Flavonoids From Malus Rockii Rehder

This thesis summarizes the research work during the period of master’s degree,which is divided into three parts.In the first chapter,the distribution changes of phloridzin in flowering and fruiting stage of Malus rockii Rehder was represented.The second chapter describes the isolated chemical constituents of flavonoids from the twigs and leaves of M.rockii.The third part reviews the natural sources and pharmacological activities of phloridzin.Objective:To reveal the flavonoids constituents of Malus rockii and the distribution changes of its main component phloridzin in flowering and fruiting stage,and lay a theoretical foundation for further research and development of M.rockii.Methods:Single crystal X-ray diffraction experiments were conducted by Cu Ka radiation to determine the exact structure of phloridzin.The distribution changes of phloridzin in flowering,fruitlet,and fruit ripening phases of Malus rockii were quantified by a HPLC with an external standard.A variety of column chromatography was used to isolate and purify the flavonoids accumulation parts of the twigs and leaves of M rockii,and their structures were identified by physicochemical properties and modern spectral analysis techniques.Results:1.The exact structure of phloridzin was further confirmed as phloretin 6’-Oglucopyranoside rather than phloretin 2’-O-glucopyranoside by a single-crystal X-ray diffraction experiment.The results showed that the contents of phloridzin were 5.10%,10.92%,6.63%,1.32%and 5.00%in twigs,leaves,bark,xylem and flowers at flowering stage.The contents of phloridzin in twigs,leaves,bark,xylem and immature fruits at fruitlet stage were 7.19%,14.43%,9.73%,2.26%and 1.00%,respectively.The contents of phloridzin in twigs,leaf,stem bark,xylem and mature fruit in fruit ripening phases were 6.44%,12.26%,7.64%,1.97%and 0.21%,respectively.The contents of phloretin in flowering,fruitlet,and fruit ripening phases of Malus rockii were 0.66‰,0.84‰ and 21.17‰,respectively.2.A total of 19 compounds,including 13 flavonoids,were isolated and identified from the flavonoids accumulation parts of the twigs and leaves of M rockii,and they were naringenin(1),quercetin(2),phloretin(3),kaempferol(4),sexangularetin(5),8-methoxyquercetin(6),juglanin(7),kaempferol-8-methoxy-3-O-α-L-arabinofuranoside(8),avicularin(9),3-O-α-L-arabinofuranosyl-8-methoxyquercetin(10),kaempferol-8-methoxy3-O-α-L-rhamnopyranoside(11),phloridzin-6"-O-cinnamate(12),4-deoxyphloridzin(13),respectively.In addition,three triterpenoids and three other type compounds were isolated and identified as ursolic acid(14),tormentic acid(15),arjunolic acid(16),3,4,5-trimethoxyphenyl-O-β-D-glucopyranoside(17),phloretic acid(18)and 4-acetonyl-3,5dimethoxy-p-quinol(19).Conclusion:1.The exact structure of phloridzin was identified as phloretin 6’-O-glucopyranoside.The results showed that the contents of phloridzin in different parts of Malus rockii were as follows:leaf>bark>twigs ≈ flower>xylem>immature fruit>mature fruit.The concentrations of phloridzin in leaves,twigs,and bark and xylem of twigs increased at first and then decreased,and reached the highest value in the fuitlet period.The content of phloretin was the highest in leaves.2.A total of 19 compounds including 13 flavonoids were isolated and identified from the flavonoids accumulation parts of the twigs and leaves of Malus rockii.Compound 8 was a new compound,spectral data of compound 11 was reported for the first time,and compound 12 was a new natural product.In addition,compounds 5-8,11-13 and 17,19 were isolated from plants of Malus for the first time,and all compounds were isolated from M.rockii for the first time.