Synthesis and structure-activity relationships of novel pyrrolocarbazole lactam analogs as potent and cell-permeable inhibitors of poly(ADP-ribose)polymerase-1 (PARP-1)

Molecular pharmacokinetic mechanism of the drug-drug interaction between genistein and repaglinide mediated by P-gp

This study was devised to investigate if P-glycoprotein (P-gp) mediated the drug-drug interaction (DDI) between genistein and repaglinide. When genistein was added, the plasma concentrations of repaglinide in rats were increased. The maximum plasma concentration (Cmax) of repaglinide increased from 70.80 ± 7.98 ng/mL to 124.71 ± 9.02 ng/mL and the area under the plasma concentration-time curve (AUC) increased from 134.89 ± 13.65 μg·h/L to 245.95 ± 7.24 μg·h/L. Intestinal absorption of repaglinide was markedly enhanced by genistein or P-gp inhibitor verapamil (Ver), both in situ rat jejunal perfusion studies and in vitro transport assays using everted rat intestinal sac preparations. Furthermore, the accumulation of repaglinide in both Caco-2 cells and IEC-6 cells also increased significantly in the presence of genistein and Ver. The transepithelial transport rate of repaglinide from basolateral-to-apical in MDR1-MDCK cells was 3.6-fold higher than the apical-to-basolateral rate with a net efflux ratio of 1.92 compared with mock-MDCK cells, which was significantly decreased following co-administration with genistein or Ver. In an intracellular accumulation experiment using Rhodamine 123 as a P-gp substrate, genistein significantly increased the intracellular fluorescence of Rhodamine 123. These results indicated that genistein had an inhibitory effect on the efflux function of P-gp. Through molecular docking assays we further found that genistein could bind to the nucleotide-binding domains (NBD) in the cytoplasm of P-gp, thus affecting the functions of P-gp. In conclusion, genistein inhibited the efflux of repaglinide mediated by P-gp in rats and in vitro. The findings suggested that the DDI between genistein and repaglinide is mediated by P-gp, and a dosage adjustment may be needed when they are co-administered in a clinical setting.

Synthesis of Novel Podocarpa-8,11,13-Triene-7- and 13-Nitriles and Evaluation of their Anti-Inflammatory and Cytotoxic Activity

A series of novel podocarpa-8,11,13-triene-7- and 13-nitriles were prepared from the naturally occurring labdane diterpenoid (+)-manool, using podocarp-8(14)-en-13-one and 13-methoxypodocarpa-8,11,13-trien-7-one as key intermediates and TMSCN and acetonitrile as source of the nitrile. The synthesised compounds were screened for cytotoxicity against mouse macrophage cell line (RAW 264.7), human colon adenocarcinoma cell lines (HT-29) and human prostate adenocarcinoma cell lines (PC3) and for anti-inflammatory, as measured by the inhibition of nitric oxide (NO) production by RAW cells. 7-Oxopodocarpa-8,11,13-triene-13-nitrile exhibited significant inhibition of NO production (IC50 = 6 μM) and was not cytotoxic.

Marine pyrrolocarbazoles and analogues: synthesis and kinase inhibition

Granulatimide and isogranulatimide are alkaloids obtained from marine sources which have been shown to inhibit cell-cycle G2-checkpoint, targeting more particularly checkpoint 1 kinase (Chk1). At a structural level, they possess a characteristic pyrrolocarbazole framework also shared by the well-known rebeccamycin and staurosporine microbial metabolites which have been described to inhibit topoisomerase I and diverse kinases, respectively. This review reports precisely on the synthesis and kinase inhibitory activities of pyrrolocarbazole-based analogues of granulatimide.

Mechanism of action of an imidopiperidine inhibitor of human polynucleotide kinase/phosphatase

The small molecule, 2-(1-hydroxyundecyl)-1-(4-nitrophenylamino)-6-phenyl-6,7a-dihydro-1H-pyrrolo[3,4-b]pyridine-5,7(2H,4aH)-dione (A12B4C3), is a potent inhibitor of the phosphatase activity of human polynucleotide kinase/phosphatase (PNKP) in vitro. Kinetic analysis revealed that A12B4C3 acts as a noncompetitive inhibitor, and this was confirmed by fluorescence quenching, which showed that the inhibitor can form a ternary complex with PNKP and a DNA substrate, i.e. A12B4C3 does not prevent DNA from binding to the phosphatase DNA binding site. Conformational analysis using circular dichroism, UV difference spectroscopy, and fluorescence resonance energy transfer all indicate that A12B4C3 disrupts the secondary structure of PNKP. Investigation of the potential site of binding of A12B4C3 to PNKP using site-directed mutagenesis pointed to interaction between Trp(402) of PNKP and the inhibitor. Cellular studies revealed that A12B4C3 sensitizes A549 human lung cancer cells to the topoisomerase I poison, camptothecin, but not the topoisomerase II poison, etoposide, in a manner similar to small interfering RNA against PNKP. A12B4C3 also inhibits the repair of DNA single and double strand breaks following exposure of cells to ionizing radiation, but does not inhibit two other key strand-break repair enzymes, DNA polymerase beta or DNA ligase III, providing additional evidence that PNKP is the cellular target of the inhibitor.

Premalbrancheamide: synthesis, isotopic labeling, biosynthetic incorporation, and detection in cultures of Malbranchea aurantiaca

An advanced metabolite, named premalbrancheamide, involved in the biosynthesis of malbrancheamide (1) and malbrancheamide B (2) has been synthesized in double (13)C-labeled form and was incorporated into the indole alkaloid 2 by Malbranchea aurantiaca. In addition, premalbrancheamide has been detected as a natural metabolite in cultures of M. aurantiaca. The biosynthetic implications of these experiments are discussed.

Efficient Synthesis of Maleimides and Carbazoles via Zn(OTf)2-Catalyzed Tandem Annulations of Isonitriles and Allenic Esters

Lewis acid Zn(OTf)(2)-catalyzed tandem annulations of isonitriles and allenic esters which lead to efficient and flexible syntheses of a range of biologically significant maleimides and carbazoles and related compounds are reported. A mechanistic rationale is proposed to account for the observed reactivity.

Regulation of chromatin structure and chromatin-dependent transcription by poly(ADP-ribose) polymerase-1: possible targets for drug-based therapies

Poly(ADP-ribose) Polymerase-1 (PARP-1) is the prototypical and most abundantly expressed member of a family of PARPs that catalyze the polymerization of ADP-ribose (ADPR) units from donor NAD' molecules on target proteins. PARP-1 plays roles in a variety of genomic processes, including the regulation of chromatin structure and transcription in response to specific cellular signals. PARP-1 also plays important roles in many stress-induced disease states. In this chapter, we review the molecular and cellular aspects of PARP-1's chromatin-modulating activities, as well as the impact that these chromatin-modulating activities have on the regulation of gene expression. In addition, we highlight the potential therapeutic use of drugs that target PARP-1's enzymatic activity for the treatment of human diseases

Synthesis and biological activities of novel furo[2,3,4-jk][2]benzazepin-4(3H)-one derivatives

A novel seven-membered lactam formation method has been established by intramolecular ring closure reaction of 4-bromo-(E)-3-[(2-alkylvinyl)carbonylamino]benzo[b]furans under Heck coupling conditions. A number of furo[2,3,4-jk][2]benzazepin-4(3H)-ones, tricyclicbenzo[b]furans, have been prepared by this method and evaluated for their leukotriene B(4) (LTB(4)) receptor and poly(ADP-ribose)polymerase-1 (PARP-1) inhibitory activities.