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Iodimetric determination of 2-thiouracils

Ciesielski W., Zakrzewski R.

Chemia Analityczna

2000

Vol. 45, No. 1

135-144

The iodimetric determination of 2-thiouracil and its derivatives in alkaline medium is presented. In the volumetric titration with the potentiometric end-point detection the determinability range is 100-1000 umol for 2-thiouracil, 30-700 umol for 6-ami-no-2-thiouracil, 60-500 nmol for 5-carbethdxy-2-thiouracil and 100-500 pmol for 5-methyl-2-thiouracil. The relative standard deviation was below 1 % in all determinations. The elaborated method was applied to the determination of 6-propyl-2-thiouracil in drugs.

Przedstawiono jodometryczne oznaczanie 2-tiouracylu i jego pochodnych wykorzystując reakcję 2-tiouracylu z jodem w środowisku zasadowym. W miareczkowaniu objętościowym z potencjometryczną detekcją punktu końcowego można było oznaczyć 100-1000 \imola 2-tiouracylu, 30-700 umola 6-amino-2-tiouracylu, 60-500 umol 5-carboetoksy-2-tiouracylu i 100-500 umola 5-metylo-2-tiouracylu. Względne odchylenie standardowe we wszystkich wykonywanych oznaczeniach wynosiło mniej niż 1%. Opracowana metoda została zastosowana do oznaczenia 6-propylo-2-tiouracylu w lekach.

Metody syntezy siarkowych pochodnych zasad pirymidynowych

Nowakowska Z., Wyrzykiewicz E.

Wiadomości Chemiczne

1998

[Z] 52, 5-6

449-466

Uracil thio-derivatives have become to play increasingly important roles in biology and medicine. Numerous sulphur-substituted pyrimidines have found applications as clinically useful drugs. Thiouracils have recently been the subject of considerable interest as they inhibit hyperthyroidism in man [1, 2], have been isolated from E. Coli tRNA [3], and inhibit virus [4] and bacterial growth [5] by causing alterations [6] in protein synthesis. Thiouracils are also of interest because of mutagenic [7], anticancer and antithyroid activity [8], kidney stone formation inhibition [9] and antidote properties for mercury poisoning . Two of them, 2-thiouracil and 6-propyl-2-thiouracil, exhibit marked affinities for melanin-producing tissue in vitro and a similar affinity in vivo, where they presumably act as false precursors for melanin [10, 11]. Boron-containing derivatives of thiouracils [12-14] containing a dihydroxyboryl (or 1-o-carboranylalkyl) group in the 5-position are very important because of their potential applications for BNCT. Human immunodeficiency virus type 1 (HIV-1) is the causative agent of acquired immunodeficiency syndrome (AIDS), which is one of the world's most serious health problems. Since the discovery of the acyclic 6-substituted uridine derivative 1-[(2-hydroxyethoxy0methyl]-6-(phenythio)-thymine (HEPT) as a novel lead for specific anti-HIV-1 agents [15], a number of HEPT analogs have been synthesized to increase its potency [16-18]. The studies of the structure-activity relationships of HEPT analogs indicated that replacement of the 2-oxo function with a thine function potentiated their anti-HIV-1 activity [16, 19, 20]. Therofore the synthesis of thio-substituted pyrimidine bases and their derivatives appears to be a challenge for organic chemists. The methods of preparation of these compounds have been reviewed.