Assisted Extraction with Cyclodextrins as a Way of Improving the Antidiabetic Activity of Actinidia Leaves

Five varieties of Actinidia leaves (Geneva, Jumbo, Ken's Red, Kijivska Hibridna, and Sentyabraskaya) were analyzed. The profiles of active compounds were determined, namely quercetin, rutin, epicatechin, chlorogenic acid, and kaempferol, in the raw material. Suspecting that the raw material might prove important in the treatment of diabetes, the authors assessed the antioxidant activity and the ability to inhibit enzymes responsible for the development of diabetes (α-glucosidase and α-amylase). As a result of the conducted analysis, the Ken's Red variety was indicated as having the highest biological activity (DPPH IC₅₀ = 0.332 ± 0.048; FRAP IC_0.5 = 0.064 ± 0.005; α-glucosidase inhibition IC₅₀ = 0.098 ± 0.007; α-amylase inhibition IC₅₀ = 0.083 ± 0.004). In order to increase the efficiency of the extraction of active compounds from Ken's Red variety leaves, cyclodextrins (α-CD, β-CD, and γ-CD) were used as extraction process enhancers. The obtained results showed a significant increase in the contents of extracted active compounds. In addition, the type of CD used enhanced the extraction of selected compounds (quercetin, kaempferol, rutin, chlorogenic acid, and epicatechin. This study shows that the application of cyclodextrin-based extraction significantly improved the leaf activity of the Ken's Red variety (DPPH IC₅₀ = 0.160 ± 0.019; FRAP IC_0.5 = 0.008 ± 0.001; α-glucosidase inhibition IC₅₀ = 0.040 ± 0.002; α-amylase inhibition IC₅₀ = 0.012 ± 0.003).