Studies on Antioxidant and α-Glucosidase Inhibitory Activities of Ethanol Extracts from Peels and Seeds of Jaboticaba at Different Maturities

Abstract:

In order to investigate the antioxidant and α-glucosidase inhibitory activities of jaboticaba (Myrciaria cauliflora) fruits at different maturities, the contents of total polyphenols (TP) and total flavonoids (TF) of 70% ethanol extracts from its peels and seeds were measured, and the correlation of TP, TF with antioxidant capacity and α-glucosidase inhibitory activity was analyzed. The results showed the contents of TP and TF, antioxidant capacity and α-glucosidase inhibitory activity in peels and seeds of jabuticaba at different maturities had obviously difference. The contents of TP and TF ranged from 18.31 to 95.96, 16.50 to 43.48 mg g^-1DW, respectively. The content of TP was the highest in peels at green fruit stage, the lowest in peels at red fruit stage, while the content of TF was the highest in seeds at green fruit stage, the lowest in seeds at purple fruit stage. The peels of green fruits had the highest antioxidant capacity, while the seeds of purple fruits showed the lowest level. The capacity of scavenging ·OH of all extracts with EC₅₀ ranged from 0.260 6 to 1.280 4 g DW L^-1 was stronger than that of ascorbic acid (EC₅₀=2.659 0 g DW L^-1). The IC₅₀ value of α-glucosidase inhibitory activity ranged from 1.134 0 to 11.414 1 mg DW L^-1 showed lower than that of acarbose (IC₅₀=3 133.47 mg L^-1). The contents of TP and TF had positively significant correlation with the antioxidant capacity (P < 0.05), as well as α-glucosidase inhibitory activity and scavenging capacity of free radicals, such as DPPH·, ·OH and ABTS⁺. Therefore, the jaboticaba fruits at green stage were a good source of natural antioxidants and α-glucosidase inhibitors, due to its high contents of TP and TF, great antioxidation and strong inhibition on α-glucosidase.