Studies On The Content Determination And Specific Chromatogram Of The Triterpenes From Psidium Guajava Leaves

The plant Psidium guajava L. is mainly distributed in Guangdong, Guangxi, Fujianand Taiwan provinces in china. The leaves of this plant had been used for thetreatment of diarrhoea and hyperglycemia as a folk medicine for centuries. The mainchemical components of this plant are triterpenoids. Recent pharmacologicalinvestigation had shown that the total triterpenes from this planthad significantly hypoglycemic effect. In order to develop a safer and more effectivemedicine for the patient with diabetes mellitus, the quality control of Psidiumguajava leaves was studied. this paper carried out the following research work.1. Firstly, we explored the preparation technology of PG-1, PG-2and PG-3from thePsidium guajava leaves. The dried and roughly powdered Psidium guajava leaveswas extracted by95%alcohol, and the extract was collected and concentratedunder reduced pressure to about40%alcohol, then separated by a D-101resincolum, gradient elution with different concentrations of ethanol-water. The80%of ethanol-water extract was collected and concentrated under reduced pressure toprovide a residue, which was subsequently subjected to an silica gel columneluted with different concentrations of chloroform-methanol. Thechloroform-methanol (100:4) extract was evaporated under reduced pressure togive a mixture of PG-1, PG-2and PG-3, which was purified by Sephadex LH-20and reversed phase high performance liquid chromatography. Through the abovepreparation technology, PG-1(1.2g), PG-2(1.3g) and PG-3(2g)were prepared.The purity were more than98%by HPLC-DAD and HPLC-ELSD areanormalization method detection.2. The HPLC-ELSD datermination of the content of asiatic acid (PG-1), maslinicacid (PG-2) and corosolic acid (PG-3) were optimized in25batches of Psidiumguajava leaves.The method was carried out on a Cosmosil5MS-II-C18(250mm×4.6mm,5μm) column. A linear gradient elution of acetonitrile-water (0.1%formic acid) was used for separation. The flow rate was1.0mL/min and column-IV temperature was at30℃, drift tube temperature was at96℃and flow rate of gaswas2.0L/min. The linear relationship of PG-1, PG-2and PG-3were good, r>0.9996. The average recovery rate was at99.4%-104.4%, sample solution wasstable within24hours. We used this method to determine the content of PG-1,PG-2and PG-3in25batches of Psidium guajava leaves. The results showed thatin25batches of sample, the average content of PG-1was0.34%, the averagecontent of PG-2was0.48%, the average content of PG-3was1.18%, the totalaverage content of these three compounds was2.00%. Considering the medicinalorigin, processing, storage and other factors, It’s suggested that the total content ofPG-1, PG-2and PG-3should be not less than80%of the total average content ofthese three compounds. that is the sum content of these three compounds shouldbe not less than1.60%.3. The specific chromatogram of the Psidium guajava leaves was established byHPLC-ELSD. The method was same as the content determination of thetriterpenes from Psidium guajava leaves. As a result, the specific chromatogramof Psidium guajava leaves was evaluated and10common peaks were found.Among them,7peaks were identified by comparinson with the references isolatedfrom this plant, they are asiatic acid, maslinic acid, corosolic acid,3β-O-cis-coumaroyl-2α-hydroxyurs-12-en-28-oic acid,3β-O-trans-coumaroyl-2α-hydroxyurs-12-en-28-oic acid, oleanolic acid and ursolic acid. The resultsshowed that the analysis method of Psidium guajava leaves we builded wassimple, stable and repeatable.