New 6-nitroquinolones: synthesis and antimicrobial activities

Pursuing our searches on quinolonecarboxylic acids we used a simple three-step one pot procedure to synthesize novel 1,7-disubstituted-6-nitroquinolones. The new derivatives were tested against Mycobacterium tuberculosis and Mycobacterium avium complex (MAC) as well as against both gram-positive and gram-negative bacteria. In vitro assays showed some derivatives were endowed with good inhibiting activities against tested mycobacteria. Some derivatives were also found more potent than ciprofloxacin and ofloxacin (used as reference drugs) against gram-positive bacteria.     

7-Hydroxy-coumarin derivatives: synthesis, characterization and preliminary antimicrobial activities

A new series of 7-O-coumarinyl alkenoates were synthesized from 7-hydroxyl-coumarin and fatty acids using DCC and DMAP as catalyst. The synthesized compounds were characterized on the basis of their spectral data. All the target compounds were evaluated for their in vitro antimicrobial activity against Bacillus subtilis, Staphylococcus aureus, Streptococcus pyogene, Pseudomonas aeruginosa, Salmonella typhimurium, Escherichia coli and fungal cultures of Candida albicans, Candida krusei, Candida parapsilosis and Cryptococcus neoformans. The minimum inhibitory concentration (MIC) was determined for the test compounds as well as for reference standards. Among the tested compounds, 7-O-coumarinyl (9Z, 12R)-12-hydroxyoctadec-9-enoate and 7-O-coumarinyl (12Z, 9R)-9-hydroxyoctadec-12-enoate showed the most potent antifungal as well as antibacterial activities.     

Synthesis of halogenated derivatives of thymol and their antimicrobial activities

In order to test the antibacterial and antifungal activities of different halogenated thymol derivatives, thymol has been converted into chlorothymol, dichlorothymol with N-chlorosuccinimide; monobromothymol, dibromothymol with N-bromosuccinimide; O-methylated iodothymol with ceric ammonium nitrate and iodine from methylated thymol. Among the different derivatives tested, 4-chlorothymol was found to be most active against Staphylococcus aureus and Staphylococcus epidermis at a concentration of 12.5 and 25 ppm, respectively. Also it was tested to be active against Candida albicans (AI).     

Conventional and microwave-assisted synthesis of imidazole and guanidine derivatives and their biological evaluation

A number of imidazole derivatives 3a–f and 4a–f have been synthesized by the condensation of 3-methylthiophen-2-carboxaldehyde 1a, 5-methylthiophen-2-carboxaldehyde 1b, N-methylpyrrol-2-carboxaldehyde 1c, 1-naphthaldehyde 1d, 2-naphthaldehyde 1e, and 2-hydroxy-1-naphthaldehyde 1f with 1,2-diaminoanthraquinone 2a and 2,3-diaminophenazine 2b, respectively. Condensation of 2-guanidinobenzimidazole with functionalized aldehydes 1a–f leads to the formation of guanidine derivatives 5a–f. Both imidazole (3a–f, 4a–f) and guanidine derivatives (5a–f) were synthesized in good yields using conventional heating and microwave irradiation techniques. Structures assigned to compounds 3a–f, 4a–f and 5a–f are supported by correct spectral and analytic data. On screening for anti-inflammatory and anticancer activities, compounds 3e, 4a and 5a exhibited good anti-inflammatory and compounds 3d, 3f, 4d and 4f showed very good anticancer activity.     

Evaluation of antimicrobial activities of several mannich bases and their derivatives

The aim of this study was to evaluate the antimicrobial activities of several Mannich bases and their derivatives against pathogenic bacteria and fungi. 3-Dimethylamino-1-phenyl-1-propanone hydrochloride (Ig1) as mono-Mannich base, bis(beta-aroylethyl)methylamine hydrochlorides (B1, B5) as bis-Mannich bases, 3-aroyl-4-aryl-1-methyl-4-piperidinol hydrochlorides (C1, C5) as piperidinol derivatives, which are structural isomers of bis-Mannich bases, N,N'-Bis(3-dimethylamino-1-phenylpropylidene)hydra zine dihydrochlorides (D1) as azine derivative of mono-Mannich base Ig1, and some representative quaternary derivatives (Ig4 and C6), which are quaternary derivatives of Ig1 and C1, respectively, have been synthesized. Aryl parts were phenyl in B1 and C1, and 2-thienyl in B5 and C5. Bis-Mannich bases and quaternary Mannich bases were found to be effective antifungal derivatives. Quaternary mono-Mannich base Ig4 has shown twice the amount of higher antifungal potency against the human pathogenic fungus Microsporum canis compared with the reference drug amphotericin-B and it had equal potency against many other fungi species pathogenic in humans and plants. Ig4 was effective against Staphylococcus aureus among the bacteria tested. Preparation of bis-Mannich bases and qua ternization procedure seemed suitable chemical modifications to prepare effective antifungal compounds. Especially quaternary derivatives Ig4, and to some extent C6, seem to be model compounds to develop new antimicrobial agents for further studies.     

Synthesis of some triazolophthalazine derivatives for their anti-inflammatory and antimicrobial activities

Several novel series of triazolophthalazine derivatives namely; pyrazolylethenyltriazolophthalazinones (4a-d), styryltriazolophthalazinones (5a,b), aryloxopropenyltriazolophthalazinones (7a,b), pyrazolinyl- (8a,b), (9a,b) and (10a-f), pyrazolyl- (11a-d), (1,2-oxazol-5-yl)-1,2,4-triazolo[3,4-a]phthalazin-6(5H)-ones (14a,b), triazolo[3,4-a]phthalazin-3-yl-pyridine-3-carbonitriles (12a,b), triazolo[3,4-a]phthalazin-3-yl)ethylthioacetic acids (13a,b) and 2-aryl-5-arylamino-1H,5H-pyrazolo[2″,3″-1',5']imidazo[3',4'-1,5]-1,2,4-triazolo[3,4-a]phthalazin-12(13H)-ones (15a-c) have been synthesized. The anti-inflammatory activity of representative compounds has been studied. Compounds 8b, 10c, 10f, 11b, 12a, 13b, and 15a showed anti-inflammatory activities comparable to that of the reference standard, indomethacin. They exhibit also minimal ulcerogenic effect relevant to the reference standard and were found to be non-toxic up to 120 mg/kg orally or up to 75 mg/kg through parenteral route. Concerning the antimicrobial activity; compounds 12b and 13b were found to be equipotent to ampicillin against Staphylococcus aureus, while compounds 10a and 10f were found to be as potent as ampicillin against E. coli, whereas compound 14b exhibited equipotency to clotrimazole against Candida albicans. Compounds 8b, 10f, 11b, 12a, and 13b exhibited, besides their antimicrobial activity, moderate to potent anti-inflammatory profiles. This represents a fruitful matrix for the development of a new class of dual non-acidic anti-inflammatory/antimicrobial agents.     

New synthesis of 2-substituted imidazo[2,1-b]thiazoles and their antimicrobial activities

4,5-Diphenyl-2-mercaptoimidazole (I) was reacted with hydrazidoyl halides IIa?d to give the S-alkyl derivatives IIIa?d. Cyclization of IIIa?d afforded imidazo[2, 1?b]-thiazole derivatives VIa,b and VII. Treatment of I with α-chloroethylacetoacetate (IV) gave ethyl 2-(4,5-diphenyl-2-imidazolinylthio)-3-keto-butyrate (V). Compound V coupled with benzenediazonium chloride to give the corresponding phenylhydrazo compound IIId. On heating V with polyphosphoric acid, cyclization took place and 2-acetyl-5,6-diphenyl-imidazo[2, 1?b]thiazol-3-one (VIII) was obtained. The compound VIII was condensed with aromatic aldehydes to yield the cinnamoyl derivatives IXa,b. The antimicrobial activities of compounds IIIa?d, V, VIa, VII were examined.     

喹喔啉衍生物的设计合成及抗肿瘤活性研究

目的设计和合成新型喹喔啉类抗肿瘤药物。方法以4-氯-2-硝基苯胺为起始原料经取代、还原关环、氧化、和氯代合成了中间体2，7-二氯喹喔啉(7)，再在喹喔啉的2位引入不同的取代酚结构单元，合成了一系列共9个新喹喔啉衍生物。结果目标产物利用¹H NMR,MS和IR进行结构确认。结论初步体外抗肿瘤活性测试表明，在1×10^-4 mol·L^-1浓度时，部分目标化合物的抗肿瘤活性和XK469相当。     

Microwave-assisted synthesis of novel 1,2,3-triazole derivatives and their antimicrobial activity

An environmentally benign and economic synthesis of 1-[7-(1-benzyl-1H-[1,2,3]triazol-4-ylmethoxy)-2,2-dimethyl-chroman-6-yl]-3-aryl-2-propen-1-ones and 1-[5-(1-benzyl-1H-[1,2,3]triazol-4-ylmethoxy)-2,2-dimethyl-chroman-6-yl]-3-aryl-propen-1-ones is described. The procedure takes place by the 1,3-dipolar cycloaddition (‘‘click-reaction’’) between azides and alkynes catalysed by copper (I) salts. The simplicity of this reaction and the ease of formation and purification of the resulting products have opened new opportunities in generating vast arrays of compounds with biological potential. The structures of the synthesized compounds have been established on the basis of physical and spectral data. All the synthesized compounds were tested in vitro for their antibacterial and antifungal activities. Compounds 8a (R₁=H, R₂=H, R₃=H), 8b (R₁=H, R₂=CH₃, R₃=H), 8d (R₁=OCH₃, R₂=OCH₃, R₃=H), 8e (R₁=OCH₃, R₂=OCH₃, R₃=OCH₃), 13a (R₁=H, R₂=H, R₃=H), 13d (R₁=OCH₃, R₂=OCH₃, R₃=H) and 13e (R₁=OCH₃, R₂=OCH₃, R₃=OCH₃) showed significant antimicrobial properties.     

Novel quinazolinone derivatives: synthesis and antimicrobial activity

4-(4-Oxo-4H-3,1-benzoxazin-2-yl)phenyl-4-methylbenzenesulfonate (2) was prepared and reacted with some primary aromatic amines, e.g., aniline, p-chloro aniline, p-methoxy aniline, p-amino benzoic acid and p-amino acetophenone. It reacted also with some heterocyclic amines, e.g., 2-aminothiazole, 2-aminobenzothiazole, 5-amino-4-phenylazo-2,4-dihydropyrazol-3-one and 3-amino-2-methylquinazolinone and with diamines; e.g., o-phenylenediamine, p-phenylenediamine, ethylenediamine, semicarbazide hydrochloride and thiosemicarbazide under different conditions. On the other hand, compound (2) reacted with both sodium azide and active methylene compounds, e.g., ethylcyanoacetate and ethylacetoacetate to give (19) and (20), respectively. All new prepared compounds were subjected to antimicrobial activity evaluation.     

Design and synthesis of new tetrandrine derivatives and their antitumor activities

A series of tetrandrine derivatives were designed and synthesized using Suzuki coupling reaction. Eleven targeted compounds with over 50% inhibition against HL60 and A549 human cancer cell lines at 10 μM were further evaluated for the in vitro antitumor activities by MTT or SRB assay. The biological results revealed that some compounds exhibited potent antitumor activities. Thiophene derivative 6 and acetylphenyl derivative 5 were the most active ones against HL60 and A549 cell lines, with IC₅₀ values less than 5 μM, which thus could be considered as useful candidate for further development of new antitumor agents.     

芳烷酮哌嗪衍生物的设计合成及镇痛活性

以中枢兴奋性氨基酸NMDA受体多胺调节位点为靶点，设计合成芳烷酮哌嗪类全新化合物并研究它们的镇痛活性。哌嗪经甲酰基保护后，与相应的卤代芳烃进行烷基化反应，制备目标化合物。以小鼠扭体法、大鼠热板法、大鼠光热甩尾法等动物体内镇痛模型测试目标化合物的镇痛活性。共合成64个未见文献报道的新化合物，其结构经质谱、核磁共振谱及元素分析确证。镇痛药理试验显示：该类化合物具有较好的镇痛作用及作为新型非阿片类镇痛药开发的潜在价值。化合物I₁₂，I₁₄，I₂₁和I₃₇在三种镇痛模型上均显示很强的镇痛活性，具有深入研究的价值。     

Comparative study of conventional and microwave-assisted synthesis of some Schiff bases and their potential as antimicrobial agents

A series of Schiff bases (compounds 1–10) were synthesized by condensing heterocyclic/aromatic aldehydes with heterocyclic/aromatic amines through both, conventional method and microwave-assisted synthesis. The compounds were confirmed by means of IR spectroscopy, Mass spectrometry, ¹H NMR and elemental analyses. The compounds were assayed for antibacterial activity against selected strains of Gram positive, Gram negative bacteria and some fungi by zone inhibition method. Minimum inhibitory concentration (MIC) was also determined for each compound. Reaction times were drastically reduced by microwave-assisted synthesis. MIC was as low as 50 μg/ml exhibited by compounds 2 (against Escherichia coli, Aspergillus niger and Penicillium chrysogenum) and 10 (against Bacillus subtilis). The study presents a series of potential antimicrobial agents through efficient and simple reactions and mild reaction conditions, thereby offering a green chemistry approach.     

Antiviral and antimicrobial activities of new nitrobutane derivatives

It is known that some addition products of beta-nitrostyrenes exhibit potent antimicrobial activity. In order to investigate the effects of structural modifications on the biological properties, some new Michael type addition products of beta-ethyl-beta-nitrostyrenes were synthesized. In this study, eight new 1-[(2-aminophenyl)thio]-1-phenyl-2-nitrobutane (2) derivatives were synthesized by addition of 2-aminothiophenol to the double bond of beta-ethyl-beta-nitrostyrenes (1). The chemical structures were proved by IR and 1H-NMR data and by elemental analysis. Antimicrobial activities of the synthesized compound were investigated against Escherichia coil, Pseudomonas aeruginosa, Proteus mirabilis, Enterococcus faecalis, Bacillus subtilis, Staphylococcus aureus, Candida albicans by the microdilution method. In addition, the newly synthesized compounds were studied for antiviral activities. All of them were found to be almost 100 fold more active than the standard compound aciclovir (CAS 59277-89-3).     

Antioxidant and antimicrobial activities of cinnamic acid derivatives

Cinnamic acid is an organic acid occurring naturally in plants that has low toxicity and a broad spectrum of biological activities. In the search for novel pharmacologically active compounds, cinnamic acid derivatives are important and promising compounds with high potential for development into drugs. Many cinnamic acid derivatives, especially those with the phenolic hydroxyl group, are well-known antioxidants and are supposed to have several health benefits due to their strong free radical scavenging properties. It is also well known that cinnamic acid has antimicrobial activity. Cinnamic acid derivatives, both isolated from plant material and synthesized, have been reported to have antibacterial, antiviral and antifungal properties. Acids, esters, amides, hydrazides and related derivatives of cinnamic acid with such activities are here reviewed.     

Synthesis of 1-benzhydryl piperazine derivatives and evaluation of their ACE inhibition and antimicrobial activities

This study presents the synthesis of 14 new 1,4-disubstituted piperazine derivatives from allyl bromides of Baylis–Hillman adduct and 4,4-disubstituted benzhydryl piperazines. All the synthesized compounds were further screened for in vitro ACE inhibitor and antimicrobial activities. Among the synthesized piperazine derivatives, compound 12h showed moderate ACE inhibitor activity as compared to the standard, angiotensin-converting enzyme inhibitor (Sigma). The kinetic data (K _m, K _i and V _max values) of enzyme inhibition for compound 12h and ACE inhibitor standard were also determined. Similarly, all compounds were screened against different bacterial strains. Compounds 12a, 12b, 12d, 12h and 12i showed excellent to moderate activity against various tested bacterial strains. Compounds 12b and 12i showed broad spectrum of antibacterial activity against Pseudomonas aeruginosa, Staphylococcus aureus, S. aureus MLS 16, Escherichia coli, Bacillus subtilis and Klebsiella planticola, while compounds 12a, 12d and 12i showed promising activity against P. aeruginosa (MIC value of 8.96 μM), S. aureus (MIC value of 42.2 μM) and S. aureus MLS 16 (MIC value of 81.3 μM), respectively. The remaining compounds showed activity at a concentration of >491 μM.