Determining causes of genetic isolation in a large carnivore (Ursus americanus) population to direct contemporary conservation measures.

The processes leading to genetic isolation influence a population's local extinction risk, and should thus be identified before conservation actions are implemented. Natural or human-induced circumstances can result in historical or contemporary barriers to gene flow and/or demographic bottlenecks. Distinguishing between these hypotheses can be achieved by comparing genetic diversity and differentiation in isolated vs.

Synthesis and in vivo evaluation of prodrugs of 9-[2-(phosphonomethoxy)ethoxy]adenine.

A number of esters and amides of the anti-HIV nucleotide analogue 9-[2-(phosphonomethoxy)-ethoxy]adenine (1) have been synthesized as potential prodrugs and evaluated for oral bioavailability in mice. Dialkyl esters 17-20 were prepared via a Mitsunobu coupling of alcohols 8-11 with 9-hydroxypurine 12 whereas (acyloxy)alkyl esters 25-33 and bis-[(alkoxycarbonyl)methyl] and bis(amidomethyl) esters 34-39 were obtained by reaction of 1 with a suitable alkylating agent. Phosphonodichloridate chemistry was employed for the preparation of dialkyl and diaryl esters 42-65, and bis(phosphonoamidates) 66 and 67.

Novel acyclonucleotides: synthesis and antiviral activity of alkenylphosphonic acid derivatives of purines and a pyrimidine.

A series of phosphonoalkenyl and (phosphonoalkenyl)oxy derivatives of purines and a pyrimidine were synthesized. These compounds are the first reported acyclonucleotides which incorporate the alpha,beta-unsaturated phosphonic acid moiety as the phosphate mimic and include compounds in which the acyclic substituent is attached to N-9 of a purine or N-1 of a pyrimidine by either a nitrogen-carbon or a nitrogen-oxygen bond. The phosphonoalkenyl-substituted compounds 7a-c, 8a-c, 9, 10, and 12 were prepared either by Mitsunobu coupling of alcohols with purine or pyrimidine derivatives or by alternative alkylations of the heterocyclic bases.

Synthesis and antiviral activity of 9-alkoxypurines. 2. 9-(2,3-Dihydroxypropoxy)-, 9-(3,4-dihydroxybutoxy)-, and 9-(1,4-dihydroxybut-2-oxy)purines.

Reaction of alkenoxyamines (3,5) or (R,S)-, (R)-, and (S)-hydroxy-protected derivatives of hydroxyalkoxyamines (20a,b, 37a-c) with 4,6-dichloro-2,5-diformamidopyrimidine (4) and cyclization of the resultant 6-[(alkenoxy)amino]-and 6-(alkoxyamino)pyrimidines (6,7,21a,b, 38a,b,c) by heating with diethoxymethyl acetate afforded 9-alkenoxy- and 9-alkoxy-6-chloropurines (9,10,22a,b, 39a-c, 40a). These were subsequently converted to 9-(2,3-dihydroxypropoxy), 9-(3,4-dihydroxybutoxy), and 9-(1,4-dihydroxybut-2-oxy) derivatives of guanine and 2-aminopurine (13-16, 25-28, 41a-c, 42a). A 2-amino-6-methoxypurine derivative (17) was also prepared.

Synthesis and antiviral activity of 9-alkoxypurines. 1. 9-(3-Hydroxypropoxy)- and 9-[3-hydroxymethyl)propoxy]purines.

Reaction of hydroxyl-protected derivatives of hydroxyalkoxyamines (3a,b,c) with either 4,6-dichloro-2,5-diformamidopyrimidine (5) or 4,6-dichloro-5-formamidopyrimidine (31) and subsequent cyclization of the resultant 6-(alkoxyamino)pyrimidines (6, 17, 32, 35) by heating with diethoxymethyl acetate afforded 9-alkoxy-6-chloropurines (7, 18, 33, 36), which were converted subsequently to 9-(3-hydroxypropoxy)- and 9-[3-hydroxy-2-(hydroxymethyl)propoxy] derivatives of guanine, 2-amino-6-chloropurine, 2-amino-6-alkoxypurines, 2-aminopurine, 2,6-diaminopurine, adenine, hypoxanthine, and 6-methoxypurine (8, 12, 13, 19-21, 23-26, 34, 37-39). Carboxylic acid esters (9-11, 14-16, 27-29) and a cyclic phosphate derivative (22) of the 9-(hydroxyalkoxy)guanines (8, 21) and 2-amino-9-(hydroxyalkoxy)purines (13, 26) were also prepared. The guanine derivatives (8, 21) showed potent and selective activity against herpes simplex virus types 1 and 2 and varicella zoster virus in cell cultures and 8 is more active than acyclovir.

Selection of an oral prodrug (BRL 42810; famciclovir) for the antiherpesvirus agent BRL 39123 [9-(4-hydroxy-3-hydroxymethylbut-l-yl)guanine; penciclovir].

The limited oral absorption in rodents of the antiherpesvirus agent 9-(4-hydroxy-3-hydroxymethylbut-l-yl)guanine (BRL 39123 [penciclovir; British approved name]) prompted a search for oral prodrugs. The 6-deoxy derivative of penciclovir (BRL 42359) and the corresponding diacetyl and dipropionyl 6-deoxy derivatives (BRL 42810 [famciclovir; British approved name] and BRL 43599) were tested as oral prodrugs. The in vivo absorption (dose, 0.

Prodrugs of the selective antiherpesvirus agent 9-[4-hydroxy-3-(hydroxymethyl)but-1-yl]guanine (BRL 39123) with improved gastrointestinal absorption properties.

Potential oral prodrugs of the antiherpesvirus acyclonucleoside 9-[4-hydroxy-3-(hydroxymethyl)but-1-yl]guanine (1, BRL 39123) have been synthesized and evaluated for bioavailability of 1 in the blood of mice. Reduction of 9-[4-acetoxy-3-(acetoxymethyl)but-1-yl]-2-amino-6-chloropurine (13) using ammonium formate and 10% palladium on carbon afforded the 2-aminopurine 14, which was hydrolyzed to the monoacetate 15 and to 2-amino-9-[4-hydroxy-3-(hydroxymethyl)but-1-yl]purine (5). The 2-aminopurine 5 was subsequently converted to additional monoester (17, 21-23) and diester (16, 24) derivatives and to its di-O-isopropylidene derivative 18.

Synthesis and antiviral activity of 9-[4-hydroxy-3-(hydroxymethyl)but-1-yl]purines.

Alkylation of 2-amino-6-chloropurine with 5-(2-bromoethyl)-2,2-dimethyl-1,3-dioxane (5) provided 2-amino-6-chloro-9-[2,(2,2-dimethyl-1,3-dioxan-5-yl)ethyl]purine (6) in high yield. This aminochloropurine 6 was readily converted to the antiviral acyclonucleoside 9-[4-hydroxy-3-(hydroxymethyl)but-1-yl]guanine (1) and to its 6-chloro (10), 6-thio (11), 6-alkoxy (12-17), 6-amino (20), and 6-deoxy (21) purine analogues. The guanine derivative 1 was converted to its xanthine analogue 9.

Improvement of the bioavailability of the anti-herpes virus agent BVDU by use of 5'-O-alkoxycarbonyl derivatives with increased metabolic stability.

(E)-5-(2-bromovinyl)-2'-deoxyuridine (BVDU) was found by HPLC analysis to be rapidly metabolized in mice and in liver homogenates from mouse and man to the antivirally inactive (E)-5-(2-bromovinyl) uracil (BVU) but was comparatively stable in blood from both species. Of a series of 5'-O-alkoxycarbonyl derivatives of BVDU, the 5'-O-tert.-butoxycarbonyl derivative (BRL 37000) was the most stable in mouse and human blood and liver homogenates, neither its ester bond nor its N-glycosidic linkage being readily cleaved enzymically.

Synthesis and antiviral properties of some 2'-deoxy-5-(fluoroalkenyl)uridines.

The following 5-substituted 2,4-dimethoxypyrimidines were synthesized: 5-(2,2,2-trichloro-1-hydroxyethyl), 5-(2,2,2-trichloro-1-fluoroethyl),5-(2,2-dichloro-1-fluorovinyl) (5), and 5-(perfluoropropen-1-yl) (a mixture of E and Z isomers, 6 and 7). Demethylation of 5 gave 5-(2,2-dichloro-1-fluorovinyl)uracil, and demethylation of the mixture of 6 and 7 gave some pure (E)-5-(perfluoropropen-1-yl)uracil. Compound 5 was converted into its 2'-deoxyribonucleoside (12) and its alpha-anomer by standard procedures.

Easily hydrolyzable, water-soluble derivatives of (+/-)-alpha-5-[1-(indol-3-yl)ethyl]-2-methylamino-delta2-thiazoline-4-one, a novel antiviral compound.

The preparation of a series of indole N-acyl and N-carbamic esters of (+/-)-alpha-5-[1-(indol-3-yl)ethyl]-2-methylamino-delta2-thiazolin-4-one (1) is reported. These derivatives were synthesized as potential water-soluble precursors of the antiviral thiazolinone 1, for evaluation by intranasal administration against influenza and other respiratory infections caused by viruses. Salts of the basic carbamic esters (16--19) possess the required water solubility, undergo rapid hydrolysis and decarboxylation at pH values greater than 6, and have high activity against influenza A2 and Coxsackie B1 viruses in vitro.

Thiazolinone analogues of indolmycin with antiviral and antibacterial activity.

Total synthesis of a series of thiazolinone and thiazolidinone analogues of the antibacterial oxazolinone antibiotic indolmycin is described. The synthetic route involves nucleophilic displacement of mesyloxy and chloro groups from methyl 2-substituted-3-(indol-3-yl)propionates 3 and 4 and butyrate 19 with N-substituted thioureas. The formation of the rearranged chloro esters 29, 43, and 44 from beta(RS,RS)-methyl indolmycenate (27), alpha(RS,SR)-methyl 2-hydroxy-3-(2-methylindol-3-yl)butyrate (39), and alpha-methyl 2-hydroxy-3-(indol-3-yl)valerate (41) supports a reaction mechanism involving neighboring group participation by the indole C-3 carbon during nucleophilic displacement on the beta-carbon of a C-3 substituent.