https://dspace.nii.res.in//https://dspace.nii.res.in/handle/123456789/140 2026-04-27T15:58:42Z https://dspace.nii.res.in//https://dspace.nii.res.in/handle/123456789/1468 Title: Structural and mechanistic insights into modulation of α-Synuclein fibril formation by aloin and emodin Authors: Meena, Vinod Kumar; Kumar, Vijay; Karalia, Shivani; Dangi, Rohit Singh; Sundd, Monica Abstract: α-Synuclein (α-Syn) aggregation/fibrillation is a leading cause of neuronal death and is one of the major pathogenic factors involved in the progression of Parkinson's' disease (PD). Against this backdrop, discovering new molecules as inhibitors or modulators of α-Syn aggregation/fibrillation is a subject of enormous research. In this study, we have shown modulation, disaggregation, and neuroprotective potential of aloin and emodin against α-Syn aggregation/fibrillation. Thioflavin T (ThT) fluorescence assay showed an increase in lag phase from (51.14 ± 2) h to (68.58 ± 2) h and (74.14 ± 3) h in the presence of aloin and emodin respectively. ANS binding assay represents a modulatory effect of these molecules on hydrophobicity which is crucial for aggregates/fibril formation. NMR spectroscopy and tyrosine quenching studies reveal the binding of aloin/emodin with monomeric α-Syn. TEM and DLS micrographs illustrate the attenuating effect of aloin/emodin against the development of large aggregates/fibrils. Our seeding experiments suggest aloin/emodin generate seeding incompetent oligomers that direct the off-pathway aggregation/fibrillation. Also, aloin/emodin capably reduces the fibrils-induced cytotoxicity and disassembles the preexisting amyloid fibrils. These findings provide deep insight into the modulatory mechanism of α-Syn aggregation/fibrillation in the presence of aloin and emodin, thereby suggesting their potential roles as promising therapeutic molecules against aggregation/fibrillation related disorders. 2022-01-01T00:00:00Z https://dspace.nii.res.in//https://dspace.nii.res.in/handle/123456789/1447 Title: The Multistage Antimalarial Compound Calxinin Perturbates P. falciparum Ca2+ Homeostasis by Targeting a Unique Authors: Singh, Agam Prasad; Gupta, Yash; Sharma, Neha; Singh, Snigdha; G Romero, Jesus; Rajendran, Vinoth; M Mogire, Reagan; Mohammad, Kashif; Beach, Jordan; Walter, Jeske; Poonam; Bernhards, R Ogutu; Stefan M Kanzok, Kanzok; Akala, Hoseah M; Legac, Jennifer; Rosenthal, Philip J; Rademacher, David J; Durvasula, Ravi; Rathi, Brijesh; Kempaiah, Prakasha Abstract: Malaria elimination urgently needs novel antimalarial therapies that transcend resistance, toxicity, and high costs. Our multicentric international collaborative team focuses on developing multistage antimalarials that exhibit novel mechanisms of action. Here, we describe the design, synthesis, and evaluation of a novel multistage antimalarial compound, 'Calxinin'. A compound that consists of hydroxyethylamine (HEA) and trifluoromethyl-benzyl-piperazine. Calxinin exhibits potent inhibitory activity in the nanomolar range against the asexual blood stages of drug-sensitive (3D7), multidrug-resistant (Dd2), artemisinin-resistant (IPC4912), and fresh Kenyan field isolated Plasmodium falciparum strains. Calxinin treatment resulted in diminished maturation of parasite sexual precursor cells (gametocytes) accompanied by distorted parasite morphology. Further, in vitro liver-stage testing with a mouse model showed reduced parasite load at an IC50 of 79 nM. A single dose (10 mg/kg) of Calxinin resulted in a 30% reduction in parasitemia in mice infected with a chloroquine-resistant strain of the rodent parasite P. berghei. The ex vivo ookinete inhibitory concentration within mosquito gut IC50 was 150 nM. Cellular in vitro toxicity assays in the primary and immortalized human cell lines did not show cytotoxicity. A computational protein target identification pipeline identified a putative P. falciparum membrane protein (Pf3D7_1313500) involved in parasite calcium (Ca2+) homeostasis as a potential Calxinin target. This highly conserved protein is related to the family of transient receptor potential cation channels (TRP-ML). Target validation experiments showed that exposure of parasitized RBCs (pRBCs) to Calxinin induces a rapid release of intracellular Ca2+ from pRBCs; leaving de-calcinated parasites trapped in RBCs. Overall, we demonstrated that Calxinin is a promising antimalarial lead compound with a novel mechanism of action and with potential therapeutic, prophylactic, and transmission-blocking properties against parasites resistant to current antimalarials. 2022-01-01T00:00:00Z https://dspace.nii.res.in//https://dspace.nii.res.in/handle/123456789/1446 Title: A potent candidate against Zika virus infection: Synthesis, bioactivity, radiolabeling and biodistribution studies Authors: Singh, Agam Prasad; Kumar, Sumit; Sharma, Neha; Dantas, Willyenne Marilia; Nascimento, Jessica Catarine Frutuoso do; Maus, Hannah; Oliveira, Ronaldo Nascimento de; Pandit, Unnat; Schirmeister, Tanja; Hazari, Puja Panwar; Pena, Lindomar; Poonam; Rathi, Brijesh Abstract: The lack of licensed vaccines and effective drugs against Zika virus (ZIKV) disease creates alarming situations for public health and therefore warrants the discovery of therapeutics. Hydroxyethylamine (HEA) analogs have entered clinical trials for their antiviral properties, presenting a validated pharmacophore for the design of novel antiviral treatments. We thus synthesized HEA compounds (VI and VII) and tested them against ZIKV in culture. Compound VI showed 72-fold higher efficacy to block the infectivity of ZIKV infection over the positive control, 6-methylmercaptopurine riboside. Hit compound VI displayed a 50% inhibitory concentration of 0.34 μM with a selectivity index of 22.47. Biodistribution and bioimaging studies suggested a major uptake of VI in the liver and kidneys of the experimental animals. Slightly lower uptake was also noted in the brain, which showed 6-fold higher accumulation than in the blood. Rhodamine B labeled VI (Rho-VI) was treated with a 5-HT1A receptor that showed a binding affinity of 7.54 nM. Next, compound VI indicated negligible acute and subacute cytotoxicity evaluated in mice. This study supports compound VI as a prime antiviral contender for preclinical and clinical trials against ZIKV disease. 2022-01-01T00:00:00Z https://dspace.nii.res.in//https://dspace.nii.res.in/handle/123456789/1445 Title: Multistage and transmission-blocking tubulin targeting potent antimalarial discovered from the open access MMV pathogen box Authors: Singh, Agam Prasad; Kumari, Geeta; Jain, Ravi; Sah, Raj Kumar; Kalia, Inderjeet; Vashistha, Manu; Singh, Pooja; Samby, Kirandeep; Burrows, Jeremy; Singh, Shailja Abstract: The development of resistance to current antimalarial therapies remains a significant source of concern. To address this risk,newdrugswithnoveltargetsin distinct developmental stages ofPlasmodiumparasites are required. In the current study,we have targetedP. falciparumTubulin(PfTubulin)proteins which represent some of thepotentialdrug targetsfor malaria chemotherapy. PlasmodialMicrotubules (MTs) play a crucial role during parasite proliferation, growth, and transmission, which render them highlydesirabletargets for the development ofnext-generation chemotherapeutics. Towards this,we have evaluated the antimalarial activity ofTubulintargetingcompounds received from theMedicines for Malaria Venture (MMV)"Pathogen Box"against the human malaria parasite,P. falciparumincluding 3D7 (chloroquine and artemisinin sensitive strain), RKL-9 (chloroquine-resistant strain), and R539T (artemisinin-resistant strain). At nanomolar concentrations, the filtered-out compounds exhibitedpronouncedmultistage antimalarialeffects across the parasite life cycle, including intra-erythrocytic blood stages, liver stage parasites, gametocytes, and ookinetes. Concomitantly, these compoundswere found toimpedemale gamete ex-flagellation, thus showingtheir transmission-blocking potential. Target mining of these potent compounds, by combining in silico, biochemical and biophysical assays,implicatedPfTubulinas their moleculartarget, which may possibly act bydisruptingMT assembly dynamics by binding at the interface of α-βTubulin-dimer.Further, the promising ADME profile of the parent scaffold supported its consideration as a lead compound for further development.Thus, our work highlights the potential of targetingPfTubulin proteins in discovering and developing next-generation, multistage antimalarial agents against Multi-Drug Resistant (MDR) malaria parasites. 2022-01-01T00:00:00Z