Synthesis and SAR of 2-arylbenzoxazoles, benzothiazoles and benzimidazoles as inhibitors of lysophosphatidic acid acyltransferase-β

Synthesis of Benzoxazoles by the Copper Triflate Catalysed Reaction of Nitriles and O-Aminophenols

An efficient procedure for the synthesis of benzoxazoles by the heteroannulation of nitriles and o-aminophenols in the presence of a catalytic amount of copper(II) trifluoromethanesulfonate, has been developed. This method represents a practical and attractive alternative for the synthesis of both 2-arylbenzoxazoles and 2-alkylbenzoxazoles.

Antimicrobial prospect of newly synthesized 1,3-thiazole derivatives

A new series of 1,3-thiazole and benzo[d]thiazole derivatives 10-15 has been developed, characterized, and evaluated for in vitro antimicrobial activity at concentrations of 25-200 μg/mL against Gram+ve organisms such as methicillin-resistant Staphylococcus aureus (MRSA), Gram-ve organisms such as Escherichia coli (E. coli), and the fungal strain Aspergillus niger (A. niger) by the cup plate method. Ofloxacin and ketoconazole (10 μg/mL) were used as reference standards for antibacterial and antifungal activity, respectively. Compounds 11 and 12 showed notable antibacterial and antifungal activities at higher concentrations (125-200 μg/mL), whereas benzo[d]thiazole derivatives 13 and 14 were found to display significant antibacterial or antifungal activity (50-75 μg/mL) against the Gram+ve, Gram-ve bacteria, or fungal cells used in the present study. In addition, a correlation between calculated and determined partition coefficient (log P) was established which allows future development of compounds within this series to be carried out based on calculated log P values. Moreover, compounds 13 and 14 show that the optimum logarithm of partition coefficient (log P) should be around 4.

Diversity-oriented synthesis of benzimidazole, benzoxazole, benzothiazole and quinazolin-4(3H)-one libraries via potassium persulfate-CuSO4-mediated oxidative coupling reactions of aldehydes in aqueous micelles

Libraries of 2-substituted-benzimidazoles, benzoxazoles, benzothiazoles as well as quinazolin-4(3H)-ones were synthesized via potassium persulfate-CuSO(4)-mediated oxidative coupling of aldehydes with o-phenylenediamines, o-aminophenols, o-aminothiophenols, and anthranilamide, respectively, in aqueous micelles. The strategy opens a way for rapid generation of libraries of small heterocycles for biological screening. The reagent is commercially available, cheap, and highly chemoselective. The yields were superior in aqueous micelles to those in organic solvents. Short reaction times, large-scale synthesis, excellent chemoselectivity, excellent yields, as well as environmental friendliness are the main advantages of this diversity-oriented synthesis.

Synthesis and biological evaluation of SANT-2 and analogues as inhibitors of the hedgehog signaling pathway

Hedgehog (Hh) signaling plays an important role in cell signaling of embryonic development and adult tissue homeostasis. In vertebrates, the hh gene encodes three different unique proteins: sonic hedgehog (Shh), desert hedgehog (Dhh) and indian hedgehog (Ihh). Disruption of the Hh signaling pathway leads to severe disorders in the development of vertebrates whereas aberrant activation of the Hh pathway has been associated with several malignancies including Gorlin syndrome (a disorder predisposing to basal cell carcinoma, medulloblastoma and rhabdomyosarcoma), prostate, pancreatic and breast cancers. In vivo evidence suggests the antagonism of excessive Hh signaling provides a route to unique mechanism-based anti-cancer therapies. Recently the small molecule SANT-2 was identified as a potent antagonist of Hh-signaling pathway. Here, we describe the synthesis, SAR studies as well as biological evaluation of SANT-2 and its analogues. Fifteen SANT-2 derivatives were synthesized and analyzed for their interference with the expression of the Hh target gene Gli1 in a reporter gene assay. By comparison of structure and activity important molecular descriptors for Gli inhibition could be identified. Furthermore we identified derivative TC-132 that was slightly more potent than the parent compound SANT-2. Selected compounds were tested for Hh related teratogenic effects in the small teleost model medaka. Albeit Gli expression has indicated a 16-fold higher Hh-inhibiting activity than observed for the plant alkaloid cyclopamine, none of the tested compounds were able to induce the cyclopamine-specific phenotype in the medaka assay.

Experimental and density functional theory and ab initio Hartree-Fock study on the vibrational spectra of 5-chloro-6-(4-chlorobenzoyl)-2-benzothiazolinone molecule

The vibrational frequencies and infrared intensities of 5-chloro-6-(4-chlorobenzoyl)-2-benzothiazolinone (abbreviated as CCB) molecule in the ground state were calculated by HF and DFT (B3LYP and BLYP) methods using different basis sets to elucidate the molecular structure. The solid-state FT-IR spectrum was measured and compared with calculated values. CCB was found to have two different stable conformations. The dihedral angles alpha and beta (i.e. C9-C8-C12-C18 and C8-C12-C18-C17, respectively) were computed as -59.6 degrees and -14.5 degrees for the most stable conformer. The comparison of the theoretical and experimental geometries of the title compound indicated that the X-ray parameters fairly well agree with the theoretically obtained values for the most stable conformer. The calculated vibrational frequencies are also in good agreement with the experimental results.

Vibrational spectroscopy investigation using ab initio and density functional theory analysis on the structure of 3-(6-benzoyl-2-oxobenzo[d]oxazol-3(2H)-yl)propanoic acid

The molecular structure, vibrational frequencies and infrared intensities of the 3-(6-benzoyl-2-oxobenzo[d]oxazol-3(2H)-yl)propanoic acid were calculated by the HF and DFT methods using 6-31G(d) basis set. The FT-infrared spectra have been measured for the title compound in the solid state. We obtained 11 stable conformers for the title compound, however the Conformer 1 is approximately 3.88 kcal/mol more stable than the Conformer 11. The comparison of the theoretical and experimental geometry of the title compound shows that the X-ray parameters fairly well reproduce the geometry of the Conformer 1. The harmonic vibrations computed of this compound by the B3LYP/6-31G(d) method are in a good agreement with the observed IR spectral data. Theoretical vibrational spectra of the title compound were interpreted by means of PEDs using VEDA 4 program.

One-Pot Synthesis of 2-Substituted Benzoxazoles Directly from Carboxylic Acids

Methanesulfonic acid has been found to be a highly effective catalyst for a convenient and one-pot synthesis of 2-substituted benzoxazoles by the reaction of 2-aminophenol with acid chlorides, generated in situ from carboxylic acids. Aryl, heteroaryl, and arylalkyl carboxylic acids provided excellent yields of the corresponding benzoxazoles. The reaction conditions were compatible with various substituents such as chloro, bromo, nitro, methoxy, cyclopentyloxy, phenoxy, thiophenoxy, and conjugated double bonds. Benzoxazole formation was found to be general with respect to substituted 2-aminophenols.

Diamino-C,N-diarylpyridine positional isomers as inhibitors of lysophosphatidic acid acyltransferase-β

2,6-Diamino-4,N-diarylpyridines were identified as potent, isoform selective inhibitors of the enzymatic activity of lysophosphatidic acid acyltransferase-beta (LPAAT-beta).

Induction of Apoptosis Using Inhibitors of Lysophosphatidic Acid Acyltransferase- and Anti-CD20 Monoclonal Antibodies for Treatment of Human Non-Hodgkin's Lymphomas

PURPOSE

Lysophosphatidic acid acyltransferase-beta (LPAAT-beta) is a transmembrane enzyme critical for the biosynthesis of phosphoglycerides whose product, phosphatidic acid, plays a key role in raf and AKT/mTor-mediated signal transduction.

EXPERIMENTAL DESIGN

LPAAT-beta may be a novel target for anticancer therapy, and, thus, we examined the effects of a series of inhibitors of LPAAT-beta on multiple human non-Hodgkin's lymphoma cell lines in vitro and in vivo.

RESULTS

We showed that five LPAAT-beta inhibitors at doses of 500 nmol/L routinely inhibited growth in a panel of human lymphoma cell lines in vitro by >90%, as measured by [3H]thymidine incorporation. Apoptotic effects of the LPAAT-beta inhibitors were evaluated either alone or in combination with the anti-CD20 antibody, Rituximab. The LPAAT-beta inhibitors induced caspase-mediated apoptosis at 50 to 100 nmol/L in up to 90% of non-Hodgkin's lymphoma cells. The combination of Rituximab and an LPAAT-beta inhibitor resulted in a 2-fold increase in apoptosis compared with either agent alone. To assess the combination of Rituximab and a LPAAT-beta inhibitor in vivo, groups of athymic mice bearing s.c. human Ramos lymphoma xenografts were treated with the LPAAT-beta inhibitor CT-32228 i.p. (75 mg/kg) daily for 5 d/wk x 4 weeks (total 20 doses), Rituximab i.p. (10 mg/kg) weekly x 4 weeks (4 doses total), or CT-32228 plus Rituximab combined. Treatment with either CT-32228 or Rituximab alone showed an approximate 50% xenograft growth delay; however, complete responses were only observed when the two agents were delivered together.

CONCLUSIONS

These data suggest that Rituximab, combined with a LPAAT-beta inhibitor, may provide enhanced therapeutic effects through apoptotic mechanisms.