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Biomedical subjects

Y F Shealy

Publications and source records attributed to Y F Shealy.

At least 55 records · Page 3Linked to original sources
PubMed1984

Synthesis and antiviral evaluation of carbocyclic analogues of ribofuranosides of 2-amino-6-substituted-purines and of 2-amino-6-substituted-8-azapurines.

Carbocyclic analogues of ribofuranosides of 2-amino-6-substituted-purines and of 2-amino-6-substituted-8- azapurines were prepared from the 2-amino-6-chloropurine ribofuranoside analogue (2) and the 2-amino-6-chloro-8- azapurine ribofuranoside analogue (9), respectively. Analogues of purine ribofuranosides with the chloro, amino, methylamino, or methylthio group at position 6, the thioguanosine analogue, and the previously reported guanosine analogue were evaluated in vitro against herpes simplex virus, type 1 (HSV-1). 8- Azapurine ribofuranoside analogues with the chloro, amino, or methylthio group at position 6 and the previously reported 8- azaguanosine analogue were also evaluated against HSV-1. The carbocyclic analogue (6) of 2,6-diaminopurine ribofuranoside is highly active against HSV-1 and, also, against vaccinia virus. The 2-amino-6-chloropurine, 2-amino-6-(methylamino)purine, and the 2,6-diamino-8- azapurine derivatives also demonstrated significant activity against HSV-1.

Adenosine↗
PubMed1984

Synthesis and antiviral activity of carbocyclic analogues of 2'-deoxyribofuranosides of 2-amino-6-substituted-purines and of 2-amino-6-substituted-8-azapurines.

(+/-)-(1 alpha, 2 beta, 4 alpha)-4-[(2,5-Diamino-6-chloro-4-pyrimidinyl) amino]-2-hydroxycyclopentanemethanol (9) was synthesized by beginning with 2-amino-4,6-dichloropyrimidine and (+/-)-1 alpha, 2 beta, 4 alpha)-4-amino-2-hydroxycyclopentanemethanol, preparing the 5-[(4-chlorophenyl)azo] derivative of the resulting pyrimidine, and reducing the azo derivative. The carbocyclic analogue of 2-amino-6-chloropurine 2'-deoxyribofuranoside (10) was prepared from 9 and triethyl orthoformate, and the analogous 8-azapurine (11) was obtained by diazotizing 9. From 10 or 11, the carbocyclic analogues of 2'-deoxyguanosine, 2'-deoxythioguanosine, 2,6-diaminopurine 2'-deoxyribofuranoside, 2'-deoxy-8-azaguanosine, and 2,6-diamino-8-azapurine 2'-deoxyribofuranoside were prepared. All of these 2'-deoxyribofuranoside analogues were active against herpes simplex virus (types 1 and 2) replicating in cells in culture; some demonstrated potent activity.

Animals↗
PubMed1984

Amelioration of embryotoxicity by structural modification of the terminal group of cancer chemopreventive retinoids.

An oral dose of all-trans-retinoic acid or 13-cis-retinoic acid in the pregnant [Lak:LVG(SYR)] hamster caused a dose-dependent increase in malformations in the offspring, but an equivalent dose of all-trans-N-ethyl retinamide or 13-cis-N-ethyl retinamide failed to result in embryotoxicity. The present results show that structural modification of the retinoid skeleton can produce compounds that retain cancer chemopreventive activity but that lack the teratogenic activity common to many synthetic and naturally occurring forms of vitamin A. The results indicate that in the case of the retinoids the two kinds of activity--interference with the process of carcinogenesis and interference with embryonic development--may be divorced.

Abnormalities, Drug-Induced↗
PubMed1983

Carbocyclic analogues of 5-substituted uracil nucleosides: synthesis and antiviral activity.

Carbocyclic analogues of 3'-deoxyuridines, 3'-deoxyuridines, and uridines with substituents at position 5 of the uracil moiety were prepared by direct halogenation (5-bromo and 5-iodo groups) and by displacement of the 5-bromo group by amino and substituted-amino groups. The analogue of 5-(hydroxymethyl)uridine was prepared via reaction of the isopropylidene derivative of the uridine analogue with paraformaldehyde. The carbocyclic analogues of thymidine and of 5-bromo-, 5-iodo-, and 5-(methylamino)-2'-deoxyuridine were highly active in vitro against herpes simplex virus, types 1 and 2. The corresponding analogues of 5-substituted 3'-deoxyuridines and of 5-substituted uridines were not active in this assay.

Animals↗
PubMed1983

2-haloethylating agents for cancer chemotherapy. 2-haloethyl sulfonates.

Because certain (2-chloroethyl)triazenes and (2-haloethyl)nitrosoureas have high antineoplastic activity, 2-chloroethyl and 2-fluoroethyl sulfonates were prepared to try to develop additional types of 2-haloethylating agents. In this initial study, it was demonstrated that antineoplastic activity much superior to that of the prototype, 2-chloroethyl methanesulfonate, could be found among 2-chloroethyl sulfonates. Among a variety of 2-chloroethyl alkane- and arenesulfonates, several substituted methanesulfonates displayed significant activity against P388 leukemia in mice; the chloromethanesulfonate showed high activity (T/C = 218%). None of the arenesulfonates were active in this test.

Animals↗
PubMed1982

Influence of 15 retinoic acid amides on urinary bladder carcinogenesis in the mouse.

A series of experiments was conducted to determine the efficacy of 15 synthetic retinoic acid amides (retinamides) as inhibitors of chemical carcinogenesis of the urinary bladder in C57BL/6 x DBA/2F1 mice. Eight of the retinamides tested had significant protective activity when administered at nontoxic levels in the diet. Minor structural alterations, such as the addition of a methyl or hydroxyl group to the terminal amide moiety had a major influence on the anticarcinogenic activity of the retinamides. Although 13-cis retinamides generally were less toxic on a molar basis than were their all-trans isomers, no consistent pattern of differential anticarcinogenic activity was noted among the six pairs of all-trans and 13-cis isomers tested. All-trans-4-hydroxyphenyl retinamide was among the most active and least toxic of the retinoids tested, and appears to be the compound of choice for further study.

Animals↗
PubMed1981

Carbocyclic analogues of 5-fluorouracil nucleosides.

The carbocyclic analogues of 5-fluoro-2'-deoxyuridine (5-FdUrd, 1), 5-fluorouridine, and 5-fluoro-3 alpha-deoxyuridine were prepared by fluorination of the uracil nucleoside analogues with elemental fluorine. The 5-FdUrd analogue (C-5-F-2'-dUrd, 6) was enzymatically phosphorylated to the analogue of 5-FdUrd 5'-phosphate and inhibited the incorporation of 2'-deoxyuridine into DNA of murine colon 26 tumor cells and L-1210 cells in culture. Biochemical studies also indicated that C-5-F-2'-Urd (6) was a less potent inhibitor of DNA synthesis in tumor cells than was 5-FdUrd (1). C-5-F-2'-dUrd was cytotoxic (ED50 = 2.5 mcg/mL) to L-1210 cells in culture; the other two analogues were less cytotoxic. C-5-F-2'-dUrd was inactive--or, at best, borderline active--in tests against P-388 leukemia in vivo.

Animals↗
PubMed1981

Evaluation of carbodine, the carbocyclic analog of cytidine, and related carbocyclic analogs of pyrimidine nucleosides for antiviral activity against human influenza Type A viruses.

Carbodine, the carbocyclic analog of cytidine, was found to possess significant antiviral activity against influenza virus types A0/PR-8/34 and A2/Aichi/2/68 (Hong Kong) in vitro. The compound selectively inhibited PR-8 influenza virus-induced cytopathogenic effects in Madin-Darby canine kidney and inhibited Hong Kong influenza virus replication in primary rhesus monkey kidney cell cultures. The 50% minimum inhibitory concentration for inhibition of human influenza type A viruses by carbodine was approximately 2.6 microgram/ml (i.e., in the range of antiviral potency of ribavirin, but less potent than amantadine hydrochloride in concomitant assays). The fact that carbodine is metabolized to carbodine triphosphate in mammalian cells makes interference with the viral ribonucleic acid-dependent ribonucleic acid polymerase reaction a likely possibility for its principal mode of action. The carbocyclic analogs of uridine (the deamination product of carbodine), 2'-deoxycytidine, 3'-deoxycytidine, N,N-dimethylcytidine, N-methylcytidine, and some related carbocyclic analogs of pyrimidine nucleosides were inactive against PR-8 influenza virus in vitro. The combination of carbodine plus tetrahydrouridine was no more effective in vitro than carbodine alone, thus indirectly indicating that deamination of carbodine probably did not occur to a significant degree during the cell culture experiments. Although reproducibly active in vitro, carbodine did not exhibit any efficacy against lethal influenza virus infections in mice when administered by either the intraperitoneal or intranasal routes up to dose-limiting toxic levels.

Animals↗
PubMed1981

Inhibition of urinary bladder cancer by N-(ethyl)-all-trans-retinamide and N-(2-hydroxyethyl)-all-trans-retinamide in rats and mice.

The chemopreventive activity of two synthetic retinamides of relatively low toxicity against N-butyl-N-(4-hydroxybutyl)nitrosamine (OH-BBN)-induced urinary bladder cancer was studied in F344 rats and C57BL/6 X DBA/2 F1 mice. Female and male rats were given a total dose of either 1800 or 3200 mg OH-BBN over a period of 6 or 8 weeks, respectively. Male mice were given a total dose of either 90 or 180 mg OH-BBN over a period of 9 weeks. Seven days after the final intubation of a period of 9 weeks. Seven days after the final intubation of OH-BBN, animals were fed either a placebo diet or a diet supplemented with the following retinoids: for rats, 0.8 mmol 13-cis-retinoic acid, 2 mmol N-(ethyl)-all-trans-retinamide, or 2 mmol N-(2-hydroxyethyl)-all-trans-retinamide per kg diet; and for mice, either 0.5 or 1.0 mmol of N-(ethyl)-all-trans-retinamide or N-(2-hydroxyethyl)-all-trans-retinamide per kg diet. Animals were killed 6 months after the initial gastric intubation. In comparison to male and female rats fed placebo diets, all three retinoids reduced the incidence, number, and severity of the low-grade papillary transitional cell carcinomas of the urinary bladder. Similarly, treatment of mice with either of the two retinamides reduced the incidence of highly invasive urinary bladder carcinomas. The chemopreventive effect of the less toxic retinamides was equal to or greater than that of 13-cis-retinoic acid.

Animals↗
PubMed1979

Analogues of methotrexate.

Analogues of methotrexate (MTX) were prepared by alkylation of side-chain precursors with 6-(bromomethyl)-2,4-pteridinediamine followed, where necessary, by saponification of the intermediate esters and, in two cases, by electrophilic substitution reactions in the pyridine ring portion of 3-deazamethotrexate. Effects of the various modifications on their ability to inhibit dihydrofolate reductase, cytotoxicity, and activity against L1210 leukemia in mice were examined in light of recent findings concerning active transport of MTX and related compounds and the binding features of the MTX-dihydrofolate reductase complex.

Animals↗
PubMed1975

Synthesis of 5-(3, 3-disubstituted-1-triazenyl) imidazole-4-carbonitriles.

The 3, 3-dimethyl-, 3-n-butyl-3-methyl-, 3-(2-hydroxyethyl)-3-methyl-, 3,3-bis(2-fluoroethyl)-, and 3, 3-bis(2-chloroethyl)-1-triazenyl derivatives of imidazole-4-carbonitrile were prepared from 5-diazoimidazole-4-carbonitrile, a stable compound which produced a mass spectrum consistent with its structure. In contrast to the corresponding carboxamides, none of the triazenylimidazole-4-carbonitriles were active against lymphatic leukemia L-1210 im mice. Like the analogous carboxamide, the bis(2-chloroethyl) triazene readily cyclizes to the 1, 2, 3-triazolinium chloride.

Animals↗