桑果发育期生物活性物质含量及抗氧化酶活性的变化

Changes in the Contents of Bioactive Substances and Activities of Antioxidant Enzymes during the Development of Mulberry Fruit

本研究探讨桑果发育期生物活性物质及抗氧化酶活性的变化规律。以3龄和5龄桑树果实为材料,研究果实发育期总酚、总黄酮、酚酸、单宁、叶绿素及类胡萝卜素、花色素苷、可溶性糖等生物活性物质及总抗氧化能力、抗氧化酶活性的变化。结果表明,桑果在发育成熟过程中,果肉内总酚、总黄酮、酚酸、单宁、花色素苷和可溶性糖含量逐渐升高,叶绿素a含量逐渐下降,叶绿素b和类胡萝卜素含量先上升后下降;整个发育期,3龄树桑果果肉总黄酮和酚酸含量高于5龄树桑果,但总酚、单宁和类胡萝卜素含量则低于5龄树桑果。果肉内的超氧化物歧化酶(SOD)、过氧化氢酶(CAT)和苯丙氨酸解氨酶(PAL)活性先下降后上升,过氧化物酶(POD)和抗坏血酸过氧化物酶(APX)活性逐渐降低,总抗氧化能力逐渐上升;整个发育期,3龄树桑果果肉内的SOD、CAT和PAL酶活性高于5龄树桑果,但APX酶活性低于5龄树桑果,5龄树桑果果肉的总抗氧化能力高于3龄树桑果。因此,桑果果肉中生物活性物质及抗氧化酶活性变化规律与果实成熟度、树龄大小有关。在桑果发育过程中,桑果果肉的总抗氧化能力不断提高,在花后第25 d达到最高。树龄越大的桑果总抗氧化能力比越强。

The changes in the contents of bioactive substances and the activities of antioxidant enzymes during the development of mulberry fruit were researched. The 3-year-old and 5-year-old mulberry fruits were used as the materials for the studies on the changes of the total phenolics, total flavonoids, phenolic acids, tannins, chlorophyll and carotenoids, anthocyanins, soluble sugar, total antioxidant capacity and antioxidant enzymes’ activities. The obtained results showed that the total phenolics, total flavonoids, phenolic acids, tannins, anthocyanins and soluble sugar contents increased during the fruit development, while chlorophyll a decreased gradually. The contents of chlorophyll b and carotenoids increased firstly and then decreased during the fruit development. The 3-year-old fruit had higher contents of total flavonoids and phenolic acids but lower contents of total phenolics, tannins and carotenoids than the 5-year-old fruit. The activities of superoxide dismutase(SOD), catalase(CAT) and phenylalnine ammonialyase(PAL) in the fruit flesh decreased firstly and then increased. The activities of peroxidase(POD) and ascorbate peroxidase(APX) decreased gradually whilst the total antioxidant capacity increased gradually. Throughout the development period, the 3-year-old fruit had higher activities of SOD, CAT and PAL but lower APX activity and total antioxidant capacities, compared to the 5-year-old fruit. Therefore, the changes in the contents of bioactive substances and the activities of antioxidant enzymes were closely related to fruit maturity and tree age. During the development of mulberry fruit, the total antioxidant capacity of fruit flesh increased continuously and reached the highest on the 25 th day after flowering. The older the mulberry tree, the higher the total antioxidant capacity of fruit was.