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: 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