Schiff base, N-(2-methoxyphenyl)-3-methoxysalicylaldimine (MPMS), was synthesized and characteriz... more Schiff base, N-(2-methoxyphenyl)-3-methoxysalicylaldimine (MPMS), was synthesized and characterized by spectroscopic methods. Crystal structure of the title compound crystallizing in the orthorhombic space group Pca21, a = 23.695(2), b = 7.7011(8), c = 7.3570(9) A, V = 1342.5(2) A3, Z = 4 has been solved from X-ray powder diffraction data following direct-space approach and refined by the Rietveld method. In solid state, the salicylaldimine compound exists as a phenol-imine tautomer with a strong intramolecular O–H…N hydrogen bond. The molecular geometry and electronic structure of MPMS were calculated at the DFT level using the hybrid exchange-correlation functional, BLYP. The optimized molecular geometry corresponds to the non-planar conformation of the molecule as established by the crystallographic analysis. The anticancer activity of the title Schiff base was evaluated against three different cell lines, SF-268, MCF-7 and NCI-H460.
QSAR for Analogs of 1,5–N,N'–Disubstituted–2–(substituted benzenesulphonyl) Glutamamides as A... more QSAR for Analogs of 1,5–N,N'–Disubstituted–2–(substituted benzenesulphonyl) Glutamamides as Antitumor Agents Parthasarathi Panda, Soma Samanta, Sk. Mahasin Alam, Soumya Basu, and Tarun Jha 1 1 Division of Medicinal and Pharmaceutical Chemistry, Department of Pharmaceutical Technology, P.O. Box 17020, Jadavpur University, Kolkata 700 032, India 2 School of Chemical & Biomolecular Engineering, Nanyang Technological University, 42 Nanyang Avenue, Student Services Centre, Level 3, Singapore 639815
Peroxisome Proliferator-Activated Receptors-γ (PPAR-γ), a ligand-activated transcription factor, ... more Peroxisome Proliferator-Activated Receptors-γ (PPAR-γ), a ligand-activated transcription factor, suggested having anti-inflammatory effects by activating the target genes when bound to the ligand. Herein, we examined a conformational analysis of 8708 derivatives of Kaempferol, Quercetin, and Resveratrol, the prime activators of PPAR-γ molecular target by employing molecular docking and dynamic simulation pipeline to screen out potential agonists. The structure-based docking procedure performed by FlexX tool shortlisted high binding affinities of these derivatives of Kaempferol, Quercetin and Resveratrol with the protein receptor with a score of -38.94 kcal/mol (4'-Carboxy-5, 7-Dihydroxyflavone-CDHF), -41.63 kcal/mol (Demethyltorosaflavone D- DMTF) and -31.52 kcal/mol (Resveratrol-O-disulphate- RD) respectively, signifying the selected derivatives forms interactions like H-bond, Aromatic H-Bond, Pi-Pi stacking and salt bridges with PPAR-γ. The PPAR-γ-derivative complex was stabil...
Peroxisome proliferator–activated receptors-γ (PPAR-γ), a ligand-activated transcription factor, ... more Peroxisome proliferator–activated receptors-γ (PPAR-γ), a ligand-activated transcription factor, activated by several ligands like fatty acids (linoleic acid being the most common) or their metabolites, can function as potential therapeutic target for various cancers. Although various synthetic ligands, thiazolidinediones (TZDs), serves as full agonist for PPAR-γ, application of these molecules has been discontinued due to adverse toxicity profile. Hence, with a dire need to identify novel PPAR-γ-agonists, the present in silico study aimed to determine the effectiveness of potent flavonoids, kaempferol (CID: 5280863), quercetin (CID: 5280343), and stilbenoid resveratrol (CID: 445154) and their 806 derivatives towards PPAR-γ that could combat the deleterious effect of TZDs. The molecular docking experiment performed by FlexX elucidated the efficacy of derivatives; Kem204, Qur8, and Res183 of kaempferol, quercetin, and resveratrol respectively to be more effective against PPAR-γ as compared with other derivatives. The physicochemical and pharmacokinetic parameters of Kem204, Qur8, and Res183 follow the drug-likeness and thus comprise a pharmacologically active model to be considered for advancing further potential hits. Further molecular dynamics (MD) simulation study revealed the Qur8 compound to have favorable dynamic interactions within the PPAR-γ which certainly paves away in developing futuristic potential anticancer drugs. Graphical abstract Graphical abstract Graphical abstract
On the basis of our earlier work, fortyone 5-Nsubstituted-2N-(substituted benzenesulphonyl)-L(+)g... more On the basis of our earlier work, fortyone 5-Nsubstituted-2N-(substituted benzenesulphonyl)-L(+)glutamines were synthesized and screened for cancer cell inhibitory activity. The best active compounds showed 91% tumor cell inhibition, whereas other three compounds showed more than 80% inhibition. Two-dimensional quantitative structure-activity relationship modeling and three-dimensional quantitative structure-activity relationship k-nearest neighbor molecular field analysis studies were done to get an insight into structural requirements toward further improved anticancer activity. Considering the fact that these compounds are competitive inhibitors of glutaminase, a molecular docking study followed by molecular dynamic simulation analysis were performed. The work may help to develop new anticancer agents.
Methods in molecular biology (Clifton, N.J.), 2016
Application of bioluminescence resonance energy transfer (BRET) assay has been of special value i... more Application of bioluminescence resonance energy transfer (BRET) assay has been of special value in measuring dynamic events such as protein-protein interactions (PPIs) in vitro or in vivo. It was only in the late 1990s the BRET assay using RLuc-YFP was introduced for biological research showing its use in determining interaction of two proteins involved in circadian rhythm. Several inherent attributes such as rapid and fairly sensitive ratiometric measurements, assessment of PPI irrespective of protein location in cellular compartment, and cost-effectiveness consenting to high-throughput assay development make BRET a popular genetic reporter-based assay for PPI studies. In BRET-based screening, within a defined proximity range of 10-100 Å, excited state energy of the luminescence molecule can excite the acceptor fluorophore in the form of resonance energy transfer, causing it to emit at its characteristic emission wavelength. Based on this principle, several such donor-acceptor pair...
Multidrug resistance (MDR) in cancer represents a variety of strategies employed by tumor cells t... more Multidrug resistance (MDR) in cancer represents a variety of strategies employed by tumor cells to evade the beneficial cytotoxic effects of structurally different anticancer drugs and thus confers impediments to the successful treatment of cancers. Efflux of drugs by multi-drug resistant protein-1 (MRP1), functional P-glycoprotein (P-gp) and elevated level of reduced glutathione (GSH) confer resistance to cell death or apoptosis and thus provide possible therapeutic target for overcoming MDR in cancer. Previously we reported that a Schiff base ligand, PHMBA (potassium-N-(2-hydroxy 3-methoxy-benzaldehyde)-alaninate overcomes MDR in both in vivo and in vitro by targeting intrinsic apoptotic/necrotic pathway through induction of ROS. The present study describes the synthesis and spectroscopic characterization of a copper chelate of Schiff base, viz., copper (II)-N-(2-hydroxy-3-methoxy-benzaldehyde)-alaninate (CuPHMBA) and the underlying mechanism of cell death induced by CuPHMBA in vitro. CuPHMBA kills both the drug-resistant and sensitive cell types irrespective of their drug resistance phenotype. The cell death induced by CuPHMBA follows apoptotic pathway and moreover, the cell death is associated with intrinsic mitochondrial and extrinsic receptor mediated pathways. Oxidative stress plays a pivotal role in the process as proved by the fact that antioxidant enzyme; polyethylene glycol conjugated-Catalase completely blocked CuPHMBA-induced ROS generation and abrogated cell death. To summarize, the present work provides compelling rationale for future clinical use of CuPHMBA, a redox active copper chelate in treatment of cancer patients, irrespective of their drug-resistance status.
Glutathione (GSH), an important component of the phase II detoxification system, plays a major ro... more Glutathione (GSH), an important component of the phase II detoxification system, plays a major role in storage, metabolism and transport of metals across the cell membrane. The role of copper, its metabolism and storage in living systems is not completely understood. Copper plays an important role in a number of physiological processes, e.g. several growth and transcription factors require copper for activity. In the present investigation, we focused on copper (II) (N-2-hydroxyacetophenone) glycinate (CuNG), a novel in vitro and in vivo resistance modifying agent. A conjugate of GSH and CuNG was detected in vivo in mice and was characterized by spectroscopic studies. Based on UV, IR, proton NMR and elemental analyses, the chemical structure of the conjugate was elucidated. By means of atomic absorption data, the distribution and metabolism of CuNG is described.
Background: Multi drug resistance (MDR) or cross-resistance to multiple classes of chemotherapeut... more Background: Multi drug resistance (MDR) or cross-resistance to multiple classes of chemotherapeutic agents is a major obstacle to successful application of chemotherapy and a basic problem in cancer biology. The multidrug resistance gene, MDR1, and its gene product P-glycoprotein (P-gp) are an important determinant of MDR. Therefore, there is an urgent need for development of novel compounds that are not substrates of P-glycoprotein and are effective against drug-resistant cancer. Methodology/Principal Findings: In this present study, we have synthesized a novel, redox active Fe (II) complex (chelate), iron N-(2-hydroxy acetophenone) glycinate (FeNG). The structure of the complex has been determined by spectroscopic means. To evaluate the cytotoxic effect of FeNG we used doxorubicin resistant and/or sensitive T lymphoblastic leukemia cells and show that FeNG kills both the cell types irrespective of their MDR phenotype. Moreover, FeNG induces apoptosis in doxorubicin resistance T lymphoblastic leukemia cell through mitochondrial pathway via generation reactive oxygen species (ROS). This is substantiated by the fact that the antioxidant N-acetyle-cysteine (NAC) could completely block ROS generation and, subsequently, abrogated FeNG induced apoptosis. Therefore, FeNG induces the doxorubicin resistant T lymphoblastic leukemia cells to undergo apoptosis and thus overcome MDR. Conclusion/Significance: Our study provides evidence that FeNG, a redox active metal chelate may be a promising new therapeutic agent against drug resistance cancers.
Multidrug resistance (MDR) mediated by the over expression of drug efflux protein P-glycoprotein ... more Multidrug resistance (MDR) mediated by the over expression of drug efflux protein P-glycoprotein (P-gp) is one of the major impediments to successful treatment of cancer. P-gp acts as an energy-dependent drug efflux pump and reduces the intracellular concentration of structurally unrelated drugs inside the cells. Therefore, there is an urgent need for development of new molecules that are less toxic to normal cell and preferentially effective against drug resistant malignant cells. In this preclinical study we report the apoptotic potential of copper N-(2-hydroxyacetophenone) glycinate (CuNG) on doxorubicin resistant T lymphoblastic leukaemia cells (CEM/ADR5000). To evaluate the cytotoxic effect of CuNG, we used different normal cell lines (NIH 3T3, Chang liver and human PBMC) and cancerous cell lines (CEM/ADR5000, parental sensitive CCRF-CEM, SiHa and 3LL) and conclude that CuNG preferentially kills cancerous cells, especially both leukemic cell types irrespective of their MDR status, while leaving normal cell totally unaffected. Moreover, CuNG involves reactive oxygen species (ROS) for induction of apoptosis in CEM/ADR5000 cells through the intrinsic apoptotic pathway. This is substantiated by our observation that antioxidant N-acetyle-cysteine (NAC) and PEG catalase could completely block ROS generation and, subsequently, abrogates CuNG induced apoptosis. On the other hand, uncomplexed ligand N-(2-hydroxyacetophenone) glycinate (NG) fails to generate a significant amount of ROS and concomitant induction of apoptosis in CEM/ADR5000 cells. Therefore, CuNG induces drug resistant leukemia cells to undergo apoptosis and proves to be a molecule having therapeutic potential to overcome MDR in cancer.
Potassium (K(+)) channel openers are a diverse group of compounds which are used for the treatmen... more Potassium (K(+)) channel openers are a diverse group of compounds which are used for the treatment of diseases like angina pectoris, hypertension, congestive heart failure, anti-hypoglycemic (insulinoma), bronchial asthma, etc. R/S-3,4-dihydro-2,2-dimethyl-6-halo-4-(substituted phenylaminocarbonylamino)-2H-1-benzopyrans are a new series of ATP-sensitive potassium (K(ATP-pbeta)) channel openers selective towards pancreatic beta-cells. QSAR modelling was done on these series of compounds to find a more active and selective K(ATP-pbeta) channel opener selective towards beta-cells of pancreatic tissues. Wang-Ford charges, partition coefficient, molar refractivity, principle moment of inertia at X, Y and Z axes are used as predictor variables and logarithm of percentage of residual insulin secretion is treated as response variable for the modelling. Multiple linear regressions with factor analysis were performed to develop QSAR models. Four equations were obtained using different combinations of the predictor variables based on factor loadings. Regression coefficients of all descriptors used are significant at more than 95% level. Results showed that Wang-Ford charges on atom numbers 11, 17, 18, 19 and 21 are important for the inhibition of residual insulin secretion. The presence of electron withdrawing group at m- and p-position of phenyl ring B is required for the inhibition. The energy minimized geometry of the most active compound supported our modelling.
R/S-3,4-Dihydro-2,2-dimethyl-6-halo-4-(substituted phenylaminocarbonyl-amino)-2H-1-benzopyrans ar... more R/S-3,4-Dihydro-2,2-dimethyl-6-halo-4-(substituted phenylaminocarbonyl-amino)-2H-1-benzopyrans are pancreatic β-cells potassium (KATP-pβ) channel openers with inhibitory effect on insulin secretion. To find the more active and effective benzopyrans as selective potassium (KATP-pβ) channel openers towards the pancreatic tissues, quantitative structure–activity relationships (QSAR) study was performed using E-state and R-state indices along with Wang–Ford charges, n-octanol/water partition coefficient, molar refractivity, and indicator parameters. QSAR models were developed by statistical techniques, e.g., multiple linear regression (MLR), principle component regression analysis (PCRA), and partial least squares (PLS) analysis. The generated equations were validated by the leave-one-out cross-validation method. The models show the importance of ETSA indices of atom numbers 16, 17, 18, 19, 21 as well as 22. The positive coefficient of S16, S17, S18, S19, S21, and S22 indicate that with...
Multidrug resistance-associated protein 1 (MRP1) reduces intracellular anticancer drug accumulati... more Multidrug resistance-associated protein 1 (MRP1) reduces intracellular anticancer drug accumulation either by co transporting them with glutathione (GSH) or extruding drug-GSH conjugates outside of the cell. Thus, MRP1 confers multidrug resistance (MDR) and worsen successful chemotherapeutic treatment against cancer. Although the exact mechanism of MRP1 involved in MDR remains unknown, the elevated level of intracellular GSH is considered as a key factor responsible for MDR in cancer. Hence the quest for non-toxic molecules that are able to deplete intracellular GSH has profound importance to subdue MDR. The present preclinical study depicts the resistance reversal potentiality of an iron complex; viz. Ferrous N-(2-hydroxy acetophenone) glycinate (FeNG) developed by us in doxorubicin resistant Ehrlich ascites carcinoma (EAC/Dox) cells. FeNG potentiate cytotoxic effect of doxorubicin on EAC/Dox cells ex vivo and also increases the survivability EAC/Dox bearing Swiss albino mice in vivo as well. Moreover, in vivo administration of FeNG significantly depletes intracellular GSH with ensuant increase in doxorubicin concentration in EAC/Dox cells without alternation of MRP1 expression. In addition, intra-peritoneal (i.p.) application of FeNG in normal or EAC/Dox bearing mice does not cause any systemic toxicity in preliminary trials in mouse Ehrlich ascites carcinoma model. Therefore, the present report provides evidence that FeNG may be a promising new resistance modifying agent against drug resistant cancers. Keywords Multi drug resistance Á Glutathione Á Iron complex Á Resistance modifying agent Abbreviations MDR Multi drug resistance MRP1 Multidrug resistance-associated protein 1 GSH Glutathione FeNG Iron N-(2-hydroxy acetophenone) glycinate EAC/Dox Doxorubicin resistant Ehrlich ascites carcinoma cells MTT (3-[4,5-Dimethylthiazol-2-yl]-2, 5-diphenyltetrazolium bromide BSO DL-buthionine (S,R) sulfoximine EA Ethacrynic acid DTNB 5,5 0-Dithio bis(2-nitrobenzoic acid) RMA Resistance modifying agent ROS Reactive oxygen species DCFDA 2 0 ,7 0-Dihydrodichlorofluorescin diacetate
Cancer is one of the major causes of death. For cancer, the general conventional treatment and st... more Cancer is one of the major causes of death. For cancer, the general conventional treatment and standard of care for clinical oncology remains surgery followed by radiation and/or systemic chemotherapy as deemed appropriate based on the clinical findings. Chemoimmunotherapy is an approach to treat cancer where chemotherapy is given along with immunotherapy. Chemoimmunotherapy may be useful to enhance survival time in cancer by improve immunity of the patients. This approach may enhance the therapeutic efficacy. A comparative study was done to assess the therapeutic efficacy of the whole cell vaccine and the tumor extract with or without combination chemotherapy with the synthesized glutamine and glutamic acid derivatives and analogs as well as the standard drug etoposide against Ehrlich Ascites Carcinoma (EAC) cells in Swiss Albino mice. The study showed promising results with the compound 5-N-n-hexyl-2-(4-iso-butylbenzenesulphonyl)glutamine. The compound when combined with the whole cell vaccine as well as the tumor extract increases the survival time and the therapeutic efficacy which is comparable with that of standard drug etoposide.
Multidrug resistance (MDR) in cancer, a major obstacle to successful application of cancer chemot... more Multidrug resistance (MDR) in cancer, a major obstacle to successful application of cancer chemotherapy, is often characterized by over-expression of multidrug resistance-related proteins such as MRP1, P-gp or elevated glutathione (GSH) level. Efflux of drugs by functional P-gp, MRP1 and elevated GSH level can confer resistance to apoptosis induced by a range of different stimuli. Therefore, it is necessary to develop new cell death inducers with relatively lower toxicity toward non-malignant cells that can overcome MDR by induction of apoptotic or non-apoptotic cell death pathways. Herein we report the synthesis and spectroscopic characterization of a GSH depleting, redox active Schiff's base, viz., potassium-N-(2-hydroxy-3-methoxy-benzaldehyde)-alaninate (PHMBA). Cytotoxic potential of PHMBA has been studied in doxorubicin-resistant and -sensitive T lymphoblastic leukemia cells and Ehrlich ascites carcinoma (EAC) cells. PHMBA kills both the cell types irrespective of their drug-resistance phenotype following apoptotic/necrotic pathways. Moreover, PHMBA-induced cell death is associated with oxidative stress mediated mitochondrial pathway as the H(2)O(2) inhibitor PEG-Catalase abrogated PHMBA-induced apoptosis/necrosis. PHMBA induces anti-tumor activity in both doxorubicin-sensitive and -resistant EAC-tumor-bearing Swiss albino mice. The non-toxicity of PHMBA was also confirmed through cytotoxicity studies on normal cell lines like PBMC, NIH3T3 and Chang Liver. To summarise, our data provide compelling rationale for future clinical use of this redox active Schiff's base in treatment of cancer patients irrespective of their drug-resistance status.
Multidrug resistance (MDR) mediated by the over expression of drug efflux protein P-glycoprotein ... more Multidrug resistance (MDR) mediated by the over expression of drug efflux protein P-glycoprotein (P-gp) is one of the major impediments to successful treatment of cancer. P-gp acts as an energy-dependent drug efflux pump and reduces the intracellular concentration of structurally unrelated drugs inside the cells. Therefore, there is an urgent need for development of new molecules that are less toxic to normal cell and preferentially effective against drug resistant malignant cells. In this preclinical study we report the apoptotic potential of copper N-(2-hydroxyacetophenone) glycinate (CuNG) on doxorubicin resistant T lymphoblastic leukaemia cells (CEM/ADR5000). To evaluate the cytotoxic effect of CuNG, we used different normal cell lines (NIH 3T3, Chang liver and human PBMC) and cancerous cell lines (CEM/ADR5000, parental sensitive CCRF-CEM, SiHa and 3LL) and conclude that CuNG preferentially kills cancerous cells, especially both leukemic cell types irrespective of their MDR status, while leaving normal cell totally unaffected. Moreover, CuNG involves reactive oxygen species (ROS) for induction of apoptosis in CEM/ADR5000 cells through the intrinsic apoptotic pathway. This is substantiated by our observation that antioxidant N-acetyle-cysteine (NAC) and PEG catalase could completely block ROS generation and, subsequently, abrogates CuNG induced apoptosis. On the other hand, uncomplexed ligand N-(2-hydroxyacetophenone) glycinate (NG) fails to generate a significant amount of ROS and concomitant induction of apoptosis in CEM/ADR5000 cells. Therefore, CuNG induces drug resistant leukemia cells to undergo apoptosis and proves to be a molecule having therapeutic potential to overcome MDR in cancer.
Glutathione (GSH), an important component of the phase II detoxification system, plays a major ro... more Glutathione (GSH), an important component of the phase II detoxification system, plays a major role in storage, metabolism and transport of metals across the cell membrane. The role of copper, its metabolism and storage in living systems is not completely understood. Copper plays an important role in a number of physiological processes, e.g. several growth and transcription factors require copper for activity. In the present investigation, we focused on copper (II) (N-2-hydroxyacetophenone) glycinate (CuNG), a novel in vitro and in vivo resistance modifying agent. A conjugate of GSH and CuNG was detected in vivo in mice and was characterized by spectroscopic studies. Based on UV, IR, proton NMR and elemental analyses, the chemical structure of the conjugate was elucidated. By means of atomic absorption data, the distribution and metabolism of CuNG is described.
Multidrug resistance (MDR) in cancer, a major obstacle to successful application of cancer chemot... more Multidrug resistance (MDR) in cancer, a major obstacle to successful application of cancer chemotherapy, is often characterized by over-expression of multidrug resistance-related proteins such as MRP1, P-gp or elevated glutathione (GSH) level. Efflux of drugs by functional P-gp, MRP1 and elevated GSH level can confer resistance to apoptosis induced by a range of different stimuli.
In this present study, we have synthesized a novel, redox active Fe (II) complex (chelate), iron ... more In this present study, we have synthesized a novel, redox active Fe (II) complex (chelate), iron N-(2-hydroxy acetophenone) glycinate (FeNG). The structure of the complex has been determined by spectroscopic means. To evaluate the cytotoxic effect of FeNG we used doxorubicin ...
Schiff base, N-(2-methoxyphenyl)-3-methoxysalicylaldimine (MPMS), was synthesized and characteriz... more Schiff base, N-(2-methoxyphenyl)-3-methoxysalicylaldimine (MPMS), was synthesized and characterized by spectroscopic methods. Crystal structure of the title compound crystallizing in the orthorhombic space group Pca21, a = 23.695(2), b = 7.7011(8), c = 7.3570(9) A, V = 1342.5(2) A3, Z = 4 has been solved from X-ray powder diffraction data following direct-space approach and refined by the Rietveld method. In solid state, the salicylaldimine compound exists as a phenol-imine tautomer with a strong intramolecular O–H…N hydrogen bond. The molecular geometry and electronic structure of MPMS were calculated at the DFT level using the hybrid exchange-correlation functional, BLYP. The optimized molecular geometry corresponds to the non-planar conformation of the molecule as established by the crystallographic analysis. The anticancer activity of the title Schiff base was evaluated against three different cell lines, SF-268, MCF-7 and NCI-H460.
QSAR for Analogs of 1,5–N,N'–Disubstituted–2–(substituted benzenesulphonyl) Glutamamides as A... more QSAR for Analogs of 1,5–N,N'–Disubstituted–2–(substituted benzenesulphonyl) Glutamamides as Antitumor Agents Parthasarathi Panda, Soma Samanta, Sk. Mahasin Alam, Soumya Basu, and Tarun Jha 1 1 Division of Medicinal and Pharmaceutical Chemistry, Department of Pharmaceutical Technology, P.O. Box 17020, Jadavpur University, Kolkata 700 032, India 2 School of Chemical & Biomolecular Engineering, Nanyang Technological University, 42 Nanyang Avenue, Student Services Centre, Level 3, Singapore 639815
Peroxisome Proliferator-Activated Receptors-γ (PPAR-γ), a ligand-activated transcription factor, ... more Peroxisome Proliferator-Activated Receptors-γ (PPAR-γ), a ligand-activated transcription factor, suggested having anti-inflammatory effects by activating the target genes when bound to the ligand. Herein, we examined a conformational analysis of 8708 derivatives of Kaempferol, Quercetin, and Resveratrol, the prime activators of PPAR-γ molecular target by employing molecular docking and dynamic simulation pipeline to screen out potential agonists. The structure-based docking procedure performed by FlexX tool shortlisted high binding affinities of these derivatives of Kaempferol, Quercetin and Resveratrol with the protein receptor with a score of -38.94 kcal/mol (4'-Carboxy-5, 7-Dihydroxyflavone-CDHF), -41.63 kcal/mol (Demethyltorosaflavone D- DMTF) and -31.52 kcal/mol (Resveratrol-O-disulphate- RD) respectively, signifying the selected derivatives forms interactions like H-bond, Aromatic H-Bond, Pi-Pi stacking and salt bridges with PPAR-γ. The PPAR-γ-derivative complex was stabil...
Peroxisome proliferator–activated receptors-γ (PPAR-γ), a ligand-activated transcription factor, ... more Peroxisome proliferator–activated receptors-γ (PPAR-γ), a ligand-activated transcription factor, activated by several ligands like fatty acids (linoleic acid being the most common) or their metabolites, can function as potential therapeutic target for various cancers. Although various synthetic ligands, thiazolidinediones (TZDs), serves as full agonist for PPAR-γ, application of these molecules has been discontinued due to adverse toxicity profile. Hence, with a dire need to identify novel PPAR-γ-agonists, the present in silico study aimed to determine the effectiveness of potent flavonoids, kaempferol (CID: 5280863), quercetin (CID: 5280343), and stilbenoid resveratrol (CID: 445154) and their 806 derivatives towards PPAR-γ that could combat the deleterious effect of TZDs. The molecular docking experiment performed by FlexX elucidated the efficacy of derivatives; Kem204, Qur8, and Res183 of kaempferol, quercetin, and resveratrol respectively to be more effective against PPAR-γ as compared with other derivatives. The physicochemical and pharmacokinetic parameters of Kem204, Qur8, and Res183 follow the drug-likeness and thus comprise a pharmacologically active model to be considered for advancing further potential hits. Further molecular dynamics (MD) simulation study revealed the Qur8 compound to have favorable dynamic interactions within the PPAR-γ which certainly paves away in developing futuristic potential anticancer drugs. Graphical abstract Graphical abstract Graphical abstract
On the basis of our earlier work, fortyone 5-Nsubstituted-2N-(substituted benzenesulphonyl)-L(+)g... more On the basis of our earlier work, fortyone 5-Nsubstituted-2N-(substituted benzenesulphonyl)-L(+)glutamines were synthesized and screened for cancer cell inhibitory activity. The best active compounds showed 91% tumor cell inhibition, whereas other three compounds showed more than 80% inhibition. Two-dimensional quantitative structure-activity relationship modeling and three-dimensional quantitative structure-activity relationship k-nearest neighbor molecular field analysis studies were done to get an insight into structural requirements toward further improved anticancer activity. Considering the fact that these compounds are competitive inhibitors of glutaminase, a molecular docking study followed by molecular dynamic simulation analysis were performed. The work may help to develop new anticancer agents.
Methods in molecular biology (Clifton, N.J.), 2016
Application of bioluminescence resonance energy transfer (BRET) assay has been of special value i... more Application of bioluminescence resonance energy transfer (BRET) assay has been of special value in measuring dynamic events such as protein-protein interactions (PPIs) in vitro or in vivo. It was only in the late 1990s the BRET assay using RLuc-YFP was introduced for biological research showing its use in determining interaction of two proteins involved in circadian rhythm. Several inherent attributes such as rapid and fairly sensitive ratiometric measurements, assessment of PPI irrespective of protein location in cellular compartment, and cost-effectiveness consenting to high-throughput assay development make BRET a popular genetic reporter-based assay for PPI studies. In BRET-based screening, within a defined proximity range of 10-100 Å, excited state energy of the luminescence molecule can excite the acceptor fluorophore in the form of resonance energy transfer, causing it to emit at its characteristic emission wavelength. Based on this principle, several such donor-acceptor pair...
Multidrug resistance (MDR) in cancer represents a variety of strategies employed by tumor cells t... more Multidrug resistance (MDR) in cancer represents a variety of strategies employed by tumor cells to evade the beneficial cytotoxic effects of structurally different anticancer drugs and thus confers impediments to the successful treatment of cancers. Efflux of drugs by multi-drug resistant protein-1 (MRP1), functional P-glycoprotein (P-gp) and elevated level of reduced glutathione (GSH) confer resistance to cell death or apoptosis and thus provide possible therapeutic target for overcoming MDR in cancer. Previously we reported that a Schiff base ligand, PHMBA (potassium-N-(2-hydroxy 3-methoxy-benzaldehyde)-alaninate overcomes MDR in both in vivo and in vitro by targeting intrinsic apoptotic/necrotic pathway through induction of ROS. The present study describes the synthesis and spectroscopic characterization of a copper chelate of Schiff base, viz., copper (II)-N-(2-hydroxy-3-methoxy-benzaldehyde)-alaninate (CuPHMBA) and the underlying mechanism of cell death induced by CuPHMBA in vitro. CuPHMBA kills both the drug-resistant and sensitive cell types irrespective of their drug resistance phenotype. The cell death induced by CuPHMBA follows apoptotic pathway and moreover, the cell death is associated with intrinsic mitochondrial and extrinsic receptor mediated pathways. Oxidative stress plays a pivotal role in the process as proved by the fact that antioxidant enzyme; polyethylene glycol conjugated-Catalase completely blocked CuPHMBA-induced ROS generation and abrogated cell death. To summarize, the present work provides compelling rationale for future clinical use of CuPHMBA, a redox active copper chelate in treatment of cancer patients, irrespective of their drug-resistance status.
Glutathione (GSH), an important component of the phase II detoxification system, plays a major ro... more Glutathione (GSH), an important component of the phase II detoxification system, plays a major role in storage, metabolism and transport of metals across the cell membrane. The role of copper, its metabolism and storage in living systems is not completely understood. Copper plays an important role in a number of physiological processes, e.g. several growth and transcription factors require copper for activity. In the present investigation, we focused on copper (II) (N-2-hydroxyacetophenone) glycinate (CuNG), a novel in vitro and in vivo resistance modifying agent. A conjugate of GSH and CuNG was detected in vivo in mice and was characterized by spectroscopic studies. Based on UV, IR, proton NMR and elemental analyses, the chemical structure of the conjugate was elucidated. By means of atomic absorption data, the distribution and metabolism of CuNG is described.
Background: Multi drug resistance (MDR) or cross-resistance to multiple classes of chemotherapeut... more Background: Multi drug resistance (MDR) or cross-resistance to multiple classes of chemotherapeutic agents is a major obstacle to successful application of chemotherapy and a basic problem in cancer biology. The multidrug resistance gene, MDR1, and its gene product P-glycoprotein (P-gp) are an important determinant of MDR. Therefore, there is an urgent need for development of novel compounds that are not substrates of P-glycoprotein and are effective against drug-resistant cancer. Methodology/Principal Findings: In this present study, we have synthesized a novel, redox active Fe (II) complex (chelate), iron N-(2-hydroxy acetophenone) glycinate (FeNG). The structure of the complex has been determined by spectroscopic means. To evaluate the cytotoxic effect of FeNG we used doxorubicin resistant and/or sensitive T lymphoblastic leukemia cells and show that FeNG kills both the cell types irrespective of their MDR phenotype. Moreover, FeNG induces apoptosis in doxorubicin resistance T lymphoblastic leukemia cell through mitochondrial pathway via generation reactive oxygen species (ROS). This is substantiated by the fact that the antioxidant N-acetyle-cysteine (NAC) could completely block ROS generation and, subsequently, abrogated FeNG induced apoptosis. Therefore, FeNG induces the doxorubicin resistant T lymphoblastic leukemia cells to undergo apoptosis and thus overcome MDR. Conclusion/Significance: Our study provides evidence that FeNG, a redox active metal chelate may be a promising new therapeutic agent against drug resistance cancers.
Multidrug resistance (MDR) mediated by the over expression of drug efflux protein P-glycoprotein ... more Multidrug resistance (MDR) mediated by the over expression of drug efflux protein P-glycoprotein (P-gp) is one of the major impediments to successful treatment of cancer. P-gp acts as an energy-dependent drug efflux pump and reduces the intracellular concentration of structurally unrelated drugs inside the cells. Therefore, there is an urgent need for development of new molecules that are less toxic to normal cell and preferentially effective against drug resistant malignant cells. In this preclinical study we report the apoptotic potential of copper N-(2-hydroxyacetophenone) glycinate (CuNG) on doxorubicin resistant T lymphoblastic leukaemia cells (CEM/ADR5000). To evaluate the cytotoxic effect of CuNG, we used different normal cell lines (NIH 3T3, Chang liver and human PBMC) and cancerous cell lines (CEM/ADR5000, parental sensitive CCRF-CEM, SiHa and 3LL) and conclude that CuNG preferentially kills cancerous cells, especially both leukemic cell types irrespective of their MDR status, while leaving normal cell totally unaffected. Moreover, CuNG involves reactive oxygen species (ROS) for induction of apoptosis in CEM/ADR5000 cells through the intrinsic apoptotic pathway. This is substantiated by our observation that antioxidant N-acetyle-cysteine (NAC) and PEG catalase could completely block ROS generation and, subsequently, abrogates CuNG induced apoptosis. On the other hand, uncomplexed ligand N-(2-hydroxyacetophenone) glycinate (NG) fails to generate a significant amount of ROS and concomitant induction of apoptosis in CEM/ADR5000 cells. Therefore, CuNG induces drug resistant leukemia cells to undergo apoptosis and proves to be a molecule having therapeutic potential to overcome MDR in cancer.
Potassium (K(+)) channel openers are a diverse group of compounds which are used for the treatmen... more Potassium (K(+)) channel openers are a diverse group of compounds which are used for the treatment of diseases like angina pectoris, hypertension, congestive heart failure, anti-hypoglycemic (insulinoma), bronchial asthma, etc. R/S-3,4-dihydro-2,2-dimethyl-6-halo-4-(substituted phenylaminocarbonylamino)-2H-1-benzopyrans are a new series of ATP-sensitive potassium (K(ATP-pbeta)) channel openers selective towards pancreatic beta-cells. QSAR modelling was done on these series of compounds to find a more active and selective K(ATP-pbeta) channel opener selective towards beta-cells of pancreatic tissues. Wang-Ford charges, partition coefficient, molar refractivity, principle moment of inertia at X, Y and Z axes are used as predictor variables and logarithm of percentage of residual insulin secretion is treated as response variable for the modelling. Multiple linear regressions with factor analysis were performed to develop QSAR models. Four equations were obtained using different combinations of the predictor variables based on factor loadings. Regression coefficients of all descriptors used are significant at more than 95% level. Results showed that Wang-Ford charges on atom numbers 11, 17, 18, 19 and 21 are important for the inhibition of residual insulin secretion. The presence of electron withdrawing group at m- and p-position of phenyl ring B is required for the inhibition. The energy minimized geometry of the most active compound supported our modelling.
R/S-3,4-Dihydro-2,2-dimethyl-6-halo-4-(substituted phenylaminocarbonyl-amino)-2H-1-benzopyrans ar... more R/S-3,4-Dihydro-2,2-dimethyl-6-halo-4-(substituted phenylaminocarbonyl-amino)-2H-1-benzopyrans are pancreatic β-cells potassium (KATP-pβ) channel openers with inhibitory effect on insulin secretion. To find the more active and effective benzopyrans as selective potassium (KATP-pβ) channel openers towards the pancreatic tissues, quantitative structure–activity relationships (QSAR) study was performed using E-state and R-state indices along with Wang–Ford charges, n-octanol/water partition coefficient, molar refractivity, and indicator parameters. QSAR models were developed by statistical techniques, e.g., multiple linear regression (MLR), principle component regression analysis (PCRA), and partial least squares (PLS) analysis. The generated equations were validated by the leave-one-out cross-validation method. The models show the importance of ETSA indices of atom numbers 16, 17, 18, 19, 21 as well as 22. The positive coefficient of S16, S17, S18, S19, S21, and S22 indicate that with...
Multidrug resistance-associated protein 1 (MRP1) reduces intracellular anticancer drug accumulati... more Multidrug resistance-associated protein 1 (MRP1) reduces intracellular anticancer drug accumulation either by co transporting them with glutathione (GSH) or extruding drug-GSH conjugates outside of the cell. Thus, MRP1 confers multidrug resistance (MDR) and worsen successful chemotherapeutic treatment against cancer. Although the exact mechanism of MRP1 involved in MDR remains unknown, the elevated level of intracellular GSH is considered as a key factor responsible for MDR in cancer. Hence the quest for non-toxic molecules that are able to deplete intracellular GSH has profound importance to subdue MDR. The present preclinical study depicts the resistance reversal potentiality of an iron complex; viz. Ferrous N-(2-hydroxy acetophenone) glycinate (FeNG) developed by us in doxorubicin resistant Ehrlich ascites carcinoma (EAC/Dox) cells. FeNG potentiate cytotoxic effect of doxorubicin on EAC/Dox cells ex vivo and also increases the survivability EAC/Dox bearing Swiss albino mice in vivo as well. Moreover, in vivo administration of FeNG significantly depletes intracellular GSH with ensuant increase in doxorubicin concentration in EAC/Dox cells without alternation of MRP1 expression. In addition, intra-peritoneal (i.p.) application of FeNG in normal or EAC/Dox bearing mice does not cause any systemic toxicity in preliminary trials in mouse Ehrlich ascites carcinoma model. Therefore, the present report provides evidence that FeNG may be a promising new resistance modifying agent against drug resistant cancers. Keywords Multi drug resistance Á Glutathione Á Iron complex Á Resistance modifying agent Abbreviations MDR Multi drug resistance MRP1 Multidrug resistance-associated protein 1 GSH Glutathione FeNG Iron N-(2-hydroxy acetophenone) glycinate EAC/Dox Doxorubicin resistant Ehrlich ascites carcinoma cells MTT (3-[4,5-Dimethylthiazol-2-yl]-2, 5-diphenyltetrazolium bromide BSO DL-buthionine (S,R) sulfoximine EA Ethacrynic acid DTNB 5,5 0-Dithio bis(2-nitrobenzoic acid) RMA Resistance modifying agent ROS Reactive oxygen species DCFDA 2 0 ,7 0-Dihydrodichlorofluorescin diacetate
Cancer is one of the major causes of death. For cancer, the general conventional treatment and st... more Cancer is one of the major causes of death. For cancer, the general conventional treatment and standard of care for clinical oncology remains surgery followed by radiation and/or systemic chemotherapy as deemed appropriate based on the clinical findings. Chemoimmunotherapy is an approach to treat cancer where chemotherapy is given along with immunotherapy. Chemoimmunotherapy may be useful to enhance survival time in cancer by improve immunity of the patients. This approach may enhance the therapeutic efficacy. A comparative study was done to assess the therapeutic efficacy of the whole cell vaccine and the tumor extract with or without combination chemotherapy with the synthesized glutamine and glutamic acid derivatives and analogs as well as the standard drug etoposide against Ehrlich Ascites Carcinoma (EAC) cells in Swiss Albino mice. The study showed promising results with the compound 5-N-n-hexyl-2-(4-iso-butylbenzenesulphonyl)glutamine. The compound when combined with the whole cell vaccine as well as the tumor extract increases the survival time and the therapeutic efficacy which is comparable with that of standard drug etoposide.
Multidrug resistance (MDR) in cancer, a major obstacle to successful application of cancer chemot... more Multidrug resistance (MDR) in cancer, a major obstacle to successful application of cancer chemotherapy, is often characterized by over-expression of multidrug resistance-related proteins such as MRP1, P-gp or elevated glutathione (GSH) level. Efflux of drugs by functional P-gp, MRP1 and elevated GSH level can confer resistance to apoptosis induced by a range of different stimuli. Therefore, it is necessary to develop new cell death inducers with relatively lower toxicity toward non-malignant cells that can overcome MDR by induction of apoptotic or non-apoptotic cell death pathways. Herein we report the synthesis and spectroscopic characterization of a GSH depleting, redox active Schiff's base, viz., potassium-N-(2-hydroxy-3-methoxy-benzaldehyde)-alaninate (PHMBA). Cytotoxic potential of PHMBA has been studied in doxorubicin-resistant and -sensitive T lymphoblastic leukemia cells and Ehrlich ascites carcinoma (EAC) cells. PHMBA kills both the cell types irrespective of their drug-resistance phenotype following apoptotic/necrotic pathways. Moreover, PHMBA-induced cell death is associated with oxidative stress mediated mitochondrial pathway as the H(2)O(2) inhibitor PEG-Catalase abrogated PHMBA-induced apoptosis/necrosis. PHMBA induces anti-tumor activity in both doxorubicin-sensitive and -resistant EAC-tumor-bearing Swiss albino mice. The non-toxicity of PHMBA was also confirmed through cytotoxicity studies on normal cell lines like PBMC, NIH3T3 and Chang Liver. To summarise, our data provide compelling rationale for future clinical use of this redox active Schiff's base in treatment of cancer patients irrespective of their drug-resistance status.
Multidrug resistance (MDR) mediated by the over expression of drug efflux protein P-glycoprotein ... more Multidrug resistance (MDR) mediated by the over expression of drug efflux protein P-glycoprotein (P-gp) is one of the major impediments to successful treatment of cancer. P-gp acts as an energy-dependent drug efflux pump and reduces the intracellular concentration of structurally unrelated drugs inside the cells. Therefore, there is an urgent need for development of new molecules that are less toxic to normal cell and preferentially effective against drug resistant malignant cells. In this preclinical study we report the apoptotic potential of copper N-(2-hydroxyacetophenone) glycinate (CuNG) on doxorubicin resistant T lymphoblastic leukaemia cells (CEM/ADR5000). To evaluate the cytotoxic effect of CuNG, we used different normal cell lines (NIH 3T3, Chang liver and human PBMC) and cancerous cell lines (CEM/ADR5000, parental sensitive CCRF-CEM, SiHa and 3LL) and conclude that CuNG preferentially kills cancerous cells, especially both leukemic cell types irrespective of their MDR status, while leaving normal cell totally unaffected. Moreover, CuNG involves reactive oxygen species (ROS) for induction of apoptosis in CEM/ADR5000 cells through the intrinsic apoptotic pathway. This is substantiated by our observation that antioxidant N-acetyle-cysteine (NAC) and PEG catalase could completely block ROS generation and, subsequently, abrogates CuNG induced apoptosis. On the other hand, uncomplexed ligand N-(2-hydroxyacetophenone) glycinate (NG) fails to generate a significant amount of ROS and concomitant induction of apoptosis in CEM/ADR5000 cells. Therefore, CuNG induces drug resistant leukemia cells to undergo apoptosis and proves to be a molecule having therapeutic potential to overcome MDR in cancer.
Glutathione (GSH), an important component of the phase II detoxification system, plays a major ro... more Glutathione (GSH), an important component of the phase II detoxification system, plays a major role in storage, metabolism and transport of metals across the cell membrane. The role of copper, its metabolism and storage in living systems is not completely understood. Copper plays an important role in a number of physiological processes, e.g. several growth and transcription factors require copper for activity. In the present investigation, we focused on copper (II) (N-2-hydroxyacetophenone) glycinate (CuNG), a novel in vitro and in vivo resistance modifying agent. A conjugate of GSH and CuNG was detected in vivo in mice and was characterized by spectroscopic studies. Based on UV, IR, proton NMR and elemental analyses, the chemical structure of the conjugate was elucidated. By means of atomic absorption data, the distribution and metabolism of CuNG is described.
Multidrug resistance (MDR) in cancer, a major obstacle to successful application of cancer chemot... more Multidrug resistance (MDR) in cancer, a major obstacle to successful application of cancer chemotherapy, is often characterized by over-expression of multidrug resistance-related proteins such as MRP1, P-gp or elevated glutathione (GSH) level. Efflux of drugs by functional P-gp, MRP1 and elevated GSH level can confer resistance to apoptosis induced by a range of different stimuli.
In this present study, we have synthesized a novel, redox active Fe (II) complex (chelate), iron ... more In this present study, we have synthesized a novel, redox active Fe (II) complex (chelate), iron N-(2-hydroxy acetophenone) glycinate (FeNG). The structure of the complex has been determined by spectroscopic means. To evaluate the cytotoxic effect of FeNG we used doxorubicin ...
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