The effects of Tulbaghia violacea leaf, bulb and stalk extracts on Jurkat cells.
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Date
2012
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Abstract
Studies have shown that the traditional healers have used Tulbaghia violacea (TV) (also
known as ‘wild garlic’) for the treatment of a number of ailments including fever,
tuberculosis, stomach problems, and oesophageal cancer. However, little is known with
regards to the anticancer and antiproliferative properties of this plant. Therefore, this
study investigated the effects of TV and domesticated garlic extracts on Jurkat cells, in
order to determine whether or not these extracts possess anti-proliferative properties.
Cultured Jurkat cells were treated with IC50 concentrations of garlic (14μg/ml), TV leaf
(256μg/ml), TV bulb (225μg/ml) and TV stalk (216μg/ml) extracts as determined by the
methylthiazol tetrazolium assay. Free radical production was measured using the
thiobarbituric acid reactive substance (TBARS) and nitric oxide (NO) assays, while
glutathione (GSH) concentration was measured using the GSH-Glo™ assay. The
apoptosis inducing properties of each extract were measured using flow cytometry
(Annexin V- Fluos and JC-1 assays) and luminometry (caspases 3/7, 8, 9 and ATP).
Western blots were run to determine protein expression, while comet and DNA
fragmentation assays were used to determine the level of DNA damage induced. Wild
and domesticated garlic extracts induced a significant increase in malondialdehyde
concentration ([MDA]), with TV bulb extract inducing the highest concentration
(p<0.0001). A significant increase in NO concentration was observed in the bulb
(p<0.0001) and stalk (p<0.001) extracts, and leaf (p<0.05) and stalk (p<0.05) TV
extracts significantly increasing GSH concentration. The longest comet tails were
observed in TV bulb extracts (p<0.0001) and comprised mainly of single strand breaks,
while the comets induced following garlic exposure contained double strand breaks. All
extracts, except TV leaf, increased the percentage of cells undergoing apoptosis.
Tulbaghia violacea leaf induced a significant (p<0.0001) increase in percentage of cells
undergoing necrosis, whereas TV bulb resulted in a significant (p<0.0001) decrease.
All TV extracts induced caspase 3/7 and 9 activity, with the most significant increase in
caspase 9 activity observed for TV leaf and bulb. No significant change in caspase 3/7
activity was evident for domesticated garlic. Cleavage of PARP and expression of
NF B and HSP 70 occured for all extracts. However, HSP 70 was not differentially
expressed. Exposure to wild and domesticated garlic extracts induced peroxidative lipid
and DNA damage within the cells, indicating oxidative stress. This damage occurred in
conjunction with increased percentage of cells undergoing apoptosis and expression of
caspase 3/7. Therefore, these findings suggest that TV is inducing cell death through
apoptosis in Jurkat cells using a number of mechanisms, including the induction of
oxidative stress. This is of clinical significance, as cell death through apoptosis is the
preferred method of action for anti-cancer drugs.
Description
Thesis (M.Med.)-University of KwaZulu-Natal, Durban, 2012.
Keywords
Allium vineale., T cells., Cancer--Alternative treatment., Medicinal plants., Theses--Medical biochemistry.