Synthesis and antiretrovirus properties of 5'-isocyano-5'-deoxythymidine, 5'-isocyano-2',5'-dideoxyuridine, 3'-azido-5'-isocyano-3',5'-dideoxythymidine, and 3'-azido-5'-isocyano-2',3',5'-trideoxyuridine

The 5'-azidonucleosides 3 and 4 were obtained by treating thymidine and 2'-deoxyuridine with TPP/DEAD/HN3. The 3'-O-silylated 5'-azido-5'-deoxythymidine 5 and the corresponding 2'-deoxyuridine derivative 6 were transformed to the formamides (7 and 8, respectively) and dehydrated to the protected 5'-isocyano derivatives 9 and 10; deblocking gave 5'-isocyano-5'-deoxythymidine (11) and 5'-isocyano-2',5'-dideoxyuridine (12). 2,3'-Anhydro-5'-formamido derivatives of thymidine and 2'-deoxyuridine (19 and 20, respectively) were prepared by three different ways. In the most direct synthesis 3 and 4 were transformed to the 2,3'-anhydro-5'- azidonucleosides 17 and 18 by using TPP/DEAD; following the reaction with TPP/HCO2COCH3 gave 19 and 20. Nucleophilic opening reaction with LiN3 yielded the 3'-azido-5'-formylamino derivatives 21 and 22. Dehydration to 3'-azido-5'-isocyano-3',5'-dideoxythymidine (23) and 3'-azido-5'-isocyano-2',3',5'-trideoxyuridine (24) was achieved with tosyl chloride/pyridine. In contrast with 3'-azido-3'-deoxythymidine, compounds 11, 12, 23, and 24 were devoid of any marked inhibitory effect against DNA and RNA viruses including human immunodeficiency virus type I (HIV).     

Anti-retrovirus activity of 3'-fluoro- and 3'-azido-substituted pyrimidine 2',3'-dideoxynucleoside analogues

The 3'-fluoro-and 3'-azido-substituted derivatives of 2',3'-dideoxythymidine (ddThd), 2',3'-dideoxyuridine (ddUrd), 2',3'-dideoxy-5-ethyluridine (ddEtUrd) and 2',3'-dideoxycytidine (ddCyd) have been synthesized and evaluated for their anti-retrovirus activity [against human immunodeficiency virus (HIV) and murine Moloney sarcoma virus (MSV)]. Based on their 50% effective doses the most potent inhibitors of HIV replication in human MT4 lymphocytes were: FddThd (0.001 microM), AzddThd (0.004 microM), FddUrd (0.04 microM) and AzddUrd (0.36 microM). Their selectivity indexes were 197, 5000, 500 and 677, respectively. In contrast, none of the 3'-substituted ddEtUrd derivatives had a marked antiviral effect. The 2',3'-dideoxynucleoside analogues showed poor, if any, substrate affinity for (bacterial) dThd phosphorylase. AzddThd and FddThd inhibited human dThd kinase to a much greater extent (Ki/Km: 0.66 and 3.4, respectively) than did AzddUrd or FddUrd (Ki/Km: 71 and 171, respectively). The Ki/Km values of FddCyd and AzddCyd for human dCyd kinase were about 60. Although phosphorylation is a prerequisite for the anti-retrovirus activity of the 2',3'-dideoxynucleoside derivatives, there is no close correlation between the anti-retrovirus potency of the 3'-fluoro- and 3'-azido-substituted ddUrd, ddThd, ddEtUrd and ddCyd derivatives and their affinity for dThd kinase or dCyd kinase.     

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 anti-HIV activity of various 2'- and 3'-substituted 2',3'-dideoxyadenosines: a structure-activity analysis

A systematic synthesis was undertaken of 2',3'-dideoxyadenosine analogues with either an azido, fluorine, or hydroxyl group substituted in the "up" or "down" position of C-2 or C-3 of the sugar moiety. The compounds were evaluated against the cytopathogenicity of human immunodeficiency virus (HIV) for MT-4 cells. The four azido derivatives 6, 7, 8, and 9 were synthesized by a nucleophilic displacement reaction with lithium azide on the mesylates 3, 2, 5, and 4. (Diethylamido)sulfur trifluoride was used for the synthesis of 10-12. The compound 13 was obtained by 2'-deoxygenation of 9-(3-fluoro-3-deoxy-beta-D-xylofuranosyl)adenine. Among the azido derivatives, compound 8 with the 3'-azido "down" was slightly more active than 2',3'-dideoxyadenosine (1) but considerably more toxic, and, of the fluorine series, compound 11, with the 2'-fluoro "up", was the most selective inhibitor of HIV, although it was less active than 1. Hence, none of the newly synthesized compounds proved more selective in their anti-HIV activity than the parent compound, 1.     

Synthesis and antiviral and cytostatic evaluations of the new C-5 substituted pyrimidine and furo[2,3-d]pyrimidine 4',5'-didehydro-L-ascorbic acid derivatives

The novel C-5 alkynyl substituted pyrimidine (1-11) and furo[2,3-d]pyrimidine derivatives (12-22) of l-ascorbic acid were synthesized by coupling of 5-iodouracil-4',5'-didehydro-5',6'-dideoxy-l-ascorbic acid with terminal alkynes by using Sonogashira cross-coupling reaction conditions. The new compounds were evaluated for their cytostatic and antiviral activities. Among all evaluated compounds, the octynyl-substituted uracil derivative of l-ascorbic acid (3) exhibited the most pronounced cytostatic activities against all examined tumor cell lines (IC50 = 2-12 microM). Pyrimidine derivatives of l-ascorbic acid containing p-substituted phenylacetylene groups (8-11) displayed also a rather pronounced (IC50 = 3-37 microM) inhibitory effect toward all tumor cell lines. From the bicyclic series of compounds, 6-butylfuro[2,3-d]pyrimidine derivative (12) and 6-p-bromophenylfuro[2,3-d]pyrimidine derivative (19) showed the highest cytostatic activity (IC50 = 4.5-20 microM), particularly against malignant leukemia (L1210) and T-lymphocyte (Molt4/C8 and CEM) cells. Compounds 3 and 9 showed specific albeit moderate activity against cytomegalovirus (CMV, Davis strain, EC50 = 1.8 and 3.8 microM, respectively, for compounds 3 and 9) at a approximately 5-fold lower concentration than that required to show cytotoxicity.     

The anti-HTLV-III (anti-HIV) and cytotoxic activity of 2',3'-didehydro-2',3'-dideoxyribonucleosides: a comparison with their parental 2',3'-dideoxyribonucleosides

A series of 2',3'-didehydro-2',3'-dideoxyribonucleosides (ddeNs) [i.e., 2',3'-dideoxythymidinene (ddeThd), 2',3'-dideoxyuridinene (ddeUrd), 2',3'-dideoxycytidinene (ddeCyd), and 2',3'-dideoxyadenosinene (ddeAdo)] has been synthesized and the individual members compared in terms of their in vitro antiviral, antimetabolic, and cytostatic properties to their 2',3'-saturated counterparts (ddNs) (i.e., ddThd, ddUrd, ddCyd and ddAdo). All ddeNs except ddeUrd are potent and/or selective inhibitors of human immunodeficiency virus (HIV) in vitro, ddeCyd being the most potent (MIC50, 0.30 microM). The inhibitory effect of ddeCyd on ATH8 cell proliferation and HIV-induced cytopathogenicity is comparable to that of ddCyd. ddeThd is a more potent anti-HIV agent than ddThd (MIC50, 3.4 microM and 84 microM, respectively), but also more cytostatic (ID50, 172 microM and greater than 2000 microM, respectively). However, its in vitro chemotherapeutic index is higher than that of 3'-azido-2',3'-dideoxythymidine, a drug which has recently proven effective in the treatment of acquired immunodeficiency syndrome. ddeAdo has a weaker anti-HIV and a stronger cytostatic effect than ddAdo. Neither ddeUrd nor ddUrd shows significant anti-retroviral activity at 500 microM. In contrast to their anti-retroviral activity, both ddNs and ddeNs lack any appreciable inhibitory activity against a series of nononcogenic RNA and DNA viruses, pointing to their selectivity as anti-retroviral agents. All ddeNs show a progressive loss of anti-retroviral effect upon prolonged incubation with virus-infected cells. This phenomenon is most likely due to the chemical instability of these compounds, and not to a preferential enzymatic phosphorolytic cleavage of the ddeNs. Evidence is presented that ddeCyd and ddCyd, and ddeThd and ddThd are phosphorylated by cellular dCyd kinase and dThd kinase, respectively. However, the Ki values as alternate substrate inhibitors for their respective kinases are high (greater than 500 microM), indicating poor substrate activity and, thus, poor anabolism in ATH8 cells.     

Potentielle Antineoplastica, 2. Mitt. Synthese diarylsubstituierter 2- und 3-Hexene

Synthesis of Diaryl-2- and ?3-Hexenes Dehydration of 5 yields the 2-hexene derivative 7 as the main product and the isomeric trans-stilbene 6 in small amounts. 6 and 7 are converted to the mustard derivatives 9 and 11 via 8 and 10 , respectively. Compounds 5 – 11 , the by-product 12 and some intermediates, which occur in the synthesis of 5 , were investigated by UV, IR, ¹H-NMR and (partially) mass spectroscopy.     

2',3'-Dideoxycytidine: regulation of its metabolism and anti-retroviral potency by natural pyrimidine nucleosides and by inhibitors of pyrimidine nucleotide synthesis

The antiretroviral action of 2',3'-dideoxycytidine (ddCyd) depends on its intracellular conversion to the 5'-triphosphate metabolite ddCTP. The effect of natural pyrimidines and pyrimidine nucleosides, as well as of a number of inhibitors of pyrimidine nucleotide synthesis (i.e., N-(phosphonacetyl)-L-aspartate, 6-azauridine, pyrazofurin, 3-deazauridine, and hydroxyurea) on the metabolism of the potent anti-human immunodeficiency virus drug ddCyd has been investigated in human and murine cell lines. Deoxycytidine (dCyd) and cytidine (Cyd) effectively blocked the intracellular phosphorylation of ddCyd: dCyd by competition with ddCyd for 2'-deoxycytidine kinase, and Cyd probably by competition with the higher nucleoside mono- and diphosphate kinases. These conclusions are supported by the observations that (i) the cytostatic effects of ddCyd against human Molt/4F cells are significantly reversed by dCyd; (ii) the antiviral effects of ddCyd against hman immunodeficiency virus-infected human ATH8 cells are reversed by dCyd and Cyd; (iii) phosphorylated metabolites of ddCyd could not be detected in a 2'-deoxycytidine kinase-deficient murine leukemia (L1210)/araC cell line; and (iv) ddCyd lacked any cytostatic effect against this araC-resistant L1210 cell line. In contrast to dCyd and Cyd, thymidine (dThd) stimulated formation of phosphorylated ddCyd metabolites. The degree of this stimulation proved dependent on preincubation time and dThd concentration. There was a correlation between the increased ddCTP levels upon preincubation of the cells with dThd, and decreased dCyd-5'-triphosphate pools, presumably caused by inhibition of cytidine-5' -diphosphate reductase by dThd-5'-triphosphate. In an attempt to discover compounds other than dThd that are able to stimulate ddCTP formation, a number of inhibitors of pyrimidine nucleotide metabolism were also studied. Under our experimental conditions, 3-deazauridine and hydroxyurea proved equally as effective as dThd in stimulating ddCyd phosphorylation. Finally, we could demonstrate that dThd significantly enhanced the protective effect of ddCyd against human immunodeficiency virus-infected ATH8 cells.     

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. Although without significant antiviral activity in cell cultures, the 2-aminopurines (13, 14-16, 26-29) and 2-amino-6-alkoxypurines (12, 23-25) are well absorbed after oral administration to mice and are converted efficiently to the antiviral guanine derivatives (8, 21) in vivo.     

5'-O-phosphonomethyl-2',3'-dideoxynucleosides: synthesis and anti-HIV activity.

5'-O-Phosphonomethylation of different pyrimidine 2',3'-dideoxynucleosides was accomplished by reaction of the latter with diethyl [(p-toylsulfonyl)oxy]methanephosphonate (1) in the presence of sodium hydride. The base-phosphonomethylated (15-19) and sugar-phosphonomethylated (8-12) derivatives could be readily distinguished by 1H and 13C NMR and MS analysis. Protection of the uracil or thymine residue with a N3-benzoyl group failed to prevent base modification. However, O4-methyl-protected 2',3'-dideoxyuridine readily afforded the 5'-O-phosphonomethylated derivative 12, which was converted to both the 2',3'-didoxyuridine analogue 27 and the 2',3'-dideoxycytidine counterpart 29. The 5'-O-phosphonomethyl derivatives of 3'-deoxythymidine (23), 2',3'-dideoxyuridine, (27), 2',3'-dideoxycytidine (29), 3'-O-methylthymidine (26), and 3'-amino-3'-deoxythymidine (28) did not show an appreciable anti-HIV activity in MT-4 cells. In contrast, the 5'-O-phosphonomethyl derivatives of 3'-deoxy-3'-fluorothymidine (24) and 3'-azido-3'-deoxythymidine (25) inhibited HIV-1 cytopathogenicity by 50% at a concentration of approximately 1 microM.     

Anti-AIDS agents. 37. Synthesis and structure-activity relationships of (3'R,4'R)-(+)-cis-khellactone derivatives as novel potent anti-HIV agents.

To explore the structural requirements of (+)-cis-khellactone derivatives as novel anti-HIV agents, 24 monosubstituted 3', 4'-di-O-(S)-camphanoyl-(+)-cis-khellactone (DCK) derivatives were synthesized asymmetrically. These compounds included 4 isomeric monomethoxy analogues (3-6), 4 isomeric monomethyl analogues (7-10), 4 4-alkyl/aryl-substituted analogues (11-14), and 12 4-methyl-(+)-cis-khellactone derivatives (15-26) with varying 3', 4'-substituents. These (+)-cis-khellactone derivatives were screened against HIV-1 replication in acutely infected H9 lymphocytes. The results demonstrated that the (3'R,4'R)-(+)-cis-khellactone skeleton, two (S)-(-)-camphanoyl groups at the 3'- and 4'-positions, and a methyl group on the coumarin ring, except at the 6-position, were optimal structural moieties for anti-HIV activity. 3-Methyl- (7), 4-methyl- (8), and 5-methyl- (9) 3',4'-di-O-(S)-camphanoyl-(3'R, 4'R)-(+)-cis-khellactone showed EC(50) and therapeutic index values of <5.25 x 10(-5) microM and >2.15 x 10(6), respectively, in H9 lymphocytes, which are much better than those of DCK and AZT in the same assay. Furthermore, 8 and 9 also showed potent inhibitory activity against HIV-1 replication in the CEM-SS cell line, and most monosubstituted DCK analogues were less toxic than DCK in both assays.     

Structure-activity analysis of antagonism of the feedback inhibition of thymidine kinase

The effects of a variety of 5-, 5'-, and 3'-substituted deoxyuridine derivatives on the cytoplasmic thymidine kinase (EC 2.7.1.21) purified from a human colon carcinoma cell line, HCT 116, were determined. Of particular interest was elucidation of the structural features important for antagonism of the feedback inhibition of thymidine kinase exerted by thymidine triphosphate. Substitutions at the 5-position altered the potency of the 5'-modified compounds. The replacement of the 5-hydrogen with a methyl group or an iodine greatly increased the affinity of compounds for the thymidine kinase. This was evident for enzyme substrates with 5'-hydroxyl groups [2'-deoxyuridine (dUrd), 2'-deoxythymidine (dThd) and 5-iodo-2'-deoxyuridine (IdUrd)], feedback inhibitors with 5'-triphosphate substitutions (dUTP, dTTP and IdUTP), and for 5'-amino derivatives [5'-amino-2',5'-dideoxyuridine (5'-AdUrd), 5'-amino-2'-5'-dideoxythymidine (5'-AdThd) and 5-iodo-5'-amino-2',5'-dideoxyuridine (5'-AIdUrd)]. Qualitatively, however, the 5-substitutions did not affect the nature of the interactions with dThd kinase. For example, in the presence of dTTP, 5'-AdUrd stimulated dThd kinase activity as much as 5'-AdThd, but approximately a 100-fold greater concentration of 5'-AdUrd was required. Similar results were obtained using intact cells in which substitutions at the 5-position affected the potency, but not the efficacy, of the 5'-amino derivatives to stimulate dThd phosphorylation. In contrast, substitutions at the 5'-position did alter the nature of the interaction with dThd kinase. Thus, the 5'-hydroxyl compounds, dUrd, dThd and IdUrd, did not reverse the enzyme inhibition produced by dTTP nor did they stimulate dThd uptake in intact cells. 5'-Deoxy-5'-(ethylthio)thymidine, 5'-deoxy-5'-[(2-hydroxyethyl)thio]thymidine, and dTMP, but not dTDP, also antagonized the inhibition of dThd kinase produced by dTTP. In comparison to 5'-AdThd, the 3'-amino derivatives, 3'-AdThd and 3'-5'-diAdThd, were much less potent, but still efficacious, antagonists of feedback inhibition. These results indicate that a wide range of dUrd derivatives can disrupt the regulation of dThd kinase and provide leads for the development of new nucleotide analogues.     

Tetrahydro-3-pyranon als Baustein zur Pyrano[3,2-b]pyran-Synthese

Synthesis of Pyrano[3,2-b]pyran from Tetrahydro-3-pyranone The enamine 4 , obtained from the pyranone 2 , reacts with diketene (6) to yield the pyrano[3,2-b]pyranone 7. Reaction with 1,3-dimethylbarbituric acid (10) results in the formation of the pyranylidene derivative 11. Reaction of 7 or 11 with ammonia or primary amines leads to the formation of the pyranopyridine derivatives 8, 9, 12a and 12b .     

Synthesis of N-substituted-N-acylthioureas of 4-substituted piperazines endowed with local anaesthetic,antihyperlipidemic, antiproliferative activities and antiarrythmic,analgesic, antiaggregating actions

Three series of N-acyl and N-cyclohexyl- or N-methyl or N-phenyl-thioureas of 4-substituted (methyl, phenyl, 2-pyridyl)piperazines (4-12) were synthesised according to a highly convergent one-pot procedure and tested in vivo (local anaesthetic, anti-hyperlipoproteinemic, analgesic, anti-inflammatory, antiarrythmic activities) and in vitro (antiaggregating and, for some selected derivatives, antiproliferative activities) experiments. All the test compounds showed local anaesthesia in particular 4Ar(4), 5Ar(4), 12Ar(3) (after 5 min) and 5Ar(2), 5Ar(3), 9Ar(4) (after 30 min) were equipotent to lidocaine. In lowering triglyceride levels, compounds 6Ar(4) and 7Ar(3) were more active than nicotinic acid, whereas 7Ar(4) and 11Ar(4) were approximately equipotent. As concerns analgesic activity, 5Ar(2) and 5Ar(4) were as active as indomethacin. Appreciable anti-inflammatory activity was found in 8Ar(1), 5Ar(2) and 11Ar(2), but inferior to that of indomethacin. High levels of antiarrythmic activity, comparable with that of quinidine, were found in derivatives 4Ar(2) and 10Ar(1). Compounds 4Ar(2) and 8Ar(2), assayed in antitumor in vitro screening system at National Cancer Institute (NCI), showed significant antiproliferative activity against ACHN cell line (GI50: 0.13 microM) and NCI-H226 cell line (GI50: 1.03 microM), respectively.     

Synthesis and antitumor activity of certain 3-beta-D-ribofuranosyl-1,2,4-triazolo[3,4-f]-1,2,4-triazines related to formycin prepared via ring closure of a 1,2,4-triazine precursor

Several 3-beta-D-ribofuranosyl-1,2,4-triazolo[3,4-f]-1,2,4-triazines related to formycin were prepared and tested for their antitumor activity in cell culture. Dehydrative coupling of 3-amino-6-hydrazino-1,2,4-triazin-5(4H)-one (5) with 3,4,6-tri-O-benzoyl-2,5-anhydro-D-allonic acid (6a) and further ring closure of the reaction product (7) provided 6-amino-3-(2,3,5-tri-O-benzoyl-beta-D-ribofuranosyl)-1,2,4-triazolo[3,4- f]-1,2,4-triazin-8(7H)-one (8). Condensation of 5 with 3,4,6-tri-O-benzoyl-2,5-anhydro-D-allonic acid chloride (6b), followed by ring annulation, also gave 8 in good yield. Debenzoylation of 8 furnished the guanosine analogue 6-amino-3-beta-D-ribofuranosyl-1,2,4-triazolo[3,4-f]-1,2,4-triazin -8(7H)-one (4b). Thiation of 8 with P2S5, followed by debenzoylation of the thiated product (11a), afforded 6-amino-3-beta-D-ribofuranosyl-1,2,4-triazolo[3,4-f]-1,2,4-triazin -8(7H)- thione (11b). Methylation of the sodium salt of 11a gave the 8-methylthio derivative (10), which on ammonolysis furnished 6,8-diamino-3-beta-D-ribofuranosyl-1,2,4-triazolo[3,4-f]-1,2,4-triazine (9). Diazotization of 10 with tert-butyl nitrite (TBN) and SbCl3 in 1,2-dichloroethane gave the corresponding 6-chloro derivative (12a). Reaction of 10 with TBN in THF in the absence of a halogen source gave 8-(methylthio)-3-(2,3,5-tri-O-benzoyl-beta-D-ribofuranosyl)-1,2,4- triazolo[3,4-f]-1,2,4-triazine (12b). Ammonolysis of 12b gave the azaformycin A analogue 8-amino-3-beta-D-ribofuranosyl-1,2,4- triazolo[3,4-f]-1,2,4-triazine (3), which on deamination afforded 3-beta-D-ribofuranosyl-1,2,4-triazolo[3,4- f]-1,2,4-triazin-8(7H)-one (4a). The azaformycin A analogue (3) showed pronounced inhibitory effects against L1210, WIL2, and CCRF-CEM cell lines with ID50 values ranging from 5.0 to 7.3 microM.     

Synthesis and antiproliferative activity of 3-aryl-2-[1H(2H)-benzotriazol-1(2)-yl]acrylonitriles variously substituted: Part 4

A new series of variously substituted 3-aryl-2-[1H(2H)-benzotriazol-1(2)-yl]acrylonitriles was synthesized and tested for antiproliferative and antitubercular activity as part of our continuing research program in the antimicrobial and antitumor fields. The most cytotoxic derivatives (5a,g,i,j,l and 7b) (CC50 < 3.0 microM against MT-4 cells) were evaluated against a panel of human cell lines derived from hematological and solid tumors, using 6-mercaptopurine (6-MP) and etoposide as reference drugs. In particular, E-2-(5,6-dimethyl-1H-benzotriazol-1-yl)-3-(3-nitrophenyl)acrylonitrile (5g) resulted more potent than 6-MP on all cell lines, even if 2-14-fold less potent than etoposide. In the antitubercular screening, the derivatives 5i,j and 7e showed moderate activity against some resistant strains of Mycobacterium tested.     

Aromatase inhibitors. Synthesis and evaluation of mammary tumor inhibiting activity of 3-alkylated 3-(4-aminophenyl)piperidine-2,6-diones

The synthesis and biological evaluation of 3-alkyl-substituted 3-(4-aminophenyl)piperidine-2,6-diones as inhibitors of estrogen biosynthesis are described [H (1), methyl (2), ethyl (3), n-propyl (4), isopropyl (5), n-butyl (6), isobutyl (7), sec-butyl (8), n-pentyl (9), isopentyl (10), 2-methylbutyl (11), sec-pentyl (12), n-hexyl (13), n-heptyl (14)]. In vitro compounds 4-14 showed a stronger inhibition of human placental aromatase compared to aminoglutethimide (AG, compound 3), which recently has become used for the treatment of hormone-dependent breast cancer. The most active derivative, compound 10, showed a 93-fold stronger inhibition than AG. With the exception of 5, 7, and 8, all other compounds exhibited similar or decreased inhibition of bovine adrenal desmolase compared to AG. Compounds 4 and 6-12 showed a stronger inhibition of the plasma estradiol concentration of pregnant mare serum gonadotropin (PMSG) primed Sprague-Dawley (SD) rats compared to the parent compound. Compounds 4, 6-8, 10, and 12 inhibited the testosterone-stimulated tumor growth of ovariectomized 9,10-dimethyl-1,2-benzanthracene (DMBA) tumor-bearing SD rats more strongly than AG. Being stronger and more selective inhibitors of the estrogen biosynthesis than AG, some of the newly developed derivatives of AG might be better candidates for the treatment of the hormone-dependent human breast cancer.     

Synthesis and antioxidant evaluation of some new 3-substituted coumarins

3-Acetylcoumarin (1) was utilized as a key intermediate for the synthesis of 2-aminothiazole derivative 3 via bromination of 1 to afford acetylbromide 2 followed by treatment with thiourea or via Biginelli reaction of 1. Treatment of 3 with 5-chloro-3-methyl-1-phenyl-1H-pyrazole-4-carbaldehyde, 2-methyl-4H-benzo[d][1,3]oxazin-4-one, furo[3,4-b]pyrazine-5,7-dione or 2-methyl-5,6,7,8-tetrahydro-4H-benzothieno[2,3-d][1,3]oxazin-4-one afforded diazine derivatives 4-7. Also, pyridopyrimidine 8 was obtained via a one pot reaction of 6-aminothiouracil, p-chlorobenzaldehyde and 3-acetylcoumarin. Moreover, refluxing of 6-aminothiouracil with one equivalent amount of 2 afforded the thiazolopyrimidine 9, while the pyrrolothiazolopyrimidine 10 was revealed when two equivalent amounts of 2 was used. Furthermore, treatment of enamine 11 with 2-aminobenzothiazole or 6-aminothiouracil afforded the pyrimidine derivatives 12 and 13, respectively. Transamination of enamine 11 with m-anisidine followed by cyclization of the resulting enaminone 14 gave the desired quinoline 15. Also, treatment of 11 with thiophenol in dioxane gave the mercapto derivative 16. Moreover, coupling of 11 with 4,6-dimethyl-1H-pyrazolo[3,4-b]pyridin-3-yl-diazonium chloride, followed by complete cyclization of the resulting product afforded the pyridopyrazolothiazine 19 via the intermediate 18. Furthermore, the pyrazolopyrimidine 20 was revealed via a one pot condensation of 11, 3-methyl-1-phenyl-1H-pyrazol-5(4H)-one and ammonium acetate. The thiadiazine derivatives 21-23 were obtained via treatment of 2 with the corresponding o-aminothiols. Desulphonation of 23 afforded the pyrazolotriazine 24. Finally, reaction of 2 with 2-hydroxybenzaldehyde gave benzofuran derivative 25. Representative compounds of the synthesized products were evaluated as antioxidant agents.     

Synthesis and antimicrobial activity of 3-(substituted-phenyl)-sydnones.

3-(3 or 4-Acetylphenyl)-sydnones 7, 8 have been synthesized by formation of the glycines 3, 4, followed by nitrosation to 5, 6 and cyclization with acetic anhydride to sydnones. Sydnone derivatives carrying chalcone moieties 15, 16 were prepared by formation of the chalcone analogues 11, 12 through condensation of the glycines 3, 4 with the appropriate aldehydes, followed by the reactions applied for the preparation of 7, 8. The sydnone derivatives were screened for antimicrobial activities.