Phenolic components and biological activity analysis of extracts from leaves of different cultivars of jaboticaba

【Objective】To study phenolic components and biological activity of extracts from leaves of 3 cultivars of jaboticaba，so as to provide reference for the development and utilization of jaboticaba leaves.【Method】 Content of total phenols and flavonoids content in extracts from leaves of 3 cultivars of jaboticaba，Dahongzuan，Paulista and Qiaonier were determined.The extracted phenolic components were analyzed by ultra-high performance liquid chromatography and the triple-quadrupole tandem mass spectrometry（UPLC-MS/MS）.Then the antioxidant activity［scavenging abilities of 1-diphenyl-2-trinitrophenyl hydrazine free radical（DPPH·），diammonium 2,2'-azino-bis（3-ethylbenzothiazoline-6-sulfonate）free radical（ABTS⁺），superoxide anion free radical（O₂^-· ）and their total antioxidant capacity］and hypoglycemic activity（inhibition on α-glucosidase and α-amylase）were determined.Furthermore，correlations between content of total phenols and biological activities were analyzed.【Result】 Content of total phenols and flavonoids in extracts from leaves of the 3 jaboticaba cultivars were 458.78-535.51 mg GAE/g and 99.46-233.42 mg RE/g respectively.Content of total phenols in Qiaonier leaf was the highest，while content of flavonoids in Dahongzuan leaf was the highest.The main phenolic components in Dahongzuan and Paulista leaves were gallic acid，ellagic acid，catechin and epicatechin，while those in Qiaonier were gallic acid，ellagic acid and quercetin-3-O-glucoside.Extract of Qiaonier leaf had the strongest DPPH·and ABTS⁺ scavenging abilities，their median inhibition concentration（IC₅₀）were 8.48 and 77.02 μg/mL，and it also had the highest total antioxidant ability，which was 0.922 mmol/g.Meanwhile，Paulista had the strongest scavenging ability on O₂^-·and inhibition activities on α-glucosidase and α-amylase and the IC₅₀ were 0.893 mg/mL，14.96 μg/mL and 57.42 μg/mL respectively.The correlation analysis indicated that content of total phenols was extremely，significantly and positively correlated with DPPH·，ABTS⁺，O₂^-·scavenging abilities（P<0.01），and it had significantly positive correlation with the total antioxidant capacity（P<0.05），while no significant correlation between content of total phenols and hypoglycemic activity （P>0.05）was found.【Conclusion】There are differences of content of total phenols and phenolic components in extracts from the leaves of 3 cultivars of jaboticaba.Qiaonier has the highest comprehensive antioxidant ability，while Paulista have the strongest hypoglycemic activity.Leaves of 3 cultivars of jaboticaba are good sources for develo-ping antioxidant and hypoglycemic products.