Dipayan Bose

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.

Anticancer potential of 3-(arylideneamino)-2-phenylquinazoline-4(3H)-one derivatives.

Different quinazoline derivatives have showed wide spectrum of pharmacological activities. Some 3-(arylideneamino)-phenylquinazoline-4(3H)-ones have been reported to possess antimicrobial activity. The present study has been undertaken to evaluate the anticancer effect of these quinazolinone derivatives. The quinazolinone derivatives were synthesized as reported earlier. Compounds containing NO2, OH, OCH3, or OH and OCH3 as substituent(s) on the arylideneamino group were named as P(3a), P(3b), P(3c), and P(3d) respectively. Out of these, P(3a) and P(3d) showed better cytotoxic activity than P(3b) and P(3c) on a panel of six cancer cell lines of different origin, namely, B16F10, MiaPaCa-2, HCT116, HeLa, MCF7, and HepG2, though the effect was higher in B16F10, HCT116, and MCF7 cells. P(3a) and P(3d) induced death of B16F10 and HCT116 cells was associated with characteristic apoptotic changes like cell shrinkage, nuclear condensation, DNA fragmentation, and annexin V binding. Also, cell cycle arrest at G1 phase, alteration of caspase-3, caspase-9, Bcl-2 and PARP levels, loss of mitochondrial membrane potential, and enhanced level of cytosolic cytochrome c were observed in treated B16F10 cells. Treatment with multiple doses of P(3a) significantly increased the survival rate of B16F10 tumor bearing BALB/c mice by suppressing the volume of tumor while decreasing microvascular density and mitotic index of the tumor cells.

Exploring the anti-inflammatory activity of a novel 2-phenylquinazoline analog with protection against inflammatory injury

Inflammation is a protective immune response against harmful stimuli whose long time continuation results in host disease. Quinazolinones are nitrogen containing heterocyclic compounds with wide spectrum of biological activities. The anticancer effect of a 3-(arylideneamino)-phenylquinazoline-4(3H)-one derivative was reported earlier. The anti-inflammatory effect of these quinazolinone derivatives has now been examined in endotoxin stimulated macrophages and in different in vivo models of inflammation by measuring the proinflammatory cytokines (TNF-α, IL-1β and IL-6), mediators NO and NF-κB (by ELISA and western blot), and translocation of the nuclear factor kB (by immunocytochemical analysis). To elucidate the in vivo effect, mice endotoxin model was and the various levels of edema, inflammatory pain and vascular permeability were studied. One of the quinazolinone derivatives showed significant anti-inflammatory activity in stimulated macrophage cells by inhibiting the expression of TNF-α, IL-1β, IL-6, iNOS, COX-2, p-IκB and NF-κBp65. Significant (P<0.01) improvement was observed in the mortality of endotoxemic mice. The carrageenan and formalin-induced paw edema thicknesses were found to be reduced significantly (P<0.01) along with the reduction of pain, vascular permeability and edema induced by complete Freunds adjuvant (P<0.01). These findings indicate that 3-(arylideneamino)-phenylquinazoline-4(3H)-one derivative as a potential anti-inflammatory agent.

Dinuclear zinc(II) complexes with compartmental ligands: syntheses, structures, and bioactivities as artificial nuclease

Four water-soluble dinuclear Zn(II) complexes (1–4) of compartmental ligand L = 2,6-bis(R-iminomethyl)-4-R′-phenolate (where R = N-ethylpiperidine or R = N-ethylpyrrolidine, R′ = methyl or tert-butyl) have been synthesized, characterized, and their DNA cleavage activity and cytotoxicity toward HepG2 cancerous cells are evaluated. The dinuclear complexes are formed by a pentadentate-substituted phenolate ligand chelating the metal ions separated by ca 3.27 Å. Each metal is a distorted trigonal bipyramid, completing the coordination sphere through acetate. The X-ray structural determination of 2 shows that the complex is counterbalanced by half (formulation [Zn2L2(CH3CO2)2][(Zn(SCN)4]0.5), while in 1 and 3 two crystallographically-independent complexes are present in the unit cell with a . Among the four complexes only the 4-tert-butyl-phenolato derivatives (3 and 4) show DNA cleavage activity in in-vivo conditions and appear to be promising toward metal complexes to be used as anticancer agents. The cytotoxicity of the complexes, investigated through MTT assay, suggests that 4 is a better choice as artificial nuclease.

Leishmanial lipid affords protection against oxidative stress induced hepatic injury by regulating inflammatory mediators and confining apoptosis progress.

Persistence of liver injury alters the internal milieu, promotes deregulation of inflammatory factors, and leads to dysplastic lesions like fibrosis, cirrhosis to hepatocellular carcinoma. Our previous study revealed that leishmanial lipid (pLLD) exerts potential anti-inflammatory activity in sepsis associated hepatic injury. We now show that pLLD gives protection against chemical induced hepatotoxicity in murine system. The beneficial effect of treatment with pLLD on such hepatic injury in mice was analyzed using different assays including ELISA, FACS, western blot and immunohistochemical analysis. pLLD significantly suppressed serum enzymes and rectified the histopathological alteration to induce the antioxidant level in CCl4 intoxicated liver. Levels of several growth factors including TGF-β, HGF, and EGF were significantly improved in serum and hepatic tissue with consequent reduction of caspase activities and expressions of Bad, Bax, p53, and NF-κBp65. Moreover, pLLD modulated inflammatory responses by decreasing the production of several cytokines and chemokines, thus preventing the infiltration of immune cells to the damaged area. It accelerated the repair process in liver damage with modulation of signalling cascade via alteration of apoptotic factors. Our experimental approaches suggest that pLLD effectively prevents liver injury mainly through down regulation of oxidative stress and inflammatory response towards anti-apoptotic changes.

Lipid isolated from a Leishmania donovani strain reduces Escherichia coli induced sepsis in mice through inhibition of inflammatory responses.

Sepsis is the reflection of systemic immune response that manifests in the sequential inflammatory process in presence of infection. This may occur as a result of gram-negative bacterial sepsis including Escherichia coli infection that gives rise to excessive production of inflammatory mediators and causes severe tissue injuries. We have reported earlier that the lipid of attenuated Leishmania donovani suppresses the inflammatory responses in arthritis patients. Using heat killed E. coli stimulated macrophages, we have now investigated the effect of leishmanial total lipid (LTL) isolated from Leishmania donovani (MHO/IN/1978/UR6) for amelioration of the inflammatory mediators and transcriptional factor with suppression of TLR4-CD14 expression. To evaluate the in vivo effect, E. coli induced murine sepsis model was used focusing on the changes in different parameter(s) of lung injury caused by sepsis, namely, edema, vascular permeability, and pathophysiology, and the status of different cytokine-chemokine(s) and adhesion molecule(s). Due to the effect of LTL, E. coli induced inflammatory cytokine-chemokine(s) levels were significantly reduced in serum and bronchoalveolar lavage fluid simultaneously. LTL also improved the lung injury and suppressed the cell adhesion molecules in lung tissue. These findings indicate that LTL may prove to be a potential anti-inflammatory agent and provide protection against gram-negative bacterial sepsis with pulmonary impairment.

Heat Killed Attenuated Leishmania Induces Apoptosis of HepG2 Cells Through ROS Mediated p53 Dependent Mitochondrial Pathway

Background/Aims: Cytotoxic effect of attenuated Leishmania on liver cancer cells by inducing ROS generation. Methods: Spectrophotometric study to analyze cell death and levels of different active caspases. Flow cytometric study was done to analyze apoptosis induction and ROS generation and levels of different protein. Western blot analysis was performed to study the levels of protein. Confocal microscopy was done to ascertain the expression of different apoptotic markers. Results: We have now observed that attenuated Leishmania donovani UR6 also has potentiality towards growth inhibition of HepG2 cells and investigated the mechanism of action. The effect is associated with increased DNA fragmentation, rise in number of annexinV positive cells, and cell cycle arrest at G1 phase. The detection of unregulated levels of active PARP, cleaved caspases 3 and 9, cytosolic cytochrome C, Bax, and Bad, along with the observed downregulation of Bcl-2 and loss of mitochondrial membrane potential suggested the involvement of mitochondrial pathway. Enhanced ROS and p53 levels regulate the apoptosis of HepG2 cells. NAC was found to inhibit p53 production but PFT-α has no effect on ROS generation. In conclusion, Leishmania donovani UR6 efficiently induces apoptosis in HepG2 cells through ROS mediated p53 dependent mitochondrial pathway. Conclusion: It has been reported earlier that some parasites show prominent cytotoxic effect and prevent tumor growth. From our study we found that Leishmania donovani UR6 efficiently induced apoptosis in HepG2 cells through ROS mediated p53 dependent mitochondrial pathway. This study has rejuvenated the age old idea of bio-therapy.

Leishmanial sphingolipid induces apoptosis in Sarcoma 180 cancer cells through regulation of tumour growth via angiogenic switchover.

Sphingolipids are membrane and intracellular lipids that typically modulate cellular processes to cause cell death. Exogenous administration of sphingolipids may cause restriction of tumour growth and several alternative strategies are being used to control the cell growth. The microbes, their cellular component(s) or metabolites like DHA, EPA and also FTY720 have been employed as new therapeutic entities to regulate the disease condition. The therapeutic efficacy of lipids from Leishmania donovani in rheumatoid arthritis and also in sepsis condition associated with inflammatory diseases is well established. In this study, we explored the apoptotic effect of LSPL-1 (leishmanial sphingolipid-1) in Sarcoma 180 cells towards the regulation of tumour growth. The study using a panel of cancer cell lines revealed that LSPL-1 induces cell death in Sarcoma 180. The apoptotic changes were assessed by annexin exposure and DNA content analysis using flow cytometry. LSPL-1 appears to activate several pro- and anti-apoptotic molecules through reactive oxygen species (ROS) generation and also caspase activation, as determined by Western blot and ELISA analyses. Simultaneously, it may improve the survival rate of mice bearing tumour induced by Sarcoma 180 cells, with pathological changes. LSPL-1 may also suppress the cancer-associated inflammatory responses with the expression of matrix metalloproteinase having inhibitory role. It may regulate several angiogenic factors including VEGF, Ang-2 and CD34 in angiogenic events generated in Sarcoma 180 cell-induced tumour. These studies underline the significance of anti-neoplastic potential of LSPL-1 through apoptosis induction and abrogation of angiogenic responses in Sarcoma 180 cell-associated tumour.

Lipid from Infective L. donovani Regulates Acute Myeloid Cell Growth via Mitochondria Dependent MAPK Pathway

The microbial source, which includes live, attenuated, or genetically modified microbes or their cellular component(s) or metabolites, has gained increasing significance for therapeutic intervention against several pathophysiological conditions of disease including leukemia, which remains an incurable disease till now despite recent advances in the medical sciences. We therefore took up the present study to explore if the leishmanial lipid (pLLD) isolated from L. donovani can play an anti-neoplastic role in acute myeloid leukemia cells by regulating cellular growth. Indeed pLLD significantly inhibited cell proliferation of four AML cell lines (HL-60, MOLT-4, U937, and K562). Scanning electron microscopy and DNA fragmentation analysis revealed that it significantly induced apoptosis of U937 cells through morphological alteration. Occurrence of apoptosis was checked by using Annexin exposure and this established that the cell cycle was arrested at G0/G1 phase in time-dependent manner. pLLD increased the intracellular ROS with alteration of mitochondrial membrane potential, as detected using DCFDA. It also regulated the expression of apoptosis-related proteins like Bax, Bcl2, Bad and t-Bid besides causing cleavage of PARP as determined by western blot analysis. Treatment of U937 cells with pLLD induced the activation of extracellular signal-regulated kinase (ERK)1/2, c-Jun N-terminal kinase (JNK)1/2, p38, and caspases 9/3. The results suggest that pLLD induces apoptosis in acute myeloid leukemia cells possibly via increasing intracellular ROS and regulating the MAPK pathway.

Antineoplastic impact of leishmanial sphingolipid in tumour growth with regulation of angiogenic event and inflammatory response

Very often conventional therapy, i.e. chemotherapeutic treatment, develops resistance in cancer cells and fails to be effective against disease states. An alternative strategy or a new entity may resolve the problem. Interestingly, the microbial world has begun to be explored in medicinal research as a potential new source to deliver bio-active molecules such as sphingolipids for efficacious cancer treatment. A sphingolipid of microbial origin, especially from Leishmania donovani (LSPL), is a novel entity which may exert anti-cancer activity by regulating cellular growth. The present study reveals that among a range of cancer cells evaluated, LSPL-1 (a component of LSPL) reduces cell viability, annexin exposures and arrests cell cycle in B16F10 cells in a concentration and time dependent manner. Flowcytometric analysis showed that it alters mitochondrial membrane potential and generates a number of ROS positive melanoma cells. It activates p53 at serine anchor region via up-regulation of p21 subunit along with PUMA and NOXA. It also exerts activity in vivo by reducing tumor micro vessel and mitotic index while simultaneously improving the survival rate. The inflammatory responses including elevated level of cytokine-chemokine and increased expression of PCNA and F480 are subdued by LSPL-1 treatment in tumour bearing mice. Besides, it reduces the metastatic outburst of angiogenic factors like VEGF, Ang-2, and CD34 through the involvement of several growth promoting factors. These findings indicate that LSPL-1 may be explored as a potent entity against melanoma growth and the associated angiogenic promotion.