TY  - THES
T1  - Natural polysulfides- reactive sulfur species from Allium with applications in medicine and agriculture
A1  - Anwar,Awais
Y1  - 2009/06/29
N2  - Natural sulfur compounds from plants, bacteria, fungi and animals frequently exhibit interesting biological activities, such as antioxidant, antimicrobial and anticancer activity. Considering the recent developments in medicine (e.g. oxidative stress in ageing, antibiotic resistant bacteria, and selective anticancer agents) and Agriculture (e.g. 'green'; pesticides), several of these compounds have become the focus of interdisciplinary research. Among the various sulfur agents isolated to date, polysulfides, such as diallyltrisulfide,  diallyltetrasulfide (from garlic) and dipropyltrisulfide, dipropyltetrasulfide (from onion), are of particular interest, since they combine an unusual chemistry and biochemical mode(s) of action with a distinct biological activity, which includes antimicrobial activity and cytotoxicity against certain cancer cells. As part of this PhD thesis, the activity of diallyltrisulfide and diallyltetrasulfide against the fairly 'robust'; Caco-2 colon cancer cell line and induction of apoptosis and cell cycle arrest in U937 cells have been confirmed. Accordingly, diallyltetrasulfide triggered the programmed cancer cell death- both via the extrinsic and intrinsic pathway. Similarly, these polysulfides showed a good activity in nematode toxicity assays considering them as potential green nematicides. Controls with the long chain carbon analogue 1,9-decadiene eliminate the possibility of  solely lipophilic effects of diallyltetrasulfide and, together with the 'ranking'; of activity, point toward a special sulfur redox chemistry which emerges when shifting from the di- to the trisulfide. The electrochemical studies and thiol oxidation assays, however, count against the notion of diallyltrisulfide and diallyltetrasulfide as effective oxidants. On the contrary, the rather negative oxidation and reduction potentials associated with these agents point toward a reducing chemistry, which is confirmed in the Nitrotetrazolium Blue assay. It is therefore likely that diallyltrisulfide and diallyltetrasulfide are reduced inside the cancer cells to perthiols and hydropolysulfides, which in turn trigger a lethal oxidative burst via superoxide radical anion formation. Further interdisciplinary studies are required to investigate in more detail the rather complicated chemical and biochemical processes which ultimately may explain the biological activity which is clearly associated with many natural polysulfides.
KW  - Knoblauch
KW  - Krebszelle
KW  - Pestizid
KW  - Polysulfide
CY  - Saarbrücken
PB  - Universitäts- und Landesbibliothek
AD  - Postfach 151141, 66041 Saarbrücken
UR  - http://scidok.sulb.uni-saarland.de/volltexte/2009/2237
ER  -