Inhibition of nicotinamide phosphoribosyltransferase (NAMPT) has the potential to directly limit NAD production in cancer cells and is an effective strategy for cancer treatment. Using a structure-based strategy, we have designed a new class of potent small-molecule inhibitors of NAMPT. Several designed compounds showed promising antiproliferative activities in vitro. (E)-N-(5-((4-(((2-(1H-Indol-3-yl)ethyl)(isopropyl)amino)methyl)phenyl)amino)pentyl)-3-(pyridin-3-yl)acrylamide, 30, bearing an indole moiety, has an IC50 of 25.3 nM for binding to the NAMPT protein and demonstrated promising inhibitory activities in the nanomolar range against several cancer cell lines (MCF-7 GI50 = 0.13 nM; MDA-MB-231 GI50 = 0.15 nM). Triple-negative breast cancer is the most malignant subtype of breast cancer with no effective targeted treatments currently available. Significant antitumor efficacy of compound 30 was achieved (TGI was 73.8%) in an orthotopic MDA-MB-231 triple-negative breast cancer xenograft tumor model. This paper reports promising lead molecules for the inhibition of NAMPT which could serve as a basis for further investigation.

A successful structure-based design of novel cyclic depsipeptides that selectively target class I HDAC isoforms is described. Compound 11 has an IC50 of 2.78 nM for binding to the HDAC1 protein, and the prodrugs 12 and 13 also exhibit promising antiproliferative activities in the nanomolar range against various cancer cell lines. Compounds 12 and 13 show more than 20-fold selectivity toward human cancer cells over human normal cells in comparison with romidepsin (FK228), demonstrating low probability of toxic side effects. In addition, compound 13 exhibits excellent in vivo anticancer activities in a human prostate carcinoma (Du145) xenograft model with no observed toxicity. Thus, prodrug 13 has therapeutic potential as a new class of anticancer agent for further clinical translation.

A consecutive synthetic strategy was developed toward the total synthesis of securinega alkaloids. (−)-Norsecurinine was concisely assembled by addition of a methoxyallene to a ketone for efficient side-chain installation. Ring-closing metathesis was also utilized as a key step. The first total synthesis of (−)-niruroidine was achieved from (−)-norsecurinine in three steps, while the route to (−)-flueggine A featured a 1,3-dipolar cycloaddition to forge the core structure.

•New HDAC inhibitors demonstrating class I and IIb subtype selectivity have been identified.•Several designed compounds showed much better selectivity and activity than SAHA.•A representative lead compound 22 demonstrated promising class I and IIb HDAC isoforms selectivity.A novel series of HDAC inhibitors demonstrating class I and IIb subtype selectivity have been identified using a scaffold-hopping strategy. Several designed compounds showed better selectivity for class I and IIb over class IIa HDAC isoforms comparing to the FDA approved HDAC targeting drug SAHA. A representative lead compound 22 bearing a biphenyl moiety demonstrated promising class I and IIb HDAC isoforms selectivity and in vitro anticancer activities against several cancer cell lines. This work could serve as a fundamental platform for further exploration of selective HDAC inhibitors using designed molecular scaffold.

•A convergent fragment-assembly approach was developed.•A small library of annonaceous acetogenin analogues was established.•Lots of aromatic moieties were introduced using Click chemistry.•Biological evaluation of annonaceous acetogenin analogues was studied.A small library of analogues of annonaceous acetogenins through click linkage with aromatic moieties is established using a convergent modular fragment-assembly approach. These analogues exhibited low micromolar inhibitory activities against the proliferation of several human cancer cell lines. Structure–activity relationship (SAR) of these analogues indicates that replacement of the methoxy groups of ubiquinone ring with methyl groups is proved to be a useful strategy for improving the anticancer activity of quinone–acetogenin hybrids.A variety of aromatic moieties were introduced for the first time into the right part of acetogenins, in which a triazole functionality was employed as the linkage using Click chemistry.

A series of novel bivalent mimetics of annonaceous acetogenins have been designed, synthesized, and evaluated. Among these, compound 7 bearing a homopiperazine ring in the middle region exhibited more potent growth inhibitory activity and higher selectivity against cancer cells over normal cells by comparison with AA005. This work indicates that modification of the middle piperazine ring is a useful optimizing tool for the simplified acetogenin mimetics.

We designed a series of 2-methylpyrimidine derivatives as new BCR-ABL inhibitors using scaffold-hopping strategy. These synthetic compounds exhibited significant inhibition against a broad spectrum of Bcr-Abl mutants including the gatekeeper T315I mutant. Compound 7u showed very potent kinase inhibitory activities against Bcr-Abl WT, Bcr-Abl E255K, Bcr-Abl Q252H, Bcr-Abl G250E and Bcr-Abl T315I, with IC50 values of 0.13 nM, 0.17 nM, 0.24 nM, 0.19 nM and 0.65 μM, respectively. This compound also displayed anti-proliferation activity against K562 cell line with an IC50 value of 1.1 nM, thus representing a new lead for further optimization.

2-Carbomethoxy-3-hydroxyquinoxaline-di-N-oxide was identified as an efficient novel ligand for the copper-catalyzed coupling of aryl halides with various phenols under mild conditions. The catalytic system shows great functional-group tolerance and excellent reactive selectivity.

We report the design, synthesis, and biological evaluation of a new series of largazole analogues in which a 4-methylthiazoline moiety was replaced with a triazole and tetrazole ring, respectively. Compound 7 bearing a tetrazole ring was identified to show much better selectivity for HDAC1 over HDAC9 than largazole (10-fold). This work could serve as a foundation for further exploration of selective HDAC inhibitors using a largazole molecular scaffold.Keywords: click chemistry; HDAC inhibitor; largazole; macrocycles; peptides;

Aberration in cell cycle has been shown to be a common occurrence in lung cancer, and cell cycle inhibitor represents an effective therapeutic strategy. In this study, we test the effects of a natural macrocyclic depsipeptide largazole on lung cancer cells and report that this compound potently inhibits the proliferation and clonogenic activity of lung cancer cells but not normal bronchial epithelial cells. Largazole arrests cell cycle at G1 phase with up-regulation of the expression of cyclin-dependent kinase inhibitor p21. Interestingly, largazole enhances the E2F1-HDAC1 binding affinity and induces a proteasomal degradation of E2F1, leading to suppression of E2F1 function in lung cancer but not normal bronchial epithelial cells. Because E2F1 is overexpressed in lung cancer tumor samples, these data indicate that largazole is an E2F1-targeting cell cycle inhibitor, which bears therapeutic potentials for this malignant neoplasm.Keywords: cell cycle; degradation; E2F1; largazole; Lung cancer;

We report the design, synthesis, and biological evaluation of a new series of HDAC1 inhibitors using click chemistry. Compound 17 bearing a phenyl ring at meta-position was identified to show much better selectivity for HDAC1 over HDAC7 than SAHA. The compond 17 also showed better in vitro anticancer activities against several cancer cell lines than that of SAHA. This work could serve as a foundation for further exploration of selective HDAC inhibitors using the compound 17 molecular scaffold.

2-Carbomethoxy-3-hydroxyquinoxaline-di-N-oxide was identified as an efficient novel ligand for the copper-catalyzed coupling reactions of aryl iodides, bromides, and chlorides with aliphatic amines and N-containing heterocycles under mild conditions. The catalytic system showed great functional-group tolerance and excellent chemoselectivity.

Several ligands were designed to promote transition-metal-free cross-coupling reactions of aryl halides with benzene derivatives. Among the systems probed, quinoline-1-amino-2-carboxylic acid was found to serve as an excellent catalyst for cross-coupling between aryl halides and unactivated benzene. Reactions using this inexpensive catalytic system displayed a high functional group tolerance as well as excellent chemoselectivities.

8-Hydroxyquinolin-N-oxide was found to be a very efficient ligand for the copper-catalyzed hydroxylation of aryl iodides, aryl bromides, or aryl chlorides under mild reaction conditions. This methodology provides a direct transformation of aryl halides to phenols and to alkyl aryl ethers. The inexpensive catalytic system showed great functional group tolerance and excellent selectivity.

Annonaceous acetogenins are a large family of naturally occurring polyketides exhibiting remarkable anticancer activities. The first generation of annonaceous acetogenin mimetic (1, AA005) exhibits comparable activity as that of natural products and presents much higher selectivity between cancer and normal cells. In this work, we report the design, synthesis, and evaluation of a new series of compound 1 analogues in which a variety of conformation-constrained fragments were embedded in the left hydrocarbon chain part. Compound 7 bearing a biphenyl moiety was identified to exhibit more potent antiproliferative activity and preferentially target cancer cells over normal cells and thus represents a new lead for further optimization.

Under the catalysis of CuI/2-carboxylic acid-quinoline-N-oxide, the cross coupling reactions between aryl iodides or bromides and aqueous ammonia proceed very well to afford N-unprotected aniline derivatives in excellent yields. This inexpensive catalytic system shows great functional group tolerance and excellent reaction selectivity.

An efficient palladium-catalyzed direct C–H arylation of unactivated arenes has been discovered. This method employs aryl halides as the direct coupling partners with arenes without using any external ligands. This catalysis opens a new methodology for the preparation of symmetrical as well as unsymmetrical biaryls in a user-friendly approach.

A new series of linear dimeric compounds mimicking naturally occurring annonaceous acetogenins have been synthesized by bivalent analogue design, and their cytotoxicities have been evaluated against the growth of cancer cells by MTT method. Most of these compounds show selective action favored to human cancer cell lines over normal cell lines, and compound 9 with bis-terminal benzoquinone functionality exhibits an IC50 = 0.40 μM against MCF7 cell lines. This work mentions that appropriate conformational constraints might be a useful optimizing tool for this unique class of anticancer compounds.

The total synthesis of argyrins A and E were accomplished using a convergent strategy by condensation of one tripeptide and two dipeptide fragments. The synthesis strategy, which was developed for the protection of peptide fragments and identification of the optimum macrocylization site, can be applied to further synthetic studies involving other members of the argyrin family.

Several new ligands were designed to promote copper-catalyzed Ullman C−N coupling reactions. In this group, 8-hydroxyquinolin-N-oxide was found to serve as a superior ligand for CuBr-catalyzed coupling reactions of aryl iodides, bromides, and chlorides with aliphatic amines and N-heterocycles under a low catalyst loading (1% [Cu] mol). Reactions with the inexpensive catalytic system display a high functional group tolerance as well as excellent chemoselectivity.(1)

The efficient total synthesis of the natural substance largazole is described. Using this strategy, a small library of largazole analogs was developed. Structure−activity relationship studies suggested that the geometry of the alkene in the side chain is critical. While the largazole’s analogues with trans-alkene are potent for the antiproliferative effect, those with cis-alkene are completely inactive. Most importantly, replacement of valine with tyrosine in largazole increased selectivity toward human cancer cells over human normal cells more than 100-fold.

Blocking the interaction between phosphotyrosine (pTyr)-containing activated receptors and the Src homology 2 (SH2) domain of the growth factor receptor-bound protein 2 (Grb 2) is considered to be an effective and non-cytotoxic strategy to develop new anti-proliferate agents due to its potential to shut down the Ras activation pathway. In this study, a series of phosphotyrosine containing cyclic pentapeptides were designed and synthesized based upon the phage library derived cyclopeptide, G1TE. A comprehensive SAR study was also carried out to develop potent Grb2-SH2 domain antagonists based upon this novel template. With both the peptidomimetic optimization of the amino acid side-chains and the constraint of the backbone conformation guided by molecular modeling, we developed several potent antagonists with low micromolar range binding affinity, such as cyclic peptide 15 with an Kd = 0.359 μM, which is providing a novel template for the development of Grb2-SH2 domain antagonists as potential therapeutics for certain cancers.

A consecutive synthetic strategy was developed toward the total synthesis of securinega alkaloids. (−)-Norsecurinine was concisely assembled by addition of a methoxyallene to a ketone for efficient side-chain installation. Ring-closing metathesis was also utilized as a key step. The first total synthesis of (−)-niruroidine was achieved from (−)-norsecurinine in three steps, while the route to (−)-flueggine A featured a 1,3-dipolar cycloaddition to forge the core structure.

Under the catalysis of CuI/2-carboxylic acid-quinoline-N-oxide, the cross coupling reactions between aryl iodides or bromides and aqueous ammonia proceed very well to afford N-unprotected aniline derivatives in excellent yields. This inexpensive catalytic system shows great functional group tolerance and excellent reaction selectivity.

2-Carbomethoxy-3-hydroxyquinoxaline-di-N-oxide was identified as an efficient novel ligand for the copper-catalyzed coupling of aryl halides with various phenols under mild conditions. The catalytic system shows great functional-group tolerance and excellent reactive selectivity.