High order approximation on non-uniform meshes for generalized time-fractional telegraph equation.

This paper presents a high order approximation scheme to solve the generalized fractional telegraph equation (GFTE) involving the generalized fractional derivative (GFD). The GFD is characterized by a scale function σ ( t ) and a weight function ω ( t ) . Thus, we study the solution behavior of the GFTE for different σ ( t ) and ω ( t ) . The scale function either stretches or contracts the solution while the weight function dramatically shifts the numerical solution of the GFTE. The time fractional GFTE is approximated using quadratic scheme in the temporal direction and the compact finite difference scheme in the spatial direction. To improve the numerical scheme's accuracy, we use the non-uniform mesh. The convergence order of the whole discretized scheme is, O ( τ 2 α - 3 , h 4 ) , where τ and h are the temporal and spatial step sizes respectively. The outcomes of the work are as follows: •The error estimate for approximation of the GFD on non-uniform meshes is established.•The numerical scheme's stability and convergence are examined.•Numerical results for four examples are compared with those obtained using other method. The study shows that the developed scheme achieves higher accuracy than the scheme discussed in literature.

Styryl quinazolinones and its ethynyl derivatives induce myeloid differentiation.

The tumor suppressor transcription factor CCAAT enhancer-binding protein α (C/EBPα) expression is downregulated in myeloid leukemias and enhancement of C/EBPα expression induces granulocytic differentiation in leukemic cells. Previously we reported that Styryl quinazolinones induce myeloid differentiation in HL-60 cells by upregulating C/EBPα expression. To identify more potent molecule that can induce leukemic cell differentiation we synthesized and evaluated new series of styryl quinazolinones, ethynyl styryl quinazolinones, styryl quinolinones and thienopyrimidinones. Thienopyrimidinones were found toxic and styryl quinolinones were found inactive. Ethynyl styryl quinazolinone 39 and styryl quinazolinone 5 were found active on par with the earlier reported analogues 1 and 2 suggesting that the 5-nitro furan-2-yl styryl quinazolinones find a real promise in leukemic cell differentiation. The improved potency of 5 suggested that further modifications in the 5-nitro furan-2-yl styryl quinazolinones can be at the phenyl substitution at the 3-position of the quinazolinone ring apart from the 5-position of the heteroaryl ring.

Anti-tubercular agents. Part 7: a new class of diarylpyrrole-oxazolidinone conjugates as antimycobacterial agents.

In an effort to discover new anti-tubercular agents, a series of new diarylpyrrole-oxazolidinone conjugates have been designed and synthesized. The anti-tubercular activity of these new conjugates (4a-n and 5a-d) against Mycobacterium tuberculosis H37Rv and drug resistance strains such as M. tuberculosis Rif(R) and M. tuberculosis XDR are discussed, wherein compound 4i has been found to be the most potent amongst the series. MTT assay was performed on the active conjugates of the series (4b-f, 4i and 5c) against mouse macrophage (J-774) cells to evaluate cytotoxic effects and selective index values. In addition, these conjugates (4a-n and 5a-d) are also tested against a panel of Gram-positive and Gram-negative bacterial strains. The docking studies have been carried out to provide some insight into the mechanism of action for this class of compounds.

Synthesis and biological evaluation of diaryl ether linked DC-81 conjugates as potential antitumor agents.

A series of new diaryl ether linked pyrrolobenzodiazepine (PBD) conjugates (4a-i, 5a-i and 6a-f) was synthesized and evaluated for their anticancer activity against a panel of 11 human cancer cell lines. These conjugates exhibited significant anticancer activity with GI50 values in the range of 0.1-3.88 µM. Some of the potent conjugates (4b, 4h, 5h, 6b, 6c and 6e) were further investigated on cell cycle distribution. FACS analysis showed the accumulation of cells in G0 phase indicating the apoptosis inducing nature of these conjugates. Moreover, compound 6b caused a decrease in the mitochondrial membrane potential, which indicates the apoptotic nature of the compound through mitochondrial mediated pathway. Further conjugates 4b, 4h and 6b induce the activation of caspase and PARP proteins, followed by apoptotic cell death in MCF7 cell line.

Recent advances on structural modifications of benzothiazoles and their conjugate systems as potential chemotherapeutics.

INTRODUCTION: Benzothiazole scaffold comprises a bicyclic ring system and is known to exhibit a wide range of biological properties including antimicrobial and anticancer activities. Benzothiazole derivatives have long been therapeutically used for the treatment of various diseases. However, in recent years, 2-arylbenzothiazoles have emerged as an important pharmacophore in the development of antitumor agents. The promising biological profile and synthetic accessibility have been attractive in the design and development of new benzothiazoles and their conjugate systems as potential chemotherapeutics. AREAS COVERED: This review mainly focuses on the structural modifications of benzothiazole scaffold, development of various series of benzothiazoles and their conjugates as new antitumor agents. Furthermore, heterocyclic derivatives bearing benzothiazole moiety and their in vitro as well as in vivo screening, structure-activity relationships (SAR), mechanism, pharmacokinetics, clinical use and their future therapeutic applications are discussed here. EXPERT OPINION: A large number of benzothiazole derivatives discussed here possess potent anticancer activity and can be further developed as drug candidates. Benzothiazole conjugates could also display synergistic effect and still there is a need to use the drug combinations permitting lower dose and development of new generation of drugs. Despite encouraging results that have been observed for their response to tumor in clinical studies, full characterization of their toxicity is further required for their clinical usage as safe drugs for the treatment of cancer. We believe that this review gives a better understanding and scope for future drug design and development of benzothiazole-based compounds to implicate their use in cancer chemotherapy.

3-substituted 2-phenylimidazo[2,1-b]benzothiazoles: synthesis, anticancer activity, and inhibition of tubulin polymerization.

A new series of 3-substituted 2-phenylimidazo[2,1-b]benzothiazoles (3 a-h) were synthesized by C-arylation of 2-arylimidazo[2,1-b]benzothiazoles using palladium acetate as catalyst, and the resulting compounds were evaluated for their anticancer activity. Compounds 3 a, 3 e, and 3 h exhibited good antiproliferative activity, with GI50 values in the range of 0.19-83.1 µM. Compound 3 h showed potent anticancer efficacy against 60 human cancer cell lines, with a mean GI50 value of 0.88 µM. This compound also induced cell-cycle arrest in the G2/M phase and inhibited tubulin polymerization followed by activation of caspase-3 and apoptosis. A high-throughput tubulin polymerization assay showed that the level of inhibition for compound 3 h is similar to that of combretastatin A-4. Molecular modeling studies provided a molecular basis for the favorable binding of compounds 3 a, 3 e, and 3 h to the colchicine binding pocket of tubulin.

2-Anilinonicotinyl linked 2-aminobenzothiazoles and [1,2,4]triazolo[1,5-b] [1,2,4]benzothiadiazine conjugates as potential mitochondrial apoptotic inducers.

A series of N-(2-anilino-pyridyl) linked 2-amino benzothiazoles (4a-n) and [1,2,4]triazolo [1,5-b]benzothiadiazine conjugates (5a-j) have been designed, synthesized and evaluated for their antiproliferative activity. Some of these compounds (4h-k, 4n, and 5e) have exhibited potent cytotoxicity specifically against human leukemia HL-60 cell lines with IC(50) values in the range of 0.08-0.70 µM. All these compounds were tested for their effects on the cell cycle perturbations and induction of apoptosis. Morphological evidences of apoptosis, including fragmentation of nuclei and inter nucleosomal DNA laddering formation were clearly observed after 24h exposure to compound 4i. Flow cytometry analysis revealed that compound 4i showed drastic cell cycle perturbations due to concentration dependant increase in the sub-G0 region which comprises of both the apoptotic and debris fraction, thus implying the extent of cell death. These compounds trigger the mitochondrial apoptotic pathway that results in the loss of mitochondrial membrane potential through activation of multiple caspases followed by activation of caspase-3, and finally cleavage of PARP. Further the mechanism of cell death was analysed by fluorescent microscopic analysis and also by scanning electron microscopy. The cytotoxicity of 4i correlated with induction of apoptosis, caspases activation and DNA damage and thus indicating the apoptotic pathway of anticancer effect of these compounds.

Design, synthesis and biological evaluation of 3,5-diaryl-isoxazoline/isoxazole-pyrrolobenzodiazepine conjugates as potential anticancer agents.

A series of 3,5-diaryl-isoxazoline/isoxazole linked pyrrolo[2,1-c][1,4]benzodiazepine (PBD) conjugates were prepared. These conjugates showed potent anticancer activity with GI(50) values in the range of <0.1-3.6 microM. Some of these PBD conjugates (6a-c) with promising anticancer activity were further investigated on the cell cycle distribution. Moreover, these PBD conjugates exhibited G0/G1 arrest, enhancement in the levels of p53 protein as well as mitochondrial-mediated intrinsic pathway, leading to release of cytochrome c, activation of caspase-3, cleavage of PARP and subsequent apoptotic cell death. Hence these PBD conjugates with 6a being the most potent one could be be taken up for preclinical studies either alone or in combination with existing therapies.

Synthesis, anticancer activity and apoptosis inducing ability of anthranilamide-PBD conjugates.

A series of novel anthranilamide linked pyrrolo[2,1-c][1,4]benzodiazepine conjugates were prepared and evaluated for their anticancer activity. The effects of three promising PBD conjugates on cell cycle of cancerous cell line A375 were investigated. These promising compounds showed the characteristic features of apoptosis like enhancement in the levels of p53 and activation of caspase-3.

Quinazolinone linked pyrrolo[2,1-c][1,4]benzodiazepine (PBD) conjugates: Design, synthesis and biological evaluation as potential anticancer agents.

A series of novel quinazolinone linked pyrrolobenzodiazepine (PBD) conjugates were synthesized. These compounds 4a-f and 5a-f were prepared in good yields by linking C-8 of DC-81 with quinazolinone moiety through different alkane spacers. These conjugates were tested for anticancer activity against 11 human cancer cell lines and found to be very potent anticancer agents with GI(50) values in the range of <0.1-26.2microM. Among all the PBD conjugates, one of the conjugate 5c was tested against a panel of 60 human cancer cells. This compound showed activity for individual cancer cell lines with GI(50) values of <0.1microM. The thermal denaturation studies exhibited effective DNA binding ability compared to DC-81 and these results are further supported by molecular modeling studies. The detailed biological aspects of these conjugates on A375 cell line were studied. It was observed that compounds 4b and 5c induced the release of cytochrome c, activation of caspase-3, cleavage of PARP and subsequent cell death. Further, these compounds when treated with A375 cells showed the characteristic features of apoptosis like enhancement in the levels of p53, p21 and p27 inhibition of cyclin dependent kinase-2 (CDK2) and suppression of NF-kappaB. Moreover, these two compounds 4b and 5c control the cell proliferation by regulating anti-apoptotic genes like (B-cell lymphoma 2) Bcl-2. Therefore, the data generated suggests that these PBD conjugates activate p53 and inhibit NF-kappaB and thereby these compounds could be promising anticancer agents with better therapeutic potential for the suppression of tumours.