Avijit Dutta

Publications of Avijit Dutta

• An orally effective dihydropyrimidone (DHPM) analogue induces apoptosis-like cell death in clinical isolates of Leishmania donovani overexpressing pteridine reductase 1.

  Authors: Neeloo Singh, Jaspreet Kaur, Pranav Kumar, Swati Gupta, Nasib Singh, Angana Ghosal, Avijit Dutta, Ashutosh Kumar, RamaPati Tripathi, Mohammad Siddiqi, Chitra Mandal, Anuradha Dube

  Parasitology research. 08/2009;

  The protozoan parasite Leishmania donovani is the causative agent of visceral leishmaniasis. The enzyme pteridine reductase 1 (PTR1) of L. donovani acts as a metabolic bypass for drugs targetingThe protozoan parasite Leishmania donovani is the causative agent of visceral leishmaniasis. The enzyme pteridine reductase 1 (PTR1) of L. donovani acts as a metabolic bypass for drugs targeting dihydrofolate reductase (DHFR); therefore, for successful antifolate chemotherapy to be developed against Leishmania, it must target both enzyme activities. Leishmania cells overexpressing PTR1 tagged at the N-terminal with green fluorescent protein were established to screen for proprietary dihydropyrimidone (DHPM) derivatives of DHFR specificity synthesised in our laboratory. A cell-permeable molecule with impressive antileishmanial in vitro and in vivo oral activity was identified. Structure activity relationship based on homology model drawn on our recombinant enzyme established the highly selective inhibition of the enzyme by this analogue. It was seen that the leishmanicidal effect of this analogue is triggered by programmed cell death mediated by the loss of plasma membrane integrity as detected by binding of annexin V and propidium iodide (PI), loss of mitochondrial membrane potential culminating in cell cycle arrest at the sub-G0/G1 phase and oligonucleosomal DNA fragmentation. Hence, this DHPM analogue [(4-fluoro-phenyl)-6-methyl-2-thioxo-1, 2, 3, 4-tetrahydropyrimidine-5-carboxylic acid ethyl ester] is a potent antileishmanial agent that merits further pharmacological investigation.

• Withaferin A induces apoptosis by activating p38 mitogen-activated protein kinase signaling cascade in leukemic cells of lymphoid and myeloid origin through mitochondrial death cascade.

  Authors: Chandan Mandal, Avijit Dutta, Asish Mallick, Sarmila Chandra, Laxminarain Misra, Rajender S Sangwan, Chitra Mandal

  Apoptosis : an international journal on programmed cell death. 01/2009; 13(12):1450-64.

  Withaferin A (WA) is present abundantly in Withania somnifera, a well-known Indian medicinal plant. Here we demonstrate how WA exhibits a strong growth-inhibitory effect on several human leukemicWithaferin A (WA) is present abundantly in Withania somnifera, a well-known Indian medicinal plant. Here we demonstrate how WA exhibits a strong growth-inhibitory effect on several human leukemic cell lines and on primary cells from patients with lymphoblastic and myeloid leukemia in a dose-dependent manner, showing no toxicity on normal human lymphocytes and primitive hematopoietic progenitor cells. WA-mediated decrease in cell viability was observed through apoptosis as demonstrated by externalization of phosphatidylserine, a time-dependent increase in Bax/Bcl-2 ratio; loss of mitochondrial transmembrane potential, cytochrome c release, caspases 9 and 3 activation; and accumulation of cells in sub-G0 region based on DNA fragmentation. A search for the downstream pathway further reveals that WA-induced apoptosis was mediated by an increase in phosphorylated p38MAPK expression, which further activated downstream signaling by phosphorylating ATF-2 and HSP27 in leukemic cells. The RNA interference of p38MAPK protected these cells from WA-induced apoptosis. The RNAi knockdown of p38MAPK inhibited active phosphorylation of p38MAPK, Bax expression, activation of caspase 3 and increase in Annexin V positivity. Altogether, these findings suggest that p38MAPK in leukemic cells promotes WA-induced apoptosis. WA caused increased levels of Bax in response to MAPK signaling, which resulted in the initiation of mitochondrial death cascade, and therefore it holds promise as a new, alternative, inexpensive chemotherapeutic agent for the treatment of patients with leukemia of both lymphoid and myeloid origin.

• In vitro and in vivo activity of Aloe vera leaf exudate in experimental visceral leishmaniasis.

  Authors: Avijit Dutta, Debjani Sarkar, Ameenah Gurib-Fakim, Chitra Mandal, Mitali Chatterjee

  Parasitology research. 05/2008; 102(6):1235-42.

  The leishmanicidal activity of Aloe vera leaf exudate (AVL) has been demonstrated in promastigotes and axenic amastigotes, but its effectiveness in animal models has not been evaluated. The presenceThe leishmanicidal activity of Aloe vera leaf exudate (AVL) has been demonstrated in promastigotes and axenic amastigotes, but its effectiveness in animal models has not been evaluated. The presence of alkaloids, triterpenes, cyanidines, proanthocyanidines, tannins, and saponins in AVL was identified. Its effectiveness in four Leishmania donovani strains was studied both in promastigotes (IC50 ranged from 70-115 microg/ml) and amastigotes (IC50 ranged from 3.1-11.4 microg/ml). In amastigotes, the killing by AVL was facilitated through its induction of nitric oxide in leishmania-infected macrophages. The safety index was good as AVL up to 300 microg/ml remained non-toxic to monocytes and macrophages. In a L. donovani BALB/c mouse model, oral or subcutaneous administration of AVL (15 mg/kg body weight x 5 days) reduced parasitemia by >90% in the liver, spleen, and bone marrow without impairment of hepatic and renal functions. Collectively, we conclude that AVL shows promising antileishmanial activity and may provide a new lead agent in the treatment of Leishmaniasis.

• Racemoside A, an anti-leishmanial, water-soluble, natural steroidal saponin, induces programmed cell death in Leishmania donovani.

  Authors: Avijit Dutta, Angana Ghoshal, Debayan Mandal, Nirup B Mondal, Sukdeb Banerjee, Niranjan P Sahu, Chitra Mandal

  Journal of medical microbiology. 10/2007; 56(Pt 9):1196-204.

  Leishmaniasis remains a major health problem of the tropical and subtropical world. The visceral form causes the most fatalities if left untreated. Dramatic increases in the rates of infection andLeishmaniasis remains a major health problem of the tropical and subtropical world. The visceral form causes the most fatalities if left untreated. Dramatic increases in the rates of infection and drug resistance and the non-availability of safe vaccines have highlighted the need for identification of novel and inexpensive anti-leishmanial agents. This study reports that racemoside A, a water-soluble steroidal saponin purified from the fruits of Asparagus racemosus, is a potent anti-leishmanial molecule effective against antimonial-sensitive (strain AG83) and -unresponsive (strain GE1F8R) Leishmania donovani promastigotes, with IC(50) values of 1.15 and 1.31 microg ml(-1), respectively. Incubation of promastigotes with racemoside A caused morphological alterations including cell shrinkage, an aflagellated ovoid shape and chromatin condensation. This compound exerts its leishmanicidal effect through the induction of programmed cell death mediated by the loss of plasma membrane integrity as detected by binding of annexin V and propidium iodide, loss of mitochondrial membrane potential culminating in cell-cycle arrest at the sub-G(0)/G(1) phase, and DNA nicking shown by deoxynucleotidyltransferase-mediated dUTP end labelling (TUNEL). Racemoside A also showed significant activity against intracellular amastigotes of AG83 and GE1F8R at a 7-8-fold lower dose, with IC(50) values of 0.17 and 0.16 microg ml(-1), respectively, and was non-toxic to murine peritoneal macrophages up to a concentration of 10 microg ml(-1). Hence, racemoside A is a potent anti-leishmanial agent that merits further pharmacological investigation.

• Artemisinin triggers induction of cell-cycle arrest and apoptosis in Leishmania donovani promastigotes.

  Authors: Rupashree Sen, Samiran Bandyopadhyay, Avijit Dutta, Goutam Mandal, Sudipto Ganguly, Piu Saha, Mitali Chatterjee

  Journal of medical microbiology. 10/2007; 56(Pt 9):1213-8.

  A major impediment to effective anti-leishmanial chemotherapy is the emergence of drug resistance, especially to sodium antimony gluconate, the first-line treatment for leishmaniasis. Artemisinin, aA major impediment to effective anti-leishmanial chemotherapy is the emergence of drug resistance, especially to sodium antimony gluconate, the first-line treatment for leishmaniasis. Artemisinin, a sesquiterpene lactone isolated from Artemisia annua, is an established anti-malarial compound that showed anti-leishmanial activity in both promastigotes and amastigotes, with IC(50) values of 160 and 22 microM, respectively, and, importantly, was accompanied by a high safety index (>22-fold). The leishmanicidal activity of artemisinin was mediated via apoptosis as evidenced by externalization of phosphatidylserine, loss of mitochondrial membrane potential, in situ labelling of DNA fragments by terminal deoxyribonucleotidyltransferase-mediated dUTP nick end labelling (TUNEL) and cell-cycle arrest at the sub-G(0)/G(1) phase. Taken together, these data indicate that artemisinin has promising anti-leishmanial activity that is mediated by programmed cell death and, accordingly, merits consideration and further investigation as a therapeutic option for the treatment of leishmaniasis.

• Aloe vera leaf exudate induces a caspase-independent cell death in Leishmania donovani promastigotes.

  Authors: Avijit Dutta, Suman Bandyopadhyay, Chitra Mandal, Mitali Chatterjee

  Journal of medical microbiology. 06/2007; 56(Pt 5):629-36.

  Leishmaniasis constitutes a complex of diseases with clinical and epidemiological diversity and includes visceral leishmaniasis, a disease that is fatal when left untreated. In earlier studies, theLeishmaniasis constitutes a complex of diseases with clinical and epidemiological diversity and includes visceral leishmaniasis, a disease that is fatal when left untreated. In earlier studies, the authors reported that Aloe vera leaf exudate (AVL) is a potent antileishmanial agent effective in promastigotes of Leishmania braziliensis, Leishmania mexicana, Leishmania tropica, Leishmania major and Leishmania infantum and also in axenic amastigotes of Leishmania donovani. In the present study, it has been demonstrated that, in promastigotes of L. donovani (IC(50) = 110 microg ml(-1)), AVL mediates this leishmanicidal effect by triggering a programmed cell death. Incubation of promastigotes with AVL caused translocation of phosphatidylserine to the outer leaflet of the plasma membrane as measured by annexin V binding, which was accompanied by loss of mitochondrial membrane potential, release of cytochrome c into the cytosol and concomitant nuclear alterations that included chromatin condensation, deoxynucleotidyltransferase-mediated dUTP end labelling and DNA laddering. As this AVL-induced leishmanicidal effect could not be inhibited by protease inhibitors including Z-Val-Ala-dl-Asp (methoxy)-fluoromethylketone, a broad-spectrum caspase inhibitor, non-involvement of caspases and major proteases was suggested. Additionally, AVL treatment caused no increase in cytosolic Ca(2+) or generation of reactive oxygen species, indicating that although promastigote death was induced by an apoptotic-like mechanism similar to metazoan apoptosis, the pathways of induction and/or execution differed at the molecular level.

• In vitro antileishmanial activity of Aloe vera leaf exudate: a potential herbal therapy in leishmaniasis.

  Authors: Avijit Dutta, Goutam Mandal, Chitra Mandal, Mitali Chatterjee

  Glycoconjugate journal. 02/2007; 24(1):81-6.

  Aloe vera has wide spread use in health products, and despite several reports on the whole plant and inner gel, little work has been performed on the leaf exudate. Our aim was to evaluate the inAloe vera has wide spread use in health products, and despite several reports on the whole plant and inner gel, little work has been performed on the leaf exudate. Our aim was to evaluate the in vitro efficacy of Aloe vera leaf exudate (AVL) in leishmaniasis. Irrespective of the disease manifestation, promastigotes from strains responsible for cutaneous, mucocutaneous, and visceral leishmaniasis were susceptible to AVL and their IC(50) ranged from 100 to 180 microg/ml. In axenic amastigotes cultured from a L. donovani strain 2001 responsible for visceral leishmaniasis, the IC(50) was 6.0 microg/ml. AVL caused activation of host macrophages evident by an increased release of members of reactive oxygen species that was attenuated by preincubation with free radical scavengers. Collectively, our data indicates that AVL, via its direct leishmanicidal activity which can be further enhanced by activation of host macrophages, is an effective antileishmanial agent meriting further pharmacological investigations.

• Development of a modified MTT assay for screening antimonial resistant field isolates of Indian visceral leishmaniasis.

  Authors: Avijit Dutta, Samiran Bandyopadhyay, Chitra Mandal, Mitali Chatterjee

  Parasitology international. 07/2005; 54(2):119-22.

  The semi-automated MTT colorimetric assay has previously been applied on Leishmania promastigotes based on the ability of viable parasites to reduce the tetrazolium salt to an insoluble formazanThe semi-automated MTT colorimetric assay has previously been applied on Leishmania promastigotes based on the ability of viable parasites to reduce the tetrazolium salt to an insoluble formazan product. As promastigotes are non-adherent, application of the MTT assay in its original form has a major drawback of a high and variable background absorbance due to incomplete removal of phenol red, a component of most media. We have accordingly optimised a modified MTT assay wherein the absorbance linearity was maintained for cells ranging from 1x10(4) to 1x10(7) being 0.04+/-0.003-2.38+/-0.04. In contrast, the original MTT assay had a narrower linearity range of 1x10(6)-1x10(7) cells, absorbances being 0.05+/-0.005-1.54+/-0.005. The modified MTT assay was effectively applied to study growth kinetics and identification of antimonial resistant field isolates. Considering the growing problem of antimonial unresponsiveness in the Indian subcontinent, this modified MTT assay is a useful tool for Leishmania research.

• Development of a modified MTT assay for screening antimonial resistant field isolates of Indian visceral leishmaniasis

  Authors: Avijit Dutta, Samiran Bandyopadhyay, Chitra Mandal, Mitali Chatterjee

  Parasitology International.

  The semi-automated MTT colorimetric assay has previously been applied on Leishmania promastigotes based on the ability of viable parasites to reduce the tetrazolium salt to an insoluble formazanThe semi-automated MTT colorimetric assay has previously been applied on Leishmania promastigotes based on the ability of viable parasites to reduce the tetrazolium salt to an insoluble formazan product. As promastigotes are non-adherent, application of the MTT assay in its original form has a major drawback of a high and variable background absorbance due to incomplete removal of phenol red, a component of most media. We have accordingly optimised a modified MTT assay wherein the absorbance linearity was maintained for cells ranging from 1 × 104 to 1 × 107 being 0.04 ± 0.003–2.38 ± 0.04. In contrast, the original MTT assay had a narrower linearity range of 1 × 106–1 × 107 cells, absorbances being 0.05 ± 0.005–1.54 ± 0.005. The modified MTT assay was effectively applied to study growth kinetics and identification of antimonial resistant field isolates. Considering the growing problem of antimonial unresponsiveness in the Indian subcontinent, this modified MTT assay is a useful tool for Leishmania research.