Browsing by Author "Neha Tiwari"

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Biosynthesis of carotenoids in Azospirillum brasilense Cd is mediated via squalene (C30) route
(Elsevier B.V., 2024) Neha Tiwari; Anil Kumar Tripathi
Azospirillum brasilense is a non-photosynthetic α-Proteobacteria, belongs to the family of Rhodospirillaceae and produces carotenoids to protect itself from photooxidative stress. In this study, we have used Resonance Raman Spectra to show similarity of bacterioruberins of Halobacterium salinarum to that of A. brasilense Cd. To navigate the role of genes involved in carotenoid biosynthesis, we used mutational analysis to inactivate putative genes predicted to be involved in carotenoid biosynthesis in A. brasilense Cd. We have shown that HpnCED enzymes are involved in the biosynthesis of squalene (C30), which is required for the synthesis of carotenoids in A. brasilense Cd. We also found that CrtI and CrtP desaturases were involved in the transformation of colorless squalene into the pink-pigmented carotenoids. This study elucidates role of some genes which constitute very pivotal role in biosynthetic pathway of carotenoid in A. brasilense Cd. © 2024 Elsevier Inc.
Dyshomeostasis of Iron and Its Transporter Proteins in Cypermethrin-Induced Parkinson’s Disease
(Springer, 2023) Nidhi Sachan; Neha Tiwari; Devendra Kumar Patel; Diksha Katiyar; Saripella Srikrishna; Mahendra Pratap Singh
The etiology of Parkinson’s disease (PD) is highly complex and is still indefinable. However, a number of studies have indicated the involvement of pesticides and transition metals. Copper, magnesium, iron, and zinc have emerged as important metal contributors. Exposure to pesticides causes an accumulation of transition metals in the substantia nigra (SN) region of the brain. The cypermethrin model of PD is characterized by mitochondrial dysfunction, autophagy impairment, oxidative stress, etc. However, the effect of cypermethrin on metal homeostasis is not yet explored. The study was designed to delineate the role of metals and their transporter proteins in cypermethrin-induced animal and cellular models of PD. The level of copper, magnesium, iron, and zinc was checked in the nigrostriatal tissue and serum by atomic absorption spectroscopy. Since cypermethrin consistently increased iron content in the nigrostriatal tissue and serum after 12 weeks of exposure, the level of iron transporter proteins, such as divalent metal transporter-1 (DMT-1), ceruloplasmin, transferrin, ferroportin, and hepcidin, and their in silico interaction with cypermethrin were checked. 3,3′-Diaminobenzidine-enhanced Perl’s staining showed an elevated number of iron-positive cells in the SN of cypermethrin-treated rats. Molecular docking studies revealed a strong binding affinity between cypermethrin and iron transporter protein receptors of humans and rats. Furthermore, cypermethrin increased the expression of DMT-1 and hepcidin while reducing the expression of transferrin, ceruloplasmin, and ferroportin in the nigrostriatal tissue and human neuroblastoma cells. These observations suggest that cypermethrin alters the expression of iron transporter proteins leading to iron dyshomeostasis, which could contribute to dopaminergic neurotoxicity. © 2023, The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature.
In silico designing and interaction of coumarin-amino acid(S) conjugates with integrin like protein of cryptococcus neoformans: Insights on antifungal drug design
(AMG Transcend Association, 2021) Neha Tiwari; Gunjan Uttam; Priyanka; Karuna Singh; Diksha Katiyar
In the present work, a library of 117 coumarin-amino acid(s) conjugates was designed, and molecular docking study was performed to investigate their possible role as fungal integrin like receptor antagonists. The objective of this study is in-silico designing and docking of coumarin-amino acid conjugates against integrin like protein of Cryptococcus neoformans. In the absence of a crystallographic structure of integrin of the fungal pathogen, a homology model of protein OXH63806.1 of Cryptococcus neoformans was developed using the currently available X-ray structure of human integrin as a template. The quality of the 3D model obtained by homology modeling was evaluated by the PROCHECK program. A docking study using coumarin-amino acid(s) conjugates as ligands on the binding site of the modeled receptor was carried out to understand the protein-ligand binding interactions. Some of the compounds have shown very good binding energies ranging from-10.32 to-10.94 Kcal/mol towards the target receptor. These results may be helpful in the designing and development of new antifungal agents as integrin like protein antagonists. © 2020 by the authors.
Paradendryphiella arenariae (MW504999) as a Novel Fungal Source of Tenuazonic Acid in Tomato (Lycopersicon esculentum)
(Springer, 2025) Ankita Kumari; Karuna Singh; Neha Tiwari; Diksha Katiyar; Satyendra Pratap Singh; Anurag Mishra
Tenuazonic acid (TeA) is a mycotoxin usually produced by Alternaria species. Its toxicological potency is considered to be the highest among all Alternaria-mycotoxins. The present study for the first time reports Paradendryphiella arenariae isolated from tomato (Lycopersicon esculentum) as a source of TeA mycotoxin, thus adding a new genus to the array of TeA-producing fungi. The study involves optimizing culture conditions for maximum TeA production, and employing analytical techniques to characterize the compound. Thin-layer chromatography and high-pressure liquid chromatography (HPLC) were employed for the isolation and characterization of the mycotoxin produced by P. arenariae. Structural elucidation was achieved using Fourier transform infrared spectroscopy and nuclear magnetic resonance spectroscopy. Quantitative determination of TeA was conducted using HPLC with a standard TeA reference. The presence of TeA was further confirmed through electronspray ionization-mass spectrometry and high-resolution liquid chromatography-mass spectrometry. In cytotoxicity assays, the isolated TeA exhibited significant toxicity to murine splenocytes, with an IC50 of 25 µg/mL. This study highlights the need for vigilance regarding TeA contamination in food products. The identification of P. arenariae as a new source of TeA underscores the importance of expanding monitoring efforts to include diverse fungal species. Ensuring food safety through stringent regulations and routine testing is essential to mitigate health risks associated with TeA exposure. © Association of Microbiologists of India 2025.
Synthesis and Antifungal Activity of Some Novel Coumarin-Amino Acid Conjugates
(John Wiley and Sons Inc, 2022) Neha Tiwari; Ankita Kumari; Gunjan Uttam; Vineeta Singh; Karuna Singh; Diksha Katiyar
A series of novel coumarin-amino acid conjugates was synthesized and structural characterization was done by various spectroscopic methods. All the conjugates were screened for their antifungal activity against five fungal strains namely T. rubrum, A. niger, A. fumigatus, A. flavus and C. albicans by two-fold serial microdilution method. Some of them showed significant activity with MIC values in the range of 6.25–25 μg/mL. Notably, compound 5 e showed potential antifungal effect against three tested strains with MIC's in the range of 6.25–12.5 μg/mL. The molecular docking studies showed that some conjugates possessed good binding affinity with the modelled receptor of integrin-like protein of Cryptococcus neoformans var. grubii. Compounds 5 d and 5 e also exhibited good binding efficiency with the Candida spp. cell wall associated proteins in in vitro binding assay. Additionally, in silico physicochemical parameters such as lipophilicity and pharmacokinetic properties such as absorption, distribution, metabolism, and excretion (ADME) of the synthesized compounds were also evaluated. © 2022 Wiley-VCH GmbH.
Synthesis, antimicrobial and chitinase inhibitory activities of 3-amidocoumarins
(Academic Press Inc., 2020) Rajesh Kumar Sharma; Vineeta Singh; Neha Tiwari; R.J. Butcher; Diksha Katiyar
A series of 3-amidocoumarins has been synthesized and tested in vitro for their anitimicrobial and chitinase inhibitory activities. Among these, compounds 5k, 5l, 8b–8d, 8f and 8g exhibited good antibacterial activity with MIC values in the range of 6.25–25 µg/mL against some of the tested strains while compounds 5l, 8b, 8c and 8f showed good activity against at least one or two fungal strains. Some of the assayed compounds 5d, 5k, 5l, 8b and 8c displayed significant chitinase inhibitory activity with IC50 values in the range of 3.74–5.6 µM. Among them, 5l proved to be potent chitinase inhibitor with IC50 value of 3.74 µM. To better understand the enzyme-inhibitor interactions molecular docking study of all the synthesized compounds was carried out on Aspergillus fumigatus chitinase 1W9U. The compound 5l showed high binding affinity with the receptor with binding energy value of −8.44 Kcal/mol. This study also provides structure activity relationship (SAR) of synthesized compounds. © 2020 Elsevier Inc.
Synthesis, In Vitro and In Vivo Antifungal Activities of Novel Coumarin–Tryptophan Conjugates
(Pleiades Publishing, 2025) Neha Tiwari; Ankita Kumari; Saurabh Sharma; Vaishali Raghuvanshi; Gunjan Uttam; Vineeta K. Singh; Karuna Singh; Diksha Katiyar
Abstract: Objective: Persistent fungal infections, especially those caused by Candida spp., pose a serious health risk to humans. Treatment of these infections is highly challenging due to the spread of resistance to first-line antifungal drugs. Therefore, the identification and development of novel antifungal agents are in great demand. In this study, a series of coumarin–tryptophan conjugates were synthesized and their antifungal activities evaluated. Methods:In vitro antifungal activities of compounds (IVa–IVe) were determined by the minimum inhibitory concentration (MIC) method. The in vivo activity of the most active compound, (IVe), was assessed using a murine model of dermal candidiasis. Docking studies were performed using the AutoDock 4.0 software package. Results and Discussion: Several compounds exhibited broad-spectrum activity against the tested strains, with favorable MIC values in the range of 6.25–25 µg/mL. Compound (IVe) showed significant antifungal activity with an MIC of 6.25 µg/mL against A. flavus and C. albicans. In the murine dermal candidiasis model, (IVe) reduced the fungal burden in nearly all vital organs of the experimental animals and demonstrated therapeutic healing effects on ulcers induced by C. albicans infection. Molecular docking results indicated that these compounds have potential as antifungal agents. Evaluation of drug-like properties of compounds (IVa–IVe) using the SwissADME web tool revealed that these molecules possess favorable druggability profiles. Conclusions: Compound (IVe), having shown excellent antifungal activity, can be considered a promising antifungal agent for further investigation. © Pleiades Publishing, Ltd. 2025.
Synthesis, Structure Elucidation, Homology Modeling and Antifilarial Activity of 7-Benzamidocoumarin Derivatives
(Wiley-Blackwell, 2019) Priyanka; Neelabh; Neha Tiwari; Rajesh K. Sharma; Poonam Gupta; Sweta Misra; Shailja Misra-Bhattacharya; Ray J. Butcher; Karuna Singh; Diksha Katiyar
A series of 7-benzamidocoumarin derivatives 10–25 starting from 7-amino coumarins 7 and 8 has been synthesized, characterized and evaluated in vitro for antifilarial activity against the human lymphatic filarial parasite, Brugia malayi. Compounds 13 and 20–23 showed permanent paralysis of the worm with 90–95% inhibition of motility of adult worms at 10 μM. All the synthesized compounds were docked on the modeled receptor of Onchocerca volvulus chitinase OvCHT1. Compound 13 with binding energy of −7.95 Kcal/mol showing three hydrogen bonds with the active site of the enzyme emerged as the best inhibitor. © 2019 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim