Synthesis and in vitro Antimycobacterial Activity of Moxifloxacin Methylene and Ethylene Isatin Derivatives

A series of novel moxifloxacin methylene and ethylene isatin derivatives with remarkable improvement in lipophilicity, compared to the parent moxifloxacin, was designed, synthesized and characterized by 1H NMR, MS and HRMS. These derivatives were initially evaluated for their in vitro antimycobacterial activity against M. smegmatis CMCC 93202. Compounds 3a―3f, 5a, 5f and 5j were chosen for the further evaluation of their in vitro activity against Mycobacterium tuberculosis(MTB) H37Rv ATCC 27294 and MDR-MTB 09710. All the target compounds[ minimum inhibitory concentration(MIC): 0.39―>16 μg/mL] were far more active than rifampin(MIC: 2.0―>256 μg/mL), but less active than moxifloxacin(MIC: 0.1―1.0 μg/mL) against the three tested strains. The most active compounds 3a and 3c were found to be 2―64 fold more potent than isoniazid and rifampin against M. smegmatis CMCC 93202, 2 fold more potent than rifampin against MTB H37Rv ATCC 27294, and 16―>64 fold more potent than ethambutol, isoniazid and rifampin against MDR-MTB 09710.     

分散固相萃取净化-超高效液相色谱-串联质谱法测定鸡蛋和鸡肉中金刚烷胺和金刚乙胺残留

建立了鸡蛋和鸡肉中金刚烷胺和金刚乙胺残留量的分散固相萃取-超高效液相色谱-串联质谱测定方法。鸡蛋和鸡肉样品经氨水-乙腈(2 : 98, v/v)提取后,提取液经氮气吹干至1 mL后,利用C18和NH₂填料进行分散固相萃取净化,过滤膜后分析。采用ZORBAX C18色谱柱分离,用1 mmol/L乙酸铵水溶液(含0.1%(v/v)甲酸)-甲醇作为流动相进行梯度洗脱,正离子多反应监测模式。结果表明,金刚烷胺和金刚乙胺在0.15~10.0 μ g/L范围内具有较好的线性关系,鸡蛋和鸡肉中的检出限均为0.05 μ g/kg,定量限均为0.20 μ g/kg。当2种药物在鸡蛋和鸡肉中的加标水平为0.2、1.0和2.0 μ g/kg时,平均回收率范围为89%~108%,相对标准偏差范围为5.0%~8.6%。该方法能够满足鸡蛋和鸡肉中金刚烷胺和金刚乙胺残留量分析的要求。     

Discovery of potential M2 channel inhibitors based on the amantadine scaffold via virtual screening and pharmacophore modeling

The M2 channel protein on the influenza A virus membrane has become the main target of the anti-flu drugs amantadine and rimantadine. The structure of the M2 channel proteins of the H3N2 (PDB code 2RLF) and 2009-H1N1 (Genbank accession number GQ385383) viruses may help researchers to solve the drug-resistant problem of these two adamantane-based drugs and develop more powerful new drugs against influenza A virus. In the present study, we searched for new M2 channel inhibitors through a combination of different computational methodologies, including virtual screening with docking and pharmacophore modeling. Virtual screening was performed to calculate the free energies of binding between receptor M2 channel proteins and 200 new designed ligands. After that, pharmacophore analysis was used to identify the important M2 protein-inhibitor interactions and common features of top binding compounds with M2 channel proteins. Finally, the two most potential compounds were determined as novel leads to inhibit M2 channel proteins in both H3N2 and 2009-H1N1 influenza A virus.     

一枝蒿酮酸酰胺衍生物的合成和抗A3, B型流感病毒和 单纯I, II型疱疹病毒活性研究

从新疆一枝蒿中分离得到了单体化合物一枝蒿酮酸, 然后以一枝蒿酮酸和有机胺为原料, 在偶联剂DCC, HOBt/DMAP的作用下, 合成了13种未见文献报道的一枝蒿酮酸酰胺衍生物2a～2m. 所合成的化合物经过IR, 1H NMR, ESI-MS等分析方法进行了表征, 并对化合物2a～2m进行初步的体外抗A3, B型流感病毒和单纯I, II型疱疹病毒活性研究. 初步试验结果表明化合物2a同时具有抗A3, B型流感病毒活性, 而且抗B型流感病毒活性比母体化合物的活性较高. 化合物2d的抗B型流感病毒活性比母体化合物高16倍, 化合物2e同时具有较强的抗单纯I, II型疱疹病毒活性.     

Understanding the Fragmentation Pathways of Carbocyclic Derivatives of Amino Acids by Using Electrospray Ionization Tandem Mass Spectrometry

Aminoacyl derivatives of aminoadamantanes amantadine and rimantadine have been investigated in regard to their antiviral properties. So far, few studies on the mass spectrometric fragmentation pathway of these compounds have been reported using high-resolution mass spectrometry (HRMS). Two major fragmentation pathways have been observed. For the rimantadine derivatives, losses of rimantadine and N-(1-adamantyl) ethylformamide were described. Similarly, in case of amantadine derivatives, there were losses of amantadine and N-(1-adamantyl) formamide. The loss of the aminoacyl group was common to all of the studied compounds. Understanding the fragmentation mechanism can bring new insight into the characterization of these compounds.     

Simultaneous liquid chromatographic assay of amantadine and its four related compounds in phosphate-buffered saline using 4-fluoro-7-nitro-2,1,3-benzoxadiazole as a fluorescent derivatization reagent

Simultaneous HPLC assay of 1-adamantanamine hydrochloride (amantadine) and its four related compounds [2-adamantanamine hydrochloride (2-ADA), 1-adamantanmethylamine (ADAMA), 1-(1-adamantyl)ethylamine hydrochloride (rimantadine) and 3,5-dimethyl-1-adamantanamine hydrochloride (memantine)] in phosphate-buffered saline (pH 7.4) after pre-column derivatization with 4-fluoro-7-nitro-2,1,3-benzoxadiazole (NBD-F) was developed. Phosphate-buffered saline samples were mixed with borate buffer and NBD-F solution in acetonitrile at 60 degrees C for 5 min and injected into HPLC. Five derivatives were well separated from each other. The lower limits of detection of amantadine, 2-ADA, ADAMA, rimantadine and memantine were 0.008, 0.001, 0.0008, 0.0015 and 0.01 microg/mL, respectively. The coefficients of variation for intra- and inter-day assay were less than 6.4 and 8.2%, respectively. The method presented was applied to a binding study of these compounds to human alpha(1)-acid glycoprotein. While affinity constants and capacities for ADAMA, rimantadine and memantine were calculated by means of Scatchard plots, those for the others were not determined. ADAMA, rimantadine and memantine were bound with different affinities and capacities. These results indicate that NBD-F is a good candidate as a fluorescent reagent to simultaneously determine amantadine and its four related compounds by HPLC after pre-column derivatization. Our method can be applied to binding studies for protein.     

New bronchodilators. II. 3H-imidazo[4,5-c]quinolin-4(5H)-ones.

A series of novel 3-substituted imidazo[4,5-c]quinolin-4(5H)-ones (2a-w) was prepared by the reaction of imidazo[4,5-c]quinolin-4(5H)-ones (6) with several electrophiles under basic conditions. The bronchodilatory activity of these compounds was evaluated on the basis of their protective effects against antigen-induced contraction (the Schultz-Dale reaction) of guinea-pig trachea (in vitro) and antigen inhalation-induced bronchospasm in passively sensitized guinea-pigs (in vivo). Although correlations between in vitro and in vivo activities were not clear, short alkyl chains such as the methyl and ethyl groups at the 3-position were important for potent activity, especially in vivo. Substituents at the 5-position were more tolerant of the activity than those at the 3-position. 5-Ethyl-3-methyl-3H-imidazo[4,5-c]quinolin-4(5H)-one (21) exhibits the most potent bronchodilatory activity among our tested compounds and is at least 5-fold more active than theophylline in vivo.     

Design, synthesis and cytotoxicity of novel 2-arylvinyl-4-aminoquinoline derivatives

With an aim to develop promising anti-tumor agents, a novel series of 2-arylvinyl-4-aminoquinoline derivatives were designed, synthesized and evaluated for their cytotoxicity against H-460, HT-29, HepG2 and SGC-7901 cell lines in vitro. The pharmacological results indicated that most compounds were more potent than the positive controls, especially compounds 8, 14 and 16 with IC(50) values ranging from 0.05 to 0.85 μM against all tested cell lines respectively, which were 5.7- to 112-fold better than Iressa. The most active compound 14 (IC(50) values of 0.05, 0.25, 0.16, 0.68 μM), bearing 4-fluorostyryl at C-2 position and 3-(dimethylamino)-1-propylamino at C-4 position, showed great promise as a lead for the development of more effective quinoline analogues.     

Heterodimers of Histidine and Amantadine as Inhibitors for Wild Type and Mutant M2 Channels of Influenza A

Inhibitors bearing the imidazole, adamantane and related structures were synthesized and tested against WT, S31N and S31N‐L26I mutant M2 channels. Although amantadine ( 1 ) only inhibited WT M2 channel, compound 6 containing the imidazole and adamantane groups showed good inhibitory activity to WT and mutant M2 channels. The stereochemistry and basic pK_a of α‐amine are important for the activity of inhibitors and our data showed that derivatives of natural histidine are more active for M2 channels than those of unnatural histidine. The significance of our present results is that we have established a prospective strategy of drug discovery of WT and mutant M2 channels against influenza A.     

Benzylidene-bis-(4-hydroxycoumarin) and benzopyrano-coumarin derivatives: synthesis, ¹H/¹³C-NMR conformational and X-ray crystal structure studies and in vitro antiviral activity evaluations

We report on the synthesis of 4-hydroxycoumarin dimers 1-15 bearing an aryl substituent on the central linker and fused benzopyranocoumarin derivatives 16-20 and on their in vitro broad anti-DNA and RNA virus activity evaluations. The chemical identities and structure of compounds 1-20 were deduced from their homo- and heteronuclear NMR measurements whereas the conformational properties of 5, 14 and 20 were assessed by the use of 1D difference NOE enhancements. Unequivocal proof of the stereostructure of compounds 7, 9, 16 and 18 was obtained by single crystal X-ray diffraction method. The X-ray crystal structure analysis revealed that two 4-hydroxycoumarin moieties in the 4-trifluoromethylphenyl- and 2-nitrophenyl derivatives (compounds 7 and 9, respectively) are intramolecularly hydrogen-bonded between hydroxyl and carbonyl oxygen atoms. Consequently, the compounds 7 and 9 adopt conformations in which two 4-hydroxy-coumarin moieties are anti-disposed. Antiviral activity evaluation results indicated that the 4-bromobenzylidene derivative of bis-(4-hydroxycoumarin) (compound 3) possesses inhibitory activity against HSV-1 (KOS), HSV-2 (G), vaccinia virus and HSV-1 TK? KOS (ACVr) at a concentration of 9-12 μM and at a minimum cytotoxic concentration (MCC) greater than 20 μM. Compounds 4-6, 8, and 20 were active against feline herpes virus (50% effective concentration, EC?? = 5-8.1 μM), that is at a 4-7-fold lower concentration than the MCC.     

Studies on antiulcer drugs. II. Synthesis and antiulcer activities of imidazo[1,2-alpha]pyridinyl-2-alkylaminobenzoxazoles and 5,6,7,8-tetrahydroimidazo[1,2-alpha]pyridinyl derivatives.

A series of imidazo[1,2-alpha]pyridinylbenzoxazoles (4) and 5,6,7,8-tetrahydroimidazo[1,2-alpha]pyridinylbenzoxazoles (5) were synthesized and tested for anti-stress ulcer activity in rats. Several compounds were found to be more active than the reference compounds, sucralfate, cimetidine and ranitidine. Some of them exhibited potent protective activity against ethanol-induced gastric lesion. The synthesis and structure-activity relationships of these compounds are discussed.     

Synthesis and in vitro antitumor activity of novel naphthyridinone derivatives

A series of naphthyridinone derivatives based on la(a precursor of Voreloxin) were designed and synthesized.Seven compounds having 70%inhibition against HL60 at 30 μmol/L were further evaluated for their in vitro antitumor activity by SRB assay.Results reveal that thiazol-2-yl and 3-aminomethyl-4-benzyloxyimino-3-methylpyrrolidin-l-yl groups are optimal at the N-1 and C-7positions of naphthyridinone core,respectively.10 j exhibits broad-spectrum activity(IC_(50):0.5-6.25 μmol/L) against all of the tested cell lines including Etoposide- and/or la-resistant ones,and is 1.3-fold to 100-fold more potent than the two references against eight of these cell lines.     

How do aminoadamantanes block the influenza M2 channel, and how does resistance develop?

The interactions between channels and their cognate blockers are at the heart of numerous biomedical phenomena. Herein, we unravel one particularly important example bearing direct pharmaceutical relevance: the blockage mechanism of the influenza M2 channel by the anti-flu amino-adamantyls (amantadine and rimantadine) and how the channel and, consequently, the virus develop resistance against them. Using both computational analyses and experimental verification, we find that amino-adamantyls inhibit M2's H(+) channel activity by electrostatic hindrance due to their positively charged amino group. In contrast, the hydrophobic adamantyl moiety on its own does not impact conductivity. Additionally, we were able to uncover how mutations in M2 are capable of retaining drug binding on the one hand yet rendering the protein and the mutated virus resistant to amino-adamantyls on the other hand. We show that the mutated, drug-resistant protein has a larger binding pocket for the drug. Hence, despite binding the channel, the drug remains sufficiently mobile so as not to exert a H(+)-blocking positive electrostatic hindrance. Such insight into the blocking mechanism of amino-adamantyls, and resistance thereof, may aid in the design of next-generation anti-flu agents.     

Design,Synthesis, and Antimycobacterial Activities of Diethylene Glycol Tethered Moxifloxacin–Isatin Hybrids

A new class of diethylene glycol tethered moxifloxacin–isatin hybrids 5a–l was designed, synthesized, and evaluated for their in vitro antimycobacterial activity against Mycobacterium tuberculosis (MTB) H37Rv and multidrug‐resistant tuberculosis (MDR‐TB) strains. Our results showed that all hybrids with higher lipophilicity than the parent moxifloxacin exhibited promising activity against the tested strains with minimum inhibitory concentration (MIC) in a range of 0.2–16 μg/mL. In particular, hybrid 5h (MIC: 0.20 and 0.5 μg/mL), which was found to be most active against MTB H37Rv and MDR‐TB, was twofold more potent than isoniazid (MIC: 0.39 μg/mL) against MTB H37Rv and ≥64‐fold more active than isoniazid and rifampicin (MIC: >128 and 32 μg/mL, respectively) against MDR‐TB.     

Inhibition of influenza virus sialidase and anti-influenza virus activity by plant flavonoids

Flavonoids (103 species) were tested for inhibitory activity against influenza virus sialidase using sodium p-nitrophenyl-N-acetyl-alpha-D-neuraminate as substrate. 5,7,4'-Trihydroxy-8-methoxyflavone from the root of Scutellaria baicalensis showed the most potent activity (IC50, 55 microM), and this flavone appeared to be a non-competitive inhibitor of the enzyme. Whereas, negligible or weak inhibitory activities were observed for mouse liver sialidase, beta-galactosidase and alpha-mannosidase as tested. This flavone also inhibited the infection by influenza virus A/PR/8/34 of Madin-Darby canine kidney cells, and replication of the virus in the allantoic sack of embryonated egg. These results suggest that flavone, which has potent influenza virus sialidase inhibitory activity, may have anti-influenza virus activity.     

Synthesis of conformationally constrained adamantane imidazolines with trypanocidal activity

Aiming at the development of new adamantano building blocks for treating African trypanosomiasis, we report on the synthesis of spiro adamantane 2‐imidazolines 8a‐f and 9a‐c , and their congeneric 5‐(1‐adamantyl)imidazolines 14 and 15 . The potency of these compounds against Trypanosoma brucei was compared to that of rimantadine and found, in the case of compound 14e , to be three fold higher. Together with the other active compounds, 14b and 15b , which were equipotent to rimantadine, the new molecules illustrate the synergistic effect of the lipophilic character of adamantane and the C1 amidine functionality on trypanocidal activity.     

Specific binding of adamantane drugs and direction of their polar amines in the pore of the influenza M2 transmembrane domain in lipid bilayers and dodecylphosphocholine micelles determined by NMR spectroscopy

The transmembrane domain of the influenza M2 protein (M2TM) forms a tetrameric proton channel important for the virus lifecycle. The proton-channel activity is inhibited by amine-containing adamantyl drugs amantadine and rimantadine, which have been shown to bind specifically to the pore of M2TM near Ser31. However, whether the polar amine points to the N- or C-terminus of the channel has not yet been determined. Elucidating the polar group direction will shed light on the mechanism by which drug binding inhibits this proton channel and will facilitate rational design of new inhibitors. In this study, we determine the polar amine direction using M2TM reconstituted in lipid bilayers as well as dodecylphosphocholine (DPC) micelles. (13)C-(2)H rotational-echo double-resonance NMR experiments of (13)C-labeled M2TM and methyl-deuterated rimantadine in lipid bilayers showed that the polar amine pointed to the C-terminus of the channel, with the methyl group close to Gly34. Solution NMR experiments of M2TM in DPC micelles indicate that drug binding causes significant chemical shift perturbations of the protein that are very similar to those seen for M2TM and M2(18-60) bound to lipid bilayers. Specific (2)H-labeling of the drugs permitted the assignment of drug-protein cross peaks, which indicate that amantadine and rimantadine bind to the pore in the same fashion as for bilayer-bound M2TM. These results strongly suggest that adamantyl inhibition of M2TM is achieved not only by direct physical occlusion of the channel, but also by perturbing the equilibrium constant of the proton-sensing residue His37. The reproduction of the pharmacologically relevant specific pore-binding site in DPC micelles, which was not observed with a different detergent, DHPC, underscores the significant influence of the detergent environment on the functional structure of this membrane protein.     

Optical 2-benzyl-5-hydroxy-4-oxopentanoic acids against carboxypeptidase A: synthesis, kinetic evaluation and X-ray crystallographic study

<正>2-Benzyl-5-hydroxy-4-oxopentanoic acid 1 and its enantiomers were designed,synthesized and assayed for inhibitory activity against carboxypeptidase A(CPA,EC 3.4.17.1).To verify the role of the terminal hydroxyl group in 1 binding to CPA,2-benzyl-5- benzyloxy-4-oxopentanoic acid 2 was also synthesized and evaluated.The inhibition constants show that both L-1 and D-1 were shown to have strong binding affinity with L-1 being more potent than its enantiomer by 165-fold.On the other hand,the inhibition constant of 2 increases 4-fold comparing with that of 1.In order to explore the exact binding mode of the hydroxyacteyl group of 1 to the active site zinc ion of CPA,we have solved the crystal structure of CPA complexed with L-1 up to 1.85(?) resolution.In CPA·L-1 complex,the phenyl ring is fitted in the substrate recognition pocket at the S′_1 subsite,and the carboxylate forms bifurcated hydrogen bonds with the guanidinium moiety of Arg-145 and Arg-127 and a hydrogen bond with the phenolic hydroxyl of the down-positioned Tyr-248.The carbonyl oxygen of L-1 does coordinate to the active site zinc ion of CPA as expectedly.Unexpectedly,the terminal hydroxyl group of L-1 is engaged in hydrogen bonding with carbonyl oxygen of Ser-197 instead of coordinating to the active site zinc ion.     

Synthesis,Biological Evaluation and Molecular Docking Studies of 5-Indolylmethylen-4-oxo-2-thioxothiazolidine Derivatives

Background: Infectious diseases represent a significant global strain on public health security and impact on socio-economic stability all over the world. The increasing resistance to the current antimicrobial treatment has resulted in the crucial need for the discovery and development of novel entities for the infectious treatment with different modes of action that could target both sensitive and resistant strains. Methods: Compounds were synthesized using the classical organic chemistry methods. Prediction of biological activity spectra was carried out using PASS and PASS-based web applications. Pharmacophore modeling in LigandScout software was used for quantitative modeling of the antibacterial activity. Antimicrobial activity was evaluated using the microdilution method. AutoDock 4.2^® software was used to elucidate probable bacterial and fungal molecular targets of the studied compounds. Results: All compounds exhibited better antibacterial potency than ampicillin against all bacteria tested. Three compounds were tested against resistant strains MRSA, P. aeruginosa and E. coli and were found to be more potent than MRSA than reference drugs. All compounds demonstrated a higher degree of antifungal activity than the reference drugs bifonazole (6–17-fold) and ketoconazole (13–52-fold). Three of the most active compounds could be considered for further development of the new, more potent antimicrobial agents. Conclusion: Compounds 5b (Z)-3-(3-hydroxyphenyl)-5-((1-methyl-1H-indol-3-yl)methylene)-2-thioxothiazolidin-4-one and 5g (Z)-3-[5-(1H-Indol-3-ylmethylene)-4-oxo-2-thioxo-thiazolidin-3-yl]-benzoic acid as well as 5h (Z)-3-(5-((5-methoxy-1H-indol-3-yl)methylene)-4-oxo-2-thioxothiazolidin-3-yl)benzoic acid can be considered as lead compounds for further development of more potent and safe antibacterial and antifungal agents.