C-30 analogues of betulinic acid as potent cytotoxic agents: design, synthesis, biological evaluation and in-silico studies.

In an endeavour to improve the anti-cancer activity of betulinic acid (BA), a series of C-30 derivatives were envisaged and synthesized with a novel synthetic approach. All the derivatives were evaluated for cytotoxic activity by MTT assay against six different human cancer cell lines: prostate (PC3), lung (A549), human hepatocellular carcinoma (HepG2), human leukemia (Molt-4), pancreatic (Panc-1) and breast (MCF-7). The data revealed that compound 16 was observed most promising cytotoxic agent with IC50 values of 7.43 µM, 9.1 µM, and 9.64 µM against A549, MCF-7, and PC3 cancer cell lines respectively. A further mechanistic study confirmed compound 16 showed significant cell death by arresting the cell cycle in the G1 phase and inducing apoptosis in A549 cells.Communicated by Ramaswamy H. Sarma.

Pd-catalyzed synthesis of hetero 1,2-interlinked C-disaccharides by coupling of iodo glycals with glycals.

A facile synthesis of C1-C2 interlinked disaccharides is achieved from readily available iodo-glycals and unsubstituted glycals. Ester-protected donors reacted with ether-protected acceptors under Pd-Ag catalysis to access C-disaccharides bearing C-3 vinyl ether, which upon ring opening by Lewis acid furnished pi-extended conjugated orthogonally protected chiral ketones. Benzyl deprotection and reduction of the double bonds resulted in a fully saturated disaccharide stable toward acid hydrolysis.

Isolation and anticancer activity evaluation of rare Bisaryl anthraquinone antibiotics from novel Streptomyces sp. strain of NW Himalayan region.

Biosynthesis of bisaryl preanthraquinone antibiotics by various microorganisms differs in monomeric subunits as well as their dimerization positions leading to different configurations. The present study relates to the production of rare bisaryl anthraquinone antibiotics by a new Streptomyces strain isolated from Shivalik region of NW Himalayas. In vitro anticancer and anti-migratory effects of Setomimycin (9,9' bisanthraquinone antibiotic) was seen with a significant reduction in the expression of both MEK as well as ERK pathways in a dose dependent manner at 6.5 µM & 8 µM concentration in HCT-116 and 5.5 µM & 7 µM concentration in MCF-7 cells. In vivo studies in aggressive orthotopic mouse mammary carcinoma model (4T1) demonstrated about 76% reduction of primary tumor weight and 90.5% reduction in the tumor volume within two weeks. In vivo pharmacokinetics study of setomimycin revealed that it can be rapidly absorbed with an adequate plasma exposure and half-life which can be linked to its in vivo efficacy.

Ni-catalyzed domino transformation of enopyranoses and 2-iodo phenols/anilines to pyrano cis fused dihydro-benzofurans/indoles.

A Ni-catalyzed direct access to various pyrano cis-fused dihydro benzofurans and indoles from unsaturated enopyranoses and o-iodo phenols/anilines is developed. The domino synthesis of pyrano C2-C1 and C3-C2 cis-fused heteroarynes were achieved both from glycals and pseudo glycals in which heteroatoms are linked at C2 and C3 positions, respectively, with excellent chemo-selectivity.

Design, Synthesis, biological investigations and molecular interactions of triazole linked tacrine glycoconjugates as Acetylcholinesterase inhibitors with reduced hepatotoxicity.

Tacrine is a known Acetylcholinesterase (AChE) inhibitors having hepatotoxicity as main liability associated with it. The present study aims to reduce its hepatotoxicity by synthesizing tacrine linked triazole glycoconjugates via Huisgen's [3 + 2] cycloaddition of anomeric azides and terminal acetylenes derived from tacrine. A series of triazole based glycoconjugates containing both acetylated (A-1 to A-7) and free sugar hydroxyl groups (A-8 to A-14) at the amino position of tacrine were synthesized in good yield taking aid from molecular docking studies and evaluated for their in vitro AChE inhibition activity as well as hepatotoxicity. All the hybrids were found to be non-toxic on HePG2 cell line at 200 µM (100 % cell viability) as compared to tacrine (35 % cell viability) after 24 h of incubation period. Enzyme kinetic studies carried out for one of the potent hybrids in the series A-1 (IC50 0.4 µM) revealed its mixed inhibition approach. Thus, compound A-1 can be used as principle template to further explore the mechanism of action of different targets involved in Alzheimer's disease (AD) which stands as an adequate chemical probe to be launched in an AD drug discovery program.

Description of Druglike Properties of Safranal and Its Chemistry behind Low Oral Exposure.

Safranal, a plant secondary metabolite isolated from saffron, has been reported for several promising pharmacological properties toward the management of Alzheimer's disease. In the present study, we observe and report for the first time about several druglike attributes of safranal, such as adherence to Lipinski's rule of five; optimum lipophilicity; high permeability; low blood-to-plasma ratio; less to moderate propensity to interact with P-glycoprotein (P-gp) or breast cancer-resistant protein (BCRP) transporters; and high plasma protein binding as common to most of the marketed drugs using in vitro and ex vivo models. In spite of the above attributes, in vivo oral absorption was found to be very poor, which is linked to the structural integrity of safranal in simulated gastric fluid, simulated intestinal fluid, plasma, and liver microsomes. Moreover, the presence of unsaturated aldehyde moiety in safranal remains in equilibrium with its hydroxylated acetal form. Further research work is required to find out the stable oral absorbable form of safranal by derivatization of its aldehyde group without losing its potency.

Carbohydrate Modifications of Neoandrographolide for Improved Reactive Oxygen Species-Mediated Apoptosis through Mitochondrial Pathway in Colon Cancer.

Modifications at the carbohydrate moiety of neoandrographolide, isolated from the medicinal plant Andrographis paniculata, result in more potent and less toxic derivatives, namely, 4',6'-benzylidene neoandrographolide (2b) and 4'6'-p-methoxybenzylidene neoandrographolide (2c). These showed improved cytotoxicity against SW-620, PC-3, and A549 cancer cell lines. Nuclear morphology studies were conducted on compound 2b by 4',6-diamidino-2-phenylidole staining and detection of intracellular reactive oxygen species (ROS) accumulation. It showed an increase in the generation of cellular and mitochondrial ROS level. The probable relation of B-cell lymphoma-2 (Bcl-2, an apoptosis inhibitor) to B-cell lymphoma-2-associated X protein (Bax, an apoptosis promoter) ratio with caspase-3 (apoptosis coordination enzyme) in the colon cancer cell line SW-620 was investigated, and it was discovered that upon 2b treatment, the expression of caspase-3 Bax increased remarkably. However, in 2b-treated cells, the expression of Bcl-2 was downregulated as compared to untreated cells.

Green chemistry appended synthesis, metabolic stability and pharmacokinetic assessment of medicinally important chromene dihydropyrimidinones.

A green chemistry approach has been developed for the synthesis of chromene dihydropyrimidinone (CDHPM) using recyclable Fe/Al pillared clay catalyst. Pharmacokinetic parameters like aqueous solubility, lipophilicity, P-glycoprotein (P-gp) ATPase activity, permeability, plasma protein binding, red blood cell (RBC) partitioning, metabolic stability in liver microsomes and in silico computations have been studied for the most potent anticancer chromene dihydropyrimidinone hybrid 1. This compound exhibited low solubility, optimum lipophilicity, no P-gp inhibitory activity, intermediate permeability, high plasma protein binding, low RBC partitioning, acceptable metabolic stability in rat liver microsomes (RLM) as well as human liver microsomes (HLM) with transitional hepatic extraction ratio.

Indolylkojyl methane analogue IKM5 potentially inhibits invasion of breast cancer cells via attenuation of GRP78.

PURPOSE: More than 90% of the breast cancer deaths occur due to the metastasis of the cancer cells to secondary organ sites. Increased Glucose-regulated protein 78 (GRP78) expression is critical for epithelial-mesenchymal transition (EMT) and invasion in breast cancer resulting in poor patient survival outcomes. Therefore, there is an urgent need of potential inhibitors of GRP78 for the abrogation of invasion and metastasis in breast cancer. METHODS: We investigated the effect of IKM5 (2-(1-(1H-indol-3-yl)octyl)-3-hydroxy-6-(hydroxymethyl)-4H-pyran-4-one) (a novel Indolylkojyl methane analogue) on invasion abilities of human breast cancer cells employing invadopodia formation, Matrigel invasion assays, and mouse models for metastasis. The mechanism underlying the anti-invasive effect of IKM5 was examined through molecular docking, immunoblotting, immunocytochemistry, co-immunoprecipitation analysis, siRNA silencing, and sub-cellular fractionation studies. RESULTS: Treatment with IKM5 at its sub-toxic concentration (200 nM) suppressed invasion and invadopodia formation, and growth factor-induced cell scattering of aggressive human breast cancer MDA-MB-231, MDA-MB-468, and MCF7 cells. IKM5 spontaneously binds to GRP78 (Ki = 1.35 µM) and downregulates its expression along with the EMT markers MMP-2, Twist1, and Vimentin. Furthermore, IKM5 amplified the expression and nuclear translocation of tumor suppressor Par-4 to control NF-kB-mediated pro-EMT activities. Interestingly, IKM5 disrupts the interaction between GRP78 and TIMP-1 by inhibiting GRP78 in a Par-4-dependent manner. Moreover, IKM5 inhibited tumor growth and lung metastasis at a safe dose of 30 mg/kg/body weight. CONCLUSION: Our study warrants IKM5, a potential anticancer agent that can abrogate invasion and metastasis, suggesting its clinical development for the treatment of patients with advanced breast cancer.

Synthesis and Investigation of the Role of Benzopyran Dihydropyrimidinone Hybrids in Cell Proliferation, Migration and Tumor Growth.

BACKGROUND: Cancer is the second leading cause of mortality worldwide after heart diseases, and lung cancer is the topmost cause of all cancer-related deaths in both sexes. Dihydropyrimidinones (DHPMs) are medicinally important class of molecules with diverse pharmacological activities including anticancer activity. The present study focuses on the molecular hybridization of novel Benzopyran with Dihydropyrimidinone and evaluation of the resulting hybrids for cancer cell proliferation, migration and tumor growth. METHODS: We have synthesized a focused library of dihydropyrimidinone benzopyran hybrids (compounds 1-11) by joining the aromatic as well as pyran portions of the benzopyran core with dihydropyrimidinone. All the synthesized hybrid molecules were evaluated for their cytotoxic activities against a panel of four human cancer cell lines of diverse tissue origin, viz: A549 (lung carcinoma), MCF7 (mammary gland adenocarcinoma), HCT-116 (colorectal carcinoma), and PANC-1 (pancreatic duct carcinoma) with the help of MTT cell viability assay. A structure-activity relationship was made on the basis of IC50 values of different hybrids. Effect on cell proliferation was examined through colony formation assay, reactive oxygen species generation and mitochondrial membrane potential studies. Wound healing assays and cell scattering assays were employed to check the effect on cell migration. Western blotting experiments were performed to find out the molecular mechanism of action and anti-tumor studies were carried out to evaluate the in vivo efficacy of the selected lead molecule. RESULTS: Two types of novel hybrids were synthesized efficiently from benzopyran aldehydes, ethylacetoacetate and urea under heteropolyacid catalysis. Compound 3 was found to be the most potent hybrid among the synthesized compounds with consistent cytotoxic activities against four human cancer cell lines (IC50 values: 0.139 - 2.32 µM). Compound 3 strongly inhibited proliferation abilities of A549 cells in colony formation assay. Compound 3 exerted oxidative stress-mediated mitochondrial dysfunction, in which mitochondrial reactive oxygen species (ROS) generation as a mechanism of its anti-proliferative effects was analysed. Further, the molecule abrogated migration and cell scattering properties of aggressive PANC-1 cells. Mechanistic studies revealed that compound 3 modulated NF-kB expression and its downstream oncogenic proteins involved in cancer cell proliferation and invasion. Finally, compound 3 confirmed its in vivo anti-tumor efficacy; there observed 41.87% tumor growth inhibition at a dose of 30 mg/kg/body weight against a mouse model of Ehrlich solid tumor. CONCLUSION: Our study unravels a potential anticancer lead (compound 3) from DHPMs that have opened up new research avenues for the development of promising anticancer therapeutic agents.

Dual role of Par-4 in abrogation of EMT and switching on Mesenchymal to Epithelial Transition (MET) in metastatic pancreatic cancer cells.

Epithelial-mesenchymal transition (EMT) is a critical event that occurs during the invasion and metastatic spread of cancer cells. Here, we conceive a dual mechanism of Par-4-mediated inhibition of EMT and induction of MET in metastatic pancreatic cancer cells. First, we demonstrate that 1,1'-ß-D-glucopyranosyl-3,3'-bis(5-bromoindolyl)-octyl methane (NGD16), an N-glycosylated derivative of medicinally important phytochemical 3,3'-diindolylmethane (DIM) abrogates EMT by inducing pro-apoptotic protein Par-4. Induction of Par-4 (by NGD16 or ectopic overexpression) strongly impedes invasion with inhibition of major mesenchymal markers viz. Vimentin and Twist-1 epithelial marker- E-cadherin. Further, NGD16 triggers MET phenotypes in pancreatic cancer cells by augmenting ALK2/Smad4 signaling in a Par-4-dependent manner. Conversely, siRNA-mediated silencing of endogenous Par-4 unveil reversal of MET with diminished E-cadherin expression and invasive phenotypes. Additionally, we demonstrate that intact Smad4 is essential for Par-4-mediated maintenance of E-cadherin level in MET induced cells. Notably, we imply that Par-4 induction regulates E-cadherin levels in the pancreatic cancer cells via modulating Twist-1 promoter activity. Finally, in vivo studies with syngenic mouse metastatic pancreatic cancer model reveal that NGD16 strongly suppresses metastatic burden, ascites formation, and prolongs the overall survival of animals effectively.

Detailed account on activation mechanisms of ruthenium coordination complexes and their role as antineoplastic agents.

Ruthenium (Ru) complexes are known for their promising anticancer activity presumably due to octahedral coordination geometry, slow ligand exchange rate, the range of different oxidation states and target specificity. This review article summarizes the physicochemical processes which are responsible for the selectivity of Ru complexes toward cancer cells over the normal cells. Emphasis has been given on the activation mechanism of Ru(III) complex administered as a prodrug and then the release of active species in an acidic environment of cancer cell through normal or photo induced hydrolysis or ligand oxidation. This article also elaborates how active Ru complex can be designed by their rate of hydrolysis, kinetics of ligand exchange, pKa of the aquated species. The article further articulates how Ru complexes inhibit tumor growth via multiple events such as transferrin/albumin binding, ROS generation, inhibition of glutathione-S-transferases and kinases and DNA intercalation. Based on the above understanding, examples of various Ru complexes with their in-vitro cell based cytotoxicity and mechanism of action have been described to make this review comprehensive for future Ru based anticancer drug development. In the end, comments have been made on some emerging concepts regarding lack of innertness of Ru(III) complexes vis-à-vis Ru(II) species.

Regiospecific Synthesis of Ring A Fused Withaferin A Isoxazoline Analogues: Induction of Premature Senescence by W-2b in Proliferating Cancer Cells.

Induction of premature senescence represents a novel functional strategy to curb the uncontrolled proliferation of malignant cancer cells. This study unveils the regiospecific synthesis of novel isoxazoline derivatives condensed to ring A of medicinal plant product Withaferin-A. Intriguingly, the cis fused products with ß-oriented hydrogen exhibited excellent cytotoxic activities against proliferating human breast cancer MCF7 and colorectal cancer HCT-116 cells. The most potent derivative W-2b triggered premature senescence along with increase in senescence-associated ß-galactosidase activity, G2/M cell cycle arrest, and induction of senescence-specific marker p21Waf1/Cip1 at its sub-toxic concentration. W-2b conferred a robust increase in phosphorylation of mammalian checkpoint kinase-2 (Chk2) in cancer cells in a dose-dependent manner. Silencing of endogenous Chk2 by siRNA divulged that the amplification of p21 expression and senescence by W-2b was Chk2-dependent. Chk2 activation (either by ectopic overexpression or through treatment with W-2b) suppressed NM23-H1 signaling axis involved in cancer cell proliferation. Finally, W-2b showed excellent in vivo efficacy with 83.8% inhibition of tumor growth at a dose of 25 mg/kg, b.w. in mouse mammary carcinoma model. Our study claims that W-2b could be a potential candidate to limit aberrant cellular proliferation rendering promising improvement in the treatment regime in cancer patients.

Dual modulation of Ras-Mnk and PI3K-AKT-mTOR pathways: A Novel c-FLIP inhibitory mechanism of 3-AWA mediated translational attenuation through dephosphorylation of eIF4E.

The eukaryotic translation initiation factor 4E (eIF4E) is considered as a key survival protein involved in cell cycle progression, transformation and apoptosis resistance. Herein, we demonstrate that medicinal plant derivative 3-AWA (from Withaferin A) suppressed the proliferation and metastasis of CaP cells through abrogation of eIF4E activation and expression via c-FLIP dependent mechanism. This translational attenuation prevents the de novo synthesis of major players of metastatic cascades viz. c-FLIP, c-Myc and cyclin D1. Moreover, the suppression of c-FLIP due to inhibition of translation initiation complex by 3-AWA enhanced FAS trafficking, BID and caspase 8 cleavage. Further ectopically restored c-Myc and GFP-HRas mediated activation of eIF4E was reduced by 3-AWA in transformed NIH3T3 cells. Detailed underlying mechanisms revealed that 3-AWA inhibited Ras-Mnk and PI3-AKT-mTOR, two major pathways through which eIF4E converges upon eIF4F hub. In addition to in vitro studies, we confirmed that 3-AWA efficiently suppressed tumor growth and metastasis in different mouse models. Given that 3-AWA inhibits c-FLIP through abrogation of translation initiation by co-targeting mTOR and Mnk-eIF4E, it (3-AWA) can be exploited as a lead pharmacophore for promising anti-cancer therapeutic development.

Par-4 dependent modulation of cellular ß-catenin by medicinal plant natural product derivative 3-azido Withaferin A.

Here, we provide evidences that natural product derivative 3-azido Withaferin A (3-AWA) abrogated EMT and invasion by modulating ß-catenin localization and its transcriptional activity in the prostate as well as in breast cancer cells. This study, for the first time, reveals 3-AWA treatment consistently sequestered nuclear ß-catenin and augmented its cytoplasmic pool as evidenced by reducing ß-catenin transcriptional activity in these cells. Moreover, 3-AWA treatment triggered robust induction of pro-apoptotic intracellular Par-4, attenuated Akt activity and rescued Phospho-GSK3ß (by Akt) to promote ß-catenin destabilization. Further, our in vitro studies demonstrate that 3-AWA treatment amplified E-cadherin expression along with sharp downregulation of c-Myc and cyclin D1 proteins. Strikingly, endogenous Par-4 knock down by siRNA underscored 3-AWA mediated inhibition of nuclear ß-catenin was Par-4 dependent and suppression of Par-4 activity, either by Bcl-2 or by Ras transfection, restored the nuclear ß-catenin level suggesting Par-4 mediated ß-catenin regulation was not promiscuous. In vivo results further demonstrated that 3-AWA was effective inhibitor of tumor growth and immunohistochemical studies indicated that increased expression of total ß-catenin and decreased expression of phospho-ß-catenin and Par-4 in breast cancer tissues as compared to normal breast tissue suggesting Par-4 and ß-catenin proteins are mutually regulated and inversely co-related in normal as well as cancer condition. Thus, strategic regulation of intracellular Par-4 by 3-AWA in diverse cancers could be an effective tool to control cancer cell metastasis. Conclusively, this report puts forward a novel approach of controlling deregulated ß-catenin signaling by 3-AWA induced Par-4 protein.

PAWR-mediated suppression of BCL2 promotes switching of 3-azido withaferin A (3-AWA)-induced autophagy to apoptosis in prostate cancer cells.

An active medicinal component of plant origin with an ability to overcome autophagy by inducing apoptosis should be considered a therapeutically active lead pharmacophore to control malignancies. In this report, we studied the effect of concentration-dependent 3-AWA (3-azido withaferin A) sensitization to androgen-independent prostate cancer (CaP) cells which resulted in a distinct switching of 2 interrelated conserved biological processes, i.e. autophagy and apoptosis. We have observed 3 distinct parameters which are hallmarks of autophagy in our studies. First, a subtoxic concentration of 3-AWA resulted in an autophagic phenotype with an elevation of autophagy markers in prostate cancer cells. This led to a massive accumulation of MAP1LC3B and EGFP-LC3B puncta coupled with gradual degradation of SQSTM1. Second, higher toxic concentrations of 3-AWA stimulated ER stress in CaP cells to turn on apoptosis within 12 h by elevating the expression of the proapoptotic protein PAWR, which in turn suppressed the autophagy-related proteins BCL2 and BECN1. This inhibition of BECN1 in CaP cells, leading to the disruption of the BCL2-BECN1 interaction by overexpressed PAWR has not been reported so far. Third, we provide evidence that pawr-KO MEFs exhibited abundant autophagy signs even at toxic concentrations of 3-AWA underscoring the relevance of PAWR in switching of autophagy to apoptosis. Last but not least, overexpression of EGFP-LC3B and DS-Red-BECN1 revealed a delayed apoptosis turnover at a higher concentration of 3-AWA in CaP cells. In summary, this study provides evidence that 3-AWA is a strong anticancer candidate to abrogate protective autophagy. It also enhanced chemosensitivity by sensitizing prostate cancer cells to apoptosis through induction of PAWR endorsing its therapeutic potential.

A therapeutically relevant, 3,3'-diindolylmethane derivative NGD16 attenuates angiogenesis by targeting glucose regulated protein, 78kDa (GRP78).

Angiogenesis remain a critical procedure for tumor progression and malignancy. Anticancer agents targeting angiogenic cascades have been proved to be an effective strategy in the field of cancer therapeutics. The current study aims to explore the mechanistic prevention of angiogenesis and cancer cell proliferation by 1,1'-ß-d-glucopyranosyl-3,3'-bis(5-bromoindolyl)-octyl methane (NGD16), a novel N-glycosylated derivative of 3,3'-diindolylmethane (DIM). NGD16 suppressed the viability of prostate cancer (PC-3), pancreatic adenocarcinoma (MiaPaca-2), colorectal cancer (COLO-205) and human umbilical vein endothelial cells (HUVECs) effectively with IC50 values 0.8 µM, 2.8 µM, 5.3 µM and 2.5 µM respectively. Abrogation of angiogenesis by NGD16 was promising in in vivo mouse Matrigel plug assay as well as in ex vivo sprouting of rat thoracic aorta. At the molecular level, NGD16 inhibited the expression of glucose regulated protein, 78 kDa (GRP78), vascular endothelial growth factor receptor-2 (VEGFR2) and matrix metalloproteinase-9 (MMP-9) expression, the main mediators of angiogenesis and neovessel formation. Overexpression of GRP78 upregulated the expression of MMP-9 and VEGFR2 in PC-3 and HUVECs. Antibody blocking of GRP78 further potentiated NGD16 in attenuating angiogenesis through inhibition of MMP-9. NGD16 depicted its promising biodistribution profile in a pharmacokinetic study with 46.9% intraperitoneal bioavailability. Our findings suggest NGD16 is a potent inhibitor of neo-angiogenesis with a desirable pharmacokinetic profile, which can be taken forward in its development as an anticancer drug.

Medicinal chemistry of dihydropyran-based medium ring macrolides related to aspergillides: selective inhibition of PI3Kα.

A set of nine trans-disubstituted dihydropyran-based medium ring macrolides has been synthesized using d-glucal as chiral pool and evaluated against a panel of three human cancer cell lines and a normal cell line. The synthetic route to the targeted molecule is simple, concise, and high yielding compared to other reported methods. Bioevaluation studies have resulted in the identification of a potent cytotoxic molecule (10) exhibiting dose-dependent growth inhibition against HL-60 cell line with an IC50 value of 1.10 ± 0.075 µM, which is lower than that of naturally occurring molecules of this class and of comparable activity to the synthetic drug fludarubin. Compound 10 inhibits the PI3K/AKT signaling pathway by selectively targeting the p110α subunit of PI3Kα. This leads to mitochondrial stress that causes translocation of cytochrome c from mitochondria to cytosol, which in turn activates caspase-mediated apoptotic cell death. Further in silico docking simulations of four macrolides with p110α subunits have been carried out to visualize the orientation pattern.

A novel MMP-2 inhibitor 3-azidowithaferin A (3-azidoWA) abrogates cancer cell invasion and angiogenesis by modulating extracellular Par-4.

BACKGROUND: Withaferin A, which is a naturally derived steroidal lactone, has been found to prevent angiogenesis and metastasis in diverse tumor models. It has also been recognized by different groups for prominent anti-carcinogenic roles. However, in spite of these studies on withanolides, their detailed anti-metastatic mechanism of action remained unknown. The current study has poised to address the machinery involved in invasion regulation by stable derivative of Withaferin A, 3-azido Withaferin A (3-azidoWA) in human cervical HeLa and prostate PC-3 cells. METHODS AND PRINCIPAL FINDINGS: Sub-toxic concentration of 3-azidowithaferin A (3-azido WA) inhibited cancer cell motility and invasion in wound healing and Boyden chamber invasion by suppressing MMP-2 activity in gelatin zymography and its expression has proved to be a major obstacle in chemo-sensitivity. We have uncovered a novel mechanism of 3-azidoWA induced extracellular pro-apoptotic candidate tumor suppressor Par-4 protein stimulation in conditioned media and also noticed a concomitant marked reduction in pAkt and pERK signaling by immunoblot analysis. Furthermore, our zymography results suggest 3-azidoWA induced MMP-2 inhibition was mediated through secretory Par-4. The inhibition of apoptosis by 3-azidoWA could not restore MMP-2 gelatinase activity. In addition to this, our in vivo animal experiments data showed 3-azidoWA abrogated neovascularisation in dose dependent manner in mouse Matrigel plug assay. CONCLUSION/SIGNIFICANCE: For this report, we found that 3-azidoWA suppressed motility and invasion of HeLa and PC-3 cells in MMP-2 dependent manner. Our in vitro result strongly suggests that sub-toxic doses of 3-azidoWA enhanced the secretion of extracellular Par-4 that abolished secretory MMP-2 expression and activity. Depletion of secretory Par-4 restored MMP-2 expression and invasion capability of HeLa and PC-3 cells. Further, our findings implied that 3-azidoWA attenuated internal phospho-ERK and phospho-Akt expression in a dose dependent manner might play a key role in inhibition of mouse angiogenesis by 3-azidoWA.

Ring A structural modified derivatives of withaferin A and the evaluation of their cytotoxic potential.

Regio-/stereoselective Michael addition to ring A of withaferin-A was performed using an optimized reaction procedure to synthesise a library of 2,3-dihydro,3-ß-substituted withaferin-A derivatives. The analogues thus obtained were evaluated for in vitro cytotoxicity against various human cancer cell lines. 3-Azido analogue exhibited 35-fold increase (IC(50)=0.02-1.9 µM) in cytotoxicity against almost the entire cell lines tested when compared to the parent molecule. However, further modifications of 3-azido analogue with various alkynes under Husigen's cycloaddition conditions generated a variety of triazole derivatives with reduced cytotoxicity.