Design, synthesis and broad spectrum antibreast cancer activity of diarylindoles via induction of apoptosis in aggressive breast cancer cells.

Breast cancer is the second leading cause of cancer deaths in women with significant morbidity and mortality. Present study describes design, synthesis and detailed pharmacology of indole derivatives exhibiting remarkable broad spectrum antiproliferative activity against breast cancer cells. Detailed mechanistic evaluations confirmed induction of G0/G1 arrest, apoptosis induction, loss of mitochondrial integrity, enhanced ROS generation, autophagy, estrogen receptor ß-transactivation and increased tubulin polymerization. In in-vivo efficacy studies in rodent model, these indole derivatives induced significant regression in mice mammary tumour on 21 days daily oral dose. Moreover, compounds 19 and 23 were safe in Swiss albino mice in safety studies. These diarylindoles may further be optimized for better efficacy.

Design, synthesis, in vitro and in silico studies of 2, 3-diaryl benzofuran derivatives as antitubercular agents.

As a part of our drug discovery program for anti-tubercular agents, a total of seventeen 2, 3-diaryl benzofuran hybrids were designed, synthesized and screened for their anti-tubercular potential against Mycobacterium tuberculosis H37Ra avirulent strain. Out of seventeen, four derivatives showed significant activity against M. tuberculosis H37Ra avirulent strain (ATCC 25177) with MIC value ranging from 12.5 to 50 µg/mL but out of four, one derivative (9E) was significantly active (MIC 12.5 µg/mL), which was further supported by the molecular docking energy (-8.4 kcal/mol) with respect to the first line anti-tubercular drug, isoniazid (-6.2 kcal/mol) on the target Polyketide Synthase-13. All the derivatives were also evaluated for their cytotoxicity against the normal lung cell line L-132 by the MTT assay and no toxicity was observed up to 27.4 µg/mL concentration. This report on the antitubercular potential of benzofuran derivatives may be of great help in anti-tubercular drug development.

Insight into microtubule destabilization mechanism of 3,4,5-trimethoxyphenyl indanone derivatives using molecular dynamics simulation and conformational modes analysis.

Colchicine site inhibitors are microtubule destabilizers having promising role in cancer therapeutics. In the current study, four such indanone derivatives (t1, t9, t14 and t17) with 3,4,5-trimethoxyphenyl fragment (ring A) and showing significant microtubule destabilization property have been explored. The interaction mechanism and conformational modes triggered by binding of these indanone derivatives and combretastatin at colchicine binding site (CBS) of αß-tubulin dimer were studied using molecular dynamics (MD) simulation, principle component analysis and free energy landscape analysis. In the MD results, t1 showed binding similar to colchicine interacting in the deep hydrophobic core at the CBS. While t9, t14 and t17 showed binding conformation similar to combretastatin, with ring A superficially binding at the CBS. Results demonstrated that ring A played a vital role in binding via hydrophobic interactions and got anchored between the S8 and S9 sheets, H8 helix and T7 loop at the CBS. Conformational modes study revealed that twisting and bending conformational motions (as found in the apo system) were nearly absent in the ligand bound systems. Absence of twisting motion might causes loss of lateral contacts in microtubule, thus promoting microtubule destabilization. This study provides detailed account of microtubule destabilization mechanism by indanone ligands and combretastatin, and would be helpful for designing microtubule destabilizers with higher activity.

A novel synthesis of 2-arylbenzimidazoles in molecular sieves-MeOH system and their antitubercular activity.

Arylbenzimidazoles have been synthesized as antimycobacterial agents. An efficient synthesis has been developed for 2-arylbenzimidazoles from o-phenylenediamines and aromatic aldehydes in molecular sieves-methanol system. The methodology is straightforward to get 2-arylbenzimidazoles (3a-3z) in excellent yields with high chemoselectivity over 2-aryl-1-benzylbenzimidazoles (4a-4z). All these benzimidazole analogues were evaluated against M. tuberculosis in BACTEC radiometric assay. The compounds 4y and 4z exhibited potential antitubercular activity against M. tuberculosis H37RV, MIC at 16 µM and 24 µM respectively. The best compound of the series i.e. compound 4y was well tolerated by Swiss-albino mice in acute oral toxicity. Compound 4y possessing a diarylbenzimidazole core, can further be optimized for better activity.

Synthesis of pharmacologically important naphthoquinones and anticancer activity of 2-benzyllawsone through DNA topoisomerase-II inhibition.

Naphthoquinones are naturally occurring biologically active entities. Practical de novo syntheses of three naphthoquinones i.e. lawsone (1), lapachol (2), and ß-lapachone (3b) have been achieved from commercially available starting materials. The conversion of lapachol (2) to ß-lapachone (3b) was achieved through p-TSA/Iodine/BF3-etherate mediated regioselective cyclisation. Further, 2-alkyl and 2-benzyllawsone derivatives have been prepared as possible anticancer agents. Four derivatives exhibited significant anticancer activity and the best analogue i.e. compound 21a exhibited potential anticancer activity (IC50=5.2µM) against FaDu cell line. Compound 21a induced apoptosis through activation of caspase pathway and exerted cell cycle arrest at S phase in FaDU cells. It also exhibited significant topoisomerase-II inhibition activity. Compound 21a was found to be safe in Swiss albino mice up to 1000mg/kg oral dose.

Natural antitubulin agents: importance of 3,4,5-trimethoxyphenyl fragment.

Microtubules are polar cytoskeletal filaments assembled from head-to-tail and comprised of lateral associations of α/ß-tubulin heterodimers that play key role in various cellular processes. Because of their vital role in mitosis and various other cellular processes, microtubules have been attractive targets for several disease conditions and especially for cancer. Antitubulin is the most successful class of antimitotic agents in cancer chemotherapeutics. The target recognition of antimitotic agents as a ligand is not much explored so far. However, 3,4,5-trimethoxyphenyl fragment has been much highlighted and discussed in such type of interactions. In this review, some of the most important naturally occurring antimitotic agents and their interactions with microtubules are discussed with a special emphasis on the role of 3,4,5-trimethoxyphenyl unit. At last, some emerging naturally occurring antimitotic agents have also been tabulated.

Synthesis of neolignans as microtubule stabilisers.

Tubulin is a well established target for anticancer drug development. Lignans and neolignans were synthesized as tubulin interacting agents. Neolignans 10 and 19 exhibited significant anticancer activity against MCF-7 and MDAMB-231 human breast cancer cell lines. Both the compounds effectively induced stabilization of microtubule at 4 and 20 µM concentrations respectively. Neolignan 10 induced G2/M phase arrest in MCF-7 cells. Docking experiments raveled that 10 and 19 occupied the same binding pocket of paclitaxel with some difference in active site amino acids and good bioavailability of both the compounds. In in vivo acute oral toxicity 10 was well tolerated up to 300 mg/kg dose in Swiss-albino mice.

Identification of 1-chloro-2-formyl indenes and tetralenes as novel antistaphylococcal agents exhibiting sortase A inhibition.

Tetralene and indene compounds have shown inhibitory activity against human pathogen, Mycobacterium tuberculosis. Their potential use as antistaphylococcal agent against drug-resistant Staphylococcus aureus has not been explored so far. We determined in vitro antistaphylococcal activity and mechanism of action of these compounds as sortase A inhibitors through in silico analysis followed by biological assays. Tetralene and indene series were tested against S. aureus strains MTCC96, MRSA, and VA30. Three compounds showed significant reduction in MIC in both wild-type and drug-resistant S. aureus strains. In silico absorption, distribution, metabolism, excretion, and toxicity analysis of identified leads and cytotoxicity testing with colorimetric method using Vero and WRL-68 cell lines showed no significant cytotoxic effects. Molecular docking of these molecules with sortase A (PDB: 2KID) showed H-bond interaction with functional site residue Arg197 of sortase A. Sortase A inhibition assay was developed by expressing SrtA∆N from S. aureus strain MTCC96. Tetralene and indene compounds were found to have sortase A inhibitory potential. S. aureus strain MTCC96 treated with these compounds showed surface-sorting inhibition of fibronectin-binding protein and reduction in adherence to host extracellular matrix protein, fibronectin. 1-Chloro, 2-formyl, 6-methoxy, 1-tetralene (Tet-5), 1,5-dichloro, 2-formyl, 1-indene (Tet-20) and 1-chloro, 2-formyl, 5,6-methylenedioxy, and 1-indene (Tet-21) exhibited antistaphylococcal activity along with sortase A inhibition. The results also indicate the possible role of these leads in other reactions essential for cell viability.

Studies on substituted benzo[h]quinazolines, benzo[g]indazoles, pyrazoles, 2,6-diarylpyridines as anti-tubercular agents.

Various substituted 5,6-dihydro-8-methoxybenzo[h]quinazolin-2-amine, 1-(3-(4-alkoxyphenyl)-7-methoxy-3,3a,4,5-tetrahydro-2H benzo[g]indazol-2-yl)ethanone, pyrazole and 2,6-diarylpyridine derivatives have been synthesized in good yields by an efficient methodology. The synthesized compounds (4-23) were evaluated for their in vitro anti-tubercular activity against Mycobacterium tuberculosis H37Rv strain. Compounds 6a, 6c, 8a, 19a and 19e exhibited significant anti-tubercular activity at MIC values 50, 100, 50, 25 and 100µM concentration. In vitro cytotoxicity data using THP-1 cells indicated that most active compound 19a is safe as its MIC value is much lower than the cytotoxic value.

In vitro production of steroidal saponin, total phenols and antioxidant activity in callus suspension culture of Paris polyphylla Smith: an important Himalayan medicinal plant.

Paris polyphylla Smith (Melanthiaceae) family, which is native to the Himalayan region, has received a lot of attention recently due to its extensive history of usage in traditional medicine. The production of steroidal saponin from callus suspension cultures of P. polyphylla was observed in the current study. The current study attempted to develop a P. polyphylla plant callus suspension culture through optimization of cultivation technique for callus suspension, quantification of total phenolic components and estimation of the extract's antioxidant activity. A light-yellow callus was formed within six weeks of cultivating rhizomes on Murashige and Skoog (MS) media supplemented with Thidiazuron (TDZ). Furthermore, the effect of TDZ, Methyl Jasmonate (MeJA), and Yeast Extract (YE) on callus growth, steroidal saponin (dioscin and diosgenin), total phenolic content, total flavonoids, total tannin, and total antioxidant activity was also measured. The medium containing 0.5 µM TDZ depicted the maximum callus biomass (2.98 g fresh weight). Significantly high phenolic and tannin content was observed in the MS medium containing 50 µM MeJA, whereas, no significant increase was observed in total tannin production in any treatment. Three in vitro assays, DPPH (2,2-diphenyl-1-picrylhydrazyl), ABTS (2,2'-azino-bis (3-ethylbenzothiazoline- 6-sulfonic acid)) and FRAP (ferric ion reducing antioxidant potential) and FC (Folin-Ciocalteu), were used to assess antioxidant potential of callus. Maximum antioxidant analysis reported in 1.0 µM TDZ (6.89 mM AAE/100 g) containing medium followed by 50 µM MeJA (6.44 mM AAE/100 g). The HPLC analysis showed a high presence of dioscin and diosgenin (5.43% and 21.09%, respectively) compared to the wild sample (2.56% and 15.05%, respectively). According to the results, callus produced on media supplemented with 50 µM MeJA have significant phenolic contents and elevated antioxidant activity; nevertheless, callus growth was greater in the presence of 0.5 µM TDZ. The findings of the current study have commercial implications since greater biomass production will result in active phytochemicals that the pharmaceutical and nutraceutical sectors are in need desperately.

Synthesis and anticancer activity of 2-benzylidene indanones through inhibiting tubulin polymerization.

In an attempt to discover a potent and selective anticancer agent, gallic acid has been modified to benzylidene indanones as tubulin polymerization inhibitors. These compounds were evaluated against several human cancer cell lines and also evaluated for inhibition of tubulin polymerase in in vitro assays. Three of the analogues exhibited strong cytotoxicity against human cancer cell lines IC(50)=10-880 nM and also showed tubulin polymerization inhibition (IC(50)=0.62-2.04 µM). Compound 9j, the best candidate of the series was found to be non-toxic in acute oral toxicity in Swiss-albino mice up to 1000 mg/kg dose.

1-Chloro-2-formyl indenes and tetralenes as antitubercular agents.

1-Chloro-2-formyl indenes and tetralenes have been synthesized using Vilsmeier-Haack-Arnold reaction onto indanones and tetralones. Most of these analogues exhibited antitubercular activity against Mycobacterium tuberculosis H37Rv strain with MICs ranging from 30 to 500 µg/mL. Analogue 13 was further modified to some derivatives. The most active analogue 23 showing MIC at 30 µg/mL was further evaluated for acute oral toxicity in Swiss albino mice and was found to be safe up to 300 mg/kg dose.

Brevifoliol and its Analogs: A New Class of Anti-tubercular Agents.

Brevifoliol is an abeo-taxane isolated from the Taxus wallichiana needles; eighteen semisynthetic esters derivatives of brevifoliol were prepared by Steglich esterification and screened for their anti-tubercular potential against Mycobacterium tuberculosis H37Ra avirulent strain. The 3- [chloro (7)] and 3, 5-[dinitro (8)] benzoic acid ester derivatives were most active (MIC 25 ug/ml) against the pathogen. Further, in silico docking studies of the active derivative 7 with mycobacterium enzyme inhA (enoyl-ACP reductase) gave the LibDock score of 152.68 and binding energy of -208.62 and formed three hydrogen bonds with SER94, MET98, and SER94. Similarly, when derivative 8 docked with inhA, it gave the LibDock score of 113.55 and binding energy of -175.46 and formed a single hydrogen bond with GLN100 and Pi-interaction with PHE97. On the other hand, the known standard drug isoniazid (INH) gave the LibDock score of 61.63, binding energy of -81.25 and formed one hydrogen bond with ASP148. These molecular docking results and the way of binding pattern indicated that compounds 7 and 8 bound well within the binding pocket of inhA and showed a higher binding affinity than the known drug isoniazid. Additionally, both the derivatives (7 and 8) showed no cytotoxicity, with CC50 195.10 and 111.36, respectively towards the mouse bone marrow-derived macrophages.

An improved synthesis of indanocine and antiproliferative activity of 2-benzylindanocine via microtubule destabilization.

Indanocine, a potent anticancer investigational drug of National Cancer Institute-USA, has been much discussed in recent years. Present communication aimed at total synthesis of indanocine and its close analogues. Total synthesis was improved by double yields than previously reported yields. Some of the benzylidene and 2-benzyl derivatives with free rotation at C2 position exhibited potential cytotoxicities against various human cancer cell lines. Five such analogues exhibited potential antiproliferative effect against HCT-116 and MIA PACA-2 cell lines. Benzylindanocine 12i induced microtubule destabilization by occupying colchicine binding pocket of ß-tubulin. It also exhibited anti-inflammatory activity by down-regulating IL-6 and TNF-α. In Ehrlich ascites carcinoma model, 12i reduced 78.4% of EAC tumour in Swiss albino mice at 90 mg/kg (i.p.) dose. Further, in in vivo safety studies, 12i was found to be safe to rodents up to 1,000 mg/kg dose. Concomitant anticancer and anti-inflammatory activity of benzylindanocine is distinctive, which suggests its further optimization for better efficacy and druggability.

Antitubercular potential of plants: a brief account of some important molecules.

Mycobacterium tuberculosis is the most lethal pathogen causing tuberculosis in human. After the discovery of antitubercular drugs pyrazinamide, rifampicin, isoniazid, streptomycin, and ethambutol (PRISE), the disease was controlled for a limited period. However, over the course of their usage, the pathogen acquired resistance and evolved into multi-drug resistant, single-drug resistant, and extensive drug resistant forms. A good number of plant secondary metabolites are reported to have antitubercular activity comparable to the existing antitubercular drugs or sometimes even better in potency. A well-defined strategy is required to exploit these phytomolecules as antitubercular drugs. This review gives concise up-to-date information regarding the chemistry and pharmacology of plant-based leads and some insight into their structure-activity relationship.

Antitubercular potential of some semisynthetic analogues of phytol.

Phytol, a diterpene alcohol was modified to several semisynthetic analogues. Some of the modifications were done logically to enhance lipophilicity of the molecule. Analogues 14, 16 and 18 exhibited antitubercular activity (MIC 15.6-50microg/mL) better than phytol (100microg/mL). The most potent analogue 18 was evaluated for in vivo toxicity in Swiss albino mice and was well tolerated by the experimental animals up to 300mg/kg body weight as a single oral acute dose.

Fluorinated benzylidene indanone exhibits antiproliferative activity through modulation of microtubule dynamics and antiangiogenic activity.

The application of fluorine in drug design has been understood significantly by the medicinal chemists in recent years. Modulation of tubulin-microtubule dynamics is one of the most effective targets for cancer chemotherapeutics. A logically designed and identified lead compound, fluorinated benzylidene indanone 1 has been extensively evaluated for cancer pharmacology. It occupied colchicine binding pocket acting as microtubule destabilizer and induced a G2/M phase arrest in MCF-7 cells. Compound 1 exerted an antiangiogenic effect in MCF-7 cells by down-regulating Vascular Endothelial Growth Factor (VEGF) and Hypoxia Inducible Factor-α (HIF-α). In in-vivo efficacy in C3H/Jax mice mammary carcinoma model, benzylidene indanone 1 reduced tumour volumes by 48.2%. Further in acute oral toxicity studies compound 1 was well tolerated and safe up to 1000 mg/kg dose in Swiss albino mice. The fluorinated benzylidene indanone 1, a new chemical entity (NCE) can further be optimized for better efficacy against breast adenocarcinoma.1.

Antiproliferative activity of diarylnaphthylpyrrolidine derivative via dual target inhibition.

Breast cancer is the second leading cause of deaths in women globally. Present communication deals with design and synthesis of a few diarylnaphthyls as possible anti-breast cancer agents. Among the thirty three representatives with significant antiproliferative activity compounds 23 and 50 were quite efficacious against human breast cancer cells. Compound 50 induced apoptosis in both MCF-7 and MDA-MB-231 cells and exerted S phase and G2/M phase arrest respectively via distinct mechanistic pathways. It showed moderate microtubule destabilization. Further, it exhibited DNA topoisomerase-II inhibition effect in MCF-7 cells. It was well tolerable and found safe up to 300 mg/kg dose in Swiss albino mice. The dual action antiproliferative effect of compound 50 is quite interesting and warrants for future development.

Brevifoliol ester induces apoptosis in prostate cancer cells by activation of caspase pathway.

Prostate cancer is fourth most abundant cancer type around the globe. Brevifoliol, a rearranged taxoid from Taxus walllichiana needles has been derivatized as C5 esters using Steglich esterification reaction. Seventeen diverse analogues were evaluated against a panel of human cancer cell lines by MTT assay. Among these, two of the semi-synthetic analogues, that is, 13 and 16 exhibited potent cytotoxicity, selectively against PC-3, prostate cancer cell lines. In cell cycle analysis, analogue 13 induced S and G2/M phase arrest and induced apoptosis by activating caspase-3. Compound 13 showed moderate efficacy in in-vivo Ehrlich ascites carcinoma in Swiss albino mice. Further, compound 13 was found to be safe in Swiss albino mice up to 1,000 mg/kg dose in acute oral toxicity. Brevifoliol ester 13 may further be optimized for better efficacy.

Antifungal activity of Glycyrrhiza glabra extracts and its active constituent glabridin.

Glabridin, an active constituent of Glycyrrhiza glabra roots, was found to be active against both yeast and filamentous fungi. Glabridin also showed resistance modifying activity against drug resistant mutants of Candida albicans at a minimum inhibitory concentration of 31.25-250 microg/mL. Although the compound was reported earlier to be active against Candida albicans, but this is the first report of its activity against drug resistant mutants.