| China is abundant in pear resources, however, researches on pear polyphenols were relatively few and not systematic. In this study, the pear leaf polyphenols extraction conditions were optimized through single factor and orthogonal design tests. The method of ultra performance liquid chromatography(UPLC) to determine pear leaf polyphenols was established as well. The polyphenols in 16 parts of ‘Zaosu’ and ‘Nanguo pear’ and of 198 pear mature leaves were determined based on the achieved method. The Pyrus L. with high polyphenols were selected based on the analysis of principal components and comprehensive scores to fully develop and utilize pear plants resources and make chemical classification.The main results and conclusions were as follows:1. Selecting Acquity UPLC HSS T3(2.1mm×100mm, 1.8μm) as chromatographic column, with 0.5% formic acid solution and acetonitrile as mobile phase A and B, using concentration gradient elution:0-1min,0-5%B;1-6min,5%-17%B;6-10 min,17%-25% B;10-11 min,25%-100% B;11-14 min,100% B;14-15 min,100%-0B;15-20 min, 0B and acquiring chromatograms at 280 nm, 325 nm and 350 nm, 9 polyphenols were simultaneously separated. The method is of good accuracy, high precision and suitable for simultaneous detection of polyphenols in pear leaf.2. The extraction protocol of different kinds of polyphenols(arbutin, caffeoylquinic acid and flavonol) from pear leaf was optimized. The importance of extract factors acting on pear leaf polyphenols was different, so the appropriate extraction protocol should be selected according to the type of pear leaf polyphenols. The best extraction protocol of arbutin was that: 0.3333 g of pear leaf tissues were extracted in 50 m L methanol-water mixture(70:30) for two times of 30 minutes each by ultrasonic; the best extraction protocol of caffeoylquinic acid and flavonol was that: 0.4000 g of pear leaf tissues were extracted in 50 m L methanol-water mixture(70:30) for two times of 25 minutes each by ultrasonic.3. The compositions and contents of detected polyphenols were comparatively great different in 16 parts of Zaosu and Nanguo pear, but all contained arbutin and chlorogenic acid. Exposed parts contained more compositions of polyphenols than inside parts. The young leaves of Zaosu and Nanguo pear contained the highest contents of detected polyphenols, which were 93.82 mg·g-1 and 104.04mg·g-1 respectively, followed by leaf stalks, the contents were 80.10 mg·g-1 and 103.00 mg·g-1 respectively. The pulp, core and seed contained the least contents of detected polyphenols.4. The compositions of detected polyphenols in leaves of 198 pears were generally same, but the contents were great different. 9 detected and identified polyphenols placed by the mean contents which were from high to low were arbutin(6.33 mg·g-1), isochlorogenic acid A(2.93 mg·g-1), luteolin-7-O-gl-ucoside(1.34 mg·g-1), chlorogenic acid(1.21 mg·g-1), neochlorogenic acid(0.97 mg·g-1), quercetin-3-glucoside(0.42 mg·g-1), quercetin-3-galactoside(0.37 mg·g-1), rutin(0.24 mg·g-1), cryptochlorogenic acid(0.22 mg·g-1). The top ten pear germplasms with excellent comprehensive performance in polyphenols were ‘Huangxian Changba’, ‘Bingzili’, ‘Xiaohua’, ‘Jidanguan’, ‘Yanghongxiao’, ‘Bingtang’,. ‘Bartlett’, ‘Zheli’, ‘Ruanzhiqing’, ‘Huluba’. P. bretschneideri was with more excellent comprehensive performance in polyphenols. Analyzing the genetic relationships of Pyrus L. were based on pear leaves polyphenols. The results were as follows: The genetic diversity decreased in the process from Ussuriensis Paer wild accessions to Ussuriensis Paer cultivars; P. pyrifolia and P. bretschneideri had no obvious differentiation and can’t been divided into two groups; Chinese P. pyrifolia had close genetic relationships with Japanese P. pyrifolia. |
