Krishnan Rathinasamy - Academia.edu (original) (raw)
Papers by Krishnan Rathinasamy
Journal of Biological Inorganic Chemistry, May 31, 2021
Vanadocene dichloride (VDC), a vanadium containing metallocene dihalide exhibits promising antica... more Vanadocene dichloride (VDC), a vanadium containing metallocene dihalide exhibits promising anticancer activity. However, its mechanism of action remains elusive as several diverse targets and pathways have been proposed for its anticancer activity. In this study, we observed that VDC inhibited the proliferation of mammalian cancer cells and induced apoptotic cell death by altering the mitochondrial membrane potential and the expression of bcl2 and bax. Probing further into its anticancer mechanism, we found that VDC caused depolymerization of interphase microtubules and blocked the cells at mitosis with considerable proportion of cells exhibiting monopolar spindles. The reassembly of cold depolymerized microtubules was strongly inhibited in the presence of 10 μM VDC. VDC perturbed the microtubule-kinetochore interactions during mitosis as indicated by the absence of cold stable spindle microtubules in the cells treated with 20 μM VDC. Using goat brain tubulin, we found that VDC inhibited the steady-state polymer mass of microtubules and bound to tubulin at a novel site with a Kd of 9.71 ± 0.19 μM and perturbed the secondary structure of tubulin dimer. In addition, VDC was also found to bind to the mitotic kinesin Eg5 and inhibit its basal as well as microtubule stimulated ATPase activity. The results suggest that disruption of microtubule assembly dynamics and inhibition of the ATPase activity of Eg5 could be a plausible mechanism for the antiproliferative and antimitotic activity of VDC.Graphic abstract.
Proceedings of the National Academy of Sciences of the United States of America, Jun 28, 2005
FEBS Journal, Jul 28, 2006
We found that benomyl, a benzimidazole fungicide, strongly suppressed the reassembly of cold-depo... more We found that benomyl, a benzimidazole fungicide, strongly suppressed the reassembly of cold-depolymerized spindle microtubules in HeLa cells. Benomyl perturbed microtubule-kinetochore attachment and chromosome alignment at the metaphase plate. Benomyl also significantly decreased the distance between the sister kinetochore pairs in metaphase cells and increased the level of the checkpoint protein BubR1 at the kinetochore region, indicating that benomyl caused loss of tension across the kinetochores. In addition, benomyl decreased the intercentrosomal distance in mitotic HeLa cells and blocked the cells at mitosis. Further, we analyzed the effects of benomyl on the signal transduction pathways in relation to mitotic block, bcl2 phosphorylation and induction of apoptosis. The results suggest that benomyl causes loss of tension across the kinetochores, blocks the cell cycle progression at mitosis and subsequently, induces apoptosis through the bcl2-bax pathway in a manner qualitatively similar to the powerful microtubule targeted anticancer drugs like the vinca alkaloids and paclitaxel. Considering the very high toxicity of the potent anticancer drugs and the low toxicity of benomyl in humans, we suggest that benomyl could be useful as an adjuvant in combination with the powerful anticancer drugs in cancer therapy.
Journal of Materials Chemistry, 2007
... NK Prasada, K. Rathinasamyb, D. Panda*b and D. Bahadur*a. a Department of Metallurgical Engin... more ... NK Prasada, K. Rathinasamyb, D. Panda*b and D. Bahadur*a. a Department of Metallurgical Engineering and Materials Science, Indian Institute of ... the solvent EG plays a vital role in providing a reaction temperature of 200 °C close to its boiling point which makes the formation ...
Journal of Biomedical Materials Research Part B, 2008
La1−xSrxMnO3, a ferromagnet with high magnetization and Curie temperature TC below 70°C, enables ... more La1−xSrxMnO3, a ferromagnet with high magnetization and Curie temperature TC below 70°C, enables its use for magnetic hyperthermia treatment of cancer with a possibility of in vivo temperature control. We found that La0.73Sr0.27MnO3 particles of size range 20–100 nm showed saturation magnetization around 38 emu/g at 20 kOe and a TC value of 45°C. Aqueous suspension of these nanoparticles was prepared using a polymer, acrypol 934, and the biocompatibility of the suspension was examined using HeLa cells. A good heating ability of the magnetic suspension was obtained in the presence of AC magnetic field, and it was found to increase with the amplitude of field. The suspension having concentration of 0.66 mg/mL (e.g., 0.66 mg of nanoparticles with acropyl per milliliter of culture media) was observed to be biocompatible even after 96 h of treatment, as estimated by sulforhodamine B and trypan blue dye exclusion assays. Further, the treatment with the aforementioned concentration did not alter the microtubule cytoskeleton or the nucleus of the cells. However, the bare particles (concentration of 0.66 mg of nanoparticles per milliliter of culture media, but without acropyl) decreased the viability of cell significantly. Our in vitro studies suggest that the suspension (concentration of 0.66 mg/mL) may further be analyzed for in vivo studies. © 2007 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2008
A b s t r a c t Using absorption and fluorescence spectroscopic methods, quantitative cellular up... more A b s t r a c t Using absorption and fluorescence spectroscopic methods, quantitative cellular uptake of curcumin, was calculated in two types of normal cells: spleen lymphocytes and NIH3T3 and two tumor cell lines: EL4 & MCF7. Both the uptake and fluorescence intensity of curcumin were significantly higher in tumor cells as compared to the normal cells. Using laser confocal microscopy, intracellular localization of curcumin was monitored and the results indicated that curcumin is located both in the cell membrane and in the nucleus.
Journal of Nanopharmaceutics and Drug Delivery, 2013
Biochimica et Biophysica Acta (BBA) - General Subjects, 2008
Using absorption and fluorescence spectroscopic methods, quantitative cellular uptake of curcumin... more Using absorption and fluorescence spectroscopic methods, quantitative cellular uptake of curcumin, an antioxidant and anti-tumor agent from Curcuma longa, was calculated in two types of normal cells: spleen lymphocytes, and NIH3T3 and two tumor cell lines: EL4 and MCF7. Both the uptake and fluorescence intensity of curcumin were significantly higher in tumor cells compared to the normal cells. A linear dependency on the uptake was observed with treatment concentration of curcumin. Using laser confocal microscopy, intracellular localization of curcumin was monitored and the results indicated that curcumin is located both in the cell membrane and the nucleus. Sub-cellular fractionation of curcuminloaded MCF7 cells supported the differential distribution of curcumin in membrane, cytoplasm and nuclear compartments of cell with maximum localization in the membrane. Cytotoxicity studies in different cell lines indicated that the toxicity of curcumin increased with increasing uptake.
Chemistry & Biodiversity
Biological activities of a series of palladium(II) complexes (M1–M9) bearing N∩N, N∩S, and N∩O ch... more Biological activities of a series of palladium(II) complexes (M1–M9) bearing N∩N, N∩S, and N∩O chelating ligands are reported. The palladium complexes were tested for their cytotoxic properties against human cervical cancer (HeLa) cells and antibacterial activity against Gm+ve and Gm–ve bacteria. Among the palladium complexes studied (M1‐M9), the complex M5, M8, and M9 were found to be more effective in inhibiting the proliferation of HeLa cells. Hence, these complexes were further investigated for their potential role in cellular damage and apoptosis. DCFDA staining, Rhodamine 123 staining and DNA cleavage assay revealed that complex M5, M8 and M9 induced apoptotic cell death in HeLa cells through ROS generation, DNA damage and mitochondrial depolarization. Computational and titration studies also indicated strong electrostatic interaction with DNA groove. Most of the complexes exhibited good antibacterial activity against both Gm+ve and Gm−ve bacteria. The antibacterial activity o...
Cytotechnology, 2022
Tioconazole is one of the drugs used to treat topical mycotic infections. It exhibited severe tox... more Tioconazole is one of the drugs used to treat topical mycotic infections. It exhibited severe toxicity during systemic administration; however, the molecular mechanism behind the cytotoxic effect was not well established. We employed HeLa cells as a model to investigate the molecular mechanism of its toxicity and discovered that tioconazole inhibited HeLa cell growth through mitotic block (37%). At the half-maximal inhibitory concentration (≈ 15 μM) tioconazole apparently depolymerized microtubules and caused defects in chromosomal congression at the metaphase plate. Tioconazole induced apoptosis and significantly hindered the migration of HeLa cells. Tioconazole bound to goat brain tubulin ( K d , 28.3 ± 0.5 μM) and inhibited the assembly of microtubules in the in vitro assays . We report for the first time that tioconazole binds near to the colchicine site, based on the evidence from in vitro tubulin competition experiment and computational analysis. The conformation of tubulin dimer was found to be “curved” upon binding with tioconazole in the MD simulation. Tioconazole in combination with vinblastine synergistically inhibited the growth of HeLa cells and augmented the percentage of mitotic block by synergistically inhibiting the assembly of microtubules. Our study indicates that the systemic adverse effects of tioconazole are partly due to its effects on microtubules and cell cycle arrest. Since tioconazole is well tolerated at the topical level, it could be developed as a topical anticancer agent in combination with other systemic anticancer drugs. Graphical abstract
Naunyn-Schmiedeberg's Archives of Pharmacology, 2021
Econazole, miconazole, and sertaconazole, the structurally related azoles with imidazole moiety, ... more Econazole, miconazole, and sertaconazole, the structurally related azoles with imidazole moiety, were evaluated for their cytotoxicity and their ability to bind to mammalian tubulin. Our results indicated that sertaconazole and econazole bound to goat brain tubulin with a dissociation constant of 9 and 19 μM respectively, while miconazole did not bind to goat brain tubulin. Econazole, miconazole, and sertaconazole inhibited the proliferation of HeLa cells with an IC 50 of 28, 98, and 38 μM respectively with sertaconazole alone inducing a mitotic block in the treated cells. Since sertaconazole bound to goat brain tubulin with higher affinity and blocked the cells at mitosis, we hypothesized that its cytotoxic mechanism might involve inhibition of tubulin and econazole which did not block the cells at mitosis may have additional targets than tubulin. Sertaconazole inhibited the polymerization of tubulin in HeLa cells and the in vitro assembled goat brain tubulin. Competitive tubulin-binding assay using colchicine and computational simulation studies showed that sertaconazole bound closer to the colchicine site and induced the tubulin dimer to adopt a "bent" conformation which is incompetent for the polymerization. Results from RT-PCR analysis of the A549 cells treated with sertaconazole indicated activation of apoptosis. Sertaconazole significantly inhibited the migration of HeLa cells and showed synergistic antiproliferative potential with vinblastine. Collectively, the results suggest that sertaconazole which is already in clinical practice could be useful as a topical chemotherapy agent for the treatment of skin cancers in combination with other systemic anticancer agents.
Journal of Fluorescence, 2021
Purpurin (1,2,4-trihydroxy-9,10-anthraquinone) is a natural red dye obtained from the red madder ... more Purpurin (1,2,4-trihydroxy-9,10-anthraquinone) is a natural red dye obtained from the red madder plant that is widely used in food and dyeing industries. The present study investigated the characteristics of purpurin and its application as a pH-sensitive probe to detect the pH of solutions and intracellular pH of mammalian and bacterial cells. Purpurin exhibited high pH-sensitive behavior, low analytes interference, high stability with pKa of 4.6 and visible colorimetric change. 1H NMR and FTIR studies indicated protonation of phenolic hydroxyl group under acidic condition with hypsochromic shift in the absorption and fluorescence spectra relative to that of basic condition. Cell culture studies using HeLa cells revealed that purpurin is well tolerated by the cells and the fluorescent imaging result indicated excellent cell permeability with possible use of the dye to detect the pH fluctuations in living cells under various physiological conditions such as apoptosis. Microbiological studies indicated that the dye could be used for visualization of bacteria under acidic condition.
Life Sciences, 2021
AIM Analysis of the anticancer and antimitotic activity of the plant derived alkaloid securinine ... more AIM Analysis of the anticancer and antimitotic activity of the plant derived alkaloid securinine along with its effect on the organization of cellular microtubules as well as its binding with purified goat brain tubulin in-vitro. MATERIALS AND METHODS The cytotoxicity of securinine on different cell lines was conducted using SRB assay. The effect of securinine on the cellular microtubules was analyzed using immunofluorescence microscopy. The binding of securinine on purified goat brain tubulin was evaluated using fluorescent spectroscopy. KEY FINDINGS Securinine effectively prevented the proliferation of cervical, breast and lung cancer cells with an IC50 of 6, 10 and 11 μM respectively and induced minimal toxicity in HEK cell line. Securinine at concentrations higher than IC50 induced significant depolymerization in interphase and mitotic microtubules and it suppressed the reassembly of cold depolymerized spindle microtubules in HeLa cells. In the wound healing assay, securinine effectively suppressed the migration of HeLa cells to close the wound. Securinine bound to tubulin with a Kd of 9.7 μM and inhibited the assembly of tubulin into microtubules. The treatment with securinine induced a mitochondrial dependent ROS response in HeLa cells which enhanced the cytotoxic effect of securinine. The result from gene expression studies indicates that securinine induced apoptosis in MCF-7 cells through p53 dependent pathway. SIGNIFICANCE Considering the strong anticancer and anti-metastatic property and low toxicity in non-malignant cell lines, we suggest that securinine can be used as a chemotherapeutic drug either alone or in combination with other known anticancer molecules.
Bioorganic & Medicinal Chemistry, 2021
There is an increasing demand to discover novel antibacterial drugs to counter the ever-evolving ... more There is an increasing demand to discover novel antibacterial drugs to counter the ever-evolving genetic machinery of bacteria. The cell division protein FtsZ plays a vital role in bacterial cytokinesis and has been recognized as an effective antibacterial drug target. In this study, we have shown that the madder dye purpurin inhibited bacterial cytokinesis through perturbation of FtsZ assembly. Purpurin inhibited the growth of bacterial cells in a concentration-dependent manner and induced bacterial cell filamentation. Microscopy studies showed that it inhibited the localization of the Z ring at the midcell, and FtsZ was dispersed throughout the cells. Further, purpurin bound firmly to FtsZ with a dissociation constant of 11 µM and inhibited its assembly in vitro. It reduced the GTP hydrolysis by binding closer to the nucleotide-binding site of FtsZ. Purpurin inhibited the proliferation of mammalian cancer cells at higher concentrations without disturbing the polymerization of tubulin. The results collectively suggest that the natural anthraquinone purpurin can potently inhibit the growth of bacteria and serve as a lead molecule for the development of antibacterial agents.
JBIC Journal of Biological Inorganic Chemistry, 2021
Vanadocene dichloride (VDC), a vanadium containing metallocene dihalide exhibits promising antica... more Vanadocene dichloride (VDC), a vanadium containing metallocene dihalide exhibits promising anticancer activity. However, its mechanism of action remains elusive as several diverse targets and pathways have been proposed for its anticancer activity. In this study, we observed that VDC inhibited the proliferation of mammalian cancer cells and induced apoptotic cell death by altering the mitochondrial membrane potential and the expression of bcl2 and bax. Probing further into its anticancer mechanism, we found that VDC caused depolymerization of interphase microtubules and blocked the cells at mitosis with considerable proportion of cells exhibiting monopolar spindles. The reassembly of cold depolymerized microtubules was strongly inhibited in the presence of 10 μM VDC. VDC perturbed the microtubule-kinetochore interactions during mitosis as indicated by the absence of cold stable spindle microtubules in the cells treated with 20 μM VDC. Using goat brain tubulin, we found that VDC inhibited the steady-state polymer mass of microtubules and bound to tubulin at a novel site with a Kd of 9.71 ± 0.19 μM and perturbed the secondary structure of tubulin dimer. In addition, VDC was also found to bind to the mitotic kinesin Eg5 and inhibit its basal as well as microtubule stimulated ATPase activity. The results suggest that disruption of microtubule assembly dynamics and inhibition of the ATPase activity of Eg5 could be a plausible mechanism for the antiproliferative and antimitotic activity of VDC.Graphic abstract.
International Journal of Biological Macromolecules, 2019
Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, 2019
Trifluoperazine is a potent antipsychotic drug used in the treatment of neurological disorders. T... more Trifluoperazine is a potent antipsychotic drug used in the treatment of neurological disorders. The usage of trifluoperazine is often found to be associated with more adverse side effects as compared to other low-potency antipsychotic agents. Plasma proteins play an inevitable role in determining the pharmacokinetic properties of a drug. Hence, this study was conducted with an aim to characterize the interactions of trifluoperazine with bovine serum albumin and determine the influence of other small molecules on its interaction with serum albumin. Trifluoperazine bound to BSA at two independent sites with K d values of 9.5 and 172.6 mM. F€ orster resonance energy transfer and computational docking analysis revealed that both the binding sites of trifluoperazine were located closer to TRP 213 in subdomain IIA of BSA. Evaluation of trifluoperazine-BSA interactions at three different temperatures indicated that there was a stable complex formation between the two molecules at the ground state and that the static quenching mechanism was predominant behind these interactions. Binding studies in the presence of pharmaceutically relevant drugs indicated that warfarin, paracetamol, and caffeine negatively influenced the binding of trifluoperazine on BSA. Lastly, Fourier transformed infrared spectroscopy and circular dichroism spectroscopy indicated that the binding of trifluoperazine induced a conformational change by reducing the a-helical content of BSA. The study implicates that the small molecules which prefer binding to the Sudlow site I of BSA might compete with trifluoperazine for its binding site thereby increasing the concentration of free trifluoperazine in the plasma which could lead to adverse side effects in patients.
Molecular Informatics, 2019
The interaction of Kif15 with kinesin binding protein (KBP) is critical for its microtubule local... more The interaction of Kif15 with kinesin binding protein (KBP) is critical for its microtubule localization, bundling of kinetochore microtubules and proper alignment of chromosomes at the metaphase plate. The Kif15-KBP structure was prepared from the crystal structure of Kif15 and nonhomologous model of KBP through docking. Benserazide was retrieved when we did a screening of the ZINC Drug Database using the pharmacophore model generated from the potential binding site on Kif15 in an effort to identify molecules for repurposing as Kif15 inhibitors. Live cell imaging of HeLa cells revealed that benserazide delayed metaphase to anaphase-onset by 47 � 10 min compared to control cells. Benserazide treatment perturbed the kinetochore and microtubule interaction and inhibited the proliferation of HeLa cells with an IC50 of 101 μM with a mitotic block of 12 %. It did not bind to tubulin in the in vitro assays suggesting that the observed effects could be due to its perturbation of Kif15-KBP interaction.
Materials Science and Engineering: C, 2019
Type 1 diabetes mellitus (DM) is a metabolic disorder associated with impaired carbohydrate metab... more Type 1 diabetes mellitus (DM) is a metabolic disorder associated with impaired carbohydrate metabolism. We present a promising bioinspired approach against type 1 DM using yeast microcapsule (YMC). The glucan component in the outer shell of baker's yeast undergoes receptor-mediated uptake by phagocytic cells through M cell-mediated endocytosis. Thus, a drug can be expected to be delivered to the systemic circulation via lymphatic transport if it is attached to the surface of YMC. For the first time, this possibility has been explored by surface loading of insulin onto YMC. The electrostatic interaction between oppositely charged YMC and insulin resulted in the formation of insulin-loaded yeast microcapsule (IYMC) which was confirmed by fluorescence imaging. Alginate coating provided to IYMC protects YMC from the harsh environment of the gastrointestinal tract and prevents the degradation of insulin in IYMC. Cellular uptake of FITC conjugated IYMC by RAW macrophages confirmed the proposed mechanism of insulin uptake. Moreover, an in vitro method using YMC-imprinted gel was developed for insulin release study from the bioinspired system. Molecular docking studies proved the interaction of insulin with β-glucan and alginate. A significant hypoglycemic effect was observed after oral administration of the alginate coated insulin-loaded yeast microcapsule (AL-IYMC) in diabetic rats. The AL-IYMCs could serve as a promising approach towards the oral delivery of insulin.
Journal of Biological Inorganic Chemistry, May 31, 2021
Vanadocene dichloride (VDC), a vanadium containing metallocene dihalide exhibits promising antica... more Vanadocene dichloride (VDC), a vanadium containing metallocene dihalide exhibits promising anticancer activity. However, its mechanism of action remains elusive as several diverse targets and pathways have been proposed for its anticancer activity. In this study, we observed that VDC inhibited the proliferation of mammalian cancer cells and induced apoptotic cell death by altering the mitochondrial membrane potential and the expression of bcl2 and bax. Probing further into its anticancer mechanism, we found that VDC caused depolymerization of interphase microtubules and blocked the cells at mitosis with considerable proportion of cells exhibiting monopolar spindles. The reassembly of cold depolymerized microtubules was strongly inhibited in the presence of 10 μM VDC. VDC perturbed the microtubule-kinetochore interactions during mitosis as indicated by the absence of cold stable spindle microtubules in the cells treated with 20 μM VDC. Using goat brain tubulin, we found that VDC inhibited the steady-state polymer mass of microtubules and bound to tubulin at a novel site with a Kd of 9.71 ± 0.19 μM and perturbed the secondary structure of tubulin dimer. In addition, VDC was also found to bind to the mitotic kinesin Eg5 and inhibit its basal as well as microtubule stimulated ATPase activity. The results suggest that disruption of microtubule assembly dynamics and inhibition of the ATPase activity of Eg5 could be a plausible mechanism for the antiproliferative and antimitotic activity of VDC.Graphic abstract.
Proceedings of the National Academy of Sciences of the United States of America, Jun 28, 2005
FEBS Journal, Jul 28, 2006
We found that benomyl, a benzimidazole fungicide, strongly suppressed the reassembly of cold-depo... more We found that benomyl, a benzimidazole fungicide, strongly suppressed the reassembly of cold-depolymerized spindle microtubules in HeLa cells. Benomyl perturbed microtubule-kinetochore attachment and chromosome alignment at the metaphase plate. Benomyl also significantly decreased the distance between the sister kinetochore pairs in metaphase cells and increased the level of the checkpoint protein BubR1 at the kinetochore region, indicating that benomyl caused loss of tension across the kinetochores. In addition, benomyl decreased the intercentrosomal distance in mitotic HeLa cells and blocked the cells at mitosis. Further, we analyzed the effects of benomyl on the signal transduction pathways in relation to mitotic block, bcl2 phosphorylation and induction of apoptosis. The results suggest that benomyl causes loss of tension across the kinetochores, blocks the cell cycle progression at mitosis and subsequently, induces apoptosis through the bcl2-bax pathway in a manner qualitatively similar to the powerful microtubule targeted anticancer drugs like the vinca alkaloids and paclitaxel. Considering the very high toxicity of the potent anticancer drugs and the low toxicity of benomyl in humans, we suggest that benomyl could be useful as an adjuvant in combination with the powerful anticancer drugs in cancer therapy.
Journal of Materials Chemistry, 2007
... NK Prasada, K. Rathinasamyb, D. Panda*b and D. Bahadur*a. a Department of Metallurgical Engin... more ... NK Prasada, K. Rathinasamyb, D. Panda*b and D. Bahadur*a. a Department of Metallurgical Engineering and Materials Science, Indian Institute of ... the solvent EG plays a vital role in providing a reaction temperature of 200 °C close to its boiling point which makes the formation ...
Journal of Biomedical Materials Research Part B, 2008
La1−xSrxMnO3, a ferromagnet with high magnetization and Curie temperature TC below 70°C, enables ... more La1−xSrxMnO3, a ferromagnet with high magnetization and Curie temperature TC below 70°C, enables its use for magnetic hyperthermia treatment of cancer with a possibility of in vivo temperature control. We found that La0.73Sr0.27MnO3 particles of size range 20–100 nm showed saturation magnetization around 38 emu/g at 20 kOe and a TC value of 45°C. Aqueous suspension of these nanoparticles was prepared using a polymer, acrypol 934, and the biocompatibility of the suspension was examined using HeLa cells. A good heating ability of the magnetic suspension was obtained in the presence of AC magnetic field, and it was found to increase with the amplitude of field. The suspension having concentration of 0.66 mg/mL (e.g., 0.66 mg of nanoparticles with acropyl per milliliter of culture media) was observed to be biocompatible even after 96 h of treatment, as estimated by sulforhodamine B and trypan blue dye exclusion assays. Further, the treatment with the aforementioned concentration did not alter the microtubule cytoskeleton or the nucleus of the cells. However, the bare particles (concentration of 0.66 mg of nanoparticles per milliliter of culture media, but without acropyl) decreased the viability of cell significantly. Our in vitro studies suggest that the suspension (concentration of 0.66 mg/mL) may further be analyzed for in vivo studies. © 2007 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2008
A b s t r a c t Using absorption and fluorescence spectroscopic methods, quantitative cellular up... more A b s t r a c t Using absorption and fluorescence spectroscopic methods, quantitative cellular uptake of curcumin, was calculated in two types of normal cells: spleen lymphocytes and NIH3T3 and two tumor cell lines: EL4 & MCF7. Both the uptake and fluorescence intensity of curcumin were significantly higher in tumor cells as compared to the normal cells. Using laser confocal microscopy, intracellular localization of curcumin was monitored and the results indicated that curcumin is located both in the cell membrane and in the nucleus.
Journal of Nanopharmaceutics and Drug Delivery, 2013
Biochimica et Biophysica Acta (BBA) - General Subjects, 2008
Using absorption and fluorescence spectroscopic methods, quantitative cellular uptake of curcumin... more Using absorption and fluorescence spectroscopic methods, quantitative cellular uptake of curcumin, an antioxidant and anti-tumor agent from Curcuma longa, was calculated in two types of normal cells: spleen lymphocytes, and NIH3T3 and two tumor cell lines: EL4 and MCF7. Both the uptake and fluorescence intensity of curcumin were significantly higher in tumor cells compared to the normal cells. A linear dependency on the uptake was observed with treatment concentration of curcumin. Using laser confocal microscopy, intracellular localization of curcumin was monitored and the results indicated that curcumin is located both in the cell membrane and the nucleus. Sub-cellular fractionation of curcuminloaded MCF7 cells supported the differential distribution of curcumin in membrane, cytoplasm and nuclear compartments of cell with maximum localization in the membrane. Cytotoxicity studies in different cell lines indicated that the toxicity of curcumin increased with increasing uptake.
Chemistry & Biodiversity
Biological activities of a series of palladium(II) complexes (M1–M9) bearing N∩N, N∩S, and N∩O ch... more Biological activities of a series of palladium(II) complexes (M1–M9) bearing N∩N, N∩S, and N∩O chelating ligands are reported. The palladium complexes were tested for their cytotoxic properties against human cervical cancer (HeLa) cells and antibacterial activity against Gm+ve and Gm–ve bacteria. Among the palladium complexes studied (M1‐M9), the complex M5, M8, and M9 were found to be more effective in inhibiting the proliferation of HeLa cells. Hence, these complexes were further investigated for their potential role in cellular damage and apoptosis. DCFDA staining, Rhodamine 123 staining and DNA cleavage assay revealed that complex M5, M8 and M9 induced apoptotic cell death in HeLa cells through ROS generation, DNA damage and mitochondrial depolarization. Computational and titration studies also indicated strong electrostatic interaction with DNA groove. Most of the complexes exhibited good antibacterial activity against both Gm+ve and Gm−ve bacteria. The antibacterial activity o...
Cytotechnology, 2022
Tioconazole is one of the drugs used to treat topical mycotic infections. It exhibited severe tox... more Tioconazole is one of the drugs used to treat topical mycotic infections. It exhibited severe toxicity during systemic administration; however, the molecular mechanism behind the cytotoxic effect was not well established. We employed HeLa cells as a model to investigate the molecular mechanism of its toxicity and discovered that tioconazole inhibited HeLa cell growth through mitotic block (37%). At the half-maximal inhibitory concentration (≈ 15 μM) tioconazole apparently depolymerized microtubules and caused defects in chromosomal congression at the metaphase plate. Tioconazole induced apoptosis and significantly hindered the migration of HeLa cells. Tioconazole bound to goat brain tubulin ( K d , 28.3 ± 0.5 μM) and inhibited the assembly of microtubules in the in vitro assays . We report for the first time that tioconazole binds near to the colchicine site, based on the evidence from in vitro tubulin competition experiment and computational analysis. The conformation of tubulin dimer was found to be “curved” upon binding with tioconazole in the MD simulation. Tioconazole in combination with vinblastine synergistically inhibited the growth of HeLa cells and augmented the percentage of mitotic block by synergistically inhibiting the assembly of microtubules. Our study indicates that the systemic adverse effects of tioconazole are partly due to its effects on microtubules and cell cycle arrest. Since tioconazole is well tolerated at the topical level, it could be developed as a topical anticancer agent in combination with other systemic anticancer drugs. Graphical abstract
Naunyn-Schmiedeberg's Archives of Pharmacology, 2021
Econazole, miconazole, and sertaconazole, the structurally related azoles with imidazole moiety, ... more Econazole, miconazole, and sertaconazole, the structurally related azoles with imidazole moiety, were evaluated for their cytotoxicity and their ability to bind to mammalian tubulin. Our results indicated that sertaconazole and econazole bound to goat brain tubulin with a dissociation constant of 9 and 19 μM respectively, while miconazole did not bind to goat brain tubulin. Econazole, miconazole, and sertaconazole inhibited the proliferation of HeLa cells with an IC 50 of 28, 98, and 38 μM respectively with sertaconazole alone inducing a mitotic block in the treated cells. Since sertaconazole bound to goat brain tubulin with higher affinity and blocked the cells at mitosis, we hypothesized that its cytotoxic mechanism might involve inhibition of tubulin and econazole which did not block the cells at mitosis may have additional targets than tubulin. Sertaconazole inhibited the polymerization of tubulin in HeLa cells and the in vitro assembled goat brain tubulin. Competitive tubulin-binding assay using colchicine and computational simulation studies showed that sertaconazole bound closer to the colchicine site and induced the tubulin dimer to adopt a "bent" conformation which is incompetent for the polymerization. Results from RT-PCR analysis of the A549 cells treated with sertaconazole indicated activation of apoptosis. Sertaconazole significantly inhibited the migration of HeLa cells and showed synergistic antiproliferative potential with vinblastine. Collectively, the results suggest that sertaconazole which is already in clinical practice could be useful as a topical chemotherapy agent for the treatment of skin cancers in combination with other systemic anticancer agents.
Journal of Fluorescence, 2021
Purpurin (1,2,4-trihydroxy-9,10-anthraquinone) is a natural red dye obtained from the red madder ... more Purpurin (1,2,4-trihydroxy-9,10-anthraquinone) is a natural red dye obtained from the red madder plant that is widely used in food and dyeing industries. The present study investigated the characteristics of purpurin and its application as a pH-sensitive probe to detect the pH of solutions and intracellular pH of mammalian and bacterial cells. Purpurin exhibited high pH-sensitive behavior, low analytes interference, high stability with pKa of 4.6 and visible colorimetric change. 1H NMR and FTIR studies indicated protonation of phenolic hydroxyl group under acidic condition with hypsochromic shift in the absorption and fluorescence spectra relative to that of basic condition. Cell culture studies using HeLa cells revealed that purpurin is well tolerated by the cells and the fluorescent imaging result indicated excellent cell permeability with possible use of the dye to detect the pH fluctuations in living cells under various physiological conditions such as apoptosis. Microbiological studies indicated that the dye could be used for visualization of bacteria under acidic condition.
Life Sciences, 2021
AIM Analysis of the anticancer and antimitotic activity of the plant derived alkaloid securinine ... more AIM Analysis of the anticancer and antimitotic activity of the plant derived alkaloid securinine along with its effect on the organization of cellular microtubules as well as its binding with purified goat brain tubulin in-vitro. MATERIALS AND METHODS The cytotoxicity of securinine on different cell lines was conducted using SRB assay. The effect of securinine on the cellular microtubules was analyzed using immunofluorescence microscopy. The binding of securinine on purified goat brain tubulin was evaluated using fluorescent spectroscopy. KEY FINDINGS Securinine effectively prevented the proliferation of cervical, breast and lung cancer cells with an IC50 of 6, 10 and 11 μM respectively and induced minimal toxicity in HEK cell line. Securinine at concentrations higher than IC50 induced significant depolymerization in interphase and mitotic microtubules and it suppressed the reassembly of cold depolymerized spindle microtubules in HeLa cells. In the wound healing assay, securinine effectively suppressed the migration of HeLa cells to close the wound. Securinine bound to tubulin with a Kd of 9.7 μM and inhibited the assembly of tubulin into microtubules. The treatment with securinine induced a mitochondrial dependent ROS response in HeLa cells which enhanced the cytotoxic effect of securinine. The result from gene expression studies indicates that securinine induced apoptosis in MCF-7 cells through p53 dependent pathway. SIGNIFICANCE Considering the strong anticancer and anti-metastatic property and low toxicity in non-malignant cell lines, we suggest that securinine can be used as a chemotherapeutic drug either alone or in combination with other known anticancer molecules.
Bioorganic & Medicinal Chemistry, 2021
There is an increasing demand to discover novel antibacterial drugs to counter the ever-evolving ... more There is an increasing demand to discover novel antibacterial drugs to counter the ever-evolving genetic machinery of bacteria. The cell division protein FtsZ plays a vital role in bacterial cytokinesis and has been recognized as an effective antibacterial drug target. In this study, we have shown that the madder dye purpurin inhibited bacterial cytokinesis through perturbation of FtsZ assembly. Purpurin inhibited the growth of bacterial cells in a concentration-dependent manner and induced bacterial cell filamentation. Microscopy studies showed that it inhibited the localization of the Z ring at the midcell, and FtsZ was dispersed throughout the cells. Further, purpurin bound firmly to FtsZ with a dissociation constant of 11 µM and inhibited its assembly in vitro. It reduced the GTP hydrolysis by binding closer to the nucleotide-binding site of FtsZ. Purpurin inhibited the proliferation of mammalian cancer cells at higher concentrations without disturbing the polymerization of tubulin. The results collectively suggest that the natural anthraquinone purpurin can potently inhibit the growth of bacteria and serve as a lead molecule for the development of antibacterial agents.
JBIC Journal of Biological Inorganic Chemistry, 2021
Vanadocene dichloride (VDC), a vanadium containing metallocene dihalide exhibits promising antica... more Vanadocene dichloride (VDC), a vanadium containing metallocene dihalide exhibits promising anticancer activity. However, its mechanism of action remains elusive as several diverse targets and pathways have been proposed for its anticancer activity. In this study, we observed that VDC inhibited the proliferation of mammalian cancer cells and induced apoptotic cell death by altering the mitochondrial membrane potential and the expression of bcl2 and bax. Probing further into its anticancer mechanism, we found that VDC caused depolymerization of interphase microtubules and blocked the cells at mitosis with considerable proportion of cells exhibiting monopolar spindles. The reassembly of cold depolymerized microtubules was strongly inhibited in the presence of 10 μM VDC. VDC perturbed the microtubule-kinetochore interactions during mitosis as indicated by the absence of cold stable spindle microtubules in the cells treated with 20 μM VDC. Using goat brain tubulin, we found that VDC inhibited the steady-state polymer mass of microtubules and bound to tubulin at a novel site with a Kd of 9.71 ± 0.19 μM and perturbed the secondary structure of tubulin dimer. In addition, VDC was also found to bind to the mitotic kinesin Eg5 and inhibit its basal as well as microtubule stimulated ATPase activity. The results suggest that disruption of microtubule assembly dynamics and inhibition of the ATPase activity of Eg5 could be a plausible mechanism for the antiproliferative and antimitotic activity of VDC.Graphic abstract.
International Journal of Biological Macromolecules, 2019
Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy, 2019
Trifluoperazine is a potent antipsychotic drug used in the treatment of neurological disorders. T... more Trifluoperazine is a potent antipsychotic drug used in the treatment of neurological disorders. The usage of trifluoperazine is often found to be associated with more adverse side effects as compared to other low-potency antipsychotic agents. Plasma proteins play an inevitable role in determining the pharmacokinetic properties of a drug. Hence, this study was conducted with an aim to characterize the interactions of trifluoperazine with bovine serum albumin and determine the influence of other small molecules on its interaction with serum albumin. Trifluoperazine bound to BSA at two independent sites with K d values of 9.5 and 172.6 mM. F€ orster resonance energy transfer and computational docking analysis revealed that both the binding sites of trifluoperazine were located closer to TRP 213 in subdomain IIA of BSA. Evaluation of trifluoperazine-BSA interactions at three different temperatures indicated that there was a stable complex formation between the two molecules at the ground state and that the static quenching mechanism was predominant behind these interactions. Binding studies in the presence of pharmaceutically relevant drugs indicated that warfarin, paracetamol, and caffeine negatively influenced the binding of trifluoperazine on BSA. Lastly, Fourier transformed infrared spectroscopy and circular dichroism spectroscopy indicated that the binding of trifluoperazine induced a conformational change by reducing the a-helical content of BSA. The study implicates that the small molecules which prefer binding to the Sudlow site I of BSA might compete with trifluoperazine for its binding site thereby increasing the concentration of free trifluoperazine in the plasma which could lead to adverse side effects in patients.
Molecular Informatics, 2019
The interaction of Kif15 with kinesin binding protein (KBP) is critical for its microtubule local... more The interaction of Kif15 with kinesin binding protein (KBP) is critical for its microtubule localization, bundling of kinetochore microtubules and proper alignment of chromosomes at the metaphase plate. The Kif15-KBP structure was prepared from the crystal structure of Kif15 and nonhomologous model of KBP through docking. Benserazide was retrieved when we did a screening of the ZINC Drug Database using the pharmacophore model generated from the potential binding site on Kif15 in an effort to identify molecules for repurposing as Kif15 inhibitors. Live cell imaging of HeLa cells revealed that benserazide delayed metaphase to anaphase-onset by 47 � 10 min compared to control cells. Benserazide treatment perturbed the kinetochore and microtubule interaction and inhibited the proliferation of HeLa cells with an IC50 of 101 μM with a mitotic block of 12 %. It did not bind to tubulin in the in vitro assays suggesting that the observed effects could be due to its perturbation of Kif15-KBP interaction.
Materials Science and Engineering: C, 2019
Type 1 diabetes mellitus (DM) is a metabolic disorder associated with impaired carbohydrate metab... more Type 1 diabetes mellitus (DM) is a metabolic disorder associated with impaired carbohydrate metabolism. We present a promising bioinspired approach against type 1 DM using yeast microcapsule (YMC). The glucan component in the outer shell of baker's yeast undergoes receptor-mediated uptake by phagocytic cells through M cell-mediated endocytosis. Thus, a drug can be expected to be delivered to the systemic circulation via lymphatic transport if it is attached to the surface of YMC. For the first time, this possibility has been explored by surface loading of insulin onto YMC. The electrostatic interaction between oppositely charged YMC and insulin resulted in the formation of insulin-loaded yeast microcapsule (IYMC) which was confirmed by fluorescence imaging. Alginate coating provided to IYMC protects YMC from the harsh environment of the gastrointestinal tract and prevents the degradation of insulin in IYMC. Cellular uptake of FITC conjugated IYMC by RAW macrophages confirmed the proposed mechanism of insulin uptake. Moreover, an in vitro method using YMC-imprinted gel was developed for insulin release study from the bioinspired system. Molecular docking studies proved the interaction of insulin with β-glucan and alginate. A significant hypoglycemic effect was observed after oral administration of the alginate coated insulin-loaded yeast microcapsule (AL-IYMC) in diabetic rats. The AL-IYMCs could serve as a promising approach towards the oral delivery of insulin.