Structural determinants for N1/N7 cyclization of nicotinamide hypoxanthine 5'-dinucleotide (NHD+) derivatives by ADP-ribosyl cyclase from aplysia californica: Ca2+-mobilizing activity of 8-substituted cyclic inosine 5'-diphosphoribose analogues in T-lymphocytes

A series of nicotinamide hypoxanthine 5'-dinucleotide (NHD+) analogues modified at C-8 (2-5) and 7-deaza-NHD+ were synthesized, and cyclization in the presence of Aplysia ADP-ribosyl cyclase was studied. All 8-substituted NHD+ analogues were converted into their N1-cyclic forms by the enzyme, while in contrast, 7-deaza-NHD+ 17 was hydrolyzed into 7-deazainosine 5'-diphosphoribose (7-deaza-IDPR) 25. Correlations are made showing that the conformation of the NHD+ substrate is the key to successful cyclization. The pharmacological activities of these novel cIDPR derivatives were evaluated in both permeabilized and intact Jurkat T-lymphocytes. The results show that in permeabilized cells both 8-iodo 1g and 8-N3-N1-cIDPR 1d have an activity comparable to that of cADPR, while 8-iodo 1g and 8-phenyl-N1-cIDPR 1c have a small but significant effect in intact cells and can therefore be regarded as membrane-permeant; thus, cIDPR derivatives are emerging as important novel biological tools to study cADPR-mediated Ca2+ release in T-cells.     

Psoralenamines. 3. Synthesis, pharmacological behavior, and DNA binding of 5-(aminomethyl)-8-methoxy-, 5-[[(3-aminopropyl)oxy]methyl]-, and 8-[(3-aminopropyl)oxy]psoralen derivatives

A series of derivatives of 5-(aminomethyl)-8-methoxypsoralens, 8-[(3-aminopropyl)oxy]psoralens, and 5-[[[3-(tri-methylammonio)propyl]methyl]-8-methoxypsoralen has been synthesized and their potential as PUVA reagents examined. While the DNA association constants of selected psoralens were found to be 10(5)-10(6)L mol-1, corresponding to efficient binding, flow linear dichroism studies indicated that only the 8-substituted psoralens bind to DNA by intercalation. Furthermore, the ability to photoinduce interstrand cross-links in calf thymus DNA, in vitro, was as efficient as that of 8-methoxypsoralen for the 8-substituted psoralens, which were up to 25 times as efficient as the 5-substituted psoralens. Four of the psoralens studied were radiolabeled and used to study photobinding to DNA. Analogously to the cross-binding results, the 8-substituted psoralens were more efficiently photobound than the 5-substituted, while only slight differences were found in the photobinding-cross-linking ratio. The photoreactivity of the aminopsoralens toward cyclohexene and 2'-deoxythymidine was enhanced compared to that of 8-methoxypsoralen, the effect being most pronounced when the amino group is close to the furocoumarin ring system. Most of the new compounds were less photocytotoxic than 8-methoxypsoralen to NHIK 3025 cells, in vitro, and they caused less light-induced DNA interstrand cross-linking, in situ, in these cells. A clear correlation between the photocytotoxicity and the DNA cross-linking ability of the psoralens was observed. Several of the derivatives showed more pronounced effects in the light-dependent skin thickening (inflammatory) test on mice than 8-methoxypsoralen. No correlation between DNA cross-linking capacity, in vitro, and skin phototoxicity was found for this series of psoralens.     

Synthesis and antiviral activity of novel acyclic nucleoside analogues of 5-(1-azido-2-haloethyl)uracils.

We present the discovery of a novel category of 5-substituted acyclic pyrimidine nucleosides as potent antiviral agents. A series of 1-[(2-hydroxyethoxy)methyl] (5-7), 1-[(2-hydroxy-1-(hydroxymethyl)ethoxy)methyl] (8-10), and 1-[4-hydroxy-3-(hydroxymethyl)-1-butyl] (11-13) derivatives of 5-(1-azido-2-haloethyl)uracil were synthesized and evaluated for their biological activity in cell culture. 1-[4-Hydroxy-3-(hydroxymethyl)-1-butyl]-5-(1-azido-2-chloroethyl)uracil (12) was the most effective antiviral agent in the in vitro assays against DHBV (EC(50) = 0.31-1.55 microM) and HCMV (EC(50) = 3.1 microM). None of the compounds investigated showed any detectable toxicity to several stationary and proliferating host cells.     

Synthesis and evaluation of antileukemic activity of 5-thienyl- or 5-(2-furyl)-2,3-dihydro-6,7-bis(hydroxymethyl)-1H-pyrrolizine bis(alkylcarbamates) and derivatives

Treatment of N-(2-furoyl)proline or N-thenoylprolines and N-(2-thenoyl)thiazolidine-4-carboxylic acid with acetic anhydride and dimethyl acetylenedicarboxylate gave 5-substituted derivatives of dimethyl 2,3-dihydro-1H-pyrrolizine-6,7-dicarboxylate and derivatives of dimethyl 5-(2-thienyl)pyrrolo[1,2-c]thiazole. Reduction of 2 with lithium aluminum hydride gave the diols 3a, 3b, 3c and 3d. These diols yielded the corresponding diacetates 4 by treatment with acetic anhydride. The bis(methylcarbamates) 5a, 5b, 5c, and 5d and bis(isopropylcarbamates) 6b and 6c are obtained with the appropriate isocyanates. The 1-substituted pyrrolizines were synthesized, the 1-acetoxy compounds 7b and 7c further transformed into 1-hydroxy and 1-oxo analogues. The action of hydrochloric acid on 1-acetoxy derivatives gave 3H-pyrrolizines. Evaluation of antileukemic activity was investigated on the leukemia L1210 in vivo, on several bis(alkylcarbamates). The compounds 5c and 5d show good antileukemic activity comparable with the mitomycin.     

Synthesis, cytotoxicity, and antiviral activity of some acyclic analogues of the pyrrolo[2,3-d]pyrimidine nucleoside antibiotics tubercidin, toyocamycin, and sangivamycin

A number of 7-[(1,3-dihydroxy-2-propoxy)methyl]pyrrolo[2,3d-d]pyrimidine derivatives that are structurally related to toyocamycin and sangivamycin and the seco nucleosides of tubercidin, toyocamycin, and sangivamycin were prepared and tested for their biological activity. Treatment of the sodium salt of 4-amino-6-bromo-5-cyanopyrrolo[2,3-d]-pyrimidine with 1,3-bis(benzyloxy)-2-propoxymethyl chloride afforded compound 3, which without isolation was debrominated to obtain 4-amino-5-cyano-7-[[1,3-bis(benzyloxy)-2- propoxy]methyl]pyrrolo[2,3-d]pyrimidine. Although catalytic hydrogenolysis failed, the benzyl ether functionalities of 4 were successfully cleaved by boron trichloride to afford 4-amino-5-cyano-7-[(1,3-dihydroxy-2- propoxy)methyl]pyrrolo[2,3-d]pyrimidine. Conventional functional group transformation of the cyano group of 6 provided a number of novel 5-substituted derivatives. Tubercidin (8a), toyocamycin (8b), and sangivamycin (8c) were treated separately with sodium metaperiodate and then with sodium borohydride to afford the 2',3'-seco derivatives 9a-c, respectively. The acyclic nucleoside 4-chloro-2-(methylthio)-7-[[1,3-bis(benzyloxy)-2- propoxy]methyl]pyrrolo[2,3-d]pyrimidine was aminated, desulfurized with Raney Ni, and then debenzylated to provide the tubercidin analogue 11. Cytotoxicity evaluation against L1210 murine leukemic cells in vitro showed that although the parent compounds tubercidin (8a), toyocamycin (8b), and sangivamycin (8c) were very potent growth inhibitors, the acyclic derivatives 6, 7a-c, and 9a-c had only slight growth-inhibitory activity. Evaluation of compounds 6, 7a, 7b, 7c, 9a, 9b, 9c, 11 for cytoxicity and activity against human cytomegalovirus (HCMV) and herpes simplex virus type 1 (HSV-1) revealed that only the carboxamide (7a) and the thioamide (7c) were active. Compound 7c was the more potent of the two, inhibiting HCMV but not HSV-1 at concentrations producing little cytotoxicity.     

Synthesis and biological activities of 4-O-(difluoromethyl)-5-substituted-uracil nucleoside analogues

Various 4-O-difluoromethyl analogues of 5-substituted uridine (Urd), 2'-deoxyuridine (dUrd), and arabinofuranosyluracil (araU) nucleosides were prepared via a CF2-insertion reaction into 4-O-silylated nucleosides and evaluated for activity against herpes simplex virus type 1 (HSV-1) and type 2 (HSV-2) and cytotoxicity in human embryonic lung fibroblast (HELF) cell cultures. The introduction of the 4-substituent led to a strong reduction of antiviral activity for dUrd but not for araU analogues. Three of the 4,5-disubstituted uracil nucleoside derivatives, 4-O-(difluoromethyl)-5-bromo-araU (5c),-5-methyl-araU (5e), and -(E)-5-(2-bromovinyl)-araU (5g), displayed a high and selective inhibitory effect against HSV-1, but only 5e was effective against both HSV-1 and HSV-2 comparably with the antiherpes potential of the reference compounds 9-[(2-hydroxyethoxy)methyl]guanine (acyclovir) and 1-beta-D-arabino-furanosylthymine (araT).     

Synthesis of some 1, 8- and 2, 8-disubstituted derivatives of adenosine cyclic 3', 5'-phosphate and their interaction with some enzymes of cAMP metabolism.

1, 8-Disubstituted derivatives of adenosine cyclic 3', 5'-phosphate (cAMP) were synthesized by N-oxidation or N-methylation of previously reported 8-substituted cAMP derivatives to yield 8-bromoadenosine cyclic 3', 5'-phosphate 1-oxide and 8-(benzylthio)-1-methyladenosine cyclic 3', 5'-phosphate. Substituents were introduced into the 8 position of 2-methyladenosine cyclic 3', 5'-phosphate and 2-butyladenosine cyclic 3', 5'-phosphate by bromination, followed by treatment with sodium benzylmercaptide, sodium p-chlorothiophenolate, or, in the former case, sodium azide. Each of the 1,8- and 2,8-disubstituted derivatives of cAMP was tested as activators of cAMP-dependent protein kinase and as substrates for the inhibitors of cyclic nucleotide phosphodiesterases. Depending on the substitutions, examples were found where the disubstituted derivatives were either more active, equally as active or less active than the monosubstituted parent compounds as protein kinase activators. For the compounds reported, 8-substitution completely or substantially eliminated the ability of 1- or 2-substituted derivatives of cAMP to serve as substrates for phosphodiesterase and diminished the ability of these latter derivatives to inhibit cAMP hydrolysis.     

Structure-activity relationships of 1-[(2-hydroxyethoxy)methyl]-6-(phenylthio)thymine analogues: effect of substitutions at the C-6 phenyl ring and at the C-5 position on anti-HIV-1 activity.

The effect of substitution on the pyrimidine moiety of 1-[(2-hydroxyethoxy)methyl]-6-(phenylthio)thymine (HEPT) and 1-[(2-hydroxyethoxy)methyl]-6-(phenylthio)-2-thiothymine (HEPT-S) on anti-HIV-1 activity was investigated by synthesizing a series of 5-methyl-6-(arylthio) and 5-substituted-6-(phenylthio) derivatives. Preparation of the 5-methyl-6-(arylthio) derivatives was carried out based on either LDA lithiation of 1-[[2-(tert-butyldimethylsiloxy)ethoxy]methyl]thymine (3) and 1-[[2-(tert-butyldimethylsiloxy)ethoxy]methyl]-2-thiothymine (4) followed by reaction with diaryl disulfides or an addition-elimination reaction of 1-[[2-(tert-butyldimethylsiloxy)ethoxy]-methyl]-6- (phenylsulfinyl)thymine (31) with aromatic thiols. Preparation of the 5-substituted-6-(phenylthio) derivatives was carried out based on either C-5 lithiation of the 1-[[2-(tert-butyldimethylsiloxy)ethoxy]methyl]-6-(phenylthio)uraci l (41) with LTMP or the LDA lithiation of 5-alkyl-1-[[2-(tert-butyldimethylsiloxy)ethoxy]methyl]-2-thiouraci l derivatives 45-47. Substitution at the meta position of the C-6-(phenylthio) ring by the methyl group improved the original anti-HIV-1 activity of HEPT, and introduction of two m-methyl groups to the phenylthio ring further potentiated the activity [EC50: 6-[(3,5-dimethylphenyl)thio]-1-[(2-hydroxyethoxy)methyl]thymine (28), 0.26 microM; 6-[(3,5-dimethylphenyl)thio]-1-[(2-hydroxyethoxy)methyl]-2-thiothymin e (30), 0.22 microM]. When the 5-methyl group was replaced by an ethyl or an isopropyl group, the anti-HIV-1 activity of HEPT was also improved remarkably [EC50: 5-ethyl-1-[(2-hydroxyethoxy)methyl]-6-(phenylthio)-2-thiouracil (48), 0.11 microM; 5-isopropyl-1-[(2-hydroxyethoxy)-methyl]-6-(phenylthio)-2-thiouracil (50), 0.059 microM; 5-ethyl-1-[(2-hydroxyethoxy)methyl]-6-(phenylthio)-2-thiouracil (54), 0.12 microM; 5-isopropyl-1-[(2-hydroxyethoxy)methyl]-6-(phenylthio)-2-thiouracil (56), 0.063 microM]. 6-[(3,5-Dimethylphenyl)thio]-5-ethyl-1-[(2-hydroxyethoxy)methyl]thymine derivatives 51 and 57 and 6-[(3,5-dimethylphenyl)thio]-5-isopropyl-1-[(2- hydroxyethoxy)methyl]thymine derivatives 52 and 58 inhibited the replication of HIV-1 in the nanomolar concentration range.     

2-substituted 4-E1(2-(N-methyl-thioureido)-ethylmercapto)-methyl)-imidazoles (author's transl)]

2-Substituted 4-[[2-(N′-Methyl-thioureido)-ethylmercapto]-methyl]-imidazoles The synthesis of 2-substituted 4-[[2-(Ns′-methyl-thioureido)-ethylmercapto]-methyl]-imidazoles 5a – f , as potential H₂-antihistaminics, is described. The acid catalyzed reaction of the imidazole-4-carbinols 3a – f with cysteamine gives the 2-substituted 4-[(2-amino-ethylmercapto)-methyl]-imidazoles 4a – f which react with methyl isothiocyanate to give the corresponding thiourea derivatives 5 .     

Nucleic acid related compounds. 47. Synthesis and biological activities of pyrimidine and purine "acyclic" nucleoside analogues

Various acyclic, i.e., (2-hydroxyethoxy)methyl and (2-acetoxyethoxy)methyl, analogues of pyrimidine and purine nucleosides have been prepared and evaluated for their antiviral, antimetabolic, and cytotoxic properties. All of the pyrimidine analogues, including (E)-5-(2-bromovinyl)-1-[(2-hydroxyethoxy)methyl]uracil (12) and its O-acetyl derivative (13), were virtually devoid of antiviral, cytotoxic, and antimetabolic activities. However, several of the 8-substituted derivatives of 9-[(2-hydroxyethoxy)methyl]guanine (acyclovir) had higher antiviral specificity in vitro than the parent drug. The 8-methyl-, 8-amino-, 8-bromo-, and 8-iodoacyclovir derivatives have activities worthy of further investigation.     

Synthesis and antiviral activity of certain 4- and 4,5-disubstituted 7-[(2-hydroxyethoxy)methyl]pyrrolo[2,3-d]pyrimidines

In vitro evaluation of a series of previously prepared tubercidin analogues revealed that certain 5-halogen-substituted analogues were active against human cytomegalovirus (HCMV) at concentrations lower than those that produced comparable cytotoxicity in uninfected cells. In contrast, tubercidin was cytotoxic at all antiviral concentrations. Even though the antiviral selectivity of the 5-substituted compounds was slight, this observation led us to prepare a series of acyclic analogues. Treatment of the sodium salt of 4-chloropyrrolo[2,3-d]pyrimidine (2) with (2-acetoxyethoxy)methyl bromide (2a) provided the acyclic nucleoside 4-chloro-7-[(2-acetoxyethoxy)methyl]pyrrolo[2,3-d]pyrimidine (3). A nucleophilic displacement of the 4-chloro group with methoxide, methylamine, and dimethylamine yielded the corresponding 4-substituted compounds 4, 5, and 6, respectively, in good yield. Electrophilic substitution (chlorination, bromination, and iodination) was effected at the C-5 position of compound 3 with N-chlorosuccinimide, N-bromosuccinimide, and iodine monochloride, respectively, in methylene chloride. Removal of the acetyl group from these intermediates (7a-9a) with methanolic ammonia at room temperature afforded the 5-chloro (7b), 5-bromo (8b), and 5-iodo (9b) derivatives of 4-chloro-7-[(2-hydroxyethoxy)methyl]pyrrolo[2,3-d]pyrimidine. Treatment of compounds 7b-9b with methanolic ammonia at an elevated temperature produced the corresponding 5-halotubercidin analogues 10, 11, and 12, respectively. An alternate procedure for the preparation of these 4,5-disubstituted 7-[(2-hydroxyethoxy)methyl]pyrrolo[2,3-d]pyrimidines involved an electrophilic substitution prior to the condensation of the heterocycle with 2a. Treatment of 2 with N-chlorosuccinimide and N-bromosuccinimide gave compounds 13a and 13b, respectively. The condensation of 13a and 13b with 2a and subsequent treatment with methylamine and ethylamine furnished the corresponding 5-halo-4-substituted-pyrrolo[2,3-d]pyrimidines 14a, 14b, 14c, and 14d, respectively. Evaluation of the target compounds (4-6, 7b-9b, 10-12, and 14a-14d) for cytotoxicity and activity against HCMV and herpes simplex virus type 1 (HSV-1) revealed that all compounds except the 5-halogen-substituted compounds 10, 11, and 12 were inactive. Compounds 10, 11, and 12 were active against both viruses at noncytotoxic concentrations. The activity of compound 11 was particularly noteworthy, being at least 10-fold more potent than acyclovir.     

Synthesis, cytotoxicity, and antiviral activity of certain 7-[(2-hydroxyethoxy)methyl]pyrrolo[2,3-d]pyrimidine nucleosides related to toyocamycin and sangivamycin

A number of 7-[(2-hydroxyethoxy)methyl]pyrrolo[2,3-d]pyrimidine derivatives related to the nucleoside antibiotics toyocamycin and sangivamycin were prepared and tested for their biological activity. Treatment of the sodium salt of 4-amino-6-bromo-5-cyanopyrrolo[2,3-d]pyrimidine (1) with (2-acetoxyethoxy)methyl bromide (2) afforded a mixture of 4-amino-6-bromo-5-cyano-7-[(2-acetoxyethoxy)methyl]pyrrolo[2,3-d] pyrimidine (3) and the corresponding N1 isomer. Debromination of this mixture gave the corresponding 4-amino-5-cyano-7-[(2-acetoxyethoxy)-methyl]pyrrolo[2,3-d]pyrimidi ne (4) and 4-amino-5-cyano-1-[(2-acetoxyethoxy)methyl]pyrrolo[2,3-d]pyrimidin e (5). Deacetylation of 4 and 5 furnished 4-amino-5-cyano-7-[(2-hydroxyethoxy)methyl]pyrrolo[2,3-d]pyrimidine (6) and the corresponding N1 isomer (7), respectively. The sites of attachment for the acyclic moiety for 6 and 7 were assigned on the basis of UV spectral studies as well as 13C NMR spectroscopy. Conventional functional group transformation of 6 provided a number of novel 5-substituted derivatives (8-10), including the sangivamycin derivative 8. The methyl formimidate derivative 10 was converted to the thioamide derivative 11 and the carbohydrazide derivative 12. Compounds 6 and 8-12 were tested for cytotoxicity to L1210 murine leukemic cells in vitro. None of these compounds caused significant inhibition of cell growth. Evaluation of compounds 4 and 6-12 for activity against human cytomegalovirus (HCMV) and herpes simplex virus type 1 (HSV-1) revealed that only the thioamide (11) was active. It inhibited HCMV but not HSV-1 at concentrations producing only slight cytotoxicity in human foreskin fibroblasts (HFF cells) and KB cells.     

Synthesis and antiviral activity of novel anti-VZV 5-substituted uracil nucleosides with a cyclopropane sugar moiety

A series of 5-substituted uracil nucleoside derivatives with a 1(1'S, 2'R)-[1',2'-bis(hydroxymethyl)cyclopropyl]methyl group as an acyclosugar moiety were synthesized and evaluated for their anti-herpetic activities. Among the compounds synthesized, (E)-5-halovinyluracil derivatives showed superior anti-varicella zoster virus (VZV) activity over acyclovir (ACV) but were less potent than ACV against herpes symplex virus type-1 (HSV-1). IC(50) values for the VZV Kawaguchi strain were 0.027 for Br, 0.070 for Cl, and 0.054 microg/mL for I derivatives and 3.4 microg/mL for ACV. The most potent compound, (1'S,2'R)-5-[(E)-2-bromoethenyl]-1-[[1', 2'-bis(hydroxymethyl)cycloprop-1'-yl]methyl]-2,4-(1H, 3H)-pyrimidinedione (3a), was 40-60-fold more potent than ACV against clinical isolates of VZV. It showed good oral bioavailability in rats (68.5%) and, unlike (E)-5-(2-bromovinyl)-1-beta-D-arabinofuranosyluracil (BVaraU), did not result in the release of (E)-5-(2-bromovinyl)uracil (BVU), a potent dihydropyrimidine dehydrogenase inhibitor, in plasma after oral administration.     

Synthesis of 5-substituted uracil derivatives.

The synthesis of a series of 5-substituted uracil derivatives is described. 5-Bromoacetyluracil (2a) was converted to the glycolyl (2b), glycyl (2c), N,N-dimethylglycyl (2d), 4-imidazolyl (3), and 2-amino-4-thiazolyl (4) derivatives. 5-Formyluracil (5) was used in the preparation of the 2-imidazolyl (6), the 3-acrylic acid (7b), the ester (7a), and the 3-N,N-dimethylacrylamide (8) derivatives. A Mannich reaction converted 5-acetyluracil to the amino ketone 9 which was reduced to give the 3-dimethylamino-1-propanol derivative 10. Compounds 2b,d,3,4,6, and 7b failed to inhibit the growth of Escherichia coli B and Staphylococcus aureus.     

A new class of HIV-1-specific 6-substituted acyclouridine derivatives: synthesis and anti-HIV-1 activity of 5- or 6-substituted analogues of 1-[(2-hydroxyethoxy)methyl]-6-(phenylthio)thymine (HEPT)

A series of novel acyclouridine derivatives substituted at both the C-5 and C-6 positions were synthesized for the purpose of improving the activity of a recently reported HIV-1-specific lead, 1-[(2-hydroxyethoxy)methyl]-6-(phenylthio)thymine (HEPT). Preparation of C-6 substituted derivatives was carried out based on the following three methods: (1) LDA (lithium diisopropylamide) lithiation of a thymine derivative (4) and subsequent reaction with electrophiles, (2) an addition-elimination reaction of HEPT or its 6-(phenylsulfinyl) derivative (10), or (3) palladium-catalyzed cross-coupling between a 6-iodo derivative (16) and terminal alkynes. Following the methods, 21 C-6 substituted analogues were synthesized. Among these, 6-(cyclohexylthio) (8), 6-phenoxy (13), and 6-benzyl (27) derivatives showed anti-HIV-1 (HTLV-IIIB) activity with EC50 values of 8.2, 85, and 23 microM, respectively. Preparation of C-5 substituted derivatives was based on either LTMP (lithium 2,2,6,6-tetramethylpiperidide) lithiation of 6-(phenylthio)uracil derivative 37 or the above mentioned palladium-catalyzed cross-coupling of a 5-iodo-6-(phenylthio)uracil derivative (38). Following these methods, 11 C-5 substituted analogues were synthesized. Some 5-substituted derivatives (5-I, 44; 5-CH = CPh2, 49; 5-CH = CHPh (Z), 54; and 5-CH = CH2, 55) were more active than HEPT, but their selectivity indices (SI = CC50/EC50) were lower than that of HEPT. Compound 8 was also evaluated against another HIV-1 strain (HTLV-IIIRF) and HIV-2 strains (LAV-2ROD and LAV-2EHO). Only HTLV-IIIRF was as sensitive as HTLV-IIIB.     

Use of adenine nucleotide derivatives to assess the potential of exo-active-site-directed reagents as species- or isozyme-specific enzyme inactivators. 3. Synthesis of adenosine 5'-triphosphate derivatives with N6- or 8-substituents bearing iodoacetyl groups

Several series of N6- or 8-substituted derivatives of adenosine 5'-triphosphate (ATP) were synthesized. N6-(omega-Aminoalkyl) derivatives of adenosine 5'-monophosphate (AMP) were converted into their omega-N-carbobenzyloxy derivatives, and these were converted, via the 2',3'-O-carbonyl derivatives of their 5'-phosphorimidazolidates, into the corresponding ATP derivatives. Hydrogenolytic removal of the carbobenzyloxy groups, followed by iodoacetylation of the omega-amino groups with N-(iodoacetoxy)succinimide, gave N6-R-ATP, where R = (CH2)nNHCOCH2I (n = 2--8) or (CH2)nCON)CH3)(CH2)mN(CH3)CO(CH2)nNHCOCH2I (n = m = 3; n = 3, m = 4; n = 4, m = 3; n = m = 4). Condensation of N6-(omega-aminoalkyl) derivatives of AMP with N-hydroxysuccinimide esters of omega-[N-(carbobenzyloxy)amino] carboxylic acids gave N6-(CH2)nNHCO(CH2)mNH-Cbz derivatives of AMP which, upon conversion to the corresponding derivatives of ATP, followed by removal of the carbobenzyloxy group and iodoacetylation, as described above, gave N6-(CH2)nNHCO(CH2)mNHCOCH2I-ATP derivatives (n = 3, m = 5 or 6; n = 4, m = 5; n = 6, m = 1--6). The same sequence of reactions starting with N6-[omega-(methylamino)alkyl] derivatives of N6-CH3-AMP gave N6-CH3, N6-(CH2)nH(CH3)CO(CH2)mNHCOCH2I derivatives of ATP (n = 4, m = 3, 5 or 6; n = 6, m = 5 or 6). Reaction of alpha, omega-diaminoalkanes with 8-Br-ATP gave 8-NH(CH2)nNH2 derivatives of ATP, which upon iodoacetylation gave 8-NH(CH2)nNHCOCH2I derivatives of ATP (n = 2, 4, 6, or 8). Substrate and inhibitor properties indicated that the ATP derivatives are potential exco-ATP-site-directed inactivators of hexokinases, adenylate kinases, and pyruvate kinases.     

Synthesis and antioxidant properties of some novel benzimidazole derivatives on lipid peroxidation in the rat liver

Some benzimidazole derivatives namely 1-[(substituted thiocarbamoylhydrazine carbonyl) methyl]-2-phenyl-1H-benzimidazoles (1a-13a), N-[(2-phenylbenzimidazol-1-yl methyl)-[1,3,4]-thiadiazole-2-yl]-substituted phenyl amines (1b-13b) and 5-(2-phenyl benzimidazol-1-yl-methyl)-4-substituted phenyl-4H-1,2,4-triazole-3-thiones (1c-13c) were synthesized, and their in vitro effects on the rat liver microsomal NADPH-dependent lipid peroxidation (LP) levels were determined. The most active compound 10a caused an 84% inhibition of LP at 10(-3) M, which is better than that of butylated hydroxytoluene (BHT) (65%).     

Convergent synthesis and unexpected Ca(2+)-mobilizing activity of 8-substituted analogues of cyclic ADP-carbocyclic-ribose, a stable mimic of the Ca(2+)-mobilizing second messenger cyclic ADP-ribose

Cyclic ADP-carbocyclic-ribose (cADPcR, 2) is a biologically and chemically stable equivalent of cyclic ADP-ribose (cADPR, 1), a Ca(2+)-mobilizing second messenger. In this study, a series of 8-substituted analogues of cADPcR, namely the 8-chloro analogue 6 (8-Cl-cADPcR), the 8-azido analogue 7 (8-N(3)-cADPcR), the 8-amino analogue 8 (8-NH(2)-cADPcR), and the 8-phenylthio analogue 9 (8-SPh-cADPcR), were designed as effective pharmacological tools for studies on cADPR-modulated Ca(2+) signaling pathways. These target compounds were synthesized by a convergent route via 8-Cl-cADPcR bisacetonide (14) as the common intermediate, in which a method for forming the intramolecular pyrophosphate linkage by activation of the phenylthiophosphate type substrate 15 with AgNO(3) to produce 14 was used as the key step. The carbocyclic analogues were tested for activity in the sea urchin egg homogenate system. Compounds were assessed for their calcium-mobilizing effects and their ability to cross-desensitize with calcium release induced by a normally maximal concentration of cADPR, as well as cADPR antagonism of cADPR-evoked calcium release. While cADPcR was 3-4 times more potent than cADPR, the 8-substituted analogues were less efficacious, with 8-SPh-cADPcR largely acting as a competitive antagonist. Most surprisingly, given that 8-N(3)-cADPR and 8-NH(2)-cADPR are known as potent antagonists, 8-N(3)-cADPcR and 8-NH(2)-cADPcR were full agonists, but ca. 80 and 2 times less potent than cADPR, respectively. These data contribute to developing structure-activity relationships for the interaction of cADPR with its receptor.     

8-Substituted 5-[(aminoalkyl)amino]-6H-v-triazolo[4,5,1-de]acridin-6-ones as potential antineoplastic agents. Synthesis and biological activity

A series of 8-substituted 5-[(aminoalkyl)amino]-6H-v-triazolo[4,5,1-de]acridin-6-ones (2), structurally related to the imidazoacridinones (1), was synthesized and tested for cytotoxic and antineoplastic activity. Preliminary biological results indicated that the 8-OH derivatives possess the highest antitumor activity. No relationship has been found between the nature of the C-8 substituent and antitumor activity.     

Further structural exploration of trisubstituted asymmetric pyran derivatives (2S,4R,5R)-2-benzhydryl-5-benzylamino-tetrahydropyran-4-ol and their corresponding disubstituted (3S,6S) pyran derivatives: a proposed pharmacophore model for high-affinity interaction with the dopamine, serotonin, and norepinephrine transporters

In our previous report, we described a novel series of asymmetric pyran derivatives (2S,4R,5R)-2-benzhydryl-5-benzylamino-tetrahydropyran-4-ol and their enantiomers as blockers of monoamine transporters in the brain. In this report, we describe the further exploration of this series of molecules by incorporating functional groups in the molecular template, which should promote the formation of H bonds with the transporters. In addition, a new synthetic scheme for the asymmetric synthesis of disubstituted cis-(6-benzhydryl-tetrahydro-pyran-3-yl)-benzylamine analogues and their biological characterization is reported. All synthesized derivatives were tested for their affinities for the dopamine transporter (DAT), serotonin transporter (SERT), and norepinephrine transporter (NET) in the brain by measuring their potency in inhibiting the uptake of [(3)H]DA, [(3)H]5-HT, and [(3)H]NE, respectively. The compounds were also tested for their binding potency at the DAT by their ability to inhibit binding of [(3)H]WIN 35, 428. The results indicated that the presence of functional groups, such as -OH, -NH(2), and the bioisosteric 5-substituted indole moiety in both di and trisubstituted compounds, significantly increased their potencies for the SERT and NET, especially for the NET. Among the trisubstituted compounds, (-)-4b exhibited the highest potency for the NET and the SERT (K(i) of 2.13 and 15.3 nM, respectively) and was a serotonin norepinephrine reuptake inhibitor (SNRI). Compound (-)-4a exhibited the highest selectivity for the NET. Among the disubstituted compounds, a number of compounds, such as (-)-9a, (+)-9b, (-)-9b, and (+)-9d, exhibited significant low-nanomolar potencies for the SERT and the NET. Interestingly, compound (-)-9d exhibited appreciable potencies at all three transporters. On the basis of our present and past findings, we propose a qualitative model for the interaction of these compounds with monoamine transporters, which will be refined further in the future.