István Tóth
University of Szeged
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Featured researches published by István Tóth.
Steroids | 2004
János Wölfling; László Hackler; Erzsébet Mernyák; Gyula Schneider; István Tóth; Mihály Szécsi; János Julesz; Pál Sohár; Antal Csámpai
During the alkaline methanolysis of 3beta-acetoxy-21-chloromethyl-pregn-5-ene-20beta-N-phenylurethane, and its p-substituted phenyl derivatives, cyclization occurs, in the course of which 17beta-[3-(N-phenyl)tetrahydrooxazin-2-on-6-yl]androst-5-en-3beta-ol and its p-substituted phenyl derivatives are formed. The cyclization takes place with (N(-)-6) neighboring group participation. Oppenauer oxidation of the 3beta-hydroxy-exo-heterocyclic steroids yielded the corresponding delta4-3-ketosteroids. The structures of the new compounds were proved by IR, 1H and 13C NMR spectroscopy, using up-to-date measuring techniques such as 2D-COSY, HMQC, and HMBC. The inhibitory effects (CI50) of the delta4-3-ketosteroids on 5alpha-reductase were studied.
Steroids | 2009
Dóra Ondré; János Wölfling; István Tóth; Mihály Szécsi; János Julesz; Gyula Schneider
17beta-Oxazolinyl steroids 7a-g and 8a-g were synthesized. The Lewis acid-catalysed reactions of (20R)-3beta-acetoxy-21-azidomethyl-20-hydroxypregn-5-ene with substituted aromatic aldehydes led to the formation of 3beta-acetoxyandrost-5-enes substituted in position 17beta with oxazolinyl residues (7a-g). Oppenauer oxidation of the 3beta-hydroxy-exo-heterocyclic steroids yielded the corresponding Delta(4)-3-ketosteroids. The inhibitory effects (IC(50)) of both 3-hydroxy compounds 7a-g and their Delta(4)-3-keto counterparts 8a-g on rat testicular C(17,20)-lyase were investigated with an in vitro radioligand incubation technique. The 3-chlorophenyl- (8d), and the 4-bromophenyl-17beta-(2-oxazolin-5-yl)androst-4-en-3-one derivatives (8f) were found to be modest inhibitors (IC(50)=4.8 and 5.0 microM, respectively).
Steroids | 2006
János Wölfling; Éva Andrea Oravecz; Dóra Ondré; Erzsébet Mernyák; Gyula Schneider; István Tóth; Mihály Szécsi; János Julesz
Abstract 17β-Dihydrooxazinyl steroids 5a – l and 6a – l were synthetized. The acid-catalyzed reactions of 21-azidomethyl-20-hydroxy- and 21-hydroxymethyl-20-azidosteroids with substituted aromatic aldehydes led to the formation of androst-5-en-3β-ols substituted in position 17β with dihydrooxazine residues. The inhibitory effects of these compounds on rat testicular C 17,20 -lyase were investigated with an in vitro radioincubation technique.
Steroids | 2008
Dóra Ondré; János Wölfling; Zoltán Iványi; Gyula Schneider; István Tóth; Mihály Szécsi; János Julesz
During the alkaline methanolysis of 3beta-acetoxy-21-chloropregn-5-ene-20beta-N-phenylurethane (4a), and its 4-monosubstituted (4b-e) and 3,5-disubstituted (4f) phenyl derivatives, cyclization occurs, in the course of which 17beta-[3-(N-phenyl)-2-oxazolidon-5-yl]androst-5-en-3beta-ol (5a) and its substituted phenyl derivatives (5b-f) are formed. The cyclization takes place with (N(-)-5) neighboring group participation. The reaction of 3beta-acetoxy-21-azidopregn-5-en-20beta-ol (3d) with triphenylphosphine gave 3beta-acetoxy-21-phosphiniminopregn-5-en-20beta-ol, which reacted in situ with carbon dioxide with the participation of the sterically favored 20beta-OH to give the unsubstituted steroidal cyclic carbamate (8). Oppenauer oxidation of the 3beta-hydroxy-exo-heterocyclic steroids (5a-f, 9) yielded the corresponding Delta(4)-3-ketosteroids (7a-f, 10). The inhibitory effects (IC(50)) of these compounds on rat testicular C(17,20)-lyase were investigated with an in vitro radioligand incubation technique. The N-unsubstituted 17beta-(2-oxazolidon-5-yl)-androst-4-en-3-one derivative (10) was found to be a potent inhibitor (IC(50)=3.0 microM).
Skin Pharmacology and Physiology | 1997
István Tóth; Mihály Szécsi; J. Julesz; I. Faredin
Activity and inhibition of 3 beta-hydroxysteroid dehydrogenase/delta 5-4-isomerase, a key example of biosynthesis of androgenic steroids, in human skin were studied. Whole-width dermal tissue specimens excised from various regions of the male and female body were investigated with an in vitro radioenzyme assay method using dehydroepiandrosterone as substrate. The Michaelis-Menten constant of the enzyme was found to be Km = 10nM and the maximal velocity was Vmax = 0.625 pmol produced 4-androstene-3,17-dione/mg protein/20 min. Activity of 3 beta-hydroxysteroid dehydrogenase/delta 5-4-isomerase in male inguinal skin (n = 8) was 0.132-0.412, in female abdominal skin (n = 4) 0.140-0.255, in perineal skin (n = 4) 0.138-0.962 pmol/mg protein/20 min. The synthetic steroids cyproterone acetate, 4-MA and epostane proved to be potent inhibitors, IC50 values were 150, 6.2 and 1.45 nM, respectively.
Oncology | 1992
Zsuzsanna Kahán; István Tóth; Miklós Vecsernyés
Eleven postmenopausal patients with advanced breast cancer were assessed for their response and endocrine changes to low-dose aminoglutethimide (250 mg twice a day) therapy without steroid administration. In 7 cases an objective response was registered; 1 patient had a stabilization of the disease lasting for 9 months. Significant falls in plasma estrogen and rises in plasma androgen levels were observed, while those of cortisol and ACTH remained essentially unchanged. No serious side effects occurred.
Steroids | 2001
Pál Tapolcsányi; János Wölfling; István Tóth; Mihály Szécsi; Peter Forgo; Gyula Schneider
The four possible isomers 16beta-hydroxymethyl-5alpha-androstane-3beta,17beta-diol 1, 16alpha-hydroxymethyl-5alpha-androstane-3beta,17beta-diol 2, 16beta-hydroxymethyl-5alpha-androstane-3beta,17alpha-diol 3 and 16alpha-hydroxymethyl-5alpha-androstane-3beta,17alpha-diol 4 with proven configuration were converted into the corresponding 16beta-methyl-5alpha-androstane-3beta,17beta-diol 5, 16alpha-methyl-5alpha-androstane-3beta,17beta-diol 6, 16beta-methyl-5alpha-androstane-3beta,17alpha-diol 7, 16alpha-methyl-5alpha-androstane-3beta,17alpha-diol 8, furthermore into the 16beta-methyl-17beta-hydroxy-5alpha-androstane-3-one 13, 16alpha-methyl-17beta-hydroxy-5alpha-androstan-3-one 14, 16beta-methyl-17alpha-hydroxy-5alpha-androstan-3-one 15 and 16alpha-methyl-17alpha-hydroxy-5alpha-androstan-3-one 16. The steric structures of the resulting epimers were determined by means of 1H-, and 13C-NMR spectroscopy. In this way, comparison was possible with the C-16 epimers 5, 6 and 13, 14 prepared earlier by a different route, and the series of isomers could be completed with the steric structures of 16beta-methyl-17alpha-hydroxy-5alpha-androstan-3beta-ol 7 and 16alpha-methyl-17alpha-hydroxy-5alpha 8 and with their 3-keto derivatives 15 and 16. The relative binding affinities of the 16-methyl-5alpha-androstane-3beta,17-diols 5, 6, 7, 8 and 17-hydroxy-16-methyl-5alpha-androstan-3-ones 13, 14, 15, 16 were studied. The introduction of a 16-methyl substituent into 5alpha-androstane molecules substantially decreases the binding affinity to the androgen receptor and 16alpha-methyl derivatives were always bound more weakly than the 16beta-methyl isomers.
Journal of Biochemical and Biophysical Methods | 2004
Mihály Szécsi; István Tóth; János Gardi; T. Nyári; János Julesz
Journal of Biochemical and Biophysical Methods | 2006
Mihály Szécsi; István Tóth; János Gardi; Miklós Vecsernyés; József Németh; János Julesz
Acta Biologica Hungarica | 2010
Mihály Szécsi; Dóra Ondré; István Tóth; S. Magony; János Wölfling; Gy. Schneider; J. Julesz