Publications by authors named "Srinivas Chowdappa"

10 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

In vitro therapeutic evaluation of nanoliposome loaded with Xyloglucans polysaccharides from Tamarindus flower extract.

Int J Biol Macromol 2021 May 21;178:283-295. Epub 2021 Feb 21.

Innovative Green Product Synthesis and Renewable Environment Development Research Group, Faculty of Environment and Labour Safety, Ton Duc Thang University, Ho Chi Minh City, Viet Nam. Electronic address:

Nanoparticles are interesting area of research developed for several diagnostic and therapeutic applications. Tamarind flower extract is rich in Xyloglucan, a starch like polysaccharide which promotes proliferation and various application areas like drug-delivery technology. In recent years researchers are evaluating nanoliposome using in vitro and in vivo studies to discover their biomedical applications. Considering the importance and feasibility of nanoliposome, the present study is focused on synthesis of liposomes via biological method. The biological molecules of Tamarindus indica flower were used for the synthesis of nanoliposome. The synthesized Tamarindus indica flower extract lipid nanoparticles (TifeLiNPs) loaded with xyloglucans were characterized and evaluated for therapeutic applications (antibacterial, antioxidant, antidiabetic, anticancer and anti-inflammatory activities) under in vitro condition. UV-Vis spectral analysis revealed the emission of peak at 232 nm. Further, the chemical characterization using FTIR revealed the presence of components in the functional group. EDX analysis exhibited the presence of O, Na, P and Cl, while DLS confirmed bilayer formation of xyloglucan and liposomes with uniform size (70-80 nm) and spherical shape. The Physicochemical characterization of tamarind flower extract for its chemical composition revealed the presence of carbohydrates, alkaloids, terpenoids, glycosides, saponins, tannins and flavonoids in confirmatory test. Presence of carbohydrate polymers such as rhamnose, arabinose, galactose, glucose and xylose revealed using high performance anion exchange (HPAE) chromatography under basic conditions on an ion chromatographic system were measured using Pulsed Amperometric Detection (PAD). The synthesized nanoliposome evaluated against Gram negative and Gram positive bacteria showed potential antibacterial activity. TifeLiNPs demonstrated significant in vitro antioxidant potential, antidiabetic, anti-cancer and anti-inflammatory activity. Overall, the present study exhibited the potential application of TifeLiNPs for biomedical purposes.
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http://dx.doi.org/10.1016/j.ijbiomac.2021.02.140DOI Listing
May 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

Mycogenic Synthesis of Extracellular Zinc Oxide Nanoparticles from and Its Nanoantibiotic Potential.

Int J Nanomedicine 2020 2;15:8519-8536. Epub 2020 Nov 2.

Department of Medical Laboratories, College of Applied Medical Sciences, Qassim University, Qassim 51431, Saudi Arabia.

Purpose: The study aimed to find an effective method for fungal-mediated synthesis of zinc oxide nanoparticles using endophytic fungal extracts and to evaluate the efficiency of synthesized ZnO NPs as antimicrobial and anticancerous agents.

Methods: Zinc oxide nanoparticles (ZnO NPs) were produced from zinc nitrate hexahydrate with fungal filtrate by the combustion method. The spectroscopy and microscopy techniques, such as ultraviolet-visible spectroscopy, Fourier transform infrared spectroscopy (FT-IR), powder X-ray diffraction (PXRD), scanning electron microscopy (SEM) with energy-dispersive X-ray spectroscopy (EDX), dynamic light scattering (DLS), and transmission electron microscopy (TEM) with selected area electron diffraction (SAED), were used to characterize the obtained product. Antibacterial activity on Gram-positive ( and ) and Gram-negative ( and ) samples was tested by broth microplate dilution technique. ZnO NPs antifungal activity was determined against plant pathogenic and regular contaminating fungi using the food-poison method. The anticancerous assay of the synthesized ZnO NPs was also investigated by cell uptake, MTT assay, and apoptosis assay.

Results: The fungal synthesized ZnO NPs were pure, mainly hexagonal in shape and size range of 34-55 nm. The biosynthesized ZnO NPs could proficiently inhibit both Gram-positive and Gram-negative bacteria. ZnO NPs synthesized from fungal extract exhibited antifungal activity in a dose-dependent manner with a high percentage of mycelial inhibition. The cell uptake analysis of ZnO NPs suggests that a significant amount of ZnO NPs (1 μg/mL) was internalized without disturbing cancer cells' morphology. As a result, the synthesized ZnO NPs showed significant anticancer activity against cancer cells at 1 μg/mL concentration.

Conclusion: This fungus-mediated synthesis of ZnO NPs is a simple, eco-friendly, and non-toxic method. Our results show that the synthesized ZnO NPs are an excellent novel antimicrobial and anticancer agent. Further studies are required to understand the mechanism of the antimicrobial, anticancerous action of ZnO NPs and their possible genotoxicity.
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http://dx.doi.org/10.2147/IJN.S271743DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7646447PMC
December 2020

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

Mycosynthesis of ZnO Nanoparticles Using spp. Isolated from Rhizosphere Soils and Its Synergistic Antibacterial Effect against pv. .

J Fungi (Basel) 2020 Sep 20;6(3). Epub 2020 Sep 20.

Department of Microbiology and Biotechnology, Bangalore University, Jnana Bharathi Campus, Bengaluru 560056, India.

The Plant Growth Promoting Fungi (PGPF) is used as a source of biofertilizers due to their production of secondary metabolites and beneficial effects on plants. The present work is focused on the co-cultivation of spp. ( (PGT4), (PGT5) and (PGT13)) and the production of secondary metabolites from mono and co-culture and mycosynthesis of zinc oxide nanoparticles (ZnO NPs), which were characterized by a UV visible spectrophotometer, Powder X-ray Diffraction (PXRD), Fourier Transform Infrared Spectroscopy (FTIR) and Scanning Electron Microscopy (SEM) with Energy Dispersive Spectroscopy (EDAX) and Transmission Electron Microscope (TEM) and Selected Area (Electron) Diffraction (SAED) patterns. The fungal secondary metabolite crude was extracted from the mono and co-culture of spp. And were analyzed by GC-MS, which was further subjected for antibacterial activity against pv. , the causative organism for Bacterial Leaf Blight (BLB) in rice. Our results showed that the maximum zone of inhibition was recorded from the co-culture of spp. rather than mono cultures, which indicates that co-cultivation of beneficial fungi can stimulate the synthesis of novel secondary metabolites better than in monocultures. ZnO NPs were synthesized from fungal secondary metabolites of mono cultures of Trichoderma harzianum (PGT4), Trichoderma reesei (PGT5), Trichoderma reesei (PGT13) and co-culture (PGT4 + PGT5 + PGT13). These ZnO NPs were checked for antibacterial activity against Xoo, which was found to be of a dose-dependent manner. In summary, the biosynthesized ZnO NPs and secondary metabolites from co-culture of spp. are ecofriendly and can be used as an alternative for chemical fertilizers in agriculture.
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http://dx.doi.org/10.3390/jof6030181DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7558757PMC
September 2020

Endophytic Fungi-Alternative Sources of Cytotoxic Compounds: A Review.

Front Pharmacol 2018 26;9:309. Epub 2018 Apr 26.

Plant Production Department, College of Food and Agricultural Sciences, King Saud University, Riyadh, Saudi Arabia.

Cancer is a major cause of death worldwide, with an increasing number of cases being reported annually. The elevated rate of mortality necessitates a global challenge to explore newer sources of anticancer drugs. Recent advancements in cancer treatment involve the discovery and development of new and improved chemotherapeutics derived from natural or synthetic sources. Natural sources offer the potential of finding new structural classes with unique bioactivities for cancer therapy. Endophytic fungi represent a rich source of bioactive metabolites that can be manipulated to produce desirable novel analogs for chemotherapy. This review offers a current and integrative account of clinically used anticancer drugs such as taxol, podophyllotoxin, camptothecin, and vinca alkaloids in terms of their mechanism of action, isolation from endophytic fungi and their characterization, yield obtained, and fungal strain improvement strategies. It also covers recent literature on endophytic fungal metabolites from terrestrial, mangrove, and marine sources as potential anticancer agents and emphasizes the findings for cytotoxic bioactive compounds tested against specific cancer cell lines.
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http://dx.doi.org/10.3389/fphar.2018.00309DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5932204PMC
April 2018

Cytotoxic effects of oosporein isolated from endophytic fungus Cochliobolus kusanoi.

Front Microbiol 2015 1;6:870. Epub 2015 Sep 1.

Department of Microbiology and Biotechnology, Bangalore University Bangalore, India.

In the present study, oosporein, a fungal toxic secondary metabolite known to be a toxic agent causing chronic disorders in animals, was isolated from fungus Cochliobolus kusanoi of Nerium oleander L. Toxic effects of oosporein and the possible mechanisms of cytotoxicity as well as the role of oxidative stress in cytotoxicity to Madin-Darby canine kidney kidney cells and RAW 264.7 splene cells were evaluated in vitro. Also to know the possible in vivo toxic effects of oosporein on kidney and spleen, Balb/C mouse were treated with different concentrations of oosporein ranging from 20 to 200 μM). After 24 h of exposure histopathological observations were made to know the effects of oosporein on target organs. Oosporein induced elevated levels of reactive oxygen species (ROS) generation and high levels of malondialdehyde, loss of mitochondrial membrane potential, induced glutathione hydroxylase (GSH) production was observed in a dose depended manner. Effects oosporein on chromosomal DNA damage was assessed by Comet assay, and increase in DNA damage were observed in both the studied cell lines by increasing the oosporein concentration. Further, oosporein treatment to studied cell lines indicated significant suppression of oxidative stress related gene (Superoxide dismutase1 and Catalase ) expression, and increased levels of mRNA expression in apoptosis or oxidative stress inducing genes HSP70, Caspase3, Caspase6, and Caspase9 as measured by quantitative real time-PCR assay. Histopathological examination of oosporein treated mouse kidney and splenocytes further revealed that, oosporein treated target mouse tissues were significantly damaged with that of untreated sam control mice and these effects were in directly proportional to the the toxin dose. Results of the present study reveals that, ROS is the principle event prompting increased oosporein toxicity in studied in vivio and in vitro animal models. The high previlance of these fungi in temperate climates further warrants the need of safe food grain storage and processing practices to control the toxic effects of oosporein to humans and live stock.
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http://dx.doi.org/10.3389/fmicb.2015.00870DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4556033PMC
September 2015

Characterisation and bioactivity of oosporein produced by endophytic fungus Cochliobolus kusanoi isolated from Nerium oleander L.

Nat Prod Res 2014 17;28(23):2217-20. Epub 2014 Jun 17.

a Department of Microbiology and Biotechnology , Bangalore University , Jnanabharathi Campus, Bangalore , Karnataka 560 056 , India.

Bioactive compounds comprising secondary metabolites produced by endophytic fungi have wide applications in pharmacology and agriculture. Isolation, characterisation and evaluation of biological activities of secondary metabolites were carried out from Cochliobolus kusanoi an endophytic fungus of Nerium oleander L. The fungus was identified based on 18S rDNA sequence analysis. There are no reports available on the compounds of C.kusanoi hence, antimicrobial metabolite produced by this fungus was extracted and purified by fractionation using hexane, diethyl ether, dichloromethane, ethyl acetate and methanol. Out of all the solvent fractions, the methanol fraction exhibited better antimicrobial activity which was further purified and characterised as oosporein. Oosporein from C.kusanoi exhibited broad spectrum in vitro antimicrobial, antioxidant and cytotoxic activities. The characterisation and antioxidant activity of oosporein from C. kusanoi are reported for the first time.
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http://dx.doi.org/10.1080/14786419.2014.924933DOI Listing
February 2015
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