THESIS INFORMATION - Thesis title: Chemical constituents of some species of the genus Garcinia (Guttiferae) growing in south Vietnam - Major: Organic chemistry - Code: 1.04.02 - PhD student: Vo Tan Hau - Academic batch: 2003 - Supervisors: Supervisor 1: Assoc. Prof. Dr. Pham Dinh Hung Supervisor 2: Assoc. Prof. Dr. Nguyen Dieu Lien Hoa - Organization: Ho Chi Minh City University of Science, VNU-HCM 1. ABSTRACT This thesis deals with the isolation and characterization of natural products from three members of the Garcinia genus (G. pedunculata, G. merguensis and G. schomburgkiana) collected in south Vietnam. The species have been used for the treatment of illnesses in folk medicine. G. pedunculata is used for the treatment of constipation and digestive problems and G. merguensis is used to treat oedemas while G. schomburgkiana is used for the treatment of coughs and menstrual disturbances. Isolation was carried out using a combination of flash column chromatography on silica gel, RP-18 and DIOL silica, and gel permeation column chromatography on Sephadex LH-20. Structure elucidation was performed based on spectral studies ( 1 H and 13 C NMR, HSQC, HMBC, HRMS, UV and IR). From a petroleum ether extract of the bark of G. pedunculata, we isolated eight compounds including three new ones, pedunxanthones A, B and C. From a chloroform extract of the pericarp of G. pedunculata, we obtained thirteen xanthones; three of which, pedunxanthones D, E and F, are novel. An ethyl acetate extract of the bark of G. merguensis produced three known xanthones whilst an ethyl acetate extract of the bark of G. schomburgkiana yielded three xanthones including a new one, schomburgxanthone. Totally, we isolated twenty-five compounds (of which 1,7-dihydroxyxanthone was found in all three species and counted only once) and seven of them are new. In addition, cytotoxicity towards two human cell lines, HeLa and NCI-H460, of fourteen isolated xanthones was tested using the SBR assay with camptothecin as the positive control. The result has shown that globuxanthone possessed the strongest effect, followed by dulxanthone A, pedunxanthone D and griffipavixanthone. The remaining xanthones exhibited weak activity. 2. NEW FINDINGS OF THE THESIS - Investigating the chemical constituents of three Garcinia species, G. pedunculata, G. merguensis and G. schomburgkiana, and isolating seven compounds which have not been previously reported. Part of the result was published in two peer-reviewed international articles (Phytochemistry Letters). - Suggesting possible biosynthesis pathways for the isolated xanthones. 3. FURTHER RESEARCH Study the antibacterial and antioxidant activities of the isolated compounds. SUPERVISORS 1. Assoc. Prof. Pham Dinh Hung 2. Assoc. Prof. Nguyen Dieu Lien Hoa PhD STUDENT Vo Tan Hau CONFIRMATION OF HO CHI MINH CITY UNIVERSITY OF SCIENCE THE RECTOR . THESIS INFORMATION - Thesis title: Chemical constituents of some species of the genus Garcinia (Guttiferae) growing in south Vietnam - Major: Organic chemistry -. activity. 2. NEW FINDINGS OF THE THESIS - Investigating the chemical constituents of three Garcinia species, G. pedunculata, G. merguensis and G. schomburgkiana, and isolating seven compounds. of natural products from three members of the Garcinia genus (G. pedunculata, G. merguensis and G. schomburgkiana) collected in south Vietnam. The species have been used for the treatment of