Analysis on characteristic color compounds in different varieties of Osmanthus fragrans Lour.during flowering and senescence
[目的]分析不同花色桂花品种开花及衰老过程中的花色物质成分及其含量变化规律,为桂花花色资源开发和利用提供参考依据.[方法]分别选取代表橙色品种群的镉橙丹桂、代表黄白色品种群的厚瓣银桂和代表黄色品种群的柳叶金桂,运用高效液相色谱质谱法检测其开花过程中的花色物质组分及含量,用色差仪测定花色参数L*(颜色亮度)、a*(红/绿程度)、b*(黄/蓝程度)和C*(彩度),用多元线性回归分析法逐步筛选分析花色呈现与特征花色物质含量的关系;分析不同花色桂花品种衰老过程中特征花色物质含量的变化规律.[结果]桂花中含有5种黄酮类物质,可能为金鱼草素苷元、槲皮素苷元、芹菜素苷元、鼠李金苷元和柚皮素苷元,其中槲皮素苷元在镉橙丹桂、厚瓣银桂和柳叶金桂盛花期花瓣中的含量均较高,分别为134.55、89.41和90.39 μg/gFW.对α-胡萝卜素和β-胡萝卜素进行定量分析发现,两种类胡萝卜素仅在镉橙丹桂中含量较高,分别为72.94和99.72 μg/gFW.对花色呈现与花色物质含量关系的分析结果显示,槲皮素苷元决定花色的亮度L*,柚皮素苷元决定黄色程度b*,β-胡萝卜素决定红色程度a*.其中,槲皮素苷元含量在镉橙丹桂、厚瓣银桂和柳叶金桂开花过程中均呈先降低后升高的变化趋势,β-胡萝卜素含量在镉橙丹桂开花过程中呈明显的先升高后降低的变化趋势,柚皮素苷元含量在柳叶金桂开花过程中呈缓慢上升趋势.[结论]槲皮素苷元、柚皮素苷元及β-胡萝卜素为桂花的特征花色物质,其在镉橙丹桂、厚瓣银桂和柳叶金桂开花及衰老过程中的变化规律共同决定了不同花色桂花品种花色明亮度具有随着花朵开放时间推移呈先加深后逐步黯淡的特征,而基本花色不产生明显变化.
[Objective] Variation of flower color compounds and their contents during floweringand petal senescence of Osmanthusfragrans Lour.with different colors were analyzed to provide reference for develoment and utilzation of O.fragrans with various colors.[Method] Color compounds and contents of three representative O.fragrans cultivars,O.fragrans'Gecheng Dangui'representing orange color,O.fragrans'Houban Yingui'representing yellowish white color and O.fragrans'Liuye Jingui'representing yellow-color were detected by high performance liquid chromatography-mass spectrometry (HPLC-MS).The color parameters L* (color brightness),a* (red/green degree) and b* (yellow/blue degree) and C* (chroma) were measured by the colorimeter,and then statistics of multivariate linear regressions were determined to analyze the relationship between characteristic color compounds and flower color.Changes of the content of characteristic color compounds were analyzed during petal senescence.[Result] The flavonoids analysis results indicated that there were five flavonoids compounds might present in the flowers,which were aureusidin-O-glycoside,quercetin-O-glycoside,apigenin-O-glycoside,rhamnetin-O-glycoside and naringenin-O-glycoside.Among them,quercetin-O-glycoside was the most abundant one in three representative varieties,whose contents were 134.55,89.41 and 90.39 μg/gFW in O.fragrans 'Gecheng Dangui',O.fragrans'Houban Yingui'and O.fragrans'Liuye Jingui'respectively.High contents of α-carotene (72.94 μtg/gFW) and β-carotene (99.72 μg/gFW) were only detected in O.fragrans'Gecheng Dangui'according to the quantitative analysis of carotenoids.The results of relationship between color measurement values and color compound contents showed that color brightness L* might be decided by quercetin-O-glycoside,the extent of yellow color b*might be decided by naringenin-O-glycoside and the extent of red color a* might be decided by β-carotene.The results showed that during flowering,quercetin-O-glycoside content was firstly decreased and then increased in three varieties,β-carotene content raised first and then dropped in O.fragrans'Gecheng Dangui',and Naringenin-O-glycoside content increased slowly in O.fragrans'Liuye Jingui'.[Conclusion] Quercetin-O-glycoside,naringenin-O-glycoside and β-carotene are the characteristic color compounds in O.fragrans.The changes of these three kinds of substances during flowering and senescence in O.fragrans'Gecheng Dangui',O.fragrans'Houban Yingui'and O.fragrans'Liuye Jingui'together determine that the change of flower brightness becomes deepening with flower blooming and then bleak with flower senescence,while there is no obviously change of flower color in these three cultivars.