Changes in flavonoids, total phenolics, triterpenoidic acids and antioxidant capacity during fruit development of different cultivars of apricot

Abstract: 【Objective】In order to discover and analyze the dynamic changes in the contents of flavanoids,total phenolics and triterpenoidic acids, and analyze the relationship of the contents of flavanoids, total phenolics and triterpenoidic acids with antioxidant capacity during the development of fruits of different apricot cultivars.【Methods】The contents of flavanoids, total phenolics and triterpenoidic acids as well as antioxidant capacity of fruits of all tested six cultivars including early maturing cultivars of‘Golden-sun'and‘Zaojinyan', medium maturing cultivar of‘Katy', medium-late maturing cultivars of‘Huaxiandajiexing'and‘Shajinhong', and late maturing cultivar of‘Jinxiang'. They were determined at eight different stages of fruit development, i.e. 30, 36, 42, 48, 54, 61, 68, and 75 days after blooming. The antioxidant capacity was evaluated by scavenging hydroxy radical(·OH), 1,1-diphenyl-2-picrylhydrazyl radical (DPPH·) and superoxide anion radical (·O₂^-). Four grams of chopped apricot fruit sample was put in 10 mL centrifuge tube, added with 4 mL of 80% methyl alcohol as extraction solvent, ultrasonic extracted for10 min at 30 ℃, and centrifuged for 10 min at 9 000 r·min^-1, at 4 ℃ in dark. The supernatant was collected. The residues in the centrifuge tube was extracted twice with 4 mL of 80% methyl alcohol, and the extract solution were pooled, diluted to 10 mL with methyl alcohol and cryopreserved at -80 ℃. The apricot fruit extracts were used to analyze and determine the contents of flavanoids, total phenolics and triterpenoidic acids as well as scavenging capacities of ·OH, DPPH· and ·O2-during the development of apricot fruits. The difference in the contents of flavanoids, total phenolics and triterpenoidic acids as well as antioxidant capacity in all tested six cultivars were compared, and the correlation of the contents of flavanoids,total phenolics and triterpenoidic acids with antioxidant capacity were analyzed.【Results】The results indicated that the contents of flavanoids, total phenolics, triterpenoidic acids in all the tested cultivars were lowest at 30 days after blooming. The contents of flavanoids, total phenolics and triterpenoidic acids increased most rapidly in the early stage of rapid fruit growth, while in the second stage of rapid fruit growth with rapid increase in fruit weight, the contents of flavanoids, total phenolics and triterpenoidic acids decreased rapidly. Thereafter, the contents of flavanoids, total phenolics and triterpenoidic acids showed a descending trend with fruit development, and finally, became relatively stable. The contents of flavanoids,total phenolics and triterpenoidic acids differed significantly among different cultivars(P<0.01). There was a peak value of the contents of flavanoids, total phenolics and triterpenoidic acids in all the six cultivars during fruit development. The late maturing cultivar‘Huaxiandajiexing'had maximum contents of flavanoids and total phenolics at 54 d after blooming, another late maturing cultivar,‘Shajinhong', had maximum content of triterpenoidic acids at 68 d after blooming. Correlation analysis revealed that there was a significant positive correlation between the contents of flavanoids and total phenolics(r=0.882, P<0.01). There was also a positive correlation between the scavenging capacities of hydroxy radical(·OH)and the superoxide anion radical(·O2-)(r=0.882, P<0.05). Significant positive correlations were found between the scavenging capacities of DPPH· and the contents of flavanoids(r=0.488; P<0.01) and total phenolics(0.608; P<0.01), respectively. There was also a significant positive correlation between the capacity of scavenging ·OH and the contents of triterpenoidic acids(r=0.494; P<0.01). However, the correlations of scavenging capacities of DPPH· and ·O2-with triterpenoidic acid contents were not significant.【Conclusion】The growth curve of fresh weight of apricot fruits was double sigmoid, which has two rapid periods of fruit growth. The growth pattern of double sigmoid curve was basically consistent with the contents of flavanoids, total phenolics and triterpenoidic acids. At the first stage of rapid growth, the contents of flavanoids, total phenolics and triterpenoidic acids accumulated rapidly and the displayed a descending trend in the following fruit development. But there was a significant difference among the tested apricot cultivars. The contents of flavanoids, total phenolics and triterpenoidic acids were significantly different among different cultivars. The contents of flavanoids and total phenolics were significantly correlated with scavenging capacity of DPPH·, and the content of triterpenoidic acids was significantly correlated with scavenging capacity ·OH, indicating that flavanoids, total phenolics and triterpenoidic acids are the major determinants of antioxidant capacity in apricot fruit. Furthermore, high contents of flavanoids, total phenolics and strong scavenging capacity of DPPH· were found in the late maturing cultivar of‘Huaxiandajiexing'fruit, while the late maturing cultivar of‘Shajinhong'fruit contains high content of triterpenoidic acids and has high capacity of scavenging ·OH. They are preferred apricot varieties for processing product with health benefits.