| Persimmon (Diospyros kaki L) originated from China with long cultivated history, as amainly country for producting persimmon fruits in the world, China’s possess of plentyresource and the persimmon fruit output of China is about the76%of total world production,persimmon has high economic value. Persimmon fruits are also uesd in medical treatment andhealth care by high nutrition value. Different genotypes such as wild species and maincultivars were used as materials in this study postharvest from National PersimmonGermplasm Repository in Yangling of Shaanxi province of China, the contents of totalphenolics and phenolic components, antibacterial activities and antioxidant capacity ofpersimmon fruit extracts, the characteristics of phenolics anabolic related enzymes wereevaluated, which would lay the foundation of further development and utilization to theresources of Diospyros kaki species as on functional foods and medicinal plants. The mainresults in this study as follows:(1) The contents of total phenolics, tolal flavonoids and total flavanols were measured,and several assays (ABTS, DPPH, FRAP, TBARS and HRSA) were also used to evaluate thepotential antioxidant capacity of fruit extracts from twenty different Diospyros kaki genotypes.The result showed that there were huge diversity of phenolic contents and antioxidantcapacities in different Diospyros kaki genotypes, wild species had the highest phenoliccontents and antioxidant capacities, and the astringent cultivars were higher than non-astringent cultivars. The total phenolics in D. kaki. var. silvestris M (1520.57mg gallicaci/100g FW) was100times higher than the non-astringent cultivar Yudai. The scavengingeffects of D. kaki. var. silvestris M and D.lotus L on ABTS+free radicals were both than1100μmol/100g FW, but all of the non-astringent cultivars were lower than110μmol/100gFW以下, especially the lowest cv. Nishimurawase (26.45μmol/100g FW). And there was asignificant dose-effect relationship between the contents of fruit extracts and their antioxidantactivities，and the positive correlation among the different methods was also found.(2) The antibacterial activity of ten Diospyros kaki genotypes was compared to indicatethat fruit extracts of Diospyros kaki had bacteriostatic activity on S. aureus and E. coli. Therewere great diversity of bacteriostatic activity in different genotypes, and the result showed that the bacteriostatic activities of D. kaki. var. silvestris M extract on S. aureus and E. coliwere both the highest among the ten genotypes, and non-astringent cultivar Yudai hold thelowest. D. kaki. var. silvestris M and the astringent cultivars had the stronger antibacterialactivity than the non-astringent cultivars, the bacteriostatic activities of astringent cultivarsZhouqumomoshi and Qianxianhuoshi extracts on S. aureus were2-10times higher than thenon-astringent cultivars and the astringent cultivars Meixianniuxinshi and Mopanshi. Theresult of correlation analysis showed that phenolics was active component influencing thebacteriostatic activity of persimmon fruits extracts.(3) High-performance liquid chromatography (HPLC) analysis revealed that gallic acid(0.502~2.789mg/100g FW) and quercetin (0.224~0.812mg/100g FW) were the majorphenolic components in D. kaki. var. silvestris M and the astringent cultivars, gallic acid in D.kaki. var. silvestris was3-5times higher than the astringent cultivars, but they were notdetected in non-astringent cultivar, and astringent cultivars was also not detected in astringentcultivar Jiro. p-hydroxybenzoic acid and (+)-catechin were the major phenolic components inthe2non-astringent cultivars. p-hydroxybenzoic acid in Jiro (0.746mg/100g FW) was2times higher than D. kaki. var. silvestris M. The phenolic compounds of fruits from testedDiospyros kaki genotypes exhibited a significant positive correlation with antioxidantcapacity antibacterial activity. The result of comprehensive evaluation on bioactivity showedthat biological activity of D. kaki. var. silvestris M were higher than cultivated varieties, andthere was significant differences among astringent cultivars and non-astringent cultivars,some astringent cultivars also have high bioactivity like D. kaki. cv. Zhouqumomoshi. All theresults suggested that astringent cultivars which originated in China were worth using infurther development, and it was necessary to selecte appropriate genotypes for the utilizationof Diospyros kaki species.(4) The characteristics of polyphenoloxidase, peroxidase and L-phenylalanineammonia-lyase were studied. The result showed huge difference on characteristics of theseenzymes in fruits of different Diospyros kaki genotypes. They both had different optimaltemperatures, pH, concentration of substrate, heat stability and enzyme inhibitors. Dynamicchanges of contents of total phenolics, tolal flavonoids and total flavanols, and the activitiesof these enzymes in during the development of fruit postmature of6Diospyros kakigenotypes was observed, the change laws of phenolic contents and activites of enzymesshowed diversity in different genotypes, and correlation among them were found. |
PDF Full Text Request