Publish in OALib Journal

ISSN: 2333-9721

APC: Only $99


Any time

2019 ( 4 )

2018 ( 26 )

2017 ( 6 )

2016 ( 22 )

Custom range...

Search Results: 1 - 10 of 998 matches for " Ramamourthy Gopal "
All listed articles are free for downloading (OA Articles)
Page 1 /998
Display every page Item
Enzymatic and Non-Enzymatic Antioxidant Activities of Enicostemma littorale in p-DAB Induced Hepatocarcinoma in Rats
Ramamourthy Gopal,Rajangam Udayakumar
International Journal of Pharmacology , 2008,
Abstract: The aim of this study was to investigate the effect of Enicostemma littorale (Gentianaceae) aerial part on antioxidant defense systems of plasma and liver in p-Dimethylaminoazobenzene (p-DAB)-induced hepatocarcinoma in rats. The levels of vitamin-E and vitamin-C were estimated in plasma of control and experimental groups of rats. The levels of reduced glutathione, glutathione-S-transferase and activities of superoxide dismutase, catalase and lipid peroxides were assayed in liver tissue of control and experimental groups of rats. Administration of p-DAB exhibited a significant increase in the levels of liver lipid peroxides, liver weight and a concomitant decrease in the levels of vitamin-E, vitamin-C in hepatocarcinoma rats. Thus, there was an alteration in the antioxidant enzyme system of hepatocarcinoma rats. These alterations were reverted back to near normal level after the treatment with Enicostemma littorale extract and vitamin-E. Histopathological studies also revealed that the protective effect of Enicostemma littorale on liver cells.
Applications of Circular Dichroism for Structural Analysis of Gelatin and Antimicrobial Peptides
Ramamourthy Gopal,Jin Soon Park,Chang Ho Seo,Yoonkyung Park
International Journal of Molecular Sciences , 2012, DOI: 10.3390/ijms13033229
Abstract: Circular dichroism (CD) is a useful technique for monitoring changes in the conformation of antimicrobial peptides or gelatin. In this study, interactions between cationic peptides and gelatin were observed without affecting the triple helical content of the gelatin, which was more strongly affected by anionic surfactant. The peptides did not adopt a secondary structure in the presence of aqueous solution or Tween 80, but a peptide secondary structure formed upon the addition of sodium dodecyl sulfate (SDS). The peptides bound to the phosphate group of lipopolysaccharide (LPS) and displayed an alpha-helical conformation while (KW) 4 adopted a folded conformation. Further, the peptides did not specifically interact with the fungal cell wall components of mannan or laminarin. Tryptophan blue shift assay indicated that these peptides interacted with SDS, LPS, and gelatin but not with Tween 80, mannan, or laminarin. The peptides also displayed antibacterial activity against P. a er uginosa without cytotoxicity against HaCaT cells at MIC, except for HPA3NT3-analog peptide. In this study, we used a CD spectroscopic method to demonstrate the feasibility of peptide characterization in numerous environments. The CD method can thus be used as a screening method of gelatin-peptide interactions for use in wound healing applications.
Antifungal Activity of (KW)n or (RW)n Peptide against Fusarium solani and Fusarium oxysporum
Ramamourthy Gopal,Hyungjong Na,Chang Ho Seo,Yoonkyung Park
International Journal of Molecular Sciences , 2012, DOI: 10.3390/ijms131115042
Abstract: The presence of lysine (Lys) or arginine (Arg) and tryptophan (Trp) are important for the antimicrobial effects of cationic peptides. Therefore, we designed and synthesized a series of antimicrobial peptides with various numbers of Lys (or Arg) and Trp repeats [(KW and RW) n-NH 2, where n equals 2, 3, 4, or 5]. Antifungal activities of these peptides increased with chain length. Light microscopy demonstrated that longer peptides ( n = 4, 5) strongly inhibited in vitro growth of Fusarium solani, and Fusarium oxysporum, at 4–32 μM. Furthermore, longer peptides displayed potent fungicidal activities against a variety of agronomical important filamentous fungi, including F. solani and F. oxysporum, at their minimal inhibitory concentrations (MICs) . However, RW series peptides showed slightly higher fungicidal activities than KW peptides against the two strains. Taken together, the results of this study indicate that these short peptides would be good candidates for use as synthetic or transgenic antifungal agents.
Isolation and Purification of a Novel Deca-Antifungal Peptide from Potato (Solanum tuberosum L. cv. Jopung) Against Candida albicans
Jong-Kook Lee,Ramamourthy Gopal,Chang Ho Seo,Hyeonsook Cheong,Yoonkyung Park
International Journal of Molecular Sciences , 2012, DOI: 10.3390/ijms13044021
Abstract: In a previous study, an antifungal protein, AFP-J, was purified from tubers of the potato ( Solanum tuberosum cv. L Jopung) and by gel filtration and HPLC. In this study, the functional peptide was characterized by partial acid digestion using HCl and HPLC. We obtained three peaks from the AFP-J, the first and third peaks were not active in the tested fungal strain. However, the second peak, which was named Potide-J, was active (MIC; 6.25 μg/mL) against Candida albicans. The amino acid sequences were analyzed by automated Edman degradation, and the amino acid sequence of Potide-J was determined to be Ala-Val-Cys-Glu-Asn-Asp-Leu-Asn-Cys-Cys. Mass spectrometry showed that its molecular mass was 1083.1 Da. Finally, we confirmed that a disulfide bond was present between Cys 3 and Cys 9 or Cys 10. Using this structure, Potide-J was synthesized via solid-phase methods. In these experiments, only the linear sequence was shown to display strong activity against Candida albicans. These results suggest that Potide-J may be an excellent candidate compound for the development of commercially applicable antibiotic agents.
PG-2, a Potent AMP against Pathogenic Microbial Strains, from Potato (Solanum tuberosum L cv. Gogu Valley) Tubers Not Cytotoxic against Human Cells
Jin-Young Kim,Ramamourthy Gopal,Sang Young Kim,Chang Ho Seo,Hyang Burm Lee,Hyeonsook Cheong,Yoonkyung Park
International Journal of Molecular Sciences , 2013, DOI: 10.3390/ijms14024349
Abstract: In an earlier study, we isolated potamin-1 (PT-1), a 5.6-kDa trypsin-chymotrypsin protease inhibitor, from the tubers of a potato strain ( Solanum tuberosum L cv. Gogu Valley). We established that PT-1 strongly inhibits pathogenic microbial strains, but not human bacterial strains, and that its sequence shows 62% homology with a serine protease inhibitor. In the present study, we isolated an antifungal and antibacterial peptide with no cytotoxicity from tubers of the same potato strain. The peptide (peptide-G2, PG-2) was isolated using salt-extraction, ultrafiltration and reverse-phase high performance liquid chromatography (RP-HPLC). Matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF/MS) showed the protein to have a molecular mass of 3228.5 Da, while automated Edman degradation showed the N-terminal sequence of PG-2 to be LVKDNPLDISPKQVQALCTDLVIRCMCCC-. PG-2 exhibited antimicrobial activity against Candida albicans, a human pathogenic yeast strain, and Clavibacter michiganensis subsp. michiganensis, a plant late blight strain. PG-2 also showed antibacterial activity against Staphylococcus aureus, but did not lyse human red blood cells and was thermostable. Overall, these results suggest PG-2 may be a good candidate to serve as a natural antimicrobial agent, agricultural pesticide and/or food additive.
Effect of Repetitive Lysine-Tryptophan Motifs on the Eukaryotic Membrane
Ramamourthy Gopal,Jong Kook Lee,Jun Ho Lee,Young Gwon Kim,Gwang Chae Oh,Chang Ho Seo,Yoonkyung Park
International Journal of Molecular Sciences , 2013, DOI: 10.3390/ijms14012190
Abstract: In a previous study, we synthesized a series of peptides containing simple sequence repeats, (KW) n–NH 2 ( n = 2,3,4 and 5) and determined their antimicrobial and hemolytic activities, as well as their mechanism of antimicrobial action. However, (KW) 5 showed undesirable cytotoxicity against RBC cells. In order to identify the mechanisms behind the hemolytic and cytotoxic activities of (KW) 5, we measured the ability of these peptides to induce aggregation of liposomes. In addition, their binding and permeation activities were assessed by Trp fluorescence, calcein leakage and circular dichrorism using artificial phospholipids that mimic eukaryotic liposomes, including phosphatidylcholine (PC), PC/sphingomyelin (SM) (2:1, w/ w) and PC/cholesterol (CH) (2:1, w/ w). Experiments confirmed that only (KW) 5 induced aggregation of all liposomes; it formed much larger aggregates with PC:CH (2:1, w/ w) than with PC or PC:SM (2:1, w/ w). Longer peptide (KW) 5, but not (KW) 3 or (KW) 4, strongly bound and partially inserted into PC:CH compared to PC or PC:SM (2:1, w/ w). Calcein release experiments showed that (KW) 5 induced calcein leakage from the eukaryotic membrane. Greater calcein leakage was induced by (KW) 5 from PC:CH than from PC:SM (2:1, w/ w) or PC, whereas (KW) 4 did not induce calcein leakage from any of the liposomes. Circular dichroism measurements indicated that (KW) 5 showed higher conformational transition compared to (KW) 4 due to peptide-liposome interactions. Taken together, our results suggest that (KW) 5 reasonably mediates the aggregation and permeabilization of eukaryotic membranes, which could in turn explain why (KW) 5 displays efficient hemolytic activity.
A Proline-Hinge Alters the Characteristics of the Amphipathic α-helical AMPs
Jong Kook Lee, Ramamourthy Gopal, Seong-Cheol Park, Hyun Sook Ko, Yangmee Kim, Kyung-Soo Hahm, Yoonkyung Park
PLOS ONE , 2013, DOI: 10.1371/journal.pone.0067597
Abstract: HP (2–20) is a 19-aa, amphipathic, α-helical peptide with antimicrobial properties that was derived from the N-terminus of Helicobacter pylori ribosomal protein L1. We previously showed that increasing the net hydrophobicity of HP (2–20) by substituting Trp for Gln17 and Asp19 (Anal 3) increased the peptide's antimicrobial activity. In hydrophobic medium, Anal 3 forms an amphipathic structure consisting of an N-terminal random coil region (residues 2–5) and an extended helical region (residues 6–20). To investigate the structure-activity relationship of Anal 3, we substituted Pro for Glu9 (Anal 3-Pro) and then examined the new peptide's three-dimensional structure, antimicrobial activity and mechanism of action. Anal 3-Pro had an α-helical structure in the presence of trifluoroethanol (TFE) and sodium dodecyl sulfate (SDS). NMR spectroscopic analysis of Anal 3-Pro's tertiary structure in SDS micelles confirmed that the kink potential introduced by Pro10 was responsible for the helix distortion. We also found that Anal 3-Pro exhibited about 4 times greater antimicrobial activity than Anal 3. Fluorescence activated flow cytometry and confocal fluorescence microscopy showed that incorporating a Pro-hinge into Anal 3 markedly reduced its membrane permeability so that it accumulated in the cytoplasm without remaining in the cell membrane. To investigate the translocation mechanism, we assessed its ability to release of FITC-dextran. The result showed Anal 3-Pro created a pore <1.8 nm in diameter, which is similar to buforin II. Notably, scanning electron microscopic observation of Candida albicans revealed that Anal 3-Pro and buforin II exert similar effects on cell membranes, whereas magainin 2 exerts a different, more damaging, effect. In addition, Anal 3-Pro assumed a helix-hinge-helix structure in the presence of biological membranes and formed micropores in both bacterial and fungal membranes, through which it entered the cytoplasm and tightly bound to DNA. These results indicate that the bending region of Anal 3- Pro peptide is prerequisite for effective antibiotic activity and may facilitate easy penetration of the lipid bilayers of the cell membrane.
Anti-Microbial, Anti-Biofilm Activities and Cell Selectivity of the NRC-16 Peptide Derived from Witch Flounder, Glyptocephalus cynoglossus
Ramamourthy Gopal,Jun Ho Lee,Young Gwon Kim,Myeong-Sun Kim,Chang Ho Seo,Yoonkyung Park
Marine Drugs , 2013, DOI: 10.3390/md11061836
Abstract: Previous studies had identified novel antimicrobial peptides derived from witch flounder. In this work, we extended the search for the activity of peptide that showed antibacterial activity on clinically isolated bacterial cells and bacterial biofilm. Pseudomonas aeruginosa was obtained from otitis media and cholelithiasis patients, while Staphylococcus aureus was isolated from otitis media patients. We found that synthetic peptide NRC-16 displays antimicrobial activity and is not sensitive to salt during its bactericidal activity. Interestingly, this peptide also led to significant inhibition of biofilm formation at a concentration of 4–16 μM. NRC-16 peptide is able to block biofilm formation at concentrations just above its minimum inhibitory concentration while conventional antibiotics did not inhibit the biofilm formation except ciprofloxacin and piperacillin. It did not cause significant lysis of human RBC, and is not cytotoxic to HaCaT cells and RAW264.7 cells, thereby indicating its selective antimicrobial activity. In addition, the peptide’s binding and permeation activities were assessed by tryptophan fluorescence, calcein leakage and circular dichroism using model mammalian membranes composed of phosphatidylcholine (PC), PC/cholesterol (CH) and PC/sphingomyelin (SM). These experiments confirmed that NRC-16 does not interact with any of the liposomes but the control peptide melittin did. Taken together, we found that NRC-16 has potent antimicrobial and antibiofilm activities with less cytotoxicity, and thus can be considered for treatment of microbial infection in the future.
Evaluation of Synthetic and Natural Insecticides for the Management of Insect Pest Control of Eggplant (Solanum Melongena L.) and Pesticide Residue Dissipation Pattern  [PDF]
Jayakrishnan Saimandir, Madhuban Gopal
American Journal of Plant Sciences (AJPS) , 2012, DOI: 10.4236/ajps.2012.32026
Abstract: Eggplant shoot and fruit borer (ESFB), Leucinodes orbonalis G. is a key pest of eggplant, Solanum melongena L. Organophosphates (OP) having high toxicity and persistence are used to control the pests in many developing countries, despite availability of new insecticides with better qualities. Field evaluation of thiacloprid and indoxacarb were carried out against ESFB, with an OP insecticide, methyl parathion. Two Bacillus thuriegensis (Bt) based formulations namely Biolep and PUSA Bt and two azadirachtin formulations namely Neem Seed Kernal Extract (NSKE) and Nimbo Bas were also evaluated against ESFB for the management of the pest. HPLC and GC methods for the estimation of indoxacarb, thiacloprid and methyl parathion from the fruits were developed and their dissipation patterns and safety parameters were compared. For indoxacarb, the method involving Florisil gave highest recovery (88%) whereas average recoveries of other methods varied from 59% to 82%. The mean initial deposits of indoxacarb on fruits were 2.60 mg/kg to 3.64 mg/kg and 2.63 mg/kg to 3.68 mg/kg from 75 and 150 g·ai/ha treatments from two-year field studies. The half-life of indoxacarb was 3.0 d - 3.8 d from both years. The Theoretical Maximum Daily Intake (TMDI) was found to be 0.446 mg/person/day to 0.643 mg/person/day for day-1 residues which is in par with the Maximum Permissible Intake (MPI) of 0.6 mg/person/day. The TMDI from 3 d residues was found to be less than the MPI calculated with the data of 3 d residues which ensures better margin of safety. For thiacloprid, the method involving Florisil gave highest recovery (89%). The mean initial deposits of thiacloprid on fruits were 3.39 to 5.40 mg/kg and 3.40 to 5.39 mg/kg from 30 and 60 g·ai/ha treatments from both years. The half-life values were determined to be 11.1 and 11.6 d for both years. The TMDI from maximum residues observed for first day for both the treatments during first year trials was found to be 0.682 to 1.098 mg person/day, which was higher than the MPI of 0.72 mg/person/day, which proved that the application is toxic to humans. Thiacloprid at the experimented doses (30 and 60 g·ai/ha) was found not effective to manage ESFB and was not safe for human consumption after a waiting period of 3 days. For methyl parathion, the method involving Florisil gave highest average recovery (89%). The initial residues on fruits from recommended dose declined from 3.60 to 3.12 mg/kg in one day and 0.27 mg/kg in twentyfive days from 100 g·ai/ha. Similar pattern was observed with higher dose also. The
Hybrid Control Strategy for BCD Topology Based Modular Multilevel Inverter  [PDF]
Vasudevan Karthikeyan, gopal Jamuna
Circuits and Systems (CS) , 2016, DOI: 10.4236/cs.2016.78126
Abstract: In this paper, a Binary Coded Decimal (BCD) topology of modular multilevel inverter with reduced component count is proposed. For the control of this inverter, hybrid control strategy is used. The proposed modular multilevel inverter uses asymmetrical dc sources and reduced number of switches topology. This hybrid modulation technique uses the multicarrier based Pulse Width Modulation (PWM) and the fundamental frequency modulation strategy. The hybrid modulation algorithm is implemented with “NUC140” micro-controller. In comparison with the conventional and some of the recently reported inverter topologies, the proposed inverter topology is able to generate high number of voltage levels in the output by using minimum number of components such as dc sources, power switches and driver circuits. This inverter offers significant performance with less number of components. The feasibility of the proposed topology is confirmed by simulation and experimental results.
Page 1 /998
Display every page Item

Copyright © 2008-2017 Open Access Library. All rights reserved.