South African Traditional Medicines Research Unit
Current projects 1 to 3
- The mechanism of chloroquine and mefloquine resistance in plasmodium
falciparum
Project
leaders: Dr P.J. Smith, Prof. P. Folb
Principle investigators: J. Walden
The broad objective of
this project is to explain the mechanism of chloroquine and mefloquine resistance
in Plasmodium falciparum.
Specific objectives:
- To establish whether
digestive vacuoles isolated from chloroquine and mefloquine resistant strains
of Plasmodium falciparum accumulate less drug than those isolated from sensitive
strains;
- To establish whether
differences in accumulation are due to a weakened proton pump in the vacuolar
membrane or to the presence of increased levels of the drug transport protein,
pGh1 in vacuoles isolated from resistant strains.
- Chemosensitisers
for plasmodium falciparum malaria
Project
Leaders: Dr P. Smith, Prof. P. Folb
Principle Investigators: D. Van Schalkwyk, D. Taylor
The broad scientific goal
of this project is to establish the reversal mechanism of chloroquine resistance
by verapamil and other chemosensitisers in Plasmodium falciparum.
Specific objectives:
- To culture the malarial
parasites in human erythrocytes in order to maintain them at their trophozoite
stage for experiments;
- To observe the radioactive
3H- chloroquine accumulation in a sensitive strain D10 and a resistant strain
RSA11 after adding different concentrations of each chemosensitiser alone;
- To determine the IC50
for both strains in response to increasing concentrations of each chemosensitiser
alone;
- To determine the IC50
and 3H- chloroquine accumulation for the resistant strain in response to
suboptimal and sublethal chemosensitiser combinations;
- To determine if the
effects of the chemosensitiser combinations on reversal are additive, indifferent
or synergistic;
- To identify proteins
involved in resistance reversal using photo-affinity labelled verapamil;
- To establish if chloroquine
resistance reversal is effective in vivo, using the Plasmodium berghei mouse
model.
- Isolation
and characterisation of anticancer and cytotoxic compounds from plants used
by tradtional healers
Project
Leaders: Dr P. Smith, Prof. P. Folb, Mr. W. Campbell, Prof. M.I. Parker
Principle Investigators: Ms N. Brine
The primary aim of this
project is to use HPLC methodology for the rapid isolation and purification
of anticancer and cytotoxic compounds from plants used by traditional healers
in the treatment of cancer.
Specific objectives:
- To identify and obtain
plants used by traditional healers for the treatment of cancer;
- To test the crude plant
extracts for their cytotoxic properties against a variety of cancer cell
lines;
- To develop and validate
a reverse-phase high performance liquid chromatography (HPLC) assay system
for the characterisation of the plant extracts - i.e. to achieve a ‘parent
profile' of the types of compounds present in the crude extract;
- To perform flash chromatography
on the crude extracts to obtain purer fractions of each extract, and then
to screen the individual fractions for cytotoxicity;
- To characterise the
fractions from flash chromatography showing cytotoxic properties, using
the same HPLC system, and superimposing their peak profiles onto the ‘parent
profile';
- To isolate and characterise
the cytotoxic compounds by HPLC;
- To characterise purified
compounds fully using NMR and Mass Spectroscopy;
- To investigate the
action mechanism of isolated anticancer agents.
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