Analysis on characteristic color compounds in different varieties of Osmanthus fragrans Lour.during flowering and senescence

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.