Browsing by Author "Ravi Kumar Gundampati"

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Biochemical and biophysical characterization of a peroxidase isolated from Euphorbia tirucalli with antifungal activity
(Taylor and Francis Ltd, 2016) Ankita Shukla; Ravi Kumar Gundampati; Medicherla V. Jagannadham
A novel peroxidase from the latex of medicinal plant Euphorbia tirucalli (Pencil tree) belonging to the Euphorbiaceae family is purified to homogeneity using cation exchange chromatography. The enzyme, named Euphorbia tirucalli peroxidase (ETP) has a molecular mass of 38.8 kDa. The isoelectric point of the enzyme is pH 7.5 with optimum pH and temperature of pH 6.0 and 50 °C respectively. The extinction coefficient (ɛ280 nm 1%) of the enzyme is 20.52 and the molecular structure consists of 13 tryptophan, nine tyrosine, and eight cysteine residues forming four disulfide bridges. Three peptide sequences, ALVHKECGPVVSCSDIVAIAARDSVVLTGGPKYDV, YYVDLMNRQGLFTSDQDLYT DKR, and MGQLEVVTGNQGEIR are obtained by MS/MS analysis which confirms the novelty of the enzyme. ETP belongs to α/β class of proteins with secondary structural features of approximately 10% α-helix, 29% β-sheet, and 61% random coil. ETP exhibits antifungal activity against Aspergillus niger and Candida albicans which shows its role in defense mechanism of plants. The enzyme is stable and retains its activity over a broad range of pH and temperature or prolonged storage at 4 °C. Simple purification, high yield, and stability enable exploration of the peroxidase for structure–function relationship studies as well as other biotechnological applications. © 2016 Informa UK Limited, trading as Taylor & Francis Group.
Biosynthesis of silver nanoparticles from the novel strain of Streptomyces Sp. BHUMBU-80 with highly efficient electroanalytical detection of hydrogen peroxide and antibacterial activity
(Elsevier Ltd, 2017) Rajeev Kumar Gupta; Vijay Kumar; Ravi Kumar Gundampati; Manisha Malviya; Syed Hadi Hasan; Medicherla V. Jagannadham
The use of a microbial supernatant has become a potential source for the eco-friendly and rapid synthesis of nanoparticles. In this study, we have targeted to synthesize silver nanoparticles (AgNPs) using extracellular secretion of Streptomyces sp. The strain was successfully isolated from the soil samples and identified as Streptomyces sp. BHUMBU-80 on the basis of morphological, biochemical and Phylogenetic analysis. The synthesized AgNPs was characterized using several modern characterizing techniques such as UV-vis Spectroscopy, FTIR spectroscopy, SEM, EDX spectroscopy, TEM, XRD and XPS. The presence of characteristics SPR band at 450 nm confirmed the synthesis of AgNPs. The FTIR spectra confirmed the involvement of various functional groups present in culture supernatant responsible for the reduction of Ag+ ions into Ag0. SEM and TEM analysis confirmed the presence of spherical AgNPs with an average size of 21 ± 1 nm. The XPS analysis confirmed the presence of two individual peaks which attributed to the Ag 3d3/2 and Ag 3d5/2 binding energies corresponding to the presence of metallic silver. The electrochemical studies of the green synthesized AgNPs using a glassy carbon electrode showed the superior electrocatalytic activity towards the reduction of H2O2. The calibration plot was established for H2O2 in the concentration range from 50 μM to 1000 μM with 50 μM detection limit, at a signal-to-noise ratio of 3 in a three-electrode cell with a Pt plate as the counter electrode. Additionally, the AgNPs also showed potent antibacterial activity against pathogenic bacteria like E. coli, and S. aureus. © 2017 Elsevier Ltd. All rights reserved.
Brominated Graphene as Mimetic Peroxidase for Sulfide Ion Recognition
(American Chemical Society, 2017) Shikha Singh; Kheyanath Mitra; Aparna Shukla; Rajshree Singh; Ravi Kumar Gundampati; Nira Misra; Pralay Maiti; Biswajit Ray
Brominated graphene (GBR) with ∼3% bromine content has shown novel peroxidase mimetic activity toward 3,3′,5,5′-tetramethylbenzidine (TMB) in the presence of H2O2. Optimum activity has been observed at pH 4.48 and after a minimum ∼30 min of equilibration time. Among the different analytes studied using the sensor combining TMB, H2O2, and GBR in phosphate buffer of pH 4.48, the S2- ion has effectively shown a short duration of sensing (∼2 min) within the detection range of 0.04-1 mM. A calibration curve for S2- ion estimation has been constructed with the experimental linearity in 0.04-0.4 mM range and having the limit of detection (LOD) value of 25.3 μM. A standard addition experiment has validated the method. A paper strip sensor has been fabricated for successful detection of S2- ion. © 2016 American Chemical Society.
Enhanced catalytic and antibacterial activities of silver nanoparticles immobilized on poly(N-vinyl pyrrolidone)-grafted graphene oxide
(Royal Society of Chemistry, 2015) Shikha Singh; Ravi Kumar Gundampati; Kheyanath Mitra; K. Ramesh; Medicherla V. Jagannadham; Nira Misra; Biswajit Ray
Poly(N-vinyl pyrrolidone) (PNVP)-grafted graphene oxide (GO) (GO-PNVP) has been synthesized using a GO-based macro-RAFT agent prepared via click reaction of alkyne-terminated RAFT agent (S)-2-(propynyl propionate)-(o-ethyl xanthate) and azide-functionalized GO (GO-N3). FTIR, XPS, Raman, TGA and DSC studies confirmed its formation. Silver nanoparticles are then immobilized on GO-PNVP and GO via in situ reduction of silver nitrate in the presence and absence of glucose at 40 and 95 °C, respectively. FT-IR, UV-Vis, XRD, SEM and TGA studies supported the incorporation of silver (Ag) nanoparticles. Ag nanoparticles immobilized on GO-PNVP are small, spherical and narrowly distributed (homogenous, monodisperse) compared to GO. These nanocomposites are explored as catalysts for the reduction of p-nitrophenol into p-aminophenol and also as antibacterial agents towards Gram(+) S. aureus and Gram(-) E. coli bacteria. Ag nanoparticle immobilized GO-PNVP showed efficient catalytic activity and excellent reusability along with an excellent antibacterial activity. Hence, grafting of PNVP enhances the catalytic and antibacterial properties of GO. © 2015 The Royal Society of Chemistry.
Exploring the inhibitory activity of Withaferin-A against Pteridine reductase-1 of L. donovani
(Taylor and Francis Ltd, 2016) Sambamurthy Chandrasekaran; Jalaja Veronica; Ravi Kumar Gundampati; Shyam Sundar; Radheshyam Maurya
Withaferin A is an abundant withanolide present in Withania somnifera leaves and to some extent in roots. It has been known for its profound anti-cancer properties, but its role in counteracting the Leishmania donovani infection has to be explored. Pteridine reductase 1 (PTR1) is involved in pteridine salvage and an important enzyme for the parasite growth, which could be targeted for the development of an efficient antileishmanial drug. We employed molecular docking studies to identify the binding mode of withaferin A with PTR1 in silico. We further cloned, expressed, and purified PTR1 of L. donovani and performed the enzyme kinetics using the Michaelis–Menten equation and enzyme inhibition studies with withaferin A by plotting the Lineweaver–Burk graph, which followed an uncompetitive mode of inhibition. We also showed the inhibition of the enzyme in the crude lysate of treated parasites. Thus, our study contributes towards understanding the mode of action of withaferin A against L. donovani parasite. © 2015 Informa UK Limited, trading as Taylor & Francis Group.
Extracellular l-asparaginase from a protease-deficient bacillus aryabhattai ITBHU02: Purification, biochemical characterization, and evaluation of antineoplastic activity in vitro
(2013) Yogendra Singh; Ravi Kumar Gundampati; Medicherla V. Jagannadham; S.K. Srivastava
An extracellular l-asparaginase produced by a protease-deficient isolate, Bacillus aryabhattai ITBHU02, was purified to homogeneity using ammonium sulfate fractionation and subsequent column chromatography on diethylaminoethyl- Sepharose fast flow and Seralose CL-6B. The enzyme was purified 68.9-fold with specific activity of 680.47 U mg-1. The molecular weight of the purified enzyme was approximately 38.8 kDa on SDS-PAGE and 155 kDa on native PAGE gel as well as gel filtration column revealing that the enzyme was a homotetramer. The optimum activity of purified l-asparaginase was achieved at pH 8.5 and temperature 40 C. Kinetic studies depicted that the K m, V max, and k cat values of the enzyme were 0.257 mM, 1.537 U μg-1, and 993.93 s-1, respectively. Circular dichroism spectroscopy has showed that the enzyme belonged to α + β class of proteins with approximately 74 % α-helices and 12 % β-sheets. BLASTP analysis of N-terminal sequence K-T-I-I-E-A-V-P-E-L-K-K-I-A of purified l-asparaginase had shown maximum similarity with Bacillus megaterium DSM 319. In vitro cytotoxicity assays with HL60 and MOLT-4 cell lines indicated that the l-asparaginase has significant antineoplastic properties. © 2013 Springer Science+Business Media New York.
Homology modeling and molecular docking of heme peroxidase from Euphorbia tirucalli: Substrate specificity and thiol inhibitor interactions
(Elsevier B.V., 2016) Ankita Shukla; Ravi Kumar Gundampati; Chikati Rajasekhar; Medicherla V. Jagannadham
The crystal structure of peroxidase from Barley Grain Peroxidase 1 (1BGP) provides a good template for modeling the three dimensional structure of Euphorbia tirucalli peroxidase (ETP). Homologous three dimensional structure of ETP was built on the basis of the crystal structure of 1BGP. The reliability of the model was assessed by Ramachandran plot, Profile-3D, PROCHECK, ERRAT and PROSA analysis. The overall structure of the resulting ETP model is similar to those of the template structure. The three dimensional structure of peroxidase was docked with heme and the peroxidase-heme complex was further docked with substrates of peroxidase as well as thiol inhibitors (β-mercaptoethanol and l-cysteine) using Autodock 4.2. software. The modeled peroxidase exhibited substrate specificity in the order of pyrogallol guaiacol O-dianisidine. The inhibition kinetics of peroxidase in presence of these inhibitors were investigated. IC50 values for these inhibitors were calculated and used for kinetic studies. These studies revealed that β-mercaptoethanol is more potent inhibitor on peroxidase activity as compared to l-cysteine. To explore the binding model of the substrates with the ETP model was docked into the active site of the model and hydrophobic interaction and hydrogen bonding were found to play an important role in substrate recognition and orientation. © 2016 Elsevier B.V. All rights reserved.
Immobilization of Euphorbia tirucalli peroxidase onto chitosan-cobalt oxide magnetic nanoparticles and optimization using response surface methodology
(Elsevier B.V., 2017) Ankita Shukla; Ravi Kumar Gundampati; Medicherla V. Jagannadham
Euphorbia tirucalli peroxidase (ETP) was immobilized on chitosan beads having magnetic properties for the ease of separation and increasing the reusability of ETP for cost effective assay conditions. The present work reports immobilization of ETP on polymeric support chitosan-cobalt oxide beads subsequently activated with 0.05% cynuric chloride. The magnetic immobilized enzyme was characterized by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD) analysis and scanning electron microscopy (SEM). The immobilized ETP can be reused up to 10 cycles with retention of more than 60% activity. The optimum pH was shifted from 6.0 to 5.5 for soluble ETP to immobilized ETP and optimum temperature from 50 °C and 55 °C for the immobilized ETP. Based on response surface methodology, the optimal immobilization conditions obtained were: enzyme concentration, 2 mg/286 mg beads; optimal pH, 4.93; temperature, 28.88; cynuric chloride concentration, 0.17%; reaction time, 14.4 h, which resulted 74.51% maximum immobilization. The enzyme magnetic nanoparticles could be separated magnetically for easy reuse. Immobilization of ETP onto the magnetic nanoparticles could be useful for biotechnological applications and bioassay due to its reusability and improved stability. © 2017 Elsevier B.V.
In silico and in vitro studies: Tryparedoxin Peroxidase inhibitor activity of methotrexate for antileishmanial activity
(2013) Ravi Kumar Gundampati; Shraddha Sahu; Avinash Kumar Srivastava; Sambamurthy Chandrasekaran; Parameswara Rao Vuddanda; Rajesh Kumar Pandey; Radheshyam Maurya; Sanjay Singh; Medicherla V. Jagannadham
In order to understand the mechanism of molecular interactions at the active site of Tryparedoxin Peroxidase (Try P), homology modeling and docking studies were performed. We generated a Three-Dimensional (3D) model of target protein based on the Crystal structure of Leishmania Major Try PI (PDB ID: 3TUE) using modeler software. Docking analysis was carried out to study the effects of methotrexate on Tryparedoxin Peroxidase (Try P). Inhibition of the Tryparedoxin peroxidase interaction has become a new therapeutic strategy in treating leishmaniasis. Docking analysis was carried out to study the effects of methotrexate on Tryparedoxin Peroxidase (TryP). Tryparedoxin peroxidase of Trypanosomatidae family functions as antioxidant through their peroxidase and peroxynitrite reductase activities. The theoretical docking study, conducted on a sample previously reported for anti-cancer properties of Methotrexate at the binding site of 3D models of Tryparedoxin Peroxidase of Leishmania braziliensis (L. braziliensis Try P) examine interaction energy. Our studies indicate that Methotrexate displays potent activity against Try P with lowest binding energy and RMSD values to be -14.5879 Kcal/Mol and 2.0 A. The results of the present study clearly demonstrated the Tryparedoxin Peroxidase inhibitory activity by methotrexate in in silico docking analysis and in vitro assay which contributes towards understanding the mechanism of antileishmanial activity. © 2013 Science Publication.
In silico studies on complete inhibition of Trypanothione reductase of Leishmania infantum by γ-sitosterol and antcin-A: Novel target for anti-leishmanial activity
(2013) Ravi Kumar Gundampati; Shraddha Sahu; Kirti Shila Sonkar; Mira Debnath; Medicherla V. Jagannadham
Inhibition of the trypanothione reductase (Try R) activity interaction has been becomes a new therapeutic strategy to leishmaniasis. Trypanothione reductase is a genetically validated drug target enzyme for structure-based drug design against Leishmania, the causative agent of human trypanosomiasis. We used theoretical docking study, conducted on a sample previously reported for anti-cancer, anti-diabetic and antioxidant potential of Kaempferol, guggultetrol, γ-sitosterol and antcin-A at the binding site of Leishmania infantum trypanothione reductase (Try R) examine interaction energy. These studies indicate that γ-sitosterol and antcin-A displays potent activity against Try R with lowest binding energy and RMSD values to be -9.34 kcal mol-1 for γ-sitosterol,-8.36 Kcal mol-1 for antcin-A and 2.0 Å. Docking analysis of Try R with ligands enabled us to identify specific residues viz., Pro-59, Ala-200, Ala-205, Glu-203, Lue-62, Asp-218, Val-64, Cys-193 and Gln-280 within the TryR and Val-58, Leu-95, Ala-181, Val-201, Ile-206, Asn-266, Asp-277 and Met-282 binding pocket to play an important role in ligand binding affinity. The results of our study contributes towards the development of novel therapeutics based on trypanothione reductase inhibition. © 2013 Academic Journals Inc.
Modeling and molecular docking studies on Aspergillus Rnase Niger and Leishmania Donovani actin: Antileishmanial activity
(2013) Ravi Kumar Gundampati; Shraddha Sahu; Kirti Shila Sonkar; Mira Debnath; Aveenash Kumar Srivastava; Medicherla Venkata Jagannadham
A.niger Rnase was designed from ACTBIND (PDB ID: 3D3Z). Yeast actin-human gelsolin segment 1 complex (PDB ID: 1YAG) was used as template for L. donovani actin protein for 3D model in Modeller9v8. These models were testified by PROCHECK, ERRAT, WHAT-IF, PROSA2003 and VERIFY-3D. All evidences suggest that the geometric quality of the backbone conformation, energy profile, residue interaction and contact of the structures were well within the limits of reliable structures. The interaction energy of docking was calculated using the HEX server. Etotal and calculated RMSD values were -1.902, -9.323 kcal moL-1 and 0.402 Å, respectively. The study presented here has an advantage to design molecules that may have antileishmanial activity. ©2013 Science Publication.
Molecular docking based inhibition of Trypanothione reductase activity by Taxifolin novel target for antileishmanial activity
(2012) Ravi Kumar Gundampati; Medicherla V. Jagannadham
The theoretical docking study, conducted on a sample of previously reported for anti-inflammatory and antioxidant activities of Taxifolin at the binding site of Leishmania infantum trypanothione reductase (Try R) examine interaction energy. Taxifolin is widely used in the traditional medicine have been investigated for their putative chemo preventive and antileishmanial properties for the last few decades. A theoretical docking study, the evaluation of Taxifolin as inhibitor of trypanothione reductase a validated drug target enzyme of the Leishmania parasite. Taxifolin was found to bind at active site of L. infantum TryR with lowest binding energy and RMSD values to be -8.82 Kcal/Mol and 2.0 Å respectively. Docking analysis of TryR with ligand enabled us to identify specific residues viz. Ser-14, Ala-47, Ser-162, Thr-336 and Arg-286, within the TryR binding pocket to play an important role in ligand binding affinity. The availability of TryR built model, together with insights gained from docking analysis will promote the rational design of potent and selective TryR inhibitor as antileishmanial therapeutic. The study contributes towards understanding mechanism of antileshmanial effect of the Taxifolin. This compound has shown promising biological activity in preliminary studies by targeting multiple signaling pathways. Thus on the basis of our in silico studies we hypothesize that this compound into Taxifolin can be inhibitory effect on against leishmaniasis.
Molecular docking studies of guggultetrol from nymphaea pubescens with target glucokinase (GK) related to type-ii diabetes
(2013) Kiran Kumar Angadi; Ravi Kumar Gundampati; Medicherla V. Jagannadham; Ammani Kandru
Diabetes prevalence is one of the life threatening diseases in India. In this work we address a specific suitable ligand for diabetesmellitus. A large focus has been on structure based drug designing. Guggultetrol isolated from Nymphaea pubescenswas taken as ligand for molecular docking. A theoretical docking study, the evaluation of guggultetrol as inhibitor of Glucokinase (PDB ID: 1V4S) a validated drugtarget enzyme of the Type-II diabetes, was taken up. Guggultetrol was found to bind at active site of glucokinase with lowest binding energy and RMSD values to be -9.45Kcal/Mol and 2.0 Å respectively. Dockinganalysis of 1V4S with ligand enabled us to identify specific residuesviz. Thr-168, Glu-290, Glu-51, Ser-411, Gly-410, Asn-254, Thr-206, Arg-155 and Asp-205 within the 1V4S binding pocket to play an important role in ligand binding affinity. The docking studies of the Guggultetrol with target protein showed that this is a suitable molecule which docks well with target related to diabetes mellitus. This compound has shown promising biological activity in preliminary studies by targeting multiple signaling pathways. Thus on the basis of our in silico studies we hypothesize that this compound into guggultetrol can be inhibitory effect on against diabetes. We concluded that the natural products with interesting biological properties and structural diversity have often served as valuable lead drug candidates for the treatment of human diseases.
Molecular docking study on the interaction between trypanothione reductase and mangiferin for antileishmanial activity
(2013) Ravi Kumar Gundampati; Sambamurthy Chandrasekaran; Medicherla V. Jagannadham
Mangiferin was found to bind at active site of Leishmania infantum Try R with lowest binding energy and RMSD values to be -9.16 Kcal/Mol and 1.98 respectively. Docking analysis of Try R with ligand enabled us to identify specific residues viz. Phe-203, Glu-202, Asp-218, Pro-336, Try-221 and Phe-270, within the Try R binding pocket to play an important role in ligand binding affinity. The availability of Try R built model, together with insights gained from docking analysis will promote the rational design of potent and selective Try R inhibitor as antileishmanial therapeutic. The study contributes towards understanding mechanism of antileshmanial effect of the mangiferin. We have surveyed the available literature to summarize the inhibition of Try R activity of this natural compound. Thus on the basis of our in silico studies we hypothesize that this compound into mangiferin can be inhibitory effect on against leishmaniasis.
Photo-induced rapid biosynthesis of silver nanoparticle using aqueous extract of Xanthium strumarium and its antibacterial and antileishmanial activity
(Korean Society of Industrial Engineering Chemistry, 2016) Vijay Kumar; Ravi Kumar Gundampati; Devendra Kumar Singh; Medicherla V. Jagannadham; Shyam Sundar; Syed Hadi Hasan
The current work describes the biosynthesis of stable AgNPs using aqueous extract of Xanthium strumarium (AEX) which act as both reducing as well as a stabilizing agent. The biosynthesis was confirmed by UV-visible spectroscopy where the presence of SPR band at λmax 436 nm corresponded to the existence of AgNPs in reaction mixture. The optimum conditions for biosynthesis of AgNPs were 30 min of sunlight exposure time, 3.0% (v/v) of AEX inoculum dose and 3.5 mM AgNO3 concentration. The synthesized AgNPs was characterized by HRTEM, SAED, FESEM, EDX, XRD, AFM, and FTIR which showed potent antibacterial and antileishmanial activity. © 2016 The Korean Society of Industrial and Engineering Chemistry.
Photoinduced green synthesis of silver nanoparticles with highly effective antibacterial and hydrogen peroxide sensing properties
(Elsevier B.V., 2016) Vijay Kumar; Ravi Kumar Gundampati; Devendra K. Singh; Daraksha Bano; Medicherla V. Jagannadham; Syed Hadi Hasan
In this study, an eco-friendly and sustainable green route was employed for the synthesis of stable silver nanoparticles (AgNPs) using aqueous leaf extract of Euphorbia hirta (AEE) as both reducing as well as a stabilizing agent. The synthesis of AgNPs was confirmed by UV–visible spectroscopy which produced a prominent SPR band at λmax 425 nm after 25 min of sunlight exposure. The AgNPs thus synthesized were optimized using one factor at a time approach, and these optimized conditions were 25 min of sunlight exposure time, 5.0% (v/v) of AEE inoculum dose and 3.0 mM of AgNO3 concentration. The Field Emission Scanning Electron Microscopy (FE-SEM) and High Resolution Transmission Electron Microscopy (HRTEM) analysis confirmed the presence of spherical AgNPs with average size 15.5 nm. The crystallinity was determined by X-ray Diffractometer (XRD) and Selected Area Electron Diffraction (SAED) pattern. Chemical and elemental compositions were determined by Fourier Transformed Infrared Spectroscopy (FTIR) and Energy Dispersive X-ray Spectroscopy (EDX) respectively. The Atomic Force Microscopy (AFM) images with average roughness 1.15 nm represented the lateral and 3D topological characteristic of AgNPs. The AgNPs thus synthesized showed effective antibacterial activity against gram negative and gram positive bacteria as well as hydrogen peroxide sensing property with a minimum detection limit of 10− 7 M. © 2016
Protein-protein docking on molecular models of Aspergillus niger RNase and human actin: Novel target for anticancer therapeutics
(2012) Ravi Kumar Gundampati; Rajasekhar Chikati; Moni Kumari; Anurag Sharma; Daliparthy Devi Pratyush; Medicherla V. Jagannadham; Chitta Suresh Kumar; Mira Debnath Das
The 3D models of human actin protein and A. niger RNase were designed using the templates ACTBIND (PDB ID: 3D3Z) and crystalline profilin-beta-actin (PDB ID: 2BTF), respectively in Modeller9v5. These models are testified using several validation methods including PROCHECK, ERRAT, WHAT-IF, PROSA2003 and VERIFY-3D. The stereo-chemical quality of the models was judged by Ramachandran plot with PROCHECK. The total quality G-factor -0.2, shows a good quality model. The ERRAT score for the human actin and A.niger RNase models are 86.104 and 84.615, respectively, fit well within the range of a high quality model. The ERRATscore for the templates 2BTF and 3D3Z are 91.111 and 97.391, respectively. The WHAT-IF evaluation justifies a reasonable homology model structure as none of the scores for each residue in the homology model is lower than -5.0. The energy-minimized model of human actin with PROSA reveals the Z-score value -10.52 between native conformations of the crystal structures. The VERIFY 3D average score is 0.36. All evidence suggests that the geometric quality of the backbone conformation, the residue interaction, the residue contact and the energy profile of the structures were well within the limits of reliable structures. The interaction energy of docking was calculated using the HEX server. The Etotal, lowest docked energy, and calculated RMSD values were -1.608 kcal mol-1, -8.369 kcalmol-1 and 0.617Å, respectively. The study presented in the current project may be useful to design molecules that may have anticancer activity. © Springer-Verlag 2011.
Self-assembly, doxorubicin-loading and antibacterial activity of well-defined ABA-type amphiphilic poly(N-vinylpyrrolidone)-b-poly(d,l-lactide)-b-poly(N-vinyl pyrrolidone) triblock copolymers
(Royal Society of Chemistry, 2016) K. Ramesh; Ravi Kumar Gundampati; Shikha Singh; Kheyanath Mitra; Ankita Shukla; Medicherla V. Jagannadham; Dipankar Chattopadhyay; Nira Misra; Biswajit Ray
A series of ABA type well-defined amphiphilic poly(N-vinylpyrrolidone) (PNVP)-b-poly(d,l-lactide)-b-PNVP triblock copolymers have been synthesized via the combination of ring opening polymerization and xanthate-mediated reversible addition-fragmentation chain transfer polymerization, and analyzed by 1H NMR spectroscopy and gel permeation chromatography. Aggregation properties of these amphiphilic triblock copolymers have been revealed by fluorescence spectroscopy, transmission electron microscopy and dynamic light scattering, and supported by 1H NMR spectroscopy. Doxorubicin (DOX) has successfully been loaded into the block copolymer micelles with a loading efficiency of 37.5%. DOX-loaded PNVP51-b-PDLLA48-b-PNVP51 block copolymer showed sustained release within 36 h. Antibacterial properties of DOX-loaded micelles have been found to be significantly effective with respect to free DOX in terms of minimum inhibitory concentration, disk diffusion assay, growth curve, bacterial reduction and enzymatic assay based on in vitro studies. © 2016 The Royal Society of Chemistry.