Synthesis and evaluation of benzoylbenzofurans and isoflavone derivatives as sirtuin 1 inhibitors with antiproliferative effects on cancer cells.

Isoflavone derivatives were prepared from benzoylbenzofuran precursors. The synthesized compounds were analyzed by 1D and 2D nuclear magnetic resonance (NMR) spectroscopy, as well as high-resolution mass spectrometry (HRMS) to confirm their structures. The benzoylbenzofuran and isoflavone analogues were evaluated for inhibition of sirtuin 1 (SIRT1) and cell proliferation in MDA-MB-231 triple-negative breast cancer (TNBC) cells. Several isoflavone and benzoylbenzofuran derivatives exhibited potent antiproliferative effects against the MDA-MB-231 cancer cell line. Most of the isoflavone derivatives attenuated SIRT1 activity to below 50%. The most active compounds were the isoflavone quinones 38, 39, and 40, at IC50 values of 5.58 ± 0.373, 1.62 ± 0.0720, and 7.24 ± 0.823 µM, respectively. Importantly, the most active compound, 6-methoxy-4',6'-dimethylisoflavone-2',5'-quinone (39) displayed SIRT1 inhibitory activity comparable to that of the reference compound, suramin. The in silico docking simulations in the active site of SIRT1 further substantiated the experimental results and explored the binding orientations of potent compounds in the active site of the target.

A Cytotoxic Bis(1,2,3-triazol-5-ylidene)carbazolide Gold(III) Complex Targets DNA by Partial Intercalation.

The syntheses of bis(triazolium)carbazole precursors and their corresponding coinage metal (Au, Ag) complexes are reported. For alkylated triazolium salts, di- or tetranuclear complexes with bridging ligands were isolated, while the bis(aryl) analogue afforded a bis(carbene) AuI -CNC pincer complex suitable for oxidation to the redox-stable [AuIII (CNC)Cl]+ cation. Although the ligand salt and the [AuIII (CNC)Cl]+ complex were both notably cytotoxic toward the breast cancer cell line MDA-MB-231, the AuIII complex was somewhat more selective. Electrophoresis, viscometry, UV-vis, CD and LD spectroscopy suggest the cytotoxic [AuIII (CNC)Cl]+ complex behaves as a partial DNA intercalator. In silico screening indicated that the [AuIII (CNC)Cl]+ complex can target DNA three-way junctions with good specificity, several other regular B-DNA forms, and Z-DNA. Multiple hydrophobic π-type interactions involving T and A bases appear to be important for B-form DNA binding, while phosphate O⋅⋅⋅Au interactions evidently underpin Z-DNA binding. The CNC ligand effectively stabilizes the AuIII ion, preventing reduction in the presence of glutathione. Both the redox stability and DNA affinity of the hit compound might be key factors underpinning its cytotoxicity in vitro.

Exact expressions for ensemble functionals from particle number dependence.

Some properties of exact ensemble density functionals can be determined by examining the particle number dependence of ground state ensemble density matrices for systems where the integer ground state energies satisfy a convexity condition. The results include the observation that the integral of the product of the functional derivative and Fukui function of functionals that can be expressed as the trace of an operator is particle number independent for particle numbers between successive integers and the integral itself is equal to the difference between functionals evaluated at successive integer particle numbers. Expressions that must be satisfied by 2nd and higher order functional derivatives are formulated and equations that must be satisfied point by point in space are derived. Using the analytic Hooke's atom model, it is shown that commonly used correlation functional approximations do not bear any resemblance to a spatially dependent expression derived from the exact second order functional derivative of the correlation functional. It is also shown that two expressions for the mutual Coulomb energy are not equal when approximate exchange and correlation functionals are used.

A note on poly-L-lysine-mediated gene transfer in HeLa cells.

Poly-L-lysines of chain lengths varying from 70 to 300 residues are shown to bring about luciferase pRSVL DNA uptake and expression in HeLa cells. Transfection was approximately 50% that of the cationic liposome DOTAB. Expression was higher in the presence of chloroquine. Of interest was the fact that luciferase activity depended on the polysine/DNA charge ratio (+/-). Maximum activity occurred at a charge ratio (+/-) of 3, while at a charge ratio of 1 (conjugate electrically neutral) activity was much lower. At the higher charge ratios (+/-) of 4 and 5, luciferase activity decreased. The results obtained are discussed.

Low concentrations of chlorpromazine and related phenothiazines stimulate gene transfer in HeLa cells via receptor-mediated endocytosis.

Chlorpromazine and related phenothiazine antipsychotic compounds at the low concentration of 10(-5) M stimulated luciferase pRSVL DNA uptake and expression in HeLa cells. On the other hand, chloroquine at a 10(-5) M was without effect at this low concentration. However, at the higher normally used concentration of 10(-4) M (100 microM), chloroquine strongly stimulated luciferase expression and activity. Unfortunately, at 10(-4) M, the phenothiazines were toxic to the cells and could not be tested at this concentration. Further experimental work was carried out to elucidate the mechanism of action of phenothiazines and chloroquine on DNA uptake and expression. Interaction of [3H] pBR 322 DNA with chlorpromazine, perphenazine, and chloroquine was studied using these compounds as their free bases dissolved in chloroform, followed by their impregnation onto Whatman No. 1 filter paper discs. Both phenothiazines on filter paper discs bound [3H] pBR 322 DNA to a far greater extent than chloroquine. The method of assay (free base) suggests that the major contribution to binding is through intercalation. A further possible assay for studying the interaction of phenothiazines and chloroquine made use of the ethidium bromide/calf thymus DNA intercalation method. Intercalated calf thymus (CT) DNA complexes with ethidium bromide (EB) were examined for possible dissociation into free DNA and EB on the addition of either chloroquine. SO4 or chlorpromazine.HCl (soluble salts). Partial dissociation was observed with both compounds. Further experiments on the stability of pBR 322 DNA-polylysine complexes were also carried out using an alternative method of assay. Chloroquine (10(-2)-10(-4) M) and chlorpromazine (10(-4) M) did not bring about a dissociation of [3H] pBR 322 DNA-polylysine(200) complexes when reactions were studied by nitrocellulose filter assays to measure released double-stranded DNA. The results indicate that chlorpromazine and related phenothiazines stimulate luciferase DNA uptake expression at 10(-5) M. Chloroquine at this concentration had practically no effect on expression of luciferase activity. Further studies of chloroquine and chlorpromazine on their interaction with plasmid DNA as well as DNA-polylysine complexes are reported.