Browsing by Author "Ram Sagar"

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A small bioactive glycoside inhibits epsilon toxin and prevents cell death
(Company of Biologists Ltd, 2019) Abhishek Shivappagowdar; Soumya Pati; Chintam Narayana; Rajagopal Ayana; Himani Kaushik; Raj Sah; Swati Garg; Ashish Khanna; Jyoti Kumari; Lalit Garg; Ram Sagar; Shailja Singh
Clostridium perfringens epsilon toxin (Etx) is categorized as the third most lethal bioterrorism agent by the Centers for Disease Control and Prevention (CDC), with no therapeutic counter measures available for humans. Here, we have developed a high-affinity inhibitory compound by synthesizing and evaluating the structure activity relationship (SAR) of a library of diverse glycosides (numbered 1-12). SAR of glycoside-Etx heptamers revealed exceptionally strong H-bond interactions of glycoside-4 with a druggable pocket in the oligomerization and β-hairpin region of Etx. Analysis of its structure suggested that glycoside-4 might self-aggregate to form a robust micelle-like supra-molecular complex due to its linear side-chain architecture, which was authenticated by fluorescence spectroscopy. Further, this micelle hinders the Etx monomer-monomer interaction required for oligomerization, validated by both surface plasmon resonance (SPR) and immunoblotting. This phenomenon in turn leads to blockage of pore formation. Downstream evaluation revealed that glycoside-4 effectively blocked cell death of Etx-treated cultured primary cells and maintained cellular homeostasis via disrupting oligomerization, blocking pore formation, restoring calcium homeostasis, stabilizing the mitochondrial membrane and impairing high mobility group box 1 (HMGB1) translocation from nucleus to cytoplasm. Furthermore, a single dosage of glycoside-4 protected the Etx-challenged mice and restored normal function to multiple organs. This work reports for the first time a potent, nontoxic glycoside with strong ability to occlude toxin lethality, representing it as a bio-arm therapeutic against Etx-based biological threat. © 2019. Published by The Company of Biologists Ltd
Base-Induced Annulation of Glycal-Derived α-iodopyranone with 2-Aminopyrimidinones: Access to Chiral Imidazopyrimidinones
(John Wiley and Sons Inc, 2024) Vinay Kumar Mishra; Ghanshyam Tiwari; Ashish Khanna; Yogesh Yadav; Ram Sagar
A simple, environmentally benign and catalyst-free method for the synthesis of chirally enriched imidazo[1,2-a]pyrimidinone glycohybrids has been successfully developed. The protocol is based on a base-induced annulation of α-iodo-pyranone with Michael addition of 2-aminopyrimidinones followed by intramolecular nucleophilic substitution reaction. The privilege of this method includes mild reaction conditions, eco-friendly solvent and a transition-metal-free approach. Moreover, using straightforward simple methods, this reaction method exhibits a broad range of substrate scope and remarkable tolerance toward various functional groups. © 2024 Wiley-VCH GmbH.
Cardenolide and pregnatriene compounds from the roots of Nerium oleander
(Taylor and Francis Ltd., 2021) Vinay Kumar Mishra; Braj Kishore Rathour; Sunil K. Mishra; Ram Sagar
Cardenolide and pregnatriene compounds were isolated from the chloroform fraction of the 95% aqueous ethanolic extract of dried roots of Nerium oleander. The stereochemical structure of the cardenolide and pregnatriene compounds was determined to be 3β-O-(D-diginosyl)-14β-hydroxy card-20(22)-enolide and 12β-hydroxy pregna-4,6,16-triene-3,20-dione using spectroscopic methods including IR, HRMS and NMR spectroscopy. © 2020 Informa UK Limited, trading as Taylor & Francis Group.
Copper-catalyzed synthesis of pyrazolo[1,5-a]pyrimidine based triazole-linked glycohybrids: mechanistic insights and bio-applications
(Nature Research, 2024) Ghanshyam Tiwari; Ashish Khanna; Rajdeep Tyagi; Vinay Kumar Mishra; Chintam Narayana; Ram Sagar
Hybrid molecules maintain their stronghold in the drug market, with over 60% of drug candidates in pharmaceutical industries. The substantial expenses for developing and producing biologically privileged drugs are expected to create opportunities for producing hybrid molecule-based drugs. Therefore, we have developed a simple and efficient copper-catalyzed approach for synthesizing a wide range of triazole-linked glycohybrids derived from pyrazolo[1,5-a]pyrimidines. Employing a microwave-assisted copper-catalyzed approach, we developed a concise route using various 7-O-propargylated pyrazolo[1,5-a]pyrimidines and 1-azidoglycosides. This strategy afforded a series of twenty-seven glycohybrids up to 98% yield with diverse stereochemistry. All were achieved within a remarkably shortened time frame. Our investigation extends to evaluating the anticancer potential of these synthesized triazole-linked pyrazolo[1,5-a] pyrimidine-based glycohybrids. In-vitro assays against MCF-7, MDA-MB231, and MDA-MB453 cell lines reveal intriguing findings. (2R,3S,4S,5R,6R)-2-(acetoxymethyl)-6-(4-(((5-(4-chlorophenyl)pyrazolo[1,5-a]pyrimidin-7-yl)oxy)methyl)-1H-1,2,3-triazol-1-yl)tetrahydro-2H-pyran-3,4,5-triyl triacetate emerges as a standout with better anticancer activity against MDA-MB231 cells (IC50 = 29.1 µM), while (2R,3R,4S,5R,6R)-2-(acetoxymethyl)-6-(4-(((5-(4-chlorophenyl)pyrazolo[1,5-a]pyrimidin-7-yl)oxy)methyl)-1H-1,2,3-triazol-1-yl)tetrahydro-2H-pyran-3,4,5-triyl triacetate demonstrates the best inhibitory effects against MCF-7 cells (IC50 = 15.3 µM) in all derived compounds. These results align with our docking analysis and structure–activity relationship (SAR) investigations, further validating the in-vitro outcomes. This work not only underscores the synthetic utility of our devised protocol but also highlights the promising potential of these glycohybrids as candidates for further anticancer therapeutic exploration. © 2024, The Author(s).
Design and efficient synthesis of pyrazoline and isoxazole bridged indole C-glycoside hybrids as potential anticancer agents
(Nature Research, 2020) Priti Kumari; Vishnu S. Mishra; Chintam Narayana; Ashish Khanna; Anindita Chakrabarty; Ram Sagar
C-glycosides are important class of molecules exhibit diverse biological activities and present as structural motif in many natural products. Two series of new pyrazoline and isoxazole bridged indole C-glycoside molecular hybrids (n = 36) were efficiently synthesized starting from diverse indole 3-carboxaldehydes derived α, β-unsaturated ketone derivatives of β-D-glucosyl-propan-2-one, β-D-galactosyl-propan-2-one and β-D-mannosyl-propan-2-one, reacting with hydrazine hydrate and hydroxyl amine hydrochloride in shorter reaction time (15 min) under microwave assisted condition. Anticancer activity of these newly synthesized pyrazoline and isoxazole bridged indoles C-glycoside hybrids were determined in details through cellular assays against MCF-7, MDA-MB-453 and MDA-MB-231 cancer cell lines. The selected library members displayed low micromolar (IC50 = 0.67–4.67 µM) and selective toxicity against breast cancer cell line (MCF-7). Whereas these compounds were nontoxic towards normal cell line (MCF-10A). Mechanistic studies showed that, active compounds inhibit COX-2 enzyme, which was also supported by molecular docking studies. These findings are expected to provide new leads towards anticancer drug discovery. © 2020, The Author(s).
Design and synthesis of N–acetylglucosamine derived 5a-carbasugar analogues as glycosidase inhibitors
(Elsevier Ltd, 2018) Chintam Narayana; Priti Kumari; Daisuke Ide; Nasako Hoshino; Atsushi Kato; Ram Sagar
An efficient synthesis of new six-membered carbasugars in both L-form and D-form starting from N–acetylglucosamine is described. The key synthetic steps involved regioselective protection and deprotection, Ferrier carbocyclization, Peterson olefination, hydroboration and stereoselective epoxidation followed by regioselective epoxide ring opening reactions. These six-membered carbasugars showed moderate glycosidase inhibitory activity and one of the compounds was found selective towards β-galactosidase inhibitory activity. © 2018 Elsevier Ltd
Design, Synthesis, Antimicrobial Activities, and Molecular Docking Studies of New Glyco-Conjugates of Amino Acid Derivatives
(John Wiley and Sons Inc, 2025) Sajida Banoo; Zinnu Rain; Abhinetra Jagdish Bhopale; Rajnish Kumar; Pradyot Prakash; Ram Sagar; Arun Kumar Manna
The existence of MDR and XDR strains of bacteria is a serious threat to mankind. Therefore, the development of new drug molecules with different modes of action is the need of the hour. Medicinal chemists and chemical biologists around the globe are making continuous efforts to combat this challenging health issue. In this effort, we have designed and efficiently synthesized amino acid glycoconjugates of D-glucose as new glycohybrids. These novel glyconjugates were screened against Staphylococcus aureus and Staphylococcus epidermidis Gram (+) ve and Escherichia coli Gram (−) ve bacterial strains. The antibiofilm properties of these glyconjugates were also studied. Furthermore, these compounds were evaluated for their antifungal property against two fungal strains, namely Candida albicans and Candida parapsilosis. The detailed antimicrobial activity is presented here. The molecular docking of selected active glycoconjugates is carried out with bacterial gyrase and fungal α-demethylase and compared with standard drugs novobiocin and fluconazole, respectively, which revealed some interesting molecular interactions. © 2025 Wiley-VCH GmbH.
Development of intron length polymorphic (ILP) markers in onion (Allium cepa L.), and their cross-species transferability in garlic (A. sativum L.) and wild relatives
(Springer Netherlands, 2019) Kuldip Jayaswall; Himanshu Sharma; Abhishek Bhandawat; Ram Sagar; Vinod Kumar Yadav; Vikas Sharma; Vijay Mahajan; Joy Roy; Major Singh
Onion (Allium cepa L.) is a popular spice and a plant of high medicinal value. Conventional breeding and genetic improvement efforts were largely limited due to self-incompatibility and heterozygosity. Recently, marker assisted breeding has significantly reduced time and labour in developing elite varieties. But very limited polymorphic and cross-transferable markers are available in onion. There is an urgent need to develop polymorphic markers in Allium to expedite and introgress desirable traits from wild relatives (which are rich bioresource of various biotic and abiotic resistance genes) to A. cepa. Considering limited availability of reliable molecular markers in Allium and wild relatives, in current study, 20,204 ESTs (3750 contigs and 8364 singletons), of A. cepa were successfully utilized for identification of over 2689 intron length polymorphic (ILP) markers. A set of 30 markers was tested for polymorphism in onion and cross-transferability in garlic and related wild species. Among these, eighteen markers amplified at least one of the accessions of A. cepa. Transferability of these ILP markers was ranged from 21.7 to 95.7% in Allium spp. Low level of polymorphism in A. cepa compared to wild Allium species is reported. Based on the Jaccard dissimilarity matrix, a neighbour-joining tree was constructed, which clustered all the 23 varieties/accessions under three groups. All the varieties of A. cepa were clearly clustered separately under group I. However, there was intermixing of varieties/accessions of A. sativum L. and wild relatives, which may possibly be due to less number of markers validated for cross-transferability. In future, larger set of markers will be used to resolve the genetic variations among wild varieties and A. sativum These 18 polymorphic ILP markers could be utilised for diversity characterization of Allium spp., varietal identification, mapping of genes and introgression of desirable traits from wild relatives. © 2019, Springer Nature B.V.
Efficient synthesis and in-silico studies of pyrano[3,2-c]pyrones based glycohybrids
(Elsevier B.V., 2024) Kanchan Yadav; Ashish Khanna; Rajdeep Tyagi; Sunil Sharma; Ram Sagar
This work is comprising of designing, efficient synthesis and molecular docking studies of pyrano[3,2-c]pyrones based stereodivergent glycohybrids. The diverse pyrano[3,2-c]pyrones based glycohybrids were efficiently prepared through condensation of 4-hydroxycoumarin derivatives and 4‑hydroxy-6-methyl-2H-pyran-2-ones with various enantiopure 2,3-dideoxy-α,β-unsaturated carbohydrate enals using organo-catalyst, L-proline, in EtOAc at room temperature. 3,4,6-tri-O-acetyl-D-glucal derived acetyl-protected carbohydrate enals yielded highly diastereoselective glycohybrid products. Whereas, poor selectivity was observed with α,β-unsaturated carbohydrate enals obtained from 3,4,6-tri-O-acetyl-D-galactal. The in-silico investigations show the significant binding activity of the selected compounds in the active binding site of HCK protein (PDB: 1QCF) with the better docking score of −7.13 kcal/mol as compared to the co-crystallized ligand PP1 (−6.77 kcal/mol). Additionally, MM/GBSA was calculated using the Prime module to determine the binding energy of the ligands. Selected compounds showed the maximum binding affinity of −74.18 kcal/mol compared to the co-crystallized ligand PP1 (−70.40 kcal/mol). ADMET screening of these compounds predicts the low toxicity and better metabolic profile of the synthesized compounds inside the body. © 2024 Elsevier B.V.
Efficient Synthesis of Chirally Enriched 1 H -Imidazo[1,2- b ]pyrazole- and 4 H -Imidazo[1,2- b ][1,2,4]triazole-Based Bioactive Glycohybrids
(Georg Thieme Verlag, 2023) Vinay Kumar Mishra; Ghanshyam Tiwari; Ashish Khanna; Rajdeep Tyagi; Ram Sagar
Carbohydrates, traditionally known for their energy-providing role, have gained significant attention in drug discovery due to their diverse bioactivities and stereodiversity. However, pure carbohydrate molecules often exhibit limited bioactivity and suboptimal chemical and physical characteristics. To address these challenges, bioactive scaffolds have been incorporated into carbohydrate to enhance their bioactivity and improve their overall properties. Among the various heterocyclic structural motifs known for their pharmacological properties, imidazo-pyrazole and imidazo-triazole skeleton have gained larger attention among synthetic and medicinal chemists as they possess good biological and pharmacological properties. The incorporation of these bioactive scaffolds with carbohydrates adopting developed efficient synthetic protocol to synthesize new class of imidazo-pyrazole and imidazo-triazole glycohybrid molecules is reported. The carbohydratederived ?-iodo-2,3-dihydro-4H-pyran-4-ones have been identified as suitable precursors, which were coupled with various aminopyrazoles and aminotriazoles to obtain designed glycohybrids. Thus, various imidazo-pyrazole and imidazo-triazole based glycohybrids have been prepared efficiently in good to excellent yields. These new glycohybrids were evaluated for their anticancer activity and selected compounds were found to possess submicromolar anticancer activity against MCF-7 breast cancer cell line. These molecules could potentially be developed as new chemical entities in pharmaceutical chemistry and may encourage the use of carbohydrates in stereo-divergent synthesis and drug discovery processes. © 2023 Georg Thieme Verlag. All rights reserved.
Efficient synthesis of indole-chalcones based glycohybrids and their anticancer activity
(Elsevier Ltd, 2024) Rajdeep Tyagi; Kanchan Yadav; Ashish Khanna; Sunil K. Mishra; Ram Sagar
Indole based glycosides belong to the class of pharmacologically active molecules and found in diverse natural compounds. Herein, we report the synthesis of 1,2,3-triazole bridged chirally enriched diverse indole-chalcones based glycohybrids. Three series of glycohybrids were designed and efficiently synthesized using D-glucose, D-galactose and D-mannose derived 1-azido glycosides. The reactions sequence involved were, the synthesis of indole derived chalcones which were formed via Claisen–Schmidt condensation reaction and subsequently N-propargylation which leads to the production of N-propargylated indole-chalcones. The N-propargylated indole-chalcones get transformed into 1,2,3-triazole bridged indole-chalcone based glycohybrids by reacting with 1-azido sugar glycosides under click-chemistry reaction conditions. Further, the biological activity of synthesized glycohybrids (n = 27) was assessed in-vitro against MDA-MB231, MCF-7, MDA-MB453 cancer, and MCF-10A normal cell lines. The selected compounds showed potent anti-oncogenic properties against MCF-7 and MDA-MB231 breast cancer cell line with IC50 values of 1.05 µM and 11.40 µM respectively, with very good selectivity index (SI > 161). The active compounds show better binding affinity as compared to co-crystallized inhibitor 1-(tert-butyl)-3-(p-tolyl)-1H-pyrazolo[3,4-d]pyrimidin-4-amine (PP1) with HCK (PTKs) proteins in molecular docking studies. © 2024 Elsevier Ltd
Efficient Synthesis of Natural Product Inspired Naphthoquinone-Fused Glycohybrids and Their in Silico Docking Studies
(Georg Thieme Verlag, 2023) Ashish Khanna; Ghanshyam Tiwari; Vinay Kumar Mishra; Kavita Singh; Ram Sagar
Naphthoquinones, a diverse group of natural compounds with a 1,4-naphthoquinone core structure, have gained attention for their pharmacological properties. The anticancer activity of these compounds is attributed to their ability to accept electrons, leading to the generation of reactive oxygen species that cause DNA damage and cell death. In recent studies, hydroxy-1,4-naphthoquinone derivatives, including daunorubicin, have shown promising inhibitory effects against several human cancers, such as acute myeloid leukemia, chronic myelogenous leukemia, and Kaposi s sarcoma. To further explore their potential as anticancer agents, this research article focuses on the design and synthesis of natural product inspired naphthoquinone-based glycohybrids. These glycohybrids are designed based on the structures of bioactive aryl glycosides and quinones, aiming to enhance their binding affinity and specificity towards cancer-related protein targets. The interactions between the synthesized glycohybrids and target proteins through computational docking simulations has been studied and better binding affinity was found. © 2023 Georg Thieme Verlag. All rights reserved.
Electro-organic synthesis of isatins and hydrazones through C-N cross-coupling and C(sp2)-H/C(sp3)-H functionalization
(Royal Society of Chemistry, 2023) Neetu Verma; Rajdeep Tyagi; Ashish Khanna; Manisha Malviya; Ram Sagar
An efficient and unique approach to synthesize isatin (indole-2,3-dione) from 2-aminoacetophenone under electrochemical conditions supported by I2-DMSO through C-N cross-coupling and C(sp2)-H/C(sp3)-H functionalization is presented. This synthetic method spans a wide range of substituted 2-aminoacetophenone substrates. The use of iodine as a promoter and shorter reaction times produced good to very good yields of isatin derivatives, which is a significant improvement over the reaction in a batch process. Further, hydrazones of isatin were synthesized by using hydrazine hydrate which produces electrochemically active molecules, namely isatin-hydrazones. The hydrazones of acetophenone were also obtained using the same reaction protocol. Additionally, the effect of increasing scan rate studied using cyclic voltammetry shows that the process followed a diffusion-controlled mechanism. © 2023 The Royal Society of Chemistry.
Enhanced uptake, high selective and microtubule disrupting activity of carbohydrate fused pyrano-pyranones derived from natural coumarins attributes to its anti-malarial potential
(BioMed Central, 2019) Sonal Gupta; Juveria Khan; Priti Kumari; Chintam Narayana; R. Ayana; Malabika Chakrabarti; Ram Sagar; Shailja Singh
Background: Malaria is one of the deadliest infectious diseases caused by protozoan parasite of Plasmodium spp. Increasing resistance to anti-malarials has become global threat in control of the disease and demands for novel anti-malarial interventions. Naturally-occurring coumarins, which belong to a class of benzo-α-pyrones, found in higher plants and some essential oils, exhibit therapeutic potential against various diseases. However, their limited uptake and non-specificity has restricted their wide spread use as potential drug candidates. Methods: Two series of carbohydrate fused pyrano[3,2-c]pyranone carbohybrids which were synthesized by combination of 2-C-formyl galactal and 2-C-formyl glucal, with various freshly prepared 4-hydroxycoumarins were screened against Plasmodium falciparum. The anti-malarial activity of these carbohybrids was determined by growth inhibition assay on P. falciparum 3D7 strain using SYBR green based fluorescence assay. Haemolytic activity of carbohybrid 12, which showed maximal anti-malarial activity, was determined by haemocompatibility assay. The uptake of the carbohybrid 12 by parasitized erythrocytes was determined using confocal microscopy. Growth progression assays were performed to determine the stage specific effect of carbohybrid 12 treatment on Pf3D7. In silico studies were conducted to explore the mechanism of action of carbohybrid 12 on parasite microtubule dynamics. These findings were further validated by immunofluorescence assay and drug combination assay. Results: 2-C-formyl galactal fused pyrano[3,2-c]pyranone carbohybrid 12 exhibited maximum growth inhibitory potential against Plasmodium with IC50 value of 5.861 μM and no toxicity on HepG2 cells as well as no haemolysis of erythrocytes. An enhanced uptake of this carbohybrid compound was observed by parasitized erythrocytes as compared to uninfected erythrocytes. Further study revealed that carbohybrid 12 arrests the growth of parasite at trophozoite and schizonts stage during course of progression through asexual blood stages. Mechanistically, it was shown that the carbohybrid 12 binds to α,β-heterodimer of tubulin and affects microtubule dynamics. Conclusion: These findings show carbohydrate group fusion to 4-hydroxycoumarin precursor resulted in pyrano-pyranones derivatives with better solubility, enhanced uptake and improved selectivity. This data confirms that, carbohydrate fused pyrano[3,2-c]pyranones carbohybrids are effective candidates for anti-malarial interventions against P. falciparum. © 2019 The Author(s).
Erratum: Enhanced uptake, high selective and microtubule disrupting activity of carbohydrate fused pyrano-pyranones derived from natural coumarins attributes to its anti-malarial potential (Malaria Journal (2019) 18 (346) DOI: 10.1186/s12936-019-2971-z)
(BioMed Central Ltd., 2020) Sonal Gupta; Juveria Khan; Priti Kumari; Chintam Narayana; R. Ayana; Malabika Chakrabarti; Ram Sagar; Shailja Singh
Please note, following publication of the original article [1], the authors have advised of three errors that are present in the published article. Firstly, the two instances of 'Albumax II' in the 'Methods' section of the article are incorrect: the reagent 'Albumax I' should be referred to instead. Secondly, 'giemsa' (also referred to in the 'Methods' section) should be capitalized, as 'Giemsa'. Finally, an incorrect version of Fig. 4 has been incorporated in the article; please find the correct version of Fig. 4 in this article, for reference. © 2020 The Author(s).
Exploiting Microwave-Assisted Organic Synthesis (MAOS) for Accessing Bioactive Scaffolds
(Bentham Science Publishers, 2021) Ashish Khanna; Prashant Dubey; Ram Sagar
A microwave-assisted organic synthesis is an alternative approach towards the traditional way of heating to obtain desired bioactive scaffolds as a product. This method has transformed the approaches of organic synthesis, due to shorter reaction time with high product yields, modifications of selectivity, increased product purities, and simplification of workup procedures. The microwave-assisted reactions can be performed under solvent-free conditions. Thus, Microwave-Assisted Organic Synthesis (MAOS) has become the first choice for the medicinal chemist and chemical biologist to use as a tool to perform organic reactions in drug discovery and medicinal chemistry. Microwave-assisted organic synthesis specifically results in the desired products with higher selectivity and purity which may have better pharmacological properties. In this review article, we covered the literature from 2010-till to date, focusing on the use of microwave irradiation in performing organic reactions to deliver various bioactive scaffolds. © 2021 Bentham Science Publishers.
Glycohybrid molecules in medicinal chemistry: Present status and future prospective
(Elsevier, 2020) Priti Kumari; Chintam Narayana; Ghanshyam Tiwari; Ram Sagar
Hybrid molecules combine two distinct biologically relevant molecules that act at different biological targets with new mechanism are becoming molecules for interest among medicinal chemist and biological chemists. Hybrid molecules are usually defined as a molecular framework in which a linker, often a stable hydrocarbon chain, heterocyclic ring connects the two biologically relevant molecules with altered bioactivity profile. Carbohydrates play important roles in the natural world as diverse as energy storage, molecular recognition for intracellular trafficking or interactions between pathogenic bacteria and viruses and the surfaces of vertebrate’s cells. The carbohydrates present inside and at the surface of cells mediate many biological processes that are fundamentally important for human health. In the current chapter we have covered the medicinal chemistry aspects of recently reported glycohybrid molecules with respect to their anticancer, antiviral, antibacterial, antifungal, immununomodulatory, PTP1B inhibitors, carbonic anhydrase inhibitors, antimalarial, glycosidase inhibitors, galectin-3-inhibitors and anti-inflammatory activity. © 2020 Elsevier Inc. All rights reserved.
Immunomodulator and marker-assisted identification of Allium genotypes containing immunological memory against anthracnose
(Academic Press, 2025) Kuldip Jayaswall; Deepesh Kumar; Deepanshu Jayaswal; Ram Sagar; Sanjay Kumar; Ram Kumar Sharma; Kiran Pandurang Bhagat; Vijay M. Mahajan; Himanshu Sharma; Surendra Pratap Singh; Isha Sharma
Allium cepa (onion) suffers significant yield losses due to anthracnose disease caused by Colletotrichum gloeosporioides. Current control methods, such as biocontrol agents, have limited effectiveness, while agrochemical applications pose risks to human health and the environment. Genomics-assisted breeding can be useful in getting a diverse genetic pool of wild Allium species to improve disease resistance in cultivated varieties. In this study, we used 42 intron length polymorphic and 22 chloroplast-based SSR markers to identify wild Alliums for anthracnose resistance. Genetic analysis using the marker data showed that two wild types, 6AfistAKO-17 and 15Afistul, are very different from the cultivated types. Immunomodulator benzo-thiadiazole-7-carbothioic acid S-methyl ester evoked a long-lasting immune response in wild Alliums. Transcriptome profiling showed that 131 immune-related genes were more than twice as active in wild Alliums compared to cultivated ones. These included MAPKs (7 genes), WRKY transcription factors (10), R genes (19), MYB transcription factors (28), cytochrome P450s (46), transcriptional activators (14), and other immune-associated genes (7). The results from the anatomical analysis showed that wild Alliums have more callose in their vascular bundles, thicker wax on their leaf surfaces, and closed stomata, which were confirmed by fluorescence and scanning electron microscopy, indicating that wild Alliums have a stronger immune system than the cultivated Alliums. Our findings suggest that wild Alliums possess both immunity and immune memory-related genes. This study suggests that molecular markers could help transfer the immunity-related genes from wild Alliums to cultivated Alliums to protect them from anthracnose infestation. © 2025 Elsevier Ltd
Metal free synthesis of 2,3-dideoxy-α, β-unsaturated carbohydrate enals (Perlin aldehydes)
(Elsevier Ltd, 2023) Kavita Singh; Sourav Sagar Behera; Rajdeep Tyagi; Ghanshyam Tiwari; Ram Sagar
A metal free synthesis of enantiopure 2,3-dideoxy-α, β-unsaturated carbohydrate enals (Perlin aldehydes), in CH3CN-0.02 N H2SO4 in water (1:1, v/v) with 0.5 equivalent additives (4-hydroxy-6-methyl-2-pyrone or 4-amino coumarin), has been reported. This efficient protocol works well for the acetylated glycals (glucal, galactal and arabinal) and afforded Perlin aldehydes and hemiacetals in acceptable to good yields. Whereas, benzylated glycals furnished respective Perlin aldehydes, hemiacetals and the 2-deoxy derivatives, under similar reaction conditions. The products yields were significantly reduced when the additives were removed from the reaction mixture, indicating that they constitute an essential component of this approach. Further the use of 0.02 N H2SO4 in water: acetonitrile (1:1, v/v) solvent system is essential for the formation of Perlin aldehydes. The similar reactions under neutral reaction conditions (CH3CN:H2O, 1:1, v/v) with additives, afforded the hemiacetals as major product. This methodology is a metal free approach to Perlin aldehyde synthesis and therefore having additional benefit of its use in preparation of bioactive drug molecules, where metal toxicity is the major concern. © 2023 Elsevier Ltd
Metalloprotease Gp63-Targeting Novel Glycoside Exhibits Potential Antileishmanial Activity
(Frontiers Media S.A., 2022) Amrita Chakrabarti; Chintam Narayana; Nishant Joshi; Swati Garg; Lalit C. Garg; Anand Ranganathan; Ram Sagar; Soumya Pati; Shailja Singh
Visceral leishmaniasis (VL) and post kala-azar dermal leishmaniasis (PKDL) affect most of the poor populations worldwide. The current treatment modalities include liposomal formulation or deoxycholate salt of amphotericin B, which has been associated with various complications and severe side effects. Encouraged from the recent marked antimalarial effects from plant-derived glycosides, in this study, we have exploited a green chemistry-based approach to chemically synthesize a library of diverse glycoside derivatives (Gly1–12) and evaluated their inhibitory efficacy against the AG83 strain of Leishmania donovani. Among the synthesized glycosides, the in vitro inhibitory activity of Glycoside-2 (Gly2) (1.13 µM IC50 value) on L. donovani promastigote demonstrated maximum cytotoxicity with ~94% promastigote death as compared to amphotericin B that was taken as a positive control. The antiproliferative effect of Gly2 on promastigote encouraged us to analyze the structure–activity relationship of Gly2 with Gp63, a zinc metalloprotease that majorly localizes at the surface of the promastigote and has a role in its development and multiplication. The result demonstrated the exceptional binding affinity of Gly2 toward the catalytic domain of Gp63. These data were thereafter validated through cellular thermal shift assay in a physiologically relevant cellular environment. Mechanistically, reduced multiplication of promastigotes on treatment with Gly2 induces the destabilization of redox homeostasis in promastigotes by enhancing reactive oxygen species (ROS), coupled with depolarization of the mitochondrial membrane. Additionally, Gly2 displayed strong lethal effects on infectivity and multiplication of amastigote inside the macrophage in the amastigote–macrophage infection model in vitro as compared to amphotericin B treatment. Gp63 is also known to bestow protection against complement-mediated lysis of parasites. Interestingly, Gly2 treatment enhances the complement-mediated lysis of L. donovani promastigotes in serum physiological conditions. In addition, Gly2 was found to be equally effective against the clinical promastigote forms of PKDL strain (IC50 value of 1.97 µM); hence, it could target both VL and PKDL simultaneously. Taken together, this study reports the serendipitous discovery of Gly2 with potent antileishmanial activity and proves to be a novel chemotherapeutic prototype against VL and PKDL. Copyright © 2022 Chakrabarti, Narayana, Joshi, Garg, Garg, Ranganathan, Sagar, Pati and Singh.