@article {45352, title = {Evaluating antimalarial efficacy by tracking glycolysis in Plasmodium falciparum using NMR spectroscopy}, journal = {Scientific Reports}, volume = { 8}, year = {2018}, month = {DEC}, type = {Article}, abstract = {Glucose is an essential nutrient for Plasmodium falciparum and robust glycolytic activity is indicative of viable parasites. Using NMR spectroscopy, we show that P. falciparum infected erythrocytes consume similar to 20 times more glucose, and trophozoites metabolize similar to 6 times more glucose than ring stage parasites. The glycolytic activity, and hence parasite viability, can be measured within a period of 2 h to 5 h, using this method. This facilitates antimalarial bioactivity screening on ring and trophozoite stage parasites, exclusively. We demonstrate this using potent and mechanistically distinct antimalarial compounds such as chloroquine, atovaquone, cladosporin, DDD107498 and artemisinin. Our findings indicate that ring stage parasites are inherently more tolerant to antimalarial inhibitors, a feature which may facilitate emergence of drug resistance. Thus, there is a need to discover novel antimalarial compounds, which are potent and fast acting against ring stage parasites. The NMR method reported here can facilitate the identification of such molecules.}, issn = {2045-2322}, doi = {10.1038/s41598-018-36197-3}, author = {Shivapurkar, Rupali and Hingamire, Tejashri and Kulkarni, Akshay S. and Rajamohanan, P. R. and Reddy, D. Srinivasa and Shanmugam, Dhanasekaran} } @article {46625, title = {Approach to nigericin derivatives and their therapeutic potential}, journal = {RSC Advances}, volume = {10}, year = {2020}, month = {NOV }, pages = {43085-43091}, type = {Article}, abstract = {

A new nigericin analogue that has been chemically modified was synthesized through a fluorination process from the parent nigericin, produced from a novel Streptomyces strain DASNCL-29. Fermentation strategies were designed for the optimised production of nigericin molecule and subjected for purification and structural analysis. The fermentation process resulted in the highest yield of nigericin (33\% (w/w)). Initially, nigericin produced from the strain DASNCL-29 demonstrated polymorphism in its crystal structure, i.e., monoclinic and orthorhombic crystal lattices when crystallised with methanol and hexane, respectively. Furthermore, nigericin produced has been subjected to chemical modification by fluorination to enhance its efficacy. Two fluorinated analogues revealed that they possess a very potent antibacterial activity against Gram positive and Gram negative bacteria. To date, the nigericin molecule has not been reported for any reaction against Gram-negative bacteria, which are increasingly becoming resistant to antibiotics. For the first time, fluorinated analogues of nigericin have shown promising activity. In vitro cytotoxicity analysis of fluorinated analogues demonstrated tenfold lesser toxicity than the parent nigericin. This is the first type of study where the fluorinated analogues of nigericin showed very encouraging activity against Gram-negative organisms; moreover, they can be used as a candidate for treating many serious infections.

}, doi = {10.1039/d0ra05137c}, author = {Sahu, Amit Kumar and Said, Madhukar S. and Hingamire, Tejashri and Gaur, Megha and Khan, Abujunaid and Shanmugam, Dhanasekaran and Barvkar, Vitthal T. and Dharne, Mahesh S. and Bharde, Atul A. and Dastager, Syed G.} } @article {46878, title = {Whole-cell phenotypic screening of medicines for malaria venture pathogen box identifies specific inhibitors of plasmodium falciparum late-stage development and egress}, journal = {Antimicrobial Agents and Chemotherapy}, volume = {64}, year = {2020}, month = {MAY}, pages = {e01802-19}, type = {Article}, abstract = {

We report a systematic, cellular phenotype-based antimalarial screening of the Medicines for Malaria Venture Pathogen Box collection, which facilitated the identification of specific blockers of late-stage intraerythrocytic development of Plasmodium falciparum. First, from standard growth inhibition assays, we identified 173 molecules with antimalarial activity (50\% effective concentration [EC50] \<= 10 mu M), which included 62 additional molecules over previously known antimalarial candidates from the Pathogen Box. We identified 90 molecules with EC50 of \<= 1 mu M, which had significant effect on the ring-trophozoite transition, while 9 molecules inhibited the trophozoite-schizont transition and 21 molecules inhibited the schizontring transition (with \>= 50\% parasites failing to proceed to the next stage) at 1 mu M. We therefore rescreened all 173 molecules and validated hits in microscopy to prioritize 12 hits as selective blockers of the schizont-ring transition. Seven of these molecules inhibited the calcium ionophore-induced egress of Toxoplasma gondii, a related apicomplexan parasite, suggesting that the inhibitors may be acting via a conserved mechanism which could be further exploited for target identification studies. We demonstrate that two molecules, MMV020670 and MMV026356, identified as schizont inhibitors in our screens, induce the fragmentation of DNA in merozoites, thereby impairing their ability to egress and invade. Further mechanistic studies would facilitate the therapeutic exploitation of these molecules as broadly active inhibitors targeting late-stage development and egress of apicomplexan parasites relevant to human health.

}, keywords = {DNA fragmentation, egress, Medicines for Malaria Venture, MMV, Pathogen Box, phenotypic screening, Plasmodium falciparum, schizonts, stage-specific inhibition}, issn = {0066-4804}, doi = {10.1128/AAC.01802-19}, author = {Patra, Alok Tanala and Hingamire, Tejashri and Belekar, Meenakshi A. and Xiong, Aoli and Subramanian, Gowtham and Bozdech, Zbynek and Preiser, Peter and Shanmugam, Dhanasekaran and Chandramohanadas, Rajesh} } @article {48323, title = {Histidinal-based potent antimalarial agents}, journal = {ChemMedChem}, volume = {18}, year = {2023}, month = {MAY }, type = {Article}, abstract = {

Herein we report the synthesis and evaluation of peptide-histidinal conjugated drug scaffolds, which have the potential to target the hemoglobin-degrading proteases falcipain-2/3 from the human malaria parasite. Scaffolds with various substitutions were tested for antimalarial activity, and compounds 8 g, 8 h, and 15 exhibited EC50 values of similar to 0.018 mu M, similar to 0.069 mu M, and similar to 0.02 mu M, respectively. Structure-based docking studies on falcipain-2/3 proteases (PDB:2GHU and PDB:3BWK) revealed that compounds 8 g, 8 h, and 15 interact strongly with binding sites of falcipain-2/3 in a substrate-like manner. In silico ADME studies revealed that the molecules of interest showed no or minimal violations of drug-likeness parameters. Further, phenotypic assays revealed that compound 8 g and its biotinylated version inhibit hemoglobin degradation in the parasite food vacuole. The identification of falcipain-2/3 targeting potent inhibitors of the malaria parasite can serve as a starting point for the development of lead compounds as future antimalarial drug candidates.

}, keywords = {artemisinin, chloroquine, digestive vacuole, docking, falcipains, falciparum, P}, issn = {1860-7179}, doi = {10.1002/cmdc.202200709}, author = {Meena, Chhuttan L. and Hingamire, Tejashri and Gupta, Tanya and Deshmukh, Bhagyashree and Karmodiya, Krishanpal and Joshi, Rakesh and Shanmugam, Dhanasekaran and Sanjayan, Gangadhar J.} }