Study On Isolation And Determination Of Phenolic Compounds In The Leaves Of Psidium Guajava

Guava leaves have wide applications as Chinese and foreign folk medicine in the treatment of diabetes, diarrhea and other diseases. The phenolic compounds are the main active components of guava leaves, it contains many novel structures of the phenolic compounds. Many studies showed that phenolic compounds in guava leaves have hypoglycemic, antioxidant activity, anticancer and antipathogonic microorganism effect. However, the separation and the analysis methods of the active components of guava leaves are not satisfied at present, so it is important significance to establish a fast and efficient separation and analysis method. In this study, phenolic compounds of guava leaves were preparative separation by high-speed counter-current chromatography and followed by preparative liquid chromatography, high performance liquid chromatography was applied to determination the content of flavonoid glycosides in the ethyl acetate extract of guava leaves.This paper consists of three parts: Part one:literature reviewThis paper summarizes research progress on chemical constituents, pharmacological action and preparative separation of flavonoids in the leaves of Psidium guajava., and the common used solvent systems of high-speed countercurrent chromatography separation of flavonoids. The leaves of Psidium guajava. mainly contains phenolic acids, flavonoids, terpenoids and volatile oil, it has hypoglycemic, antidiarrheal, liver protection, antioxidant activity, anticancer and antipathogenic microorganism effect. The flavonoids of guava leaves were mainly isolated and purified by macroporous resin, silica, sephedex LH-20, reverse phase silica gel and preparative liquid chromatography at present. The two-phase solvent systems composed of n-hexane-ethyl acetate-methanol-water, petroleum ether-ethyl acetate ester-mcthanol-water, chloroform-methanol-water, n-hexane-chloroform-mcthanol-watcr, ethyl acetate-methanol-watcr, n-butanol-ethyl acetate-water were used to separate of flavonoids.Part two:extraction and separation of phenolic constituents of guava leavesIn this paper, a two-phase solvent system composed of n-hexane-ethyl acetate-methanol-water (0.7:4:0.8:4, v/v/v/v) separation and preparation of hyperoside and isoquercitrin mixture, reynoutrin, quercetin-3-O-β-D-pyran-arabinoside, quercetin-3-O-α-L-furanarabinoside and2,4,6-trihydroxy-3,5-dimethylbenzophenone-4-O-(6"-O-galloyl)-β-D-pyranglucosidase was established. Then, hyperin and isoquercitrin mixture were separated by preparative liquid chromatography. Quercetin and Psidials C were separated and preparated by using the solvent system composed of petroleum ether-ethyl acetate-methanol-water (1:1:1:1,v/v/v/v) from solvent system composed of n-hexane-ethyl acetate-methanol-water (0.7:4:0.8:4v/v/v/v) failed to sample elution.Part three:determination of five flavonoid glycosides of ethyl acetate extract of guava leavesAn HPLC method determination of hyperin, isoquercitrin, reynoutrin, quercetin-3-O-β-D-arabinopyranoside, quercetin-3-O-a-L-furanarabinoside was applied with a Syncronis C18(4×250mm) column by a gradient elution using acetonitrile (A)-0.2%phosphoric acid solution(B) as the mobile phase, The flow rate was1mL/min, the detective wavelength was254nm, the column temperature was40℃. The contents of hyperin, isoquercitrin, reynoutrin, quercetin-3-O-β-D-arabinopyranoside, quercetin-3-O-α-L-furanarabinoside of ethyl acetate extract of guava leaves were0.873～5.668mg/g,1.094～5.691mg/g,3.582～16.180mg/g,2.239～14.026mg/g,4.244～13.027mg/g respectively.