| Tea(Camellia sinensis),a traditional beverage originated in China,has a wide range of consumers among different ages,places,cultures,societies,etc.due to its unique flavor and healthy benefits.Lu'an GuaPian tea,a type of baked green tea produced in Lu'an,Anhui province,is one of the top ten teas consumed in China.It is well-known for its unique quality and processing methods.Only fresh leaves without buds or stems of Camellia sinensis(C.sinensis)are used as the material and high baking temperature is needed during its drying step.However,few studies have been conducted on systematic purification and structural identification of chemical constituents from this unique processed green tea.Recently,tea has drawn increasing attention due to their contribution to potential bioactivities,which have close connection with tea chemical components.As a kind of secondary plant metabolites in tea,flavonoids have wide bioactivities and have also broad prospect of application in medicine,food industry.In this study,Lu'an GuaPian tea was extracted and fractionated by organic solvents.In order to find new active agents from this plant,the chemical study on its constituents was carried out.Silica gel,Sephadex LH-20,Toyopearl,polyamide,ODS and MCI column chromatography were applied for isolation of chemical compositions.The structures of the isolated compounds were identified by different spectroscopic methods such as NMR,IR,UV,and mass spectrometry.The bioactivities of monomeric compounds isolated from Lu'an GuaPia tea also were investigated.Furthermore,we established a rapid UPLC method to quantify nine flavonoid glycosides(FGs)in six major processing types of tea.A novel acylated flavonol tetraglycoside,kaempferol 3-O-[(E)-p-coumaroyl-(1?2)] [?-L-arabinopyranosyl-(1?3)][?-D-glucopyranosyl(1?3)-?-L-rhamnopyranosyl(1?6)]-?-D-glucopyranoside(camellikaempferoside C,1),together with two flavonoids and eighteen FGs(2-21)was isolated from the green tea Lu'an GuaPian.Their structures were identified by spectroscopic and chemical methods.The known compound were named myricetin 3-O-galactoside(2),quercetin 3-O-galactoside(3),myricetin 3-O-glucoside(4),kaempferol(5),quercetin(6),kaempferol-3-O-[(E)-p-coumaroyl-(1?2)][?-Larabinopyranosyl-(1?3)][?-L-rhamno-pyranosyl(1?6)]-?-D-glucopyranoside(7),quercetin 3-O-[(E)-p-coumaroyl-(1?2)][?-L-arabinopyranosyl-(1?3)][?-Lrhamnopyranosyl(1?6)]-?-D-glucopyranoside(8),quercetin 3-O-[(E)-p coumaroyl-(1?2)] [?-L-arabinopyranosyl-(1?3)] [?-D-glucopyranosyl-(1?3)-?-Lrhamnopyranosyl(1?6)]-?-D-glucopyranoside(9),kaempferol 3-O-glucosylrutinoside(10),kaempferol 3-O-galactosylrutinoside(11),apigenin 6,8-C-diglucoside(12),apigenin-6-C-glucosyl-8-C-arabinoside(13),apigenin-6-Carabinosyl-8-C-glucoside(14),quercetin 3-O-galactosylrutinoside(15),quercetin3-O-glucosyl rutinoside(16),kaempferol 3-O-rutinoside(17),quercetin 3-O-rhamnosylgalactoside(18),kaempferol 3-O-rhamnosylgalactoside(19),Vitexin-2''-O-glucoside(20),and kaempferol 3-O-glucoside(21).Four acylated FGs(1,7,8,9)were found to inhibit the proliferation and differentiation of 3T3-L1 preadipocytes at the concentrations 25,50,100 ?M(p< 0.05).For content of nine FGs in six major processing types of tea,the results showed that dark tea had the highest amount of 20(0.70 ± 0.017 mg/g)and black tea had the highest amount of 8(0.09 ± 0.012 mg/g)while the amounts of 10 and 16 basically decreased with the increasing degree of fermentation and could contribute to the discrimination of different processing types of tea.The highlights of this study were that we systematically investigated flavonoids in Lu'an GuaPian tea and found a novel acylated flavonol tetraglycoside with inhibition effects on lipid accumulation in 3T3-L1 preadipocytes.Moreover,a rapid UPLC method was established for determination nine FGs especially acylated FGs in tea,which would be a valuable information for quantification acylated FGs in tea. |
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