3-(3,4,5-Trimethoxyphenyl)-1-oxo-2-propene: A novel pharmacophore displaying potent multidrug resistance reversal and selective cytotoxicity

Synthesis, ADMET prediction and reverse screening study of 3,4,5-trimethoxy phenyl ring pendant sulfur-containing cyanopyrimidine derivatives as promising apoptosis inducing anticancer agents

Cancer remains considered as one of the leading global health problems either due to meagre and suboptimal therapeutic response of chemotherapeutic agents or due to the emergence of spontaneous complex multidrug resistance in cancer cells. This created a persistent need for the development of new anticancer agents. Enthralled by the high success rate for natural product-based drug discovery and current research scenario, we synthesized a new series of 3,4,5-trimethoxy phenyl ring pendant sulfur-containingcyanopyrimidine derivatives clubbed with different amines intending to search an anticancer lead compound. To probe the anti-proliferative spectrum of the synthesized derivatives, an in-vitro evaluation was piloted against a panel of 60 cancer cell lines at the National Cancer Institute (NCI) representing major types of cancer diseases. Most of the derivatives showed good to moderate anti-proliferative activity. The results revealed that compound 4e displayed the most promising broad-spectrum anticancer activity with high growth inhibition of various cell lines representing multiple cancers diseases. Mechanistic investigation of compound 4e in human breast cancer MDA-MB-231 cells showed that compound 4e triggers cell death through the induction of apoptosis. ADMET studies and reverse screening were also performed to identify the potential targets of designed molecules. It was concluded that 3,4,5-trimethoxy phenyl ring pendant sulfur-containingcyanopyrimidine derivative 4e could act as a promising hit molecule for further development of novel anticancer therapeutics.

Evaluation of substituted methyl cyclohexanone hybrids for anti-tubercular, anti-bacterial and anti-fungal activity: Facile syntheses under catalysis by ionic liquids

An library of unresolved racemic Mannich bases incorporating two stereogenic carbon centers was evaluated for antibacterial activity against clinically isolated Gram-positive bacteria i.e. Staphylococcus aureus, Gram-negative bacteria Escherichia coli and Pseudomonas aeruginosa and for antifungal activity against Candida albicans strains. Additionally, the susceptibility of microorganisms to Mannich bases prompted us to evaluate the potential for anti-tubercular activity against clinically isolated Mycobacterium tuberculosis and virulent H37Rv strains. All compounds showed potent activity against M. tuberculosis strains at MIC ranging from 50 μg/mL to 6.25 μg/mL of concentration. Facile one pot Mannich type syntheses of rac-(2S)-2-[(R)-[(4-substituted phenyl){[4-(4-substituted phenyl)-1,3-thiazol-2-yl]amino}methyl]cyclohexanone derivatives were achieved by reactions of various 2-amino-4-aryl-thiazoles, appropriately substituted aromatic aldehydes and cyclohexanone in Bronsted acidic quaternary ammonium sulfated ionic liquids serving as dual solvents and catalysts.

Biological activities and possible dental application of three major groups of polyphenols

The present article reviewed the biological activities and possible dental application of three major polyphenols, i.e., lignin-carbohydrate complexes, tannins, and flavonoids, citing mostly our in vitro studies together with those from other groups. All these polyphenols showed much lower tumor-selective cytotoxicity against oral squamous cell carcinoma cells vs. normal oral cells (gingival fibroblast, pulp cell, periodontal ligament fibroblast), in comparison to popular chemotherapeutic antitumor drugs. Several compounds showing higher tumor-selectivity did not induce internucleosomal DNA fragmentation, a biochemical hallmark of apoptosis, in oral carcinoma cell lines. Lignin-carbohydrate complex protected the cells from the cytopathic effects of HIV infection and UV irradiation more efficiently than other polyphenols. Limited digestion of lignin-carbohydrate complex suggests that the lignin moiety is involved in the prominent anti-HIV activity, whereas the carbohydrate moiety may function in immunopotentiating activity through a cell surface receptor. Alkaline extract of plant leaf, which contains higher amounts of lignin-carbohydrate complex, showed potent anti-inflammatory action against IL-1β-stimulated human gingival fibroblasts. Local application of lignin-carbohydrate complex through oral mucosa is recommended, considering its poor intestinal absorption.

Thieno[2,3-b]pyridines--a new class of multidrug resistance (MDR) modulators

To identify new potent multidrug resistance modulators, we have synthesized a series of novel thieno[2,3-b]pyridines and furo[2,3-b]pyridines, and examined their structure-activity relationships. All synthesized compounds were tested to determine BCRP1, P-gp, and MRP1 inhibitor activity, and most potent MDR modulators were also screened for their toxicity, cytotoxicity and Ca(2+) channel antagonist activity. Among these compounds, thieno[2,3-b]pyridine (6r) was found to exhibit a potent P-gp inhibitory action with EC50 = 0.3 ± 0.2 μM, MRP1 inhibitory action with EC50 = 1.1 ± 0.1 μM and BCRP1 inhibitory action with EC50 = 0.2 ± 0.05 μM and may represent suitable candidate for further pharmacological studies.

A facile solvent free Claisen-Schmidt reaction: synthesis of α,α'-bis-(substituted-benzylidene)cycloalkanones and α,α'-bis-(substituted-alkylidene)cycloalkanones

Solvent-free Claisen-Schmidt reactions of cycloalkanones with various substituted benzaldehydes (aryl aldehydes) using solid NaOH (20 mol%) and applying a grinding technique were studied. Quantitative yields (96-98%) of α,α'-bis-(substituted-benzylidene)cycloalkanones were obtained. Aliphatic aldehydes also provided α,α'-bis-(substituted-alkylidene)cycloalkanones in very good yields with minor amounts of a-(substituted-alkylidene)cycloalkanones. The catalytic performance of solid NaOH was examined. The molar ratio of NaOH was optimized. The catalytic effect of solid NaOH was also evaluated by comparing it with KOH, NaOAc, and NH(4)OAc and it turns out that 20 mol% of solid NaOH was good enough to catalyze the Claisen-Schmidt reactions of cycloalkanones with various substituted benzaldehydes. Additionally, the regioselectivity of the Claisen-Schmidt reaction of acetone with benzaldehyde was examined. Using the same method, we could synthesize the corresponding bis-benzylidene- and mono-benzylideneacetone separately in 98% and 96% yields, respectively.

Curcumin analogues as possible anti-proliferative & anti-inflammatory agents

A series of novel curcumin analogues has been designed, synthesized and tested in vitro/in vivo as potential multi-target agents. Their anti-proliferative and anti-inflammatory activities were studied. Compounds 1b and 2b were stronger inhibitors of soybean lipoxygenase (LOX) than curcumin. Analogue 1b was also the most potent aldose reductase (ALR2) inhibitor. Two compounds, (1a and 1f) exhibited in vivo anti-inflammatory activity comparable to that of indomethacin, whereas derivative 1i exhibited even higher activity. The derivatives were also tested for their anti-proliferative activity using three different human cancer cell lines. Compounds 1a, 1b, 1d and 2b exhibited significant growth inhibitory activity as compared to curcumin, against all three cancer cell lines. Lipophilicity was determined as R(M) values using RPTLC and theoretically. The results are discussed in terms of the structural characteristics of the compounds. Docking simulations were performed on LOX and ALR2 inhibitor 1b and curcumin. Compound 1b is well fitted in the active site of ALR2, binding to the ALR2 enzyme in a similar way to curcumin. Allosteric interactions may govern the LOX-inhibitor binding.

A general HPLC-UV method for the quantitative determination of curcumin analogues containing the 1,5-diaryl-3-oxo-1,4-pentadienyl pharmacophore in rat biomatrices

Curcumin and its derivatives generally display favorable cytotoxic activities against a number of cancer cell types. We focus our rational antineoplastic drug design program on curcumin analogues containing the 1,5-diaryl-3-oxo-1,4-pentadienyl pharmacophore. Favorable outcomes from pharmacological screens of this series demanded further pharmacokinetic evaluations to determine their suitability as effective compounds in vivo. To allow such evaluations and to provide a general, sensitive, rapid and simple method for the analysis of compounds containing the 1,5-diaryl-3-oxo-pentadienyl scaffold, we developed an HPLC method with ultraviolet detection for their detection in various biological matrices of a relevant preclinical species, i.e. the rat. Our HPLC method is specific for the analysis of many members in this series in rat blood, plasma, serum and hepatic microsomes following liquid-liquid extraction with TBME (1:30, v/v). The assay procedure involves chromatographic separation on a Zorbax-Eclipse C-18 column under isocratic conditions with the mobile phase consisting of acetonitrile and ammonium acetate buffer (pH 5.0, 10mM) in different ratios depending upon the compound. The method was validated for NC 2083 in rat serum and rat liver microsomes, a potential lead compound, to demonstrate its applicability. The standard curve was linear (r(2)≥0.997) from 50 to 5000ng/mL. Intra- and inter-day precision and accuracy of the method were within USFDA specified limits. The stability of NC 2083 was established in an auto-injector, on bench-top, during freeze-thaw cycles and long-term stability at -80°C for 40 days. The method is suitable for a number of compounds containing the 1,5-diaryl-3-oxo-pentadienyl scaffold with divergent logP values with only minor adjustments in the buffer to acetonitrile ratio of the mobile phase.

1,3-diaryl-2-propenones and 2-benzylidene-1,3-indandiones: a quest for compounds displaying greater toxicity to neoplasms than normal cells

A series of 1,3-diaryl-2-propenones 2a-j and analogous 2-benzylidene-1,3-indandiones 3a-j were evaluated against various neoplasms and normal cells. In general, greater cytotoxic potencies and selective toxicity to human malignant cells were observed by the compounds in series 2 rather than 3. In particular, 2i emerged as a lead molecule having an average CC(50) figure of 8.6 µM and a selective index value of 18. Various physicochemical features of 2a-j were correlated with the cytotoxic potencies to neoplastic cell lines which provide guidelines for expansion of this series of compounds. The enone 2i induced internucleosomal DNA fragmentation and activated caspase-3 in HL-60 cells suggesting that one of the ways in which the cytotoxicity of the compounds in series 2 is mediated towards some of the cell lines used in this study is by apoptosis. Neurotoxicity in mice was generally lower in series 2 than 3a-j.

Cytotoxic 2-benzylidene-6-(nitrobenzylidene)cyclohexanones which display substantially greater toxicity for neoplasms than non-malignant cells

Various 2-benzylidene-6-(nitrobenzylidene)cyclohexanones were prepared as candidate cytotoxins in which the nitro group was located in the ortho, meta and para positions leading to series 1-3, respectively. The CC(50) values towards human HSC-2 and HSC-4 oral squamous cell carcinomas as well as human HL-60 promyelocytic leukemic cells are in the low micromolar range in general. On the other hand, most of the compounds afforded clear evidence of being far less toxic towards human HGF gingival fibroblasts, HPC pulp cells and HPLF periodontal ligament fibroblasts which are non-malignant cells. Selectivity index (SI) figures were generated which are the ratios of the average CC(50) values towards normal cells and the CC(50) figure towards a malignant cell line. Huge SI values were obtained for many of the compounds. In particular 1c, 2f, 3c and 3g which have average SI values of >76, >38, 124 and 341, respectively, are clearly lead molecules affording direction for amplification of this area of study. A lead compound 1c caused internucleosomal DNA fragmentation and activation of caspase-3 in HL-60 cells but not in HSC-2 carcinomas. In a short-term toxicity study, doses up to and including 300 mg/kg of the majority of the compounds prepared in this study did not cause any mortalities to mice. Some guidelines for development of these tumor-selective cytotoxins are presented.

2-(3-Aryl-2-propenoyl)-3-methylquinoxaline-1,4-dioxides: a novel cluster of tumor-specific cytotoxins which reverse multidrug resistance

A series of 2-(3-aryl-2-propenoyl)-3-methylquinoxaline-1,4-dioxides 3a-l were prepared by condensation of various aryl aldehydes with 2-acetyl-3-methylquinoxaline-1,4-dioxide 2. These compounds inhibit the growth of human Molt 4/C8 and CEM T-lymphocytes and the IC(50) values are mainly in the 5-30 microM range. The quinoxaline 1,4-dioxide 3j inhibited the growth of 58 human tumor cell lines, particularly leukemic and breast cancer neoplasms. All of the compounds 3a-l reversed the multidrug resistance (MDR) properties of murine L-5178Y leukemic cells which were transfected with the human MDR1 gene. The MDR-reversing effect may be due to the conjugated pi-electron system forming a weak electron charge transfer complex with the P-glycoprotein-mediated efflux pump. The compounds in series 2 and 3 were assessed against HL-60, HSC-2, HSC-3 and HSC-4 malignant cells as well as HGF, HPC and HPLF normal cell lines which revealed that the majority of the compounds displayed a greater toxicity to neoplastic than normal cells. Various ways in which the project may be expanded are presented.

2-(3-Aryl-2-propenoyl)-3-methylquinoxaline-1,4-dioxides: a novel cluster of tumor-specific cytotoxins which reverse multidrug resistance

A series of 2-(3-aryl-2-propenoyl)-3-methylquinoxaline-1,4-dioxides 3a-l were prepared by condensation of various aryl aldehydes with 2-acetyl-3-methylquinoxaline-1,4-dioxide 2. These compounds inhibit the growth of human Molt 4/C8 and CEM T-lymphocytes and the IC(50) values are mainly in the 5-30 microM range. The quinoxaline 1,4-dioxide 3j inhibited the growth of 58 human tumor cell lines, particularly leukemic and breast cancer neoplasms. All of the compounds 3a-l reversed the multidrug resistance (MDR) properties of murine L-5178Y leukemic cells which were transfected with the human MDR1 gene. The MDR-reversing effect may be due to the conjugated pi-electron system forming a weak electron charge transfer complex with the P-glycoprotein-mediated efflux pump. The compounds in series 2 and 3 were assessed against HL-60, HSC-2, HSC-3 and HSC-4 malignant cells as well as HGF, HPC and HPLF normal cell lines which revealed that the majority of the compounds displayed a greater toxicity to neoplastic than normal cells. Various ways in which the project may be expanded are presented.

The cytotoxic properties and preferential toxicity to tumour cells displayed by some 2,4-bis(benzylidene)-8-methyl-8-azabicyclo[3.2.1] octan-3-ones and 3,5-bis(benzylidene)-1-methyl-4-piperidones

This study demonstrated that replacement of the axial protons on the C2 and C6 atoms of various 1-methyl-3,5-bis(benzylidene)-4-piperidones 3 by a dimethylene bridge leading to series 2 lowered cytotoxic potencies. Four compounds 2a and 3a-c emerged as lead molecules based on their toxicity towards different neoplasms and their selective toxicity for malignant rather than normal cells. Some possible reasons for the disparity between the IC(50) values in the two series of compounds are presented based on molecular modeling, logP values and respiration in rat liver mitochondria.

(2E,5E)-2,5-Bis(3,4,5-trimethoxy-benzyl-idene)cyclo-penta-none

The title compound, C₂₅H₂₈O₇, was prepared by the base-catalysed reaction of 3,4,5-trimethoxy­benzaldehyde with cyclo­penta­none. The mol­ecule has crystallographic twofold rotation symmetry and adopts an E-configuration about the central olefinic bonds. The two benzene rings and the central cyclo­penta­none ring are almost coplanar [dihedral angle = 4.7 (2)°].

Synthesis, structure, and bioevaluation of 2,5-bis(arylmethenyl)cyclopentanones

Curcumin is an excellent lead compound with a variety of bioactivity. Recent articles reported that curcumin's instability and low bioavailability in vivo are mainly due to its easily decomposable beta-diketone moiety. With the aim of bioactive curcumin analogs with better pharmacokinetic property, we present here 11 bis(arylmethenyl)cyclopentanones similar to curcumin and without beta-diketone moiety by reacting relevant arylaldehydes and cyclopentanones. The analogs were structurally determined by 1HNMR and MS spectra, and the crystal structure of 6 was analyzed by X-ray diffraction. Their antibacterial activities in vitro against seven Gram-positive and Gram-negative bacteria were tested, and their inhibition of TNF-alpha and IL-6 secretion in LPS-induced mouse macrophages was investigated using enzyme-linked immunosorbent assay. It was observed that several derivatives displayed higher activity when compared with curcumin, and most of the analogs exhibited activities against the ampicillin-resistant Gram-negative Enterobacter cloacae.

1-[4-(2-Aminoethoxy)phenylcarbonyl]-3,5-bis-(benzylidene)-4-oxopiperidines: a novel series of highly potent revertants of P-glycoprotein associated multidrug resistance

The 1-[4-(2-aminoethoxy)phenylcarbonyl]-3,5-bis-(benzylidene)-4-oxopiperidines 5-8 are a novel cluster of highly potent P-glycoprotein dependent multidrug resistance (MDR) revertants. Using a concentration of 4mug/mL, these compounds possess 11-43 times the potency of verapamil in reversing MDR in murine L-5178 lymphoma cells transfected with the human MDR1 gene. Structure-activity relationships reveal that the attachment of the N-aroyl group to various 3,5-bis(benzylidene)-4-piperidones is essential for MDR reversal to occur. In terms of potencies, the 1-piperidinyl group is the preferred terminal amine while the 4-methyl and 4-chloro substituents are the optimal groups for placement in the benzylidene aryl rings.

E,E-2-Benzylidene-6-(nitrobenzylidene)cyclohexanones: syntheses, cytotoxicity and an examination of some of their electronic, steric, and hydrophobic properties

Three series of structurally isomeric 2-benzylidene-6-(nitrobenzylidene) cyclohexanones 1-3 were prepared and evaluated against human Molt/C8 and CEM T-lymphocytes as well as murine L1210 cells. The IC(50) values of the majority of compounds are less than 10microM and in some assays, the figures for 1d and 1e are submicromolar. Correlations were discerned between cytotoxic potencies and the atomic charges on one of the olefinic carbon atoms, the torsion angles between an aryl ring, and the adjacent unsaturated group as well as logP values. Three representative compounds were examined for their effect on respiration in rat liver mitochondria.

1-Aryl-2-dimethylaminomethyl-2-propen-1-one hydrochlorides and related adducts: A quest for selective cytotoxicity for malignant cells

The primary objective of this study was to discover one or more clusters of compounds which are not equitoxic but display cytoselectivity toward different malignant cells. Furthermore a most important consideration is that such molecules should also display greater cytotoxic potencies to tumors than normal tissues. Two series of compounds are described which meet these criteria, namely the 1-aryl-2-dimethylaminomethyl-2-propen-1-one hydrochlorides 1a-e and 1-aryl-3-dimethylamino-2-hydroxymethyl-1-propanone hydrochlorides 2a-e. A number of these compounds possess marked cytotoxic potencies (IC(50) and CC(50) values within the 10(-6) and 10(-7) molar range) which are greater than these of the reference drug melphalan. Statistical analyses demonstrated that cytotoxic potencies are influenced by the size of the aryl substituents in series 1 and to some extent by the electronic properties of the aryl groups in series 2. The mode of action of a representative compound 1e in HL-60 cells included inducing apoptosis and activation of caspases -3, -8, and -9.