Samples of linear polycaprylolactam have been prepared and fractionated, and the [q]-M, relationship has been established in m-cresol. Statistically branched samples have been obtained by copolymerizing 8-caprylolactam with bislactams. The degree of branching as well as the branching ability of different bislactams are discussed and compared with the corresponding data for branched polycaprolactams. ZUSAMMENFASSUNG : Lineares Polycapryllactam wurde hergestellt und fraktioniert, und die [q]-w-Beziehung in m-Kresol wurde bestimmt. Statistisch verzweigte Proben wurden durch Copolymerisation von 8-Capryllactam mit Bislactamen erhalten. Der Verzweigungsgrad und die Fahigkeit zur Verzweigung verschiedener Bislactame wird diskutiert und mit den entsprechenden Daten fur verzweigte Polycaprolactame verglichen. * Communication XL: Makromol. Chem., in press.
LABELLING OF OCHRATOXINS WITH 3H OR1 2 5 1 D. Schmiedovd, K . V e r e S , B.Cern9 I n s t i t u t e of Nuclear Biology and Radiochemistry, Czechoslovak Academy of S c i e n c e s , Prague J. Ruprich, I n s t i t u t e of Hygiene and Epidemiology, Prague J. N6meEek , I n s t i t u t e of Microbiology , Czechoslovak Academy of S c i e n c e s , Prague SUMMARY C a t a l y t . i c hydrogenation of o c h r a t o x i n A by c a r r i e r -f r e e 5 t r i t i u m was used t o p r e p a r e H-ochratoxin B w i t h a h i g h s p e c i f i c a c t i v i t y . I o d i n a t i o n of o c h r a t o x i n B by c a r r i e r -f r e e N a ' 251 u s i n g t h e c h l o r a m i n e method y i e l d e d ' 251-ochratoxin w i t h a h i g h s p e c i f i c a c t i v i t y . Another 1 2 5 1 -d e r i v a t i v e of o c h r a t o x i n A was p r e p a r e d by i o d i n a t i o n of an o c h r a t o x i n A -L--t y r o s i n e -m e t h y l e s t e r c o n j u g a t e . A l l t h r e e r a d i o a c t i v e p r ep a r a t i o n s w e r e found t o b e u s e f u l f o r radioimmunoassay. K e y words: Ochratoxin A and B , l a b e l l i n g , t r i t i a t i o n , r a d i o i o d i n a t i o n , t y r o s i n e -m e t h y l e s t e r c o n j u g a t e
Digitoxin and digoxin 4'''-(3-carboxypropanoates)(4'''-hemisuccinates) III and X were prepared by an indirect method, using dicyclohexylcarbodiimide-induced condensation of the cardioglycoside with 4-(2,2,2-trichloroethoxy)-4-oxobutanoic acid in dichloromethane in the presence of 4-dimethylaminopyridine or pyridine followed by removal of the 2,2,2-trichloroethyl group with zinc in a mixture of tetrahydrofuran, acetic acid and water. The hemisuccinates III and X were condensed with L-tyrosine methyl ester in tetrahydrofuran, using N-ethoxycarbonyl-2-ethoxy-1,2-dihydroquinoline as the coupling reagent. Structure of the products was proved by 1H NMR and 13C NMR spectra. The conjugates IV and XI were labelled with [125I] in the L-tyrosine moiety. The obtained radioligands V and XII are designed as a part of the RIA system for cardioglycoside analyses.
Digitoxin (Ia) and digoxin (Ib) are converted to the title compounds (IV) and (VI) by the sequence shown in the scheme [reaction conditions of (I)‐(III) had to be modified for (Ib) so as to avoid the formation of di‐ and multi‐acylated products].
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