Synthesis and biological evaluation of some 17-picolyl and 17-picolinylidene androst-5-ene derivatives

Starting from dehydroepiandrosterone (1) 17-picolyl (2), 17-picolinylidene (7), 17-picolinylidene-16-one (10 and 11), and 17-picolyl-16-one (15) derivatives of androst-5-ene were synthesized in one, two, four and five steps respectively. By the Oppenauer oxidation or dehydration of 2, 7, 10, and 11 with 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ), the corresponding A and B ring modified derivatives 3, 5, 6, 8, 9, and 12-14 were obtained. The structure of 2 was unambiguously proved by the appropriate X-ray structural analysis. Compounds 3, 5, 9, 12-14 showed inhibitory activity against the enzyme aromatase. Antibacterial activity, toxicity to brine shrimp Artemia salina, antitumor activity against three tumor cell lines (human cervix carcinoma HeLa cells, human melanoma FemX cells, and human myelogenous leukemia K562 cells) and toxicity against peripheral blood mononuclear cells were evaluated. Three tested compounds, namely 11, 13, and 15, showed strong activity against all three cell lines, the IC(50) values being in the range of 4-10 microM.     

Electrospun nano-fiber mats containing cationic cellulose derivatives and poly (vinyl alcohol) with antibacterial activity

Nano-fibrous mats have been successfully prepared by electrospinning of the blend solutions of cationic cellulose derivatives (PQ-4) and polyvinyl alcohol (PVA). Effects of the blending ratio and applied voltage on the morphology and diameter of the electrospun nano-fibers were investigated. The average diameter of the PQ-4/PVA blend fibers was in the range of 150–250 nm. The electrospinning process became instable and the fiber diameter distribution broadened with increasing PQ-4 content and applied voltage. The antibacterial activity of electrospun PQ-4/PVA blend mats against Gram-negative bacteria Escherichia coli and Gram-positive bacteria Staphylococcus aureus indicated potential for biomedical use.     

Polycations. 18. The synthesis of polycationic lipid materials based on the diamine 1,4-diazabicyclo[2.2.2]octane

Herein is reported the preparation of several series of polyammonium salts that serve as cationic lipids or precursors thereof, and are structurally based on the parent diamine 1,4-diazabicyclo[2.2.2]octane (dabco). Through selective alkylation of dabco a variety of di- and tetracationic lipid species and precursors thereof have been prepared. The resultant materials are of significant interest for a variety of purposes, including serving as antimicrobial agents and antihydrophobic species, the details of which are provided in separate reports.     

新结构硫脲类化合物的合成、鉴定及抑菌活性评价

【目的】合成具有抗菌活性的新结构硫脲类化合物。【方法】通过α-异硫氰酸酯中间体与不同伯胺缩合合成硫脲类化合物,利用质谱、核磁分析鉴定结构,并评价其抑菌活性。【结果】合成了六种新结构的硫脲类化合物以及一种α-异硫氰酸酯类衍生物,对几种代表性病原细菌和真菌具有抑菌活性。其中,硫脲类化合物对新型隐球菌的抑制效果较为显著。【结论】通过不同结构硫脲类衍生物的合成,可能筛选出具有抑制新型隐球菌等致病菌的前体化合物。     

Synthesis and transfection activity of novel galactosylated polycationic lipid

In this study, we synthesized a new galactosylated cationic lipid and investigated its biological activity. The structure of lipid combines both spermine residue for DNA compaction and galactose moiety for the improvement of aggregation behavior of lipoplexes. Lipid was low toxic for different mammalian cells, and was able both to compact plasmid DNA and to mediate cellular accumulation of various nucleic acids (ODN, pDNA and siRNA) exhibiting biological activity (transgene expression, gene silencing).     

Synthesis and cytotoxicity of 17a-aza-D-homo-androster-17-one derivatives

A series of 17a-aza-d-homo-andrester-17-one derivatives, bearing hydroxyl, hydroximino, carbonyl and thiosemicarbazido groups at the position-3 or position-6 of steroidal nucleus, were prepared and evaluated in vitro against two human cell lines (Hela (human cervical carcinoma) and SMMC 7404 (human liver carcinoma)). The results showed that these compounds could exhibit a high cytotoxicity to Hela tumor cell line, especially for compounds 8 and 12, the IC₅₀ values are 15.1 and 14.0 nmol/mL, respectively. Our findings could provide new evidence showing the relationship between the chemical structure and biological activity and may be useful for the discovery of new anti-cancer drugs.     

Synthesis and antibacterial evaluation of novel oxazolidinone derivatives containing a piperidinyl moiety

In this article, a series of novel oxazolidinone derivatives containing a piperidinyl moiety was designed and synthesized. Their antibacterial activities were measured against S. aureus, MRSA, MSSA, LREF and VRE by MIC assay. Most of them exhibited potent activity against Gram-positive pathogens comparable to linezolid. Among them, compound 9h exhibited comparable activity with linezolid against human MAO-A for safety evaluation and showed moderate metabolism in human liver microsome. The most promising compound 9h, which showed remarkable antibacterial activity against S. aureus, MRSA, MSSA, LREF and VRE pathogens with MIC value of 0.25–1 μg/mL, was an interesting candidate for further investigation.     

Synthesis,molecular docking and biological evaluation of metronidazole derivatives containing piperazine skeleton as potential antibacterial agents

Metronidazole has a broad-spectrum antibacterial activity. Hereby a series of novel metronidazole derivatives were designed and synthesized based on nitroimidazole scaffold in order to find some more potent antibacterial drugs. For these compounds which were reported for the first time, their antibacterial activities against Escherichia coli, Pseudomonas aeruginosa, Bacillus subtilis and Staphylococcus aureus were tested. These compounds showed good antibacterial activities against Gram-positive strains. Compound 4m represented the most potent antibacterial activity against S. aureus ATCC 25923 with MIC of 0.003 μg/mL and it showed the most potent activity against S. aureus TyrRS with IC₅₀ of 0.0024 μM. Molecular docking of 4m into S. aureus tyrosyl-tRNA synthetase active site were also performed to determine the probable binding mode.     

Synthesis of acyl thiourea derivatives of chitosan and their antimicrobial activities in vitro

Three different acyl thiourea derivatives of chitosan (CS) were synthesized and their structures were characterized by FT-IR spectroscopy and elemental analysis. The antimicrobial behaviors of CS and its derivatives against four species of bacteria (Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus, and Sarcina) and four crop-threatening pathogenic fungi (Alternaria solani, Fusarium oxysporum f. sp. vasinfectum, Colletotrichum gloeosporioides (Penz.) Saec, and Phyllisticta zingiberi) were investigated. The results indicated that the antimicrobial activities of the acyl thiourea derivatives are much better than that of the parent CS. The minimum value of MIC and MBC of the derivatives against E. coli was 15.62 and 62.49 microg/mL, respectively. All of the acyl thiourea derivatives had a significant inhibitory effect on the fungi in concentrations of 50-500 microg/mL; the maximum inhibitory index was 66.67%. The antifungal activities of the chloracetyl thiourea derivatives of CS are noticeably higher than the acetyl and benzoyl thiourea derivatives. The degree of grafting of the acyl thiourea group in the derivatives was related to antifungal activity; higher substitution resulted in stronger antifungal activity.     

Synthesis of starch derivatives with labile cationic groups

A new route to starch derivatives bearing hydrolyzable cationic groups was developed. This was based on reacting starch compounds with betaine derivatives in the presence of diisopropylcarbodiimide and 4-dimethylaminopyridine as coupling reagents in an aprotic polar solvent. Water-soluble starches with a perfectly controlled degree of substitution were thus obtained which were fully characterized by infrared, ¹H and ¹³C spectroscopy and viscosity measurements. The cationic groups grafted on the polysaccharides are shown to hydrolyze slowly upon storage at room temperature.     

Antibacterially active phenolic lipid derivatives from Comarum salesovianum (Steph.) Aschers. et Gr.

The antibacterial activity-guided purification of the dichloromethane fraction of the aerial parts of Comarum salesovianum (Steph.) Aschers.et Gr. led to the isolation and elucidation of three phenolic lipid derivatives: 6-(non-8-enyl) salicylic acid (1), 6-nonyl salicylic acid (2) and 3-(non-8-enyl) phenol (3), which were found for the first time in the natural source. The equal mixture of compounds 1 and 2 exhibited potent inhibitory activity against all tested Gram-positive bacterial strains (Enterococcus faecalis, Micrococcus luteus, Staphylococcus epidermidis and Staphylococcus aureus) with inhibitory zones of 12.2–22.1 mm, whereas each single compound showed weaker activity than the mixture of 1 and 2. However, compound 3 strongly inhibited (29.9 ± 1.8) the growth of M. luteus. The presence of salicylic acid with the unsaturated aliphatic side chain is essential for the antibacterial activity strength of phenolic lipid molecules.     

New derivatives of salicylamides: Preparation and antimicrobial activity against various bacterial species

Three series of salicylanilides, esters of N-phenylsalicylamides and 2-hydroxy-N-[1-(2-hydroxyphenylamino)-1-oxoalkan-2-yl]benzamides, in total thirty target compounds were synthesized and characterized. The compounds were evaluated against seven bacterial and three mycobacterial strains. The antimicrobial activities of some compounds were comparable or higher than the standards ampicillin, ciprofloxacin or isoniazid. Derivatives 3f demonstrated high biological activity against Staphylococcus aureus (?0.03 μmol/L), Mycobacterium marinum (?0.40 μmol/L) and Mycobacterium kansasii (1.58 μmol/L), 3g shows activity against Clostridium perfringens (?0.03 μmol/L) and Bacillus cereus (0.09 μmol/L), 3h against Pasteurella multocida (?0.03 μmol/L) and M. kansasii (?0.43 μmol/L), 3i against methicillin-resistant S. aureus and B. cereus (?0.03 μmol/L). The structure–activity relationships are discussed for all the compounds.     

Synthesis and properties of photolabile (caged) phosphotriester derivatives of dinucleoside phosphates

Dinucleoside phosphates that harbor phosphate groups transiently blocked (caged) byo-nitrobenzyl oro-nitroveratryl residues were synthesized. It was shown that the conditions of the UV-induced deprotection largely depend on the nature of the protective group. The phosphotriesters obtained were resistant toward snake venom phosphodiesterase and nucleases of the cellular extract. The synthesis of the dinucleoside phosphates containing a photolabile group preceeded the incorporation of the modified blocks into extended oligonucleotides by the phosphoramidite method.     

Synthesis,molecular docking and biological evaluation of coumarin derivatives containing piperazine skeleton as potential antibacterial agents

A series of 4-hydroxycoumarin derivatives were designed and synthesized in order to find some more potent antibacterial drugs. Their antibacterial activities against Escherichia coli, Pseudomonas aeruginosa, Bacillus subtilis and Staphylococcus aureus were tested. These compounds showed good antibacterial activities against Gram-positive strains. Compound 4g represented the most potent antibacterial activity against Bacillus subtilis and S. aureus with MIC of 0.236, 0.355 μg/mL, respectively. What’s more, it showed the most potent activity against SaFabI with IC₅₀ of 0.57 μM. Molecular docking of 4g into S. aureus Enoyl-ACP-reductase active site were performed to determine the probable binding mode, while the QSAR model was built to check the previous work as well as to introduce new directions.     

Synthesis and antibacterial activity of new long-chain-alkyl bile acid-based amphiphiles

The efficient synthesis of some bile acid-derived cationic amphiphiles with a flexible long hydrocarbon tail was investigated. Firstly, the modification on the side-chain carboxyl of bile acids was carried out efficiently by one-pot amidation of bile acids and a long-chain aliphatic amine in the presence of HOBt and DCC to introduce a flexible long hydrocarbon tail. Then the hydrophilic concave side of bile acids with hydroxyl groups was further modified into cationic groups for strengthening hydrophilicity. This strategy offered a very straightforward and efficient method for access to the designed amphiphiles in good overall yields. The preliminary results showed that an increase both in the length of the hydrophobic tail and in the number of charged groups resulted in a decrease in the CMC of bile acid-derived cationic amphiphiles. And the bile acid-derived cationic amphiphiles with a flexible longer hydrocarbon tail and more positive charges had the highest antibacterial and antimicrobial activity.     

Synthesis and transfecting properties of a glycosylated polycationic DNA vector

A glycosylated analogue of dialkylamidoglycylcarboxyspermine was synthesized. The physico-chemical and transfecting properties of 11 were evaluated indicating that this cationic lipid forms stable particles at low charge ratio and is efficient for gene delivery.     

Synthesis and cytotoxic properties of new fluorodeoxyglucose-coupled chlorambucil derivatives

Frequently used in the treatment of malignant cells, alkylating agents, like most anticancer substances, produce adverse side effects caused by the toxicity of the agents toward normal tissues and lose efficiency through poor distribution to target sites. Our approach to developing more selective drugs with low systemic toxicity is based on the premise that the body distribution and cell uptake of a drug can be altered by attaching a neoplastic cell-specific uptake enhancer, such as 2-fluoro-2-deoxyglucose (FDG), the radiotracer most frequently used in PET for tumor imaging. Two properties of deoxyglucose, namely preferential accumulation in neoplastic cells and inhibition of glycolysis, underpin this targeting approach. Here, we report the synthesis of 19 new chlorambucil glycoconjugates in which the alkylating drug is attached to the C-1 position of FDG, directly or via different linkages. This set of compounds was evaluated for in vitro cytotoxicity against different human normal and tumor cell lines. There was a significant improvement in the in vitro cytotoxicity of peracetylated glucoconjugates compared with the free substance. Four compounds were finally selected for further in vivo studies owing to their lack of oxidative stress-inducing properties.     

Synthesis and evaluation of indole-based new scaffolds for antimicrobial activities--identification of promising candidates

Search for new antimicrobial agents led to the synthesis of series of N-1, C-3 and C-5 substituted bis-indoles. Their evaluation for antifungal and antibacterial activities resulted in the optimization of pyrrolidine/morpholine/N-benzyl moiety at the C-3 end and propane/butane/xylidine groups as linkers between two indoles for significant inhibition of microbial growth. Preliminary investigations have identified three highly potent antimicrobial agents. Dockings of these molecules in the active sites of lanosterol demethylase, dihydrofolate reductase and topoisomerase II indicate their strong interactions with these enzymes.