Publications by authors named "Narasimhamurthy Konappa"

7 Publications

  • Page 1 of 1

Ameliorated Antibacterial and Antioxidant Properties by Mediated Green Synthesis of Silver Nanoparticles.

Biomolecules 2021 04 4;11(4). Epub 2021 Apr 4.

Laboratory of Plant Healthcare and Diagnostics, PG Department of Biotechnology and Microbiology, Karnatak University, Dharwad 580 003, Karnataka, India.

Biosynthesis of silver nanoparticles using beneficial is a simple, eco-friendly and cost-effective route. Secondary metabolites secreted by act as capping and reducing agents that can offer constancy and can contribute to biological activity. The present study aimed to synthesize silver nanoparticles using cell filtrate and investigate different bioactive metabolites based on LC-MS/MS analysis. The synthesized silver nanoparticles (AgNPs) from were characterized by ultraviolet-visible spectrophotometry, Fourier transform infrared spectrometry (FT-IR), energy-dispersive spectroscopy (EDS), dynamic light scattering (DLS), X-ray powder diffraction (XRD) and scanning electron microscopy (SEM). The surface plasmon resonance of synthesized particles formed a peak centered near 438 nm. The DLS study determined the average size of AgNPs to be 21.49 nm. The average size of AgNPs was measured to be 72 nm by SEM. The cubic crystal structure from XRD analysis confirmed the synthesized particles as silver nanoparticles. The AgNPs exhibited remarkable antioxidant properties, as determined by DPPH and ferric reducing antioxidant power (FRAP) assay. The AgNPs also exhibited broad-spectrum antibacterial activity against two Gram-positive bacteria ( and ) and two Gram-negative bacteria ( and ). The minimum inhibitory concentration (MIC) of AgNPs towards bacterial growth was evaluated. The antibacterial activity of AgNPs was further confirmed by fluorescence microscopy and SEM analysis.
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http://dx.doi.org/10.3390/biom11040535DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8066458PMC
April 2021

Gamma-irradiated fenugreek extracts mediates resistance to rice blast disease through modulating histochemical and biochemical changes.

Anal Biochem 2021 04 27;618:114121. Epub 2021 Jan 27.

Laboratory of Plant Healthcare and Diagnostics, PG Department of Biotechnology and Microbiology, Karnataka University, Dharwad, 580 003, Karnataka, India. Electronic address:

The impact of gamma radiation on the activation of rice innate immunity to blast disease caused by Magnaporthe oryzae is described. In the present study, fenugreek seed extracts radiated with different doses of gamma rays viz. 5Gy, 10Gy, 15Gy, 20Gy and 25Gy were examined for their presence of biocompounds as well as for its ability to induce plant growth promotion and resistance against rice blast disease. The results of GC-MS analysis detected antimicrobial properties in methanolic extract. Enhanced germination (97%) and vigor (2718) was noticed in seeds pretreated with 20 Gy of gamma radiation in comparison with non-irradiated controls. Under greenhouse conditions, a significant disease protection of 56.7% on 3rd and 4th day after inoculation against rice blast was observed in 15Gy-irradiated rice plants challenge-inoculated with M. oryzae. Further, a significant increase in the hydrogen peroxide, phenol and lignin deposition was noticed in 20Gy-irradiated rice plants. Additionally, rice plants pretreated with 15Gy induced maximum activities of peroxidase (POX) and polyphenol oxidase (PPO) compared to untreated control plants. These findings revealed that rice plants-pretreated with gamma radiation elicit resistance against rice blast disease as well as strengthening the growth parameters by modulating cellular and biochemical defense system.
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http://dx.doi.org/10.1016/j.ab.2021.114121DOI Listing
April 2021

Bioactive compounds guided diversity of endophytic fungi from Baliospermum montanum and their potential extracellular enzymes.

Anal Biochem 2021 02 24;614:114024. Epub 2020 Nov 24.

Laboratory of Plant Healthcare and Diagnostics, PG Department of Biotechnology and Microbiology, Karnataka University, Dharwad, 580 003, Karnataka, India. Electronic address:

Baliospermum montanum (Willd.) Muell. Arg, a medicinal plant distributed throughout India from Kashmir to peninsular-Indian region is extensively used to treat jaundice, asthma, and constipation. In the current study, 203 endophytic fungi representing twenty-nine species were isolated from tissues of B. montanum. The colonization and isolation rate of endophytes were higher in stem followed by seed, root, leaf and flower. The phytochemical analysis revealed 70% endophytic isolates showed alkaloids and flavonoids, 13% were positive for phenols, saponins and terpenoids. Further, these endophytes produced remarkable extracellular enzymes such as amylase, cellulase, phosphates, protease and lipase. The most promisive three endophytic fungi were identified by ITS region and secreted metabolites were identified by gas chromatography-mass spectrometry (GC-MS/MS). The GC-MS profile detected twenty-five bioactive compounds from ethyl acetate extracts. Among endophytic fungi, Trichoderma reesei isolated from flower exhibited nine bioactive compounds namely, 2-Cyclopentenone, 2-(4-chloroanilino)-4-piperidino, Oxime-methoxy-Phenyl, Methanamine N-hydroxy-N-methyl, Strychane, Cyclotetrasiloxane, Octamethyl and 1-Acetyl-20a-hydroxy-16-methylene. The endophyte, Aspergillus brasiliensis isolated from root and Fusarium oxysporum isolated from seed produced nine and seven bioactive compounds, respectively. Overall, a significant contribution of bioactive compounds was noticed from the diverse endophytic fungi associated with B. montanum and could be explored for development of novel drug with commercial values.
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http://dx.doi.org/10.1016/j.ab.2020.114024DOI Listing
February 2021

Detection and Characterization of Antibacterial Siderophores Secreted by Endophytic Fungi from .

Biomolecules 2020 10 6;10(10). Epub 2020 Oct 6.

Laboratory of Plant Healthcare and Diagnostics, PG Department of Biotechnology and Microbiology, Karnataka University, Dharwad, Karnataka 570 006, India.

Endophytic fungi from orchid plants are reported to secrete secondary metabolites which include bioactive antimicrobial siderophores. In this study endophytic fungi capable of secreting siderophores were isolated from , a medicinal orchid plant. The isolated extracellular siderophores from orchidaceous fungi act as chelating agents forming soluble complexes with Fe. The 60% endophytic fungi of produced hydroxamate siderophore on CAS agar. The highest siderophore percentage was 57% in (CAL1), 49% in (CAR12), 46% in (CAR14) by CAS liquid assay. The optimum culture parameters for siderophore production were 30 °C, pH 6.5, maltose and ammonium nitrate and the highest resulting siderophore content was 73% in . The total protein content of solvent-purified siderophore increased four-fold compared with crude filtrate. The percent Fe scavenged was detected by atomic absorption spectra analysis and the highest scavenging value was 83% by . Thin layer chromatography of purified siderophore showed a wine-colored spot with R value of 0.54. HPLC peaks with Rs of 10.5 and 12.5 min were obtained for iron-free and iron-bound siderophore, respectively. The iron-free siderophore revealed an exact mass-to-charge ratio (/) of 400.46 and iron-bound siderophore revealed a / of 453.35. The solvent-extracted siderophores inhibited the virulent plant pathogens , that causes bacterial wilt in groundnut and pv which causes bacterial blight disease in rice. Thus, bioactive siderophore-producing endophytic can be exploited in the form of formulations for development of resistance against other phytopathogens in crop plants.
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http://dx.doi.org/10.3390/biom10101412DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7600725PMC
October 2020

GC-MS analysis of phytoconstituents from Amomum nilgiricum and molecular docking interactions of bioactive serverogenin acetate with target proteins.

Sci Rep 2020 10 2;10(1):16438. Epub 2020 Oct 2.

Laboratory of Plant Healthcare and Diagnostics, PG Department of Biotechnology and Microbiology, Karnataka University, Dharwad, Karnataka, India.

Amomum nilgiricum is one of the plant species reported from Western Ghats of India, belonging to the family Zingiberaceae, with ethno-botanical values, and is well-known for their ethno medicinal applications. In the present investigation, ethyl acetate and methanol extracts of A. nilgiricum were analyzed by Fourier transform infrared spectrometer (FTIR) and gas chromatography-mass spectrometry (GC-MS) to identify the important functional groups and phytochemical constituents. The FTIR spectra revealed the occurrence of functional characteristic peaks of aromatic amines, carboxylic acids, ketones, phenols and alkyl halides group from leaf and rhizome extracts. The GC-MS analysis of ethyl acetate and methanol extracts from leaves, and methanol extract from rhizomes of A. nilgiricum detected the presence of 25 phytochemical compounds. Further, the leaf and rhizome extracts of A. nilgiricum showed remarkable antibacterial and antifungal activities at 100 mg/mL. The results of DPPH and ferric reducing antioxidant power assay recorded maximum antioxidant activity in A. nilgiricum methanolic leaf extract. While, ethyl acetate leaf extract exhibited maximum α-amylase inhibition activity, followed by methanolic leaf extract exhibiting aldose reductase inhibition. Subsequently, these 25 identified compounds were analyzed for their bioactivity through in silico molecular docking studies. Results revealed that among the phytochemical compounds identified, serverogenin acetate might have maximum antibacterial, antifungal, antiviral, antioxidant and antidiabetic properties followed by 2,4-dimethyl-1,3-dioxane and (1,3-C)propanedioic acid. To our best knowledge, this is the first description on the phytochemical constituents of the leaves and rhizomes of A. nilgiricum, which show pharmacological significance, as there has been no literature available yet on GC-MS and phytochemical studies of this plant species. The in silico molecular docking of serverogenin acetate was also performed to confirm its broad spectrum activities based on the binding interactions with the antibacterial, antifungal, antiviral, antioxidant and antidiabetic target proteins. The results of the present study will create a way for the invention of herbal medicines for several ailments by using A. nilgiricum plants, which may lead to the development of novel drugs.
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http://dx.doi.org/10.1038/s41598-020-73442-0DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7532471PMC
October 2020

Exogenous priming of chitosan induces upregulation of phytohormones and resistance against cucumber powdery mildew disease is correlated with localized biosynthesis of defense enzymes.

Int J Biol Macromol 2020 Nov 16;162:1825-1838. Epub 2020 Aug 16.

Department of Studies in Biotechnology, University of Mysore, Manasagangotri, Mysuru 570 006, Karnataka, India.

In recent years, exploration of biopolymer-based materials to avoid hazardous chemicals in agriculture has gained enormous importance for sustainable crop improvement. In the present study, chitosan a biopolymer derived from crab-shell was used in different concentrations as priming agent to cucumber seeds and were evaluated for its effect to enhance plant growth parameters as well as its ability to induce resistance against powdery mildew disease. Among the treatments, seeds-primed with 2.5 mg/mL exhibited early seedling germination of 90% and vigour of 2665 and also remarkably enhanced the cucumber growth parameters which might be fairly attributed to the stimulation of phytohormones content in primed plants over the controls. More importantly, under greenhouse conditions a significant induced disease protection of 66.6% against powdery mildew disease was noticed in chitosan-pretreated plants at 2.5 mg/mL. The induced resistant plants also showed a significant deposition of lignin, callose and HO. Notably, polyphenol oxidase, phenylalanine ammonia-lyase, peroxidase and glucanase defense-responsive enzymes were upregulated in chitosan-primed plants. Considered together, these results determine that the susceptible cucumber cultivar elicits immunity after perception of priming with chitosan to upregulate phytohormones and synthesize defense-responsive enzymes, thereby induce resistance against powdery mildew disease and strengthen the growth-promotion of cucumber plants.
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http://dx.doi.org/10.1016/j.ijbiomac.2020.08.124DOI Listing
November 2020

Green Synthesis and Characterization of Zinc Oxide Nanoparticles Using and Their Fungicidal Ability Against Pathogenic Fungi of Apple Orchards.

Biomolecules 2020 03 9;10(3). Epub 2020 Mar 9.

Laboratory of Plant Healthcare and Diagnostics, PG Department of Biotechnology and Microbiology, Karnataka University, Dharwad 580003, Karnataka, India.

belonging to the Myrtaceae family was explored for the synthesis of zinc oxide nanoparticles and for biological applications. The aqueous extract of the synthesized zinc nanoparticles (ZnNPs) was characterized using UV-visible spectrophotometer, FTIR, SEM and TEM. The aqueous broth was observed to be an efficient reducing agent, leading to the rapid formation of ZnNPs of varied shapes with sizes ranging between 52-70 nm. In addition, antifungal activity of the biosynthesized ZnNPs was evaluated against major phytopathogens of apple orchards. At 100 ppm of ZnNPs, the fungal growth inhibition rate was found to be 76.7% for followed by 65.4 and 55.2% inhibition rate for and , respectively. The microscopic observations of the treated fungal plates revealed that ZnNPs damages the topography of the fungal hyphal layers leading to a reduced contraction of hyphae. This considerable fungicidal property of ZnNPs against phytopathogenic fungi can have a tremendous impact on exploitation of ZnNPs for fungal pest management and ensure protection in fruit crops.
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http://dx.doi.org/10.3390/biom10030425DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7175351PMC
March 2020
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