The parasites of the order kinetoplastidae including Leishmania spp. emerge from most ancient phylogenic branches of unicellular eukaryotic lineages. In their life cycle, topoisomerase I plays a significant role in carrying out vital cellular processes. Camptothecin (CPT), an inhibitor of DNA topoisomerase I, induces programmed cell death (PCD) both in the amastigotes and promastigotes form of L. donovani parasites. CPT-induced cellular dysfunction in L. donovani promastigotes is characterized by several cytoplasmic and nuclear features of apoptosis. CPT inhibits cellular respiration that results in mitochondrial hyperpolarization taking place by oligomycin-sensitive F0-F1 ATPase-like protein in leishmanial cells. During the early phase of activation, there is an increase in reactive oxygen species (ROS) inside cells, which causes subsequent elevation in the level of lipid peroxidation and decrease in reducing equivalents like GSH. Endogenous ROS formation and lipid peroxidation cause eventual loss of mitochondrial membrane potential. Furthermore, cytochrome c is released into the cytosol in a manner independent of involvement of CED3/CPP32 group of proteases and unlike mammalian cells it is insensitive to cyclosporin A. These events are followed by activation of both CED3/CPP32 and ICE group of proteases in PCD of Leishmania. Taken together, our study indicates that different biochemical events leading to apoptosis in leishmanial cells provide information that could be exploited to develop newer potential therapeutic targets.

Luteolin and quercetin are effective antileishmanial agents. Quercetin has nonspecific effects on normal human T cells, but luteolin appears nontoxic. So, luteolin can be a strong candidate for antileishmanial drug design.

Natural products are important sources of anti-cancer lead molecules. Many successful anti-cancer drugs are natural products or their analogues. Many more are under clinical trials. The present review focuses on chemopreventive and anti-cancer activities of polar and non-polar extracts, semi purified fractions and pure molecules from terrestrial plants of India reported between 2005 and 2010 emphasizing possible mechanisms of action of pure molecules.

The virulence of Leishmania donovani in mammals depends at least in part on cysteine proteases because they play a key role in CD4+ T cell differentiation. A 6-fold increase in NO production was observed with 0.5 μM chicken cystatin, a natural cysteine protease inhibitor, in IFN-γ-activated macrophages. In a 45-day BALB/c mouse model of visceral leishmaniasis, complete elimination of spleen parasite burden was achieved by cystatin in synergistic activation with a suboptimal dose of IFN-γ. In contrast to the case with promastigotes, cystatin and IFN-γ inhibited the growth of amastigotes in macrophages. Although in vitro cystatin treatment of macrophages did not induce any NO generation, significantly enhanced amounts of NO were generated by macrophages of cystatin-treated animals. Their splenocytes secreted soluble factors required for the induction of NO biosynthesis, and the increased NO production was paralleled by a concomitant increase in antileishmanial activity. Moreover, splenocyte supernatants treated with anti-IFN-γ or anti-TNF-α Abs suppressed inducible NO generation, whereas i.v. administration of these anticytokine Abs along with combined therapy reversed protection against infection. mRNA expression and flow cytometric analysis of infected spleen cells suggested that cystatin and IFN-γ treatment, in addition to greatly reducing parasite numbers, resulted in reduced levels of IL-4 but increased levels of IL-12 and inducible NO synthase. Not only was this treatment curative when administered 15 days postinfection, but it also imparted resistance to reinfection. These studies provide a promising alternative for protection against leishmaniasis with a switch of CD4+ differentiation from Th2 to Th1, indicative of long-term resistance.

Leishmania, a unicellular trypanosomatid protozoan parasite, causes a wide range of human diseases ranging from the localized self-healing cutaneous lesions to fatal visceral leishmaniasis. However, it undergoes a process of programmed cell death during treatment with the topoisomerase I poison camptothecin (CPT). The present study shows that CPT-induced formation of reactive oxygen species increases the level of cytosolic calcium through the release of calcium ions from intracellular stores as well as by influx of extracellular calcium. Elevation of cytosolic calcium is responsible for depolarization of mitochondrial membrane potential (⌬⌿ m ), which is followed by a significant decrease in intracellular pH levels. CPT-induced oxidative stress also causes impairment of the Na ؉ -K ؉ -ATPase pump and subsequently decreases the intracellular K ؉ level in leishmanial cells. A decrease in both intracellular pH and K ؉ levels propagates the apoptotic process through activation of caspase 3-like proteases by rapid formation of cytochrome c-mediated apoptotic complex. In addition to caspase-like protease activation, a lower level of intracellular K ؉ also enhances the activation of apoptotic nucleases at the late stage of apoptosis. This suggests that the physiological level of pH and K ؉ are inhibitory for apoptotic DNA fragmentation and caspase-like protease activation in leishmanial cells. Moreover, unlike mammalian cells, the intracellular ATP level gradually decreases with an increase in the number of apoptotic cells after the loss of ⌬⌿ m . Taken together, the elucidation of biochemical events, which tightly regulate the process of growth arrest and death of Leishmania donovani promastigotes, allows us to define a more comprehensive view of cell death during treatment with CPT.

In obese individuals, visceral adipose tissue (VAT) is the seat of chronic low-grade inflammation (metaflammation), but the mechanistic link between increased adiposity and metaflammation largely remains unclear. In obese individuals, deregulation of a specific adipokine, chemerin, contributes to innate initiation of metaflammation by recruiting circulating plasmacytoid dendritic cells (pDCs) into VAT through chemokine-like receptor 1 (CMKLR1). Adipose tissue-derived high-mobility group B1 (HMGB1) protein activates Toll-like receptor 9 (TLR9) in the adipose-recruited pDCs by transporting extracellular DNA through receptor for advanced glycation end products (RAGE) and induces production of type I interferons (IFNs). Type I IFNs in turn help in proinflammatory polarization of adipose-resident macrophages. IFN signature gene expression in VAT correlates with both adipose tissue and systemic insulin resistance (IR) in obese individuals, which is represented by ADIPO-IR and HOMA2-IR, respectively, and defines two subgroups with different susceptibility to IR. Thus, this study reveals a pathway that drives adipose tissue inflammation and consequent IR in obesity.

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We report that chlorogenic acid (Chl) induces apoptosis of several Bcr-Ablpositive chronic myelogenous leukemia (CML) cell lines and primary cells from CML patients in vitro and destroys BcrAbl-positive K562 cells in vivo. In contrast, this compound has no effect on the growth and viability of Bcr-Abl-negative lymphocytic and myeloid cell lines and primary CML cells. Sodium chlorogenate (NaChl) exhibits 2-fold higher efficiency in killing K562 cells compared with Chl. NaChl also induces growth inhibition of squamous cell carcinoma (HSC-2) and salivary gland tumor cells (HSG), although at 50-fold higher concentration. NaChl inhibits autophosphorylation of p210 Bcr-Abl fusion protein rapidly. We demonstrate that p38 phosphorylation is increased in Bcr-Abl-positive cells after treatment with NaChl and closely paralleled the inhibition of Bcr-Abl phosphorylation. NaChl did not increase phosphorylation of p38 in Bcr-Abl-negative cells including HSC-2 and HSG that are responsive to this compound, indicating that p38 activation by NaChl is dependent on Bcr-Abl kinase inhibition. Inhibition of p38 activity by SB203580 significantly reduced NaChl-induced apoptosis of K562 cells, whereas activation of p38 by anisomycin augmented the apoptosis. These findings indicate that inhibition of BcrAbl kinase leading to activation of p38 mitogen-activated protein ( IntroductionChronic myelogenous leukemia (CML) is a malignant clonal disorder of hematopoietic stem cells leading to massive expansion of myeloid lineage cells. 1 The natural fate of CML is to progress from a benign chronic phase into the fatal blast crisis between approximately 3 and 5 years. Development of CML is associated with a specific chromosomal translocation known as the Philadelphia (Ph) chromosome that is detectable throughout the course of the disease. 2 Somatic mutation in Ph chromosome originates from reciprocal translocation between the long arms of chromosomes 9 and 22 and fuses Bcr with c-Abl genetic sequences. Both the Bcr-Abl fusion proteins p210 and p185 can cause CML or acute leukemia. 3,4 The p210 form of Bcr-Abl is seen in 95% of CML and in 20% of acute lymphocytic leukemia, whereas the p185 form is identified in about 10% of acute lymphocytic leukemia patients. 5,6 The Bcr-Abl fusion proteins are constitutively active non-receptor tyrosine kinases whose activity is essential for transforming abilities. 7 An almost universal presence of Bcr-Abl in CML patients made this fusion protein an attractive target for drug development. Bcr-Abl inhibitors, STI571, adaphostin, and PD173955, are capable of inducing a variable degree of apoptosis in human CML cells. [8][9][10] The signal transduction pathways involved in mediating apoptosis by Bcr-Abl inhibitors are poorly defined. In the current study, we describe a novel Bcr-Abl kinase inhibitor that triggers p38 mitogen-activated protein (MAP) kinase-dependent apoptosis of Bcr-Abl-positive CML cells. Materials and methods Cells and reagentsThe Ph chromosome ϩ CML cell line K562, 11 Ph chromosome-negative T-...