Antioxidant and anti-diabetic activity of pomegranate (Punica granatum L.) leaves extracts

Introduction. This study aimed to evaluate the antioxidant and anti-diabetic activity of aqueous and hydroalcoholic extracts of pomegranate (Punica granatum L.) leaves in vitro, as well as to determine the content of polyphenols, flavonoids, and flavonols. Study objects and methods. The antioxidant activity was determined by the DPPH test using the free radical 1,1-diphenyl-2-picrylhydrazyle and the FRAP method, as well as by measuring total antioxidant capacity and the hydrogen peroxide scavenging activity. Results and discussion. The content of total polyphenols varied between 4.43 ± 0.3 and 12.66 ± 1.6 mg EAG/g. The highest content of flavonoids was observed in the hydroalcoholic extract of P. granatum leaves (P < 0.05). The flavonol contents in the hydroalcoholic and aqueous extracts were 7.68 ± 0.6 and 9.20 ± 2.8 mg EQ/g, respectively. The IC50 of the antioxidant potential of the hydroalcoholic and aqueous extracts was 32.4 ± 1.109 and 35.12 ± 4.107 mg/mL, respectively. According to the DPPH test, the aqueous extract was the least active (IC50 = 14.15 ± 1.513 mg/mL). The highest percentage of hydrogen peroxide trapping was found in the aqueous extract (45.97 ± 6.608 %). The inhibition of α-amylase showed an IC50 of between 9.804 ± 0.67 and 19.011 ± 9.82 mg/mL in the aqueous and hydroalcoholic extracts, respectively. The inhibition of glucose uptake by yeast recorded a high inhibitory capacity at 50 mg/mL of glucose. Conclusion. We found that the antioxidant and anti-diabetic activity of P. granatum leaves extracts was due to the presence of bioactive compounds such as flavonoids, which is why they are effective in preventing diabetes and its complications.