Ribose-modified purine nucleosides as ribonucleotide reductase inhibitors. Synthesis, antitumor activity, and molecular modeling of N6-substituted 3'-C-methyladenosine derivatives

A series of cycloalkyl, bicycloalkyl, aryl, and heteroaryl N (6)-substituted derivatives of the antitumor agent 3'- C-methyladenosine (3'-Me-Ado), an inhibitor of the alpha Rnr1 subunit of mammalian ribonucleotide reductase (RR), were synthesized. The cytotoxicity of these compounds was evaluated against a panel of human leukemia and carcinoma cell lines and compared to that of some corresponding N (6)-substituted adenosine analogues. N (6)-cycloalkyl-3'- C-methylribonucleosides 2- 7 and N (6)-phenyl analogue 8 were found to inhibit the proliferation of K562 leukemia cells. N (6)-(+/-)- endo-2-norbornyl-3'- C-methyladenosine ( 7) was found to be the most cytotoxic compound, with GI 50 values slightly higher than that of 3'-Me-Ado against K562 and carcinoma cell lines and 2.7 fold higher cytotoxicity against human promyelocytic leukemia HL-60 cells. The SAR study confirms that an unsubstituted N (6)-amino group is essential for optimal cytotoxicity of 3'-Me-Ado against both K562 and carcinoma cell lines. Computational studies, carried out on the eukaryotic alpha subunit (Rnr1) of RR from Saccharomyces cerevisiae were performed to rationalize the observed structure-activity relationships.     

Synthesis and SAR studies of novel 6,7,8-substituted 4-substituted benzyloxyquinolin-2(1H)-one derivatives for anticancer activity

Background and Purpose

4-Phenylquinolin-2(1H)-one (4-PQ) derivatives can induce cancer cell apoptosis. Additional new 4-PQ analogs were investigated as more effective, less toxic antitumour agents.

Experimental Approach

Forty-five 6,7,8-substituted 4-substituted benzyloxyquinolin-2(1H)-one derivatives were synthesized. Antiproliferative activities were evaluated using a 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazoliun bromide assay and structure–activity relationship correlations were established. Compounds 9b, 9c, 9e and 11e were also evaluated against the National Cancer Institute-60 human cancer cell line panel. Hoechst 33258 and Annexin V-FITC/PI staining assays were used to detect apoptosis, while inhibition of microtubule polymerization was assayed by fluorescence microscopy. Effects on the cell cycle were assessed by flow cytometry and on apoptosis-related proteins (active caspase-3, -8 and -9, procaspase-3, -8, -9, PARP, Bid, Bcl-xL and Bcl-2) by Western blotting.

Key Results

Nine 6,7,8-substituted 4-substituted benzyloxyquinolin-2(1H)-one derivatives (7e, 8e, 9b, 9c, 9e, 10c, 10e, 11c and 11e) displayed high potency against HL-60, Hep3B, H460, and COLO 205 cancer cells (IC₅₀ < 1 μM) without affecting Detroit 551 normal human cells (IC₅₀ > 50 μM). Particularly, compound 11e exhibited nanomolar potency against COLO 205 cancer cells. Mechanistic studies indicated that compound 11e disrupted microtubule assembly and induced G2/M arrest, polyploidy and apoptosis via the intrinsic and extrinsic signalling pathways. Activation of JNK could play a role in TRAIL-induced COLO 205 apoptosis.

Conclusion and Implications

New quinolone derivatives were identified as potential pro-apoptotic agents. Compound 11e could be a promising lead compound for future antitumour agent development.     

Synthesis of novel 4-substituted phenazone derivatives as potential antibacterial and antineoplastic agents

A new series of substituted phenazone derivatives has been prepared, through a series of reactions that are illustrated in Scheme I. The antibacterial and antineoplastic activities of the prepared compounds were evaluated. While none of the synthesized products showed marked antibacterial activity, all of them possessed a significant antitumor effect.     

Synthesis and biological evaluation of 8-substituted berberine derivatives as novel anti-mycobacterial agents

Tuberculosis (TB) is a disease which kills two million people every year and infects over one-third of the world′s population. Eighteen new 8-substituted berberine derivatives were synthesized and evaluated for their anti-mycobacterial activities against Mycobacterium tuberculosis (M. tuberculosis) strain H₃₇Rv. Among these compounds, compound 6i was the most effective antitubercular agent with an MIC of 1.0 μg/mL. Most importantly, compound 6i also exhibited a potent effect against clinically isolated rifampicin- and isoniazid-resistant M. tuberculosis strains, suggesting a different mode of action from the current drugs. Therefore, it shows potential for the development of new anti-TB agents.     

Synthesis and biological evaluation of 6-bromo-6-substituted penicillanic acid derivatives as beta-lactamase inhibitors

The synthesis of a selected set of 6-bromopenicillanic acid derivatives with an additional C6 substituent is reported. All these substances were tested as inhibitors of class A and C beta-lactamase enzymes derived from Escherichia coli (TEM-1) and E. cloacae (P99). As 6-(1-hydroxyethyl) derivatives 4c and 6c were found to be weak beta-lactamase inhibitors, they were further investigated in combination with amoxicillin against a series of beta-lactamase-producing bacterial strains. Some structure-activity relationships are discussed.     

6-取代亚甲肼基-2，4-双吗啉嘧啶及三嗪类衍生物的合成与抗肿瘤活性研究

目的设计合成一系列6-取代亚甲肼基嘧啶及三嗪衍生物,并对其体外抗肿瘤活性进行初步评价。方法以2,4,6-三氯嘧啶或三聚氯氰、苯胺、苯并咪唑、吡咯为起始原料,经多步反应合成目标化合物;采用MTT法,以BMCL-200908069—1为阳性对照药,以H460、A549和H226为测试细胞株,对目标化合物进行抗肿瘤活性评价。结果合成了20个未见文献报道的6-取代亚甲肼基-2,4-双吗啉嘧啶及三嗪类化合物,其结构经MS、1H-NMR谱确证。结论体外活性实验显示：该系列化合物具有较强的抗肿瘤活性,其中,化合物6a活性最佳,其对H460、A549和H226抑制作用的IC50值分别为3．4、0L75、0．86pxnol·L-1,其活性为阳性对照药的28～16．8倍。     

Synthesis and structure of purine derivatives as antitumor effects

The nucleophilic substitution reaction of 6-chloro purines (I) with malononitrile and ethyl cyanoacetate is carried out in DMSO and in the presence of an alkali. The possible tautomeric-ylidene form for the products is considered and discussed in view of IR, UV, NMR and mass spectral determinations. The derivatives were tested for their antitumor activities.     

Synthesis of purine derivatives

The methylation of 2-chloro-7-methylhypoxanthine in aqueous alkali forms, as well as 2-chloro-1,7-dimethylhypoxanthine, two isomers of this compound. These isomers were isolated and characterized as 2 chloro-3,7-dimethylhypoxanthine and 2 chloro-6-oxo-7, 9-dimethylpurine betaine.Translated from Khimiko-Farmatsevticheskii Zhurnal, No. 3, pp. 32–37, March, 1967.     

Synthesis of some novel substituted purine derivatives as potential anticancer, anti-HIV-1 and antimicrobial agents

In search of novel purine antimetabolites, a series of 8-substituted methylxanthine derivatives was prepared in order to explore their in vitro anticancer, anti-HIV-1 and antimicrobial activities. The target compounds include: 8-[(3-substituted-4-oxo-thiazolidin-2-ylidene)hydrazino]-1,3-dimethyl (or 1,3,7-trimethyl)-3,7-dihydropurine-2,6-diones 5a-e, 8-[(3,4-disubstituted 2,3-dihydrothiazol-2-ylidene)hydrazino]-1,3,7-trimethyl-3,7-dihydropurine-2,6-diones 6a-d and 8-(5-amino-3-arylpyrazol-1-yl)-1,3-dimethyl- (or 1,3,7-trimethyl)-3,7-dihydropurine-2,6-diones 7a-g. The in vitro anticancer results revealed that compound 5d exhibited a super sensitivity profile towards leukemia K-562 with a GI(50) value of <0.01 microM. Compound 7c showed significant activity against colon cancer HCT-15 and renal cancer CAKI-1 (GI(50) values of 0.47 and 0.78 microM, respectively). Compound 7a displayed high activity against colon cancer HCT-15 (GI(50 )= 0.8 microM). The anti-HIV-1 results indicated that compound 6b displayed a good reduction of viral cytopathic effect (56.69%). The antimicrobial results showed that compound 5a was four times more active than ampicillin against P. aerugenosa (MIC =or< 25 microg/mL), compound 5b had twice the activity of ampicillin, while compounds 5d, 7c and 7f were equipotent to ampicillin. On the other hand, compound 7a was equipotent to ampicillin against P. vulgaris (MIC = 50 microg/mL).     

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.     

Synthesis,characterization and biological evaluation of some novel 2-substituted mercaptobenzimidazole derivatives.

Synthesis and biological assessment of six novel 2-substituted mercaptobenzimidazole derivatives is performed. The title compounds are characterized by their analytical and spectral data. All the synthesized compounds are screened for their anti-ulcer and anti-microbial activity. 2-(1H-benzimidazole-2-sulfinyl) –N-(4-benzyloxy-phenyl)-acetamide, N-(4-benzyloxy-phenyl)-4-(1H-benzimidazole-2-sulfinyl)-butyramide, N-(4-benzyloxy phenyl)-4-(5-methoxy 1H-benzimidazole-2-sulfinyl)-butyramide showed significant antiulcer activity. All the compounds moderate antibacterial and antifungal activity.     

Synthesis and selective cytotoxicity of novel biphenyl-based tetrazole derivatives

Cancer today represents a significant public health problem worldwide, and the challenge is to produce cost-effective drugs. Recently, biphenyl compounds as well as tetrazole derivatives is known for their potential non-selective anticancer activities. In search of novel selective anticancer agents, a series of newly hybrid molecules was designed and synthesized by combining the structural features of biphenyl and tetrazole moieties. The structures of newly synthesized compounds were characterized using spectroscopic techniques (FT-IR, ¹H NMR, ¹³C NMR, and HMBC). Cytotoxic evaluations of these novels compound on human cancer cell lines showed a significant anticancer activity against more than one tested cell lines. Compounds 5n, 5j, and 5o proved to exhibit the strongest and selective cytotoxic effect on HepG2 and MCF-7 lines. Taken together, this study has led to the development of promising leads for cancer therapy.     

Synthesis and antimicrobial activity of some novel 2,5- and/or 6-substituted benzoxazole and benzimidazole derivatives

A new series of 2,5- and/or 6-substituted benzoxazoles (7a–f), benzimidazoles (8a–g) holding cyclohexyl or cyclopentyl moieties at position 2 and 5- or 6-substituted-2-cyclohexylaminomethylbenzoxazoles (9a, b) was synthesized in order to determine their antimicrobial activities and feasible structure–activity relationships. The synthesized compounds were tested in vitro against three Gram-positive, two Gram-negative bacteria and the yeast Candida albicans in comparison with several control drugs. Microbiological results showed that the synthesized compounds were possessing a broad spectrum of antibacterial activity against the tested microorganisms. 5-Chloro-2-(2-cyclohexylethyl)benzimidazole (8g) was found as the most active compound against the screened Gram-positive bacteria strains at a minimum inhibitory concentration (MIC) value of 12.5 μg/ml. However, it exhibited lower antibacterial potency than the compared control drugs. On the other side, compounds 7–9 indicated significant antibacterial activity against the Gram-negative enterobacter Pseudomonas aeruginosa having MIC values of 50 μg/ml, providing either the same effect as tetracycline or higher activity than streptomycin, but showing less potency than the compared control drug gentamycin. Moreover, the synthesized compounds also possessed antimycotic activity against the yeast C. albicans showing MIC values between 25–50 μg/ml.     

Synthesis, antimicrobial evaluation, and docking studies of novel 4-substituted quinazoline derivatives as DNA-gyrase inhibitors

Quinazoline derivatives are reported to have anti‐inflammatory, analgesic, antibacterial, and anticancer activities. The incorporation of “OCH₂CONH₂” (oxymethylcarbamide) at 4^th position of the quinazoline ring was found to influence the biological activities of the molecules. With this rationale, some new oxadiazolyl methyloxy quinazolines, pyrazolyl acetoxy methyl quinazolines, triazolylmethyloxy quinazolines were synthesized from anthranilic acid through quinazolyl oxyacetylhydrazide intermediates. All the compounds were characterized by IR, ¹H‐NMR, EI‐MS, and C, H, N analyses and evaluated for their antimicrobial activity. Docking studies on the DNA‐gyrase enzyme (1KZN) show their role in the antimicrobial activity of the molecules and explain the higher potency of compounds 6a , 6b , 8a , 8b based on ReRanking scores and binding poses of the molecules.     

Synthesis of novel 26-substituted milbemycin A4 derivatives and their acaricidal activities

A series of novel 26-substituted milbemycin A4 derivatives was synthesized from 5-O-t-butyldimethylsilyl-26-hydroxymilbemycin A4 prepared by selenium dioxide oxidation of 5-O-t-butyldimethylsilyl-milbemycin A4. Their acaricidal activities were assessed against the organophosphorus-sensitive two-spotted spider mite (Tetranychus urticae) on the primary leaves of cowpea plants (Vigna sinesis Savi species) by spraying.     

Synthesis and antidepressant properties of novel 2-substituted 4,5-dihydro-1H-imidazole derivatives

A unique combination of alpha 2-adrenoreceptor antagonist and serotonin-selective reuptake inhibitory activities has been identified in a series of 2-substituted 4,5-dihydro-1H-imidazole derivatives. This combination of blocking activities has provided one of these derivatives, napamezole hydrochloride (2), with potential as an antidepressant. A discussion of the syntheses of these compounds includes a convenient method for the conversion of nitriles to imidazolines with ethylenediamine and trimethylaluminum.