Krishna Das Saha

Nanocapsulated curcumin: Oral chemopreventive formulation against diethylnitrosamine induced hepatocellular carcinoma in rat

Toxic outcome of chemical therapeutics as well as multidrug resistance are two serious phenomena for their inacceptance in cancer chemotherapy. Antioxidants like curcumin (Cur) have gained immense importance for their excellent anticarcinogenic activities and minimum toxic manifestations in biological system. However, Cur is lipophilic and thus following oral administration hardly appears in blood indicating its potential therapeutic challenge in cancer therapy. Nanocapsulated Cur has been used as a drug delivery vector to focus the effectiveness of these vesicles against hepatocellular carcinoma. The theme of work was to evaluate effectiveness in oral route of polylactide co-glycolide (PLGA) Nanocapsulated curcumin (Nano Cur) against diethylnitrosamine (DEN) induced hepatocellular carcinoma (HCC) in rat. Nano Cur of average diameter 14nm and encapsulation efficiency of 78% were prepared. Fourier Transform Infra Red (FTIR) analysis revealed that there is no chemical interaction between drug and the polymer. Three i.p. injections of the chemical hepatocarcinogen DEN at 15days interval causes hepatotoxicity, the generation of reactive oxygen species (ROS), lipid peroxidation, decrease in plasma membrane microviscosity and depletion of antioxidant enzyme levels in liver. Nano Cur (weekly oral treatment for 16weeks at 20mg/kg b.wt) in DEN induced HCC rats exerted significant protection against HCC and restored redox homeostasis in liver cells. Nanocapsulated Cur caused cancer cell apoptosis as visualized by ApoBrdU analysis. Histopathological analysis confirmed the pathological improvement in the liver. Nano Cur was found to be a potential formulation in oral route in combating the oxidative damage of hepatic cells and eliminating DEN induced hepatocellular cancer cells in rat whereas identical amount of free Cur treatment was found almost ineffective.

Quercetin in vesicular delivery systems: evaluation in combating arsenic-induced acute liver toxicity associated gene expression in rat model.

Arsenic, the environmental toxicant causes oxidative damage to liver and produces hepatic fibrosis. The theme of our study was to evaluate the therapeutic efficacy of liposomal and nanocapsulated herbal polyphenolic antioxidant quercetin (QC) in combating arsenic induced hepatic oxidative stress, fibrosis associated upregulation of its gene expression and plasma TGF beta (transforming growth factor beta) in rat model. A single dose of arsenic (sodium arsenite-NaAsO(2), 13 mg/kgb.wt) in oral route causes the generation of reactive oxygen species (ROS), arsenic accumulation in liver, hepatotoxicity and decrease in hepatic plasma membrane microviscosity and antioxidant enzyme levels in liver. Arsenic causes fibrosis associated elevation of its gene expression in liver, plasma TGF ss (from normal value 75.2+/-8.67 ng/ml to 196.2+/-12.07 ng/ml) and release of cytochrome c in cytoplasm. Among the two vesicular delivery systems formulated with QC, polylactide nanocapsules showed a promising result compared to liposomal delivery system in controlling arsenic induced alteration of those parameters. A single dose of 0.5 ml of nanocapsulated QC suspension (QC 2.71 mg/kg b.wt) when injected to rats 1h after arsenic administration orally protects liver from arsenic induced deterioration of antioxidant levels as well as oxidative stress associated gene expression of liver. Histopathological examination also confirmed the pathological improvement in liver. Nanocapsulated plant origin flavonoidal compound may be a potent formulation in combating arsenic induced upregulation of gene expression of liver fibrosis through a complete protection against oxidative attack in hepatic cells of rat liver.

A sphingolipid rich lipid fraction isolated from attenuated Leishmania donovani promastigote induces apoptosis in mouse and human melanoma cells in vitro

Lipids, especially sphingolipids, are emerging as inducer of apoptosis in a wide range of immortal cells, potentiating their therapeutic application in cancer. In the present study, a sphingolipid rich lipid fraction (denoted here as ALL), isolated from an attenuated strain of Leishmania donovani promastigote, was tested for its tumoricidal activity taking melanoma, the dreaded form of skin cancer cells, as model. ALL was found to induce chromatin condensation, internucleosomal DNA fragmentation and phosphatidylserine externalization with enhanced cell population in sub-G1 region in both mouse and human melanoma systems, namely B16F10 and A375 respectively. These are the hallmarks of cells undergoing apoptosis. Further analysis demonstrated that ALL treated melanoma cells showed significant increase in ROS generation, mitochondrial membrane potential depolarization, release of cytochrome c, and caspase-3 activation, which are the events closely involved in apoptosis. These findings indicate that one or more bioactive sphingolipid(s)/ceramide(s) present in ALL could be the causative agent(s) for the induction of apoptosis in melanoma cells. Further studies are thus necessary to identify these specific bioactive sphingolipid(s)/ceramide(s) and to establish their mechanism of action, in order to explore their use as anticancer agents.

Role of Ferulic Acid in the Amelioration of Ionizing Radiation Induced Inflammation: A Murine Model

Ionizing radiation is responsible for oxidative stress by generating reactive oxygen species (ROS), which alters the cellular redox potential. This change activates several redox sensitive enzymes which are crucial in activating signaling pathways at molecular level and can lead to oxidative stress induced inflammation. Therefore, the present study was intended to assess the anti-inflammatory role of ferulic acid (FA), a plant flavonoid, against radiation-induced oxidative stress with a novel mechanistic viewpoint. FA was administered (50 mg/kg body wt) to Swiss albino mice for five consecutive days prior to exposing them to a single dose of 10 Gy 60Co γ-irradiation. The dose of FA was optimized from the survival experiment and 50 mg/kg body wt dose showed optimum effect. FA significantly ameliorated the radiation induced inflammatory response such as phosphorylation of IKKα/β and IκBα and consequent nuclear translocation of nuclear factor kappa B (NF-κB). FA also prevented the increase of cycloxygenase-2 (Cox-2) protein, inducible nitric oxide synthase-2 (iNOS-2) gene expression, lipid peroxidation in liver and the increase of tumor necrosis factor-alpha (TNF-α) and interleukin-6 (IL-6) in serum. It was observed that exposure to radiation results in decreased activity of superoxide dismutase (SOD), catalase (CAT) and the pool of reduced glutathione (GSH) content. However, FA treatment prior to irradiation increased the activities of the same endogenous antioxidants. Thus, pretreatment with FA offers protection against gamma radiation induced inflammation.

Au(I)- and Pt(II)-N-heterocyclic carbene complexes with picoline functionalized benzimidazolin-2-ylidene ligands; synthesis, structures, electrochemistry and cytotoxicity studies

Novel Au(I)-N-heterocyclic carbene complexes, 1-methyl-3-(2-pyridylmethyl)-benzimidazolylidenegold(I)-chloride, 1; 1-benzyl-3-(2-pyridylmethyl)-benzimidazolylidenegold(I)chloride, 2; and Pt(II)-N-heterocyclic carbene complexes 1-methyl-3-(2-pyridylmethyl) benzimidazolylidene platinum(II)chloride, 3; and 1-benzyl-3-(2-pyridylmethyl) benzimidazolylidene platinum-(II)chloride, 4, have been synthesized, based on CN-donor proligands 1-alkyl-3-(2-pyridylmeth-yl)-benzimidazoliumchloride L1 and L2 [alkyl, R = –CH3 = L1; R = –CH2Ph = L2]. All the compounds have been synthesized and characterized by different spectroscopic methods. The Au(I) complexes 1 and 2 have been synthesized by a silver carbene transfer method. The solid-state structures of 1 and 3 have been determined by single crystal X-ray diffraction studies. The square planar Pt(II) complexes 3 and 4 show a reversible Pt(II)/Pt(IV) couple at 0.69 eV and 0.67 eV respectively. Among the complexes 1–4, complexes 1 and 3 have been used for cytotoxicity studies on the cell lines B16F10 (mouse melanoma), HepG2 (human hepatocarcinoma) and HeLa (human cervical carcinoma). IC50 values are compared with cisplatin, among 1 and 3, the Au(I) complex 1 is more effective than Pt(II) complex 3.

Gold (I) N-heterocyclic carbene complex inhibits mouse melanoma growth by p53 upregulation.

BackgroundCancer treatment using gold (I) complexes is becoming popular. In this study, a gold (I) N-heterocyclic complex designated as complex 3 was synthesized, its cytotoxicity was examined, and its anti-melanoma activity was evaluated in vitro and in vivo.MethodsViability of cancer cells was determined by MTT assay upon treatment with various concentrations of a gold (I) N-heterocyclic carbene complex (complex 3) in a dose and time dependent manner. Mouse melanoma cells B16F10 were selected for further apoptotic studies, including flowcytometric analysis of annexin binding, cell cycle arrest, intracellular ROS generation and loss in the mitochondrial membrane potential. ELISA based assays were done for caspase activities and western blots for determining the expression of various survival and apoptotic proteins. Immunocytology was performed to visualize the translocation of p53 to the nucleus. B16F10 cells were inoculated into mice and post tumor formation, complex 3 was administered. Immunohistology was performed to determine the expressions of p53, p21, NF-κB (p65 and p50), MMP-9 and VEGF. Student’s t test was used for determining statistical significance. The survival rate data were analyzed by Kaplan-Meier plots.ResultsComplex 3 markedly inhibited the growth of HCT 116, HepG2, and A549, and induced apoptosis in B16F10 cells with nuclear condensation, DNA fragmentation, externalization of phosphatidylserine, activation of caspase 3 and caspase 9, PARP cleavage, downregulation of Bcl-2, upregulation of Bax, cytosolic cytochrome c elevation, ROS generation, and mitochondrial membrane potential loss indicating the involvement of an intrinsic mitochondrial death pathway. Further, upregulation of p53, p-p53 (ser 15) and p21 indicated the role of p53 in complex 3 mediated apoptosis. The complex reduced tumor size, and caused upregulation of p53 and p21 along with downregulation of NF-κB (p65 and p50), VEGF and MMP-9. These results suggest that it induced anti-melanoma effect in vitro and in vivo by modulating p53 and other apoptotic factors.ConclusionsThe gold (I) N-heterocyclic carbene complex (C22H26N6AuO2PF6) designated as complex 3 induced ROS and p53 dependent apoptosis in B16F10 cells involving the mitochondrial death pathway along with suppression of melanoma tumor growth by regulating the levels of pro and anti apoptotic factors (p53, p21, NF-κB, VEGF and MMP-9).

Porous Polyurea Network Showing Aggregation Induced White Light Emission, Applications as Biosensor and Scaffold for Drug Delivery

We have designed a urea functionalized novel nanoporous material, POP-PU, which showsaggregation induced white light emission in the presence of suitable polar solvents. This nanomaterial has been explored as a pseudowhite light emitter where the polymeric luminogen moiety can interact with the suitable polar solvent, leading to charge transfer. Thus, solvent assisted rotational freezing of nonrigid polymeric nanoparticles gives radiative emission and the whole solution emits white light with color temperature of 8533 K. This nanoporous material also holds the pockets (donor-donor-acceptor array) for specific biomolecular interaction. Among three pyrimidine based nucleotide bases, only cytosine can amplify the PL emission intensity of POP-PU and the other two bases cannot, suggesting its future potential as a biosensor. Further, this urea functionalized porous organic nanomaterial can be utilized as an efficient drug-delivery vehicle for liver cancer diagnostics and therapy based on the specific biomolecular interaction at its surface.

N-heterocyclic carbene supported Au(I) and Au(III) complexes: a comparison of cytotoxicities

The N-heterocyclic carbene (NHC) precursor 2-pyridin-2-yl-2H-imidazo[1,5-a]pyridin-4-ylium hexafluorophosphate (1·HPF6) was used to synthesize various Ag and Au complexes, including [Ag(1)2][PF6] (2), [Au(1)2][PF6] (3) and [Au(1)Cl3] (4). The structure of the silver(I) complex 2 was established via NMR spectroscopy, mass spectrometry and single crystal X-ray crystallography. The gold(I)–NHC complex 3 was synthesized via transmetallation of the aforementioned silver complex and characterized using various spectroscopic methods. Treatment of 3 with Au(SMe2)Cl afforded 4, ostensibly via a disproportionation process. Close inspection of the solid state structure of 2 revealed that the Ag(I) center adopted a linear geometry; in contrast, a square planar geometry was observed for the solid structure of 4. The cytotoxicities of the gold complexes 3 and 4 were tested in vitro against Human colorectal carcinoma (HCT 116), Human hepatocellular carcinoma (HepG2), Human breast adenocarcinoma (MCF-7) and Murine melanoma (B16F10). The measured IC50 values showed that the Au(I) complex 3 was more potent than the Au(III) complex 4 as well as cisplatin.

Design of dual MMP-2/HDAC-8 inhibitors by pharmacophore mapping, molecular docking, synthesis and biological activity

Recent analyses have highlighted the promotion of cancer migration and invasion, mediated through HDAC via MMP-2 and MMP-9. Since both class 1 HDACs and MMP-2/9 are involved in the migration and invasion of cancer, an attempt has been taken to design dual MMP-2/HDAC-8 inhibitors by pharmacophore mapping and molecular docking approaches. The designed molecules were synthesized and showed a range of inhibitory activity against different MMP subtypes. Most of these designed compounds were selective towards MMP-2 but less potent against anti-targets like MMP-8, -12, etc. The highly active MMP-2 inhibitors were also found to be active towards HDAC-8 but less potent against other class 1 HDACs (HDAC-1 and -2). Molecular dynamics simulations revealed that the designed compounds may be acting through a distinct mechanism of action in the ‘acetate ion channel’ of HDAC-8. Some potent dual MMP-2/HDAC-8 inhibitors were further explored for in vitro cellular assays against human lung carcinoma cell line A549. These analyses revealed that some of these dual inhibitors have considerable anti-migratory and anti-invasive properties. The work may help to obtain some useful dual inhibitors.

Comparative validated molecular modeling of p53-HDM2 inhibitors as antiproliferative agents.

Tumor suppressor protein p53 regulates the cell cycle and inhibits tumor growth. It is inactivated by mutation or binding with human double minute 2 (HDM2) protein. The HDM2 is a promising target for treatment of p53 protein related cancers. Molecular modeling techniques such as 2D-QSAR, pharmacophore mapping and 3D-QSAR analyses were performed on 155 structurally diverse HDM2 inhibitors to understand structural and physicochemical requirements for higher activity. The linear and spline 2D-QSAR models were developed through multiple linear regression and genetic functional algorithm methods. The 2D-QSAR models suggested that number of fluorine, chlorine, tertiary nitrogen atoms as well as donor feature, stereogenic centers and higher value of solvent accessible surface area are important features in defining activity. Monte Carlo method was applied to generate QSAR models that determined structural indicators (alerts) for increase or decrease of the biological activity. Ligand-based pharmacophore mapping showed importance of two hydrophobic, one hydrophobic aromatic, one ring aromatic and one donor features. The structure-based pharmacophore model demonstrated significance of two hydrophobic, one ring aromatic and two acceptor features. The pharmacophore (ligand) aligned structures were subjected to 3D-QSAR analyses. The structure-based pharmacophore was also used for pharmacophore restraint molecular docking to analyze ligand-receptor interactions and for adjudging predictability as well as validation of different modeling techniques. These comparative molecular modeling techniques may help to design novel HDM2 inhibitors.