Alleviation of hyperglycaemia and oxidative stress by fruit extracts of different cultivars of the cornelian cherry (Cornus mas L. and Cornus mas x Cornus officinalis) in rats with diabetes mellitus

The development of new cornelian cherry cultivars with stronger antidiabetic properties than those of previously studied Cornus mas L. extracts is essential. Accordingly, the aim of the present study was to assess the biological effects of fruit extracts derived from the 'Uholok' and 'Koralovyi' cultivars of C. mas and mix of two hybrids of C. mas x C. officinalis ('Jerzy' and 'Tomasz' cultivars) in rats with streptozotocin-induced diabetes mellitus. The quantitative and qualitative identification of bioactive substances in cornelian cherry fruits was conducted using HPLC-PDA. Fruit extracts from different cultivars were administered orally to rats with diabetes for 14 days at a dose of 20 mg per kg b.w. This resulted in a notable decrease in glucose-related parameters in the blood, proving the extracts' effectiveness as inhibitors of alpha-glucosidase activity. The fruit extract from the hybrids showed the most pronounced effect among the studied extracts with regard to these indicators. In addition, the fruit extracts demonstrated a positive corrective impact on the metabolites of glycolysis (pyruvate and l-lactate) and lactate dehydrogenase activity. The extracts produced antioxidant effect in diabetic rats by reducing oxidative stress biomarkers in plasma. Extracts from fruits of the 'Uholok' and 'Koralovyi' cultivars exhibited a higher efficiency than the extracts from C. mas 'Yantarnyi' and 'Flava' cultivars. The biological effects of the fruit extract from the 'Uholok' cultivar are comparable to those of the 'Podolski' cultivar. These findings contribute to the understanding of the antidiabetic effect of the studied extracts and indicate their potential application as promising drugs.