chemical constituents of some species of the genus garcinia (guttiferae) growing in south viet

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

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 (1H and

13C 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