doctoral thesis
Effect of glutathione S – transferase inhibitors on aflatoxin production by Aspergillus flavus

Bojan Šarkanj (2014)
Josip Juraj Strossmayer University of Osijek
FACULTY OF FOOD TECHNOLOGY
Department of Applied Chemistry and Ecology
Sub-department of Biochemistry and Toxicology
Metadata
TitleUtjecaj inhibitora glutation S – transferaze na produkciju aflatoksina plijesni Aspergillus flavus
AuthorBojan Šarkanj
Mentor(s)Tomislav Klapec
Abstract
Glutation S-transferaza (GST) je enzim s višestrukom funkcijom kojim se eukarioti mogu braniti od štetnog djelovanja metabolički aktiviranih aflatoksina, ali i reaktivnih vrsta kisika. Utvrđeno je da se kod plijesni povećava aktivnost GST-a kod povećane produkcije aflatoksina. Cilj ovog rada je bio ispitivanje utjecaja odabranih inhibitora ligandinske i katalitičke domene GST-a u stanici plijesni Aspergillus flavus na biosintezu aflatoksina. Rezultati su pokazali da inhibitori GST-a inhibiraju i produkciju aflatoksina u mikrobiološkoj podlozi u in vitro uvjetima kod svih ispitivanih koncentracija (10; 1; 0,1; 0,01 ppm), ali plijesni preživjele na podlozi s dodanim inhibitorima, imaju povišenu aktivnost GST-a, glutation reduktaze te katalaze. Ujedno, utvrđeni su dodatni sekundarni metaboliti koje ova plijesan proizvodi na ispitivanoj mikrobiološkoj podlozi LC-ESI-MS/MS analizom (QTrap). Uz osnovne intermedijere aflatoksina detektirane su ciklopijazonična, 3-nitropropionska te kojična kiselina Podešeni su odgovarajući parametri za primjenu ultrazvuka kao sigurnije i jeftinije metode razbijanja stanica plijesni. Također je praćena ekspresija regulatornih gena za biosintezu aflatoksina (aflR i aflS), pri čemu uz dodatak inhibitora GST-a dolazi do smanjenja ekspresije regulatornih gena te posljedične redukcije biosinteze aflatoksina.
Keywordsmoulds aflatoxins Aspergillus flavus glutathione S – transferase inhibitors antiaflatoxigenic effect LC-MS/MS RT-PCR
Parallel title (English)Effect of glutathione S – transferase inhibitors on aflatoxin production by Aspergillus flavus
Committee MembersIvan Kosalec (committee chairperson)
Tomislav Klapec (committee member)
Ivica Strelec (committee member)
Daniela Čačić Kenjerić (committee member)
GranterJosip Juraj Strossmayer University of Osijek
FACULTY OF FOOD TECHNOLOGY
Lower level organizational unitsDepartment of Applied Chemistry and Ecology
Sub-department of Biochemistry and Toxicology
PlaceOsijek
StateCroatia
Scientific field, discipline, subdisciplineBIOTECHNICAL SCIENCES
Food Technology
Food Chemistry
UDK615
APPLIED SCIENCES. MEDICINE. TECHNOLOGY
Pharmacology. Therapeutics. Toxicology
Study programme typeuniversity
Study levelpostgraduate
Study programmeFood Engineering
Academic title abbreviationdr. sc.
Genredoctoral thesis
Language Croatian
Defense date2014-06-06
Parallel abstract (English)
Glutathione S-transferase (GST) is used in eukaryotic cell as defence enzyme from harmful effect of metabolically activated aflatoxin form. It is known that GST is positively correlated with aflatoxin biosynthesis. The aim of this thesis is to determine the effect of several GST inhibitors (both catalytic and ligand site) on aflatoxin production n in A. flavus. Results have shown that GST inhibitors inhibit also the aflatoxin production at all tested concentrations (10; 1; 0.1; 0.01 ppm) in vitro on microbiological medium, but survived cells have higher GST, glutathione reductase and catalase activity. Also the knowledge on A. flavus secondary metabolites produced on GMS medium has been expanded by LC-ESI-MS/MS (QTrap) analysis. In addition to basic aflatoxin biosynthesis pathway intermediates, cyclopiazonic acid, 3-nitropropionic acid, and kojic acid were detected. Ultrasonic disintegration method was also adjusted for mycelium as a safer and cheaper alternative of cell disruption. The expression of aflatoxin biosynthesis regulatory genes (aflR and aflS) was monitored and a lower expression followed addition of GST inhibitorsresulting in a lower aflatoxin biosynthesis rate.
Parallel keywords (Croatian)plijesni aflatoksini Aspergillus flavus inhibitori glutation S – transferaze antiaflatoksikogeni učinak LC-MS/MS RT-PCR
Extent257 str.; 30 cm
Versionaccepted version
Resource typetext
Access conditionAccess restricted to students and staff of home institution
Terms of usehttp://rightsstatements.org/vocab/InC/1.0/
Noteaccepted version
URN:NBNhttps://urn.nsk.hr/urn:nbn:hr:109:619825
CommitterSanda Hasenay