Study on the changes of secondary metabolites and antioxidant activity in Xinjiang jujube leaves
The content of total flavonoids, total phenols, total triterpenoids and total saponins in jujube leaves grown in Aral, Xinjiang were determined by spectrophotometry and the scavenging and reducing capacities of leaf extracts on DPPH, ABTS and hydroxyl radicals were analyzed. The results show that the average annual content of total flavonoids and total phenols in jujube and jujube leaves was higher than that in sour jujube leaves, while the average annual content of total triterpenoids and total saponins was higher in sour jujube and jujube leaves and lowest in sour jujube leaves. Annual developmental trends in total flavonoids, total phenols, and total saponin content were similar in date palm and date palm leaves, but different from sour date palm leaves. Total triterpene content was similar in jujube and sour jujube leaves, but different from that in jujube leaves. The levels of secondary metabolites vary with the phenological period. The highest content of flavonoids was 35.68±3.56 mg g-1 from Huizao jujube leaf on May 21, the highest content of total phenol and triterpenoids were 230.37±6.35 and 309.79±3.70 mg g-1 from wild jujube leaf collected on July 2 and Oct. 8, respectively. The highest saponin content was 71.93±0.78 mg g-1 from leaf of Junzao jujube on Oct. 8. The results of the antioxidant activity assay showed that DPPH, ABTS, hydroxyl radicals, and total reducing capacity of three jujube leaves showed similar trends during their annual development, except for ABTS scavenging capacity, which showed a significant decrease with leaf development, the other activities were comparable in content during annual development. The reducing ability and ABTS radical scavenging ability of the three jujube leaf extracts were comparable, and the hydroxyl radical scavenging ability in leaves of Junzao jujube and wild jujube was stronger than that of Huizao jujube leaves. DPPH radical scavenging ability in leaves of Junzao jujube and Huizao jujube was greater than that of wild jujube.
Wei, L., Zou, L., Shi, J.M., Shi, Q.L., Wu, C.Y., Bai, H.J. and Zhao, Z.H. (2020). Study on the changes of secondary metabolites and antioxidant activity in Xinjiang jujube leaves. Acta Hortic. 1287, 305-316
jujube leaves, secondary metabolites, antioxidation, dynamic changes