy vegetable also reputed for their potential in managing metabolic disorders, including diabetes. In previous investigations conducted by our group, extracts from Amaranthus cruentus and Amaranthus hybridus, along with isolated compounds, exhibited strong α-glucosidase enzyme and moderate α-amylase inhibition in vitro.

The present study evaluated the antidiabetic effects of extracts and isolated compounds on C3A hepatocytes and L6 myoblasts. In addition, to elucidate the potential molecular mechanisms behind the observed enzymatic inhibition, we conducted docking studies of the isolated compounds against α-glucosidase and α-amylase. The finely powdered leaf samples were mixed with methanol and extracted using a cold maceration process. Three compounds were obtained from the aerial sections of the plant material using silica gel chromatography. Glucose metabolism of the extracts and the isolated compounds was carried out using L6 myoblasts and C3A cells.

The plant extracts of A. cruentus and A. hybridus and isolated compounds; palmitic acid and α-spinasterol, were found to stimulate glucose uptake in L6 myoblasts and C3A cells at 31.25 µg/mL, A. cruentus and A. hybridus stimulated glucose uptake by 15.67% and 15.95%, respectively, while insulin (10 µg/mL) boosted glucose uptake by 27.1% in L6 myoblasts, although their mechanisms of action remained unclear. Palmitic acid and α-spinasterol enhanced glucose uptake in L6 myoblasts by 28.88% and 21.61%, respectively. After 48 h of pre-treatment, only α-spinasterol showed a significant increase in glucose absorption (56.82%) in L6 myoblasts at a treatment dose of 62.5 µg/mL, while insulin showed a glucose uptake of 78.02%. A. hybridus demonstrated significant glucose uptake (20.86%) in C3A hepatocytes after 24 h of pre-treatment at a dosage of 15.63 µg/mL, in contrast to insulin, which enhanced glucose uptake by 34.8% at 10 µg/mL. Compared to acarbose with a binding affinity of -7.7 Kcal/mol, palmitic acid, α-spinasterol and pheophorbide A-methyl ester showed the binding affinities of -5.7 Kcal/mol, -7.6 Kcal/mol and - 7.8 Kcal/mol respectively, on α-glucosidase. Acarbose showed a comparable binding affinity of -6 Kcal/mol to those of pheophorbide A-methyl ester and α-spinasterol, which showed the binding scores of -6.7 Kcal/mol and - 6.8 Kcal/mol, respectively.

This study validates A. cruentus and A. hybridus's traditional use for the treatment of diabetes mellitus. Future studies will investigate the underlying mechanisms by which the extracts and compounds enhance glucose uptake in L6 myoblasts and C3A hepatocytes. Additionally, to provide a more comprehensive understanding of the antidiabetic potential of the Amaranthus extracts and compounds, in vivo experiments using appropriate animal models will be conducted.