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Title: Diallyl polysulfides from garlic : mode of action and applications in agriculture
Author: Arbach, Miriam
ISNI:       0000 0004 5359 3639
Awarding Body: University of East Anglia
Current Institution: University of East Anglia
Date of Award: 2014
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Garlic (Allium sativum) contains a wide range of organosulfur compounds which show a variety of biological effects including broad spectrum antibacterial, antifungal and antiviral activity, as well as selective anticancer activity. One highly bioactive class of compounds from garlic are diallyl polysulfides (DAS), containing one to six sulfur atoms in a linear chain. The bioactivity of DAS has been shown to increase with increasing sulfur chain length up to DAS4 and in this study the even higher bioactivity of DAS5 and DAS6 was demonstrated. The bioactivity of DAS is believed to be initiated following initial reaction with intracellular low molecular weight (LMW) and protein thiols. In this study the interaction between DAS and LMW thiols was investigated and for the first time the reduced DAS metabolites allyl hydropolysulfides have been detected in vitro and in vivo in the Gram positive bacterium Bacillus subtilis. Additionally, formation of mixed polysulfides between DAS and LMW thiols with up to five sulfur atoms was observed in vitro. Proteomic studies revealed a large number of proteins in B. subtilis that formed mixed di- and trisulfides with DAS. Therefore multiple points of DAS attack have been proven and the disturbance of the cellular redox status through lowering the pool of reduced LMW thiols was established in two different organisms (B. subtilis and the nematode Steinernema feltiae). To exploit the polysulfide chemistry for the development of a “green” nematicide, the nematicidal activity of DAS was investigated in bioassays as well as the efficacy of DAS formulations towards plant pathogenic nematodes (Meloidogyne spp. and Globodera spp.) in potato and carrot field trials. It was demonstrated that the DAS derived nematicides form an equally effective alternative compared to synthetic nematicides at a much lower environmental and health risk.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available