Halogen Bonding Directed Supramolecular Quadruple and Double Helices from Hydrogen-Bonded Arylamide Foldamers.

Halogen bonding has been used to glue together hydrogen-bonded short arylamide foldamers to achieve new supramolecular double and quadruple helices in the solid state. Three compounds, which bear a pyridine at one end and either a CF2 I or fluorinated iodobenzene group at the other end, engage in head-to-tail N⋅⋅⋅I halogen bonds to form one-component supramolecular P and M helices, which stack to afford supramolecular double-stranded helices. One of the double helices can dimerize to form a G-quadruplex-like supramolecular quadruple helix. Another symmetric compound, which bears a pyridine at each end, binds to ICF2 CF2 I through N⋅⋅⋅I halogen bonds to form two-component supramolecular P and M helices, with one turn consisting of four (2+2) molecules. Half of the pyridine-bearing molecules in two P helices and two M helices stack alternatingly to form another supramolecular quadruple helix. Another half of the pyridine-bearing molecules in such quadruple helices stack alternatingly with counterparts from neighboring quadruple helices, leading to unique quadruple helical arrays in two-dimensional space.

Homo- and heteroleptic Pt(II) complexes of ONN donor hydrazone and 4-picoline: A synthetic, structural and detailed mechanistic anticancer investigation.

Two series of homoleptic Pt(II)(hydrazone)Cl (C1a-C5a) and heteroleptic Pt(II)(hydrazone)(4-picoline). BF4 (C1b-C5b) complexes were prepared and characterized by 1H, 13C, 19F NMR and HR ESI-MS. Structure of C2b was confirmed by single crystal X-ray analysis. These complexes were studied for their in vitro anticancer activities in human multiple cancer cells including breast (MCF-7), liver (HepG2), lung (H460), colon (HCT116) and cervical (Hela) cancers. C1a-C5a and C1b-C5b showed considerable anticancer effect. The overall anticancer effect of all these complexes was higher in liver (HepG2) and lung (H460) cancer cell lines and the effect of C2b and C3b was observed to be the highest among these 10 complexes. Therefore, we selected C2b and C3b to study their in vitro anticancer mechanism in HepG2 and H460 cancer cells. C2b and C3b changed cancer cell morphology and inhibited cell migration. The anticancer mechanistic studies demonstrated that C2b and C3b induced cell apoptosis, as evidenced by DAPI and AO/EB staining and flow cytometry analyses. Moreover, qRT-PCR and western blotting analysis showed that H460 and HepG2 cells treated with C2b and C3b significantly increased the expression of p53, p63, p21, p15, Bax and decreased Bcl-2 and c-Myc levels. The DNA binding property of these complexes was investigated by gel electrophoresis using pBR322 plasmid DNA. Taken together, the results obtained from the present study demonstrated the potentials of this new class of Pt(II) complexes in reduction of cell viability, suppression of cell migration and acceleration of apoptosis in different cancer cells.

Synthesis and anticancer evaluation of 3-aryl-6-phenylimidazo [2,1-b]thiazoles.

A series of new 3,6-diphenylimidazo[2,1-b]thiazole derivatives (4a-l) are synthesized and evaluated for their anticancer activity. Some of the synthesized compounds have shown potent anti-proliferative activity against HeLa, MDA-MB-231, A549 and THP1 human cancer cell lines. Among the active compounds, 3-(3-trifluoromethylphenyl)-6-phenylimidazo[2,1-b]thiazole (4j) has caused significant cytotoxicity in HeLa cells, with IC50 as low as 6.5 µM. Compound 4j has induced caspase-3 and caspase-8 activation, leading to an apoptotic cell death. FACS analysis has revealed that compound 4j arrests cells in G0/G1 phase. The presence of 3-(3-trifluoromethylphenyl)- or 3-(3-chlorophenyl)-substituent, in that order, on the 6-phenylimidazo[2,1-b]thiazole impacts more positively than other aryl-substituents, on the anti-proliferative properties of these compounds.

Demonic axe-like conjugated alkynes in combating microbes.

A new series of disubstituted alkynes was obtained by microwave induced internal splitting of the corresponding ß-oxo-alkylidenetriphenylphosphoranes. The antimicrobial potential of these conjugated alkynes and phosphoranes was assayed in vitro against three Gram-positive bacteria (Staphylococcus aureus, Bacillus subtilis, Staphylococcus epidermidis), three Gram-negative bacteria (Escherichia coli, Pseudomonas aeruginosa, Klebsiella pneumoniae) and five fungal strains (Aspergillus niger, Candida albicans, Aspergillus flavus, Candida rugosa, Saccharomyces cerevisiae). The 3-pyridylalkyne derivatives viz., 3-(6-chloropyridin-3-yl)propynenitrile (6a), 3-(2-chloropyridin-3-yl)propynenitrile (6b), ethyl 3-(6-chloropyridin-3-yl)propiolate (6c), iso-propyl 3-(6-chloropyridin-3-yl)propiolate (6d) and 3-(2,6-dichloro-5-fluoropyridin-3-yl)propynenitrile (6e) were found to be highly potent towards all tested microorganisms except E. coli.

Novel 2-(2,4-dioxo-1,3-thiazolidin-5-yl)acetamides as antioxidant and/or anti-inflammatory compounds.

A series of novel N-(4-aryl-1,3-thiazol-2-yl)-2-(2,4-dioxo-1,3-thiazolidin-5-yl)acetamides (4a-k) and N-(1,3-benzothiazol-2-yl)-2-(2,4-dioxo-1,3-thiazolidin-5-yl)acetamide derivatives (4l-o) are synthesized and evaluated for their anti-inflammatory and antioxidant activity (DPPH radical scavenging, superoxide anion scavenging, lipid peroxide inhibition, erythrocyte hemolytic inhibition). Compounds 4k and 4l have exhibited good antioxidant activity in four assays, while compounds 4c, 4d, 4m, 4n and 4o have shown good DPPH radical scavenging efficacy. Compounds 4a, 4h, 4i, 4k, 4m and 4n have possessed excellent anti-inflammatory activity. N-[4-(o-methoxyphenyl)-1,3-thiazol-2-yl]-2-(2,4-dioxo-1,3-thiazolidin-5-yl)acetamide (4k) and N-(6-nitro-/methoxy-1,3-benzothiazol-2-yl)-2-(2,4-dioxo-1,3-thiazolidin-5-yl)acetamide (4m and 4n) have exhibited both antioxidant and anti-inflammatory activities.