Synthesis and antimicrobial activity of some novel 2-(p-substituted-phenyl)-5-substituted-carbonylaminobenzoxazoles

A series of 2-(p-substituted-phenyl)-5-substituted-carbonylamino benzoxazole derivatives (5-22) was synthesized and their antimicrobial activities determined in comparison to several control drugs. The synthesized compounds were tested in vitro against Staphylococcus aureus, Streptococcus faecalis and Bacillus subtilis as Gram-positive, Pseudomonas aeruginosa and Escherichia coli as Gram-negative bacteria and the yeast Candida albicans. Microbiological results showed that the compounds possessed a diffuse spectrum of antibacterial activity against these microorganisms. Compound 9 which bears a phenylacetamido moiety at position 5 and a 4-fluorophenyl group at the 2-position of benzoxazole ring was the most active derivative against S. aureus, S. faecalis and P. aeruginosa with a MIC value of 12.5 microg/ml. Compound 11 provided higher potency than the other tested compounds against B. subtilis at a MIC value of 12.5 microg/ml. Compounds 5-22 showed antifungal activity against C. albicans with MIC values between 50 and 12.5 microg/ml.     

Investigation of the antimicrobial and anticancer activity of aminonaphthoquinones

In this study, we report on the inhibitory activity of synthesized aminonaphthoquinones against two bacterial and one fungal species to determine their antimicrobial properties. A minimum inhibitory concentration (MIC) of 7.8 μg/mL was obtained against the fungus, Candida albicans, which was better than that of Amphotericin B (MIC = 31.25 μg/mL). Escherichia coli (Gram -), was inhibited at a MIC of 23.4 μg/mL and Staphylococcus aureus (Gram +) at a MIC of 31.3 μg/mL. The aminonaphthoquinones were also screened against HCT116 colon, PC3 prostate and HepG2 liver cancer cell lines to evaluate their cytostatic effects. They had potent activity (GI₅₀ = 5.87–9.90 μM) which was about three-6-fold better than that of parthenolide (GI₅₀ = 25.97 μM) against the prostate cancer cell line. These compounds were generally more selective for cancer cells than for normal human lung fetal fibroblasts (WI-38).     

Biologically active steroidal glycosides from Tribulus terrestris

The steroidal saponin constituents obtained from Tribulus terrestris were tested for their antimicrobial and cytotoxic effects. The spirostanol-based steroidal saponins 1-3 exhibited remarkable activity against fungal organisms (Candida albicans and Cryptococcus neoformans) and cancer cell lines [human malignant melanoma (SK-MEL), human oral epidermoid carcinoma (KB), human breast ductal carcinoma (BT-549), and human ovary carcinoma (SK-OV-3)], while none of the compounds possessing the furostanol framework 4-7 showed activity. The most active spirostanol glycoside, compound 3 exhibited a broad range of anticancer activity against cell lines, SK-MEL, KB, BT-549 and SK-OV-3 at IC50s of 6.0, 7.0, 6.0 and 8.2 micrograms/ml, respectively, while compounds 1 and 2 showed selective cytotoxicity against SK-MEL at 6.7 and 9.1 micrograms/ml, respectively. The minimum inhibitory concentrations (MIC) in antifungal bioassay for compounds 1-3 varied from 1.5 to 6.2 micrograms/ml, which prompted to conclude certain structural features are required for these bioactivities.     

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 and biological evaluation of 5-formyl-6-arylimidazo(2,1-b)-1,3,4-thiadiazole-2-N-(dimethylaminomethi no) sulfonamides as antitumor agents.

In search for potential anti cancer drug candidates in imidazo (2,1-b)-1,3,4-thiadiazole series, two series of 5-formyl-6-arylimidazo(2,1-b)-1,3,4-thiadiazole-2-N- (dimethylaminomethino) sulfonamides and 5-bromo-6-aryl/ethylacetateimidazo(2,1-b)-1,3,4- thiadiazole-2-sulfonamides were synthesised. All compounds showed significant cytotoxic effects (log10 GI50 < -4.0, log molar drug concentration required to cause 50% growth inhibition) against a variety of human tumor cell lines of the National Cancer Institute in vitro screen, including cells derived from solid tumors such as non-small cell lung, colon, central nervous system, melanoma, ovarian, prostate and breast cancer, and also few cell lines of leukemia and renal cancer. Introduction of a formyl group at the 5- and substituted aromatic group at 6-position generated compounds with potent antitumor activity. Incorporation of a bromo at 5- and ester group at 6-position produced compounds with reduced activity.     

Antibacterial activity against resistant bacteria and cytotoxicity of four alkaloid toxins isolated from the marine sponge Arenosclera brasiliensis.

Arenosclerins A-C and haliclonacyclamine E, new tetracyclic alkylpiperidine alkaloids isolated from the marine sponge Arenosclera brasiliensis, were subjected to antimicrobial and cytotoxic bioassays. Fourteen samples of microorganisms were used: Candida albicans, Staphylococcus aureus, Escherichia coli, and 12 antibiotic-resistant bacteria isolated from hospital environment. The minimum inhibitory concentration activity of each alkaloid was determined. The four compounds displayed antibacterial activity, but no antifungal activity against C. albicans. Haliclonacyclamine E and arenosclerins A and C were active against a larger number of bacteria strains than arenosclerin B. However, arenosclerins B and C presented more potent antibacterial activity. The alkaloids displayed inhibitory activity against both Gram positive and Gram negative bacteria. Cytotoxicity bioassays using the MTT method showed that these compounds present cytotoxic activity against human HL-60 (leukemia), L929 (fibrosarcoma), B16 (melanoma) and U138 (colon) cancer cell lines at concentrations between 1.5 and 7.0microg/ml. The results obtained indicated that A. brasiliensis alkaloids have a potent toxic activity. The broad cytotoxic and antimicrobial activities presented by A. brasiliensis alkaloids suggest a defensive role of arenosclerins and haliclonacyclamine E against microbial infection and/or the action of potential predators at the sponge's natural habitat.     

Effect of substituents on benzenesulfonyl motif of 4-phenyl-1-arylsulfonylimidazolidinones for their cytotoxicity

To explore the effect of substituents' on phenyl motif on sulfonyl function of novel anticancer 4-phenyl-1-benzenesulfonylimidazolidinones (1), electron donating or withdrawing substituents were introduced at 3 or 4-position and the analogs were tested against human lung (A549) and colon (HCT-15) cancer cell lines. Quantitative structure activity relationship of the 4-substituted series shows that only STERIMOL L values are well correlated. The increment of substituent's volume enhances the activity against both cell lines. The small substituent at 3-position additionally increases the activity. However naphthyl group in place of phenyl reduces the activity. Therefore the phenyl motif with sterically large substituent at 4-position and small substituent at 3-position may be important for their activity. Integration of these substituents' effects into the structural design led to discover the more potent analog, 4-phenyl-1-(N-acetylindoline-5-sulfonyl) imidazolidinone (1n).     

Biological Evaluation of Isoniazid Derivatives as an Anticancer Class

A series of thirty-two isoniazid derivatives have been evaluated for their activity against four human cancer cell lines with potent cytotoxicity (IC50 ranging from 0.61 to 3.36 μg/mL). The structure-activity relationship (SAR) analysis indicated the number, the positions, and the types of substituents attached to the aromatic ring as being critical factors for the biological activity. Briefly, we observed that the presence of a hydroxyl group on the benzene ring plays an important role in the anticancer activity of this series, especially when it is located in ortho-position. Among the thirty-two compounds, three displayed good cytotoxic activity when compared to the reference drug doxorubicin and are thus being considered leading compounds of this new class.     

Synthesis,Analysis and Biological Evaluation of Novel Steroidal Estrogenic Prodrugs for the Treatment of Breast Cancer

Breast cancer is the most prevalent type of cancer in pre- and postmenopausal women in most Western countries. In the treatment of metastatic breast cancer, doxorubicin has the broadest spectrum of antitumor activity of any drug currently available but produces a dose-dependent cardiomyopathy that limits its clinical usefulness. The aim of this research project was to target the affected tissues, which contain estrogen receptors (ERs). Initially, a series of estrogen derivatives with side chains linked at the 3- and 17-positions of estrone were synthesized, and then novel anticancer prodrugs were obtained from these by further linking these compounds to doxorubicin by means of various alkyl spacer groups. These estrogenic prodrugs were designed to target tumor cells containing ERs, found in human breast cancer cells, and to release the active anticancer moiety when internalized. The estrogenic prodrugs were then biologically evaluated using in vitro chemosensitivity assays against human ER-positive (MCF-7) and ER-negative (MCF-7ADR and MT-1) breast tumor cells and a leukemia (K562) cell line. The results showed that estrone derivatives with substituted amino-alcohol side chains of various lengths (2-6 carbons) linked to the 17-position of estrone were mostly inactive. Estrone-doxorubicin prodrugs containing doxorubicin at the 3-position of estrone (CCRL 1042 and CCRL 1036) were relatively inactive and nonselective against all cell lines tested. However, when doxorubicin was linked to the 17-position of estrone, these prodrugs had at least an order greater activity than their 3-linked counterparts. Using a short aminoxy-spacer group (2 carbons) at this position produced CCRL 1035, which had a lower activity against all cell lines tested compared to doxorubicin. In contrast, the prodrug incorporating doxorubicin at the 17-position of estrone via a long spacer group (12 carbons, CCRL 1033) was both potent and selective against ER-positive cells MCF-7. These studies have shown that linking doxorubicin to the 17-position of estrone via a long alkyl spacer group conferred selectivity of cytotoxic action against ER-positive breast cancer tumor cells.     

Synthesis and Biological Evaluation of Some Novel Polysubstituted Pyrimidine Derivatives as Potential Antimicrobial and Anticancer Agents

Synthesis and evaluation of the antimicrobial and cytotoxic activity of two series of polysubstituted pyrimidines comprising the thioether functionality and other pharmacophores, reported to contribute to various chemotherapeutic activities are described. All newly synthesized compounds were subjected to in‐vitro antibacterial and antifungal screening. Out of the compounds tested, 18 derivatives displayed an obvious inhibitory effect on the growth of the tested Gram‐positive and Gram‐negative bacterial strains, with special effectiveness against the Gram‐positive strains. Compounds 1 , 2 , 6 , 7 , 9 , 10 , 11 , 21 , and 24 revealed remarkable broad antibacterial spectrum profiles. Among those, compounds 1 , 2 , 6 , 7 , 9 , and 24 exhibited an appreciable antifungal activity against C. albicans. Compound 2 proved to be the most active antimicrobial member identified here as it showed twice the activity of ampicillin against B. subtilis and the same activity of ampicillin against M. Luteus and P. aeruginosa together with a moderate antifungal activity. Further, eleven analogs were evaluated for their in‐vitro cytotoxic potential utilizing the standard MTT assay against a panel of three human cell lines: breast adenocarcinoma MCF7, hepatocellular carcinoma HePG2, and colon carcinoma HT29. The obtained data revealed that six of the tested compounds 1 , 3 , 7 , 12 , 13 , and 15 showed a variable degree of cytotoxic activity against the tested cell lines at both the LC₅₀ and LC₉₀ levels. Compound 7 proved to be the most active cytotoxic member in this study with special effectiveness against the colon carcinoma HT29 and breast cancer MCF7 human cell lines for LC₅₀ and LC₉₀. Thus, compounds 1 and 7 could be considered as possible dual antimicrobial‐anticancer agents.     

Antitumor activity of C-methyl-beta-D-ribofuranosyladenine nucleoside ribonucleotide reductase inhibitors

A series of adenosine derivatives substituted at the 1'-, 2'-, or 3'-position of the ribose ring with a methyl group was synthesized and evaluated for antitumor activity. From this study 3'-C-methyladenosine (3'-Me-Ado) emerged as the most active compound, showing activity against human myelogenous leukemia K562, multidrug resistant human leukemia K562IU, human promyelocytic leukemia HL-60, human colon carcinoma HT-29, and human breast carcinoma MCF-7 cell lines with IC(50) values ranging from 11 to 38 muM. Structure-activity relationship studies showed that the structure of 3'-Me-Ado is crucial for the activity. Substitution of a hydrogen atom of the N(6)-amino group with a small alkyl or cycloalkyl group, the introduction of a chlorine atom in the 2-position of the purine ring, or the moving of the methyl group from the 3'-position to other ribose positions brought about a decrease or loss of antitumor activity. The antiproliferative activity of 3'-Me-Ado appears to be related to its ability to deplete both intracellular purine and pyrimidine deoxynucleotides through ribonucleotide reductase inhibition.     

Synthesis and Biological Evaluation of Novel Pyrazoles and Pyrazolo[3,4‐d]pyrimidines Incorporating a Benzenesulfonamide Moiety

Synthesis and biological evaluation of novel pyrazoles and pyrazolo[3,4‐d]pyrimidines are reported. Fourteen compounds were selected by the NCI and tested for their preliminary in‐vitro anticancer activity, whereas all the synthesized compounds were evaluated for their in‐vitro antimicrobial activity. Compound 12a was proven to possess the highest anticancer activity with a broad spectrum profile. It showed particular effectiveness towards leukemia HL‐60 (TB), K‐562, non‐small cell lung cancer NCI‐H23, and colon cancer HT 29, KM 12 cell lines (GI₅₀ = 6.59, 4.44, 1.37, 3.33, and 9.63 μM, respectively). Out of the synthesized compounds, thirteen derivatives were found to display pronounced antimicrobial activity especially against P. aeruginosa. Compounds 2c , 5b , 10 , 11b , 17b , 18b , and 19 were proven to be the most active with a broad spectrum of activity. Compound 19 was found to be equipotent to ampicillin against B. subtilis, whereas compounds 11b and 19 were four times superior to ampicillin against P. aeruginosa, while compounds 5b and 18b were equipotent to ampicillin against the same organism. Moreover, compounds 2c , 10 , and 11b were nearly equipotent to ampicillin against E. coli. On the other hand, compounds 2c , 5b , 10 , 11a , 17b , and 18b exerted nearly half the activity of clotrimazole against C. albicans.     

6-取代胺基嘌呤衍生物的制备及抗菌活性研究

鸟嘌呤经酰化、氯化并水解得2-氨基-6-氯嘌呤,与苄硫醇反应所得2-氨基-6-苯甲硫基嘌呤,再与取代胺反应制得6-取代胺摹嘌呤衍生物1a～1d.体外抗菌活性试验结果表明,1a～1d对稻草芽孢杆菌抗菌活性较好,1b、1c和1d对黑曲酶抗菌活性较好,1c和1d对热带假丝酵母抗菌活性较好.     

聚乙烯亚胺单独及与三种抗菌药物联用对白念珠菌的体外抗菌活性

目的评估多支链的阳离子高分子聚合物——聚乙烯亚胺(PEI)单独及与三种不同类别的常规抗菌药物(两性霉素B、氟康唑和多黏菌素B)联合使用对白念珠菌(MY7245和MY7238)的两种临床分离物的抗真菌活性。方法通过体外实验测定不同分子质量聚乙烯亚胺单独及与三种不同类别的常规抗菌药物联合使用对两株白念珠菌的最小抑菌浓度和杀灭时间,确定PEI单独及联合使用的体外抗真菌活性。结果分子量在2～745ku范围内的PEI均对这两种白念珠菌产生很好的抗真菌活性,且分子量小的PEI比分子量大的PEI的抗菌作用更显著。与单独作用的PEI相比,分子量较大的PEI与常规药物联合使用时可产生较强的协同作用。在体外致死研究实验中可以看到,PEI-两性霉素B和PEI-氟康唑结合物可以提高抑菌作用,但PEI-多黏菌素B结合物却拮抗抑菌作用。结论PEI单独与联合使用均对白念珠菌产生很好的抗菌效果。     

Synthesis, antimicrobial and antineoplastic activities for agelasine and agelasimine analogs with a beta-cyclocitral derived substituent

Agelasines and agelasimines are antimicrobial and cytotoxic purine derivatives isolated from marine sponges (Agelas sp.). We have synthesized structurally simplified analogs of these natural products starting from beta-cyclocitral. The novel compounds were found to be strong inhibitors of a wide variety of pathogenic microorganisms (incl. Mycobacterium tuberculosis) as well as cancer cell lines. The biological activities were generally in the same range as those previously found for the structurally more complex agelasines and agelasimines isolated in small amounts from natural sources. We also report for the first time that agelasine and agelasimine analogs inhibit growth of protozoa (Acanthamoeba castellanii and Acanthamoeba polyphaga). Acanthamoeba keratitis is an increasingly common and severe corneal infection, closely associated with contact lens wear.     

Synthesis and microbiological activity of some N-(2-hydroxy-4-substitutedphenyl)benzamides,phenylacetamides and furamides as the possible metabolites of antimicrobial active benzoxazoles

The synthesis of some N-(2-hydroxy-4-substitutedphenyl)benzamides, phenylacetamides and furamides as the possible metabolites of benzoxazoles (II1-15) was performed in order to determine their in vitro antimicrobial activity against three Gram-positive bacteria, two Gram-negative bacteria and the fungus Candida albicans and their activities were compared with several control drugs. The compounds II11, II12, and II13 were found active at a MIC value of 12.5 microg/ml against the Gram-negative microorganism Pseudomonas aeruginosa. Most of the compounds show antibacterial activity at MIC a value of 25 microg/ml against the Gram-positive bacteria Staphylococcus aureus. For the antifungal activity against C. albicans, compound II10 was found more active than the other derivatives. The antimicrobial activity of some of these benzamides, phenylacetamides (II1 and II10) which are the possible metabolites of benzoxazoles, was also compared to their corresponding cyclic analogues III-IV. Compound II10 possesses two dilutions better antifungal activity than its cyclic analogue, benzoxazole IV, against C. albicans.     

Cytotoxicity and Antimicrobial Activity of Some Naphthol Derivatives

2-Hydroxymethyl-1-naphthol diacetate (TAC) and sixteen Mannich base derivatives of naphthol were prepared and examined for cytotoxicity and antimicrobial activity. Cytotoxicity was examined against four human carcinoma cell lines. Several derivatives were effective at concentrations < 4 μg/ml. TAC showed the highest cytotoxicity. Inhibition of DNA-, RNA-, and protein synthesis by TAC was also studied and discussed. TAC also exhibits potent antimicrobial activity against Enterobacter clocae 23355, Klebsiella pneumonia 13883, Proteus vulgaris 13315, Pseudomonas aeruginosa 27853, Candida parapsilosis, Candida tropicalis, Trichosposon beigelli, and Rhodotorul spp. with minimum inhibitory concentrations of 0.1 ∼ 0.4 μM. These results indicate that esterification by Bruson reaction of 1-naphthol Mannich base to TAC enhances the cytotoxicity and antimicrobial activity.     

Synthesis, biological activity, and SAR of antimycobacterial 9-aryl-, 9-arylsulfonyl-, and 9-benzyl-6-(2-furyl)purines

9-Aryl-, 9-arylsulfonyl- and 9-benzyl-6-(2-furyl)purines were synthesized by N-alkylation or N-arylation of the purine followed by Stille coupling to introduce the furyl substituent in the 6-position and the compounds screened for activity against Mycobacterium tuberculosis. The 9-aryl- and 9-sulfonylarylpurines exhibited weak activity toward the bacteria, but 9-benzylpurines were good inhibitors especially those carrying electron-donating substituents on the phenyl ring. A chlorine atom in the purine 2-position further enhanced activity. The high antimycobacterial activity (MIC 0.39 microg/mL against M. tuberculosis), low toxicity against mammalian cells and activity inside macrophages found for 2-chloro-6-(2-furyl)-9-(4-methoxyphenylmethyl)-9H-purine makes this compound a highly interesting potential antituberculosis drug.     

Synthesis of new 3-(substituted phenacyl)-5-[3'-(4H-4-oxo-1-benzopyran-2-yl)-benzylidene]-2,4-thiazolidinediones and their antimicrobial activity

Synthesis of 3-(3-nitrophenacyl)thiazolidine-2,4-dione 2g and 3-(substituted phenacyl)-5-[3'-(4H-4-oxo-1-benzopyran-2-yl)-benzylidene]-2,4-thiazolidinediones 4a-g are reported in this paper. These compounds 4a-g were prepared from 3'-flavone carboxaldehyde and 3-substituted phenacyl-2,4-thiazolidinediones using Knoevenagel reaction. The structures of all compounds were confirmed by IR, 1H-NMR, mass spectral data, and elemental analyses. The molecules 4a-g were evaluated for in-vitro antimicrobial activity against Staphylococcus aureus, Candida albicans, Candida krusei, Candida glabrata, and Candida parapsilosis. Compounds 4c and 4f showed better inhibitory activity when compared to fluconazole against Candida krusei and Candida glabrata.