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Barbara R. Conway - One of the best experts on this subject based on the ideXlab platform.
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mechanical and release behaviour of theophylline from matrix tablets containing psyllium powder in combination with Grewia polysaccharides
2020Co-Authors: Elijah I. Nep, Barbara R. Conway, Alan Smith, N Kaur, Seham Shaboun, Adeola O Adebisi, Kofi AsareaddoAbstract:Abstract This study was aimed at investigating the effect of Grewia polysaccharides on the mechanical and release properties of tablet matrices containing binary mixtures of the polysaccharide with psyllium. Two grades of Grewia polysaccharides (GG and GDS) were extracted and binary mixtures of the polysaccharides with psyllium were formulated into tablet matrices containing theophylline as the model drug. The true, bulk and tapped densities, Carr’s compressibility index of the powders and binary composites were determined before tablet compression. Tablet properties (hardness, porosity, and drug release from the matrices) were investigated. The dissolution test was carried out in 0.1 M HCl (pH 1.2) and phosphate buffer (pH 6.8). The results show that GG and GDS produced tablets with good mechanical strength (108.33 N and 95.70 N, respectively) while psyllium produced softer tablets (7.13 N). The combination of psyllium and Grewia polysaccharides in the matrices resulted in a significant increase in the mechanical strength of the matrices when compared to matrices containing psyllium alone as the matrix former. The results also showed that GG and GDS reduced the dissolution rate and effectively eliminated the burst release of theophylline from the psyllium matrices at both pHs. The matrices of GG or GDS and the binary mixtures conform to non-Fickian anomalous diffusion with n > 0.45. When overcoming the burst release of drug from matrices such as psyllium, Grewia polysaccharides may provide an effective reduction and a more sustained drug release from such matrices.
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the influence of hydroalcoholic media on the performance of Grewia polysaccharide in sustained release tablets
2017Co-Authors: Elijah I. Nep, Barbara R. Conway, Alan Smith, Adeola O Adebisi, Mohammed H Mahdi, C Dawson, Karl Walton, Paul J Bills, Kofi AsareaddoAbstract:Abstract Co-administration of drugs with alcohol can affect the plasma concentration of drugs in patients. It is also known that the excipients used in the formulation of drugs may not always be resistant to alcohol. This study evaluates effect of varying alcohol concentrations on theophylline release from two grades of Grewia mollis polysaccharides. X-ray microtomography showed that native polysaccharide formulation compacts were not homogenous after the mixing process resulting in its failure in swelling studies. Removal of starch from the native polysaccharide resulted in homogenous formulation compacts resistant to damage in high alcoholic media in pH 6.8 (40%v/v absolute ethanol). Destarched polymer compacts had a significantly higher hardness (375 N) than that of the native polysaccharide (82 N) and HPMC K4 M (146 N). Dissolution studies showed similarity at all levels of alcohol tested ( f 2 = 57–91) in simulated gastric media (pH 1.2). The dissolution profiles in the simulated intestinal fluids were also similar ( f 2 = 60–94), with the exception of the native polysaccharide in pH 6.8 (40%v/v absolute ethanol) ( f 2 = 43). This work highlights the properties of Grewia polysaccharide as a matrix former that can resist high alcoholic effects therefore; it may be suitable as an alternative to some of the commercially available matrix formers with wider applications for drug delivery as a cheaper alternative in the developing world.
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starch free Grewia gum matrices compaction swelling erosion and drug release behaviour
2015Co-Authors: Elijah I. Nep, Barbara R. Conway, Kofi Asareaddo, Muhammad Usman Ghori, Alan SmithAbstract:Polysaccharides are suitable for application as hydrophilic matrices because of their ability to hydrate and swell upon contact with fluids, forming a gel layer which controls drug release. When extracted from plants, polysaccharides often contain significant quantities of starch that impacts upon their functional properties. This study aimed to evaluate differences in swelling, erosion and drug release from matrix tablets prepared from Grewia gum (GG) and starch-free Grewia gum (GDS) extracted from the stems of Grewia mollis. HPMC was used as a control polymer with theophylline as a model drug. Swelling, erosion, and in-vitro release were performed in deionized water, pH 1.2 and pH 6.8 media. The Vergnaud and Krosmeyer-Peppas model were used for swelling and drug release kinetics, respectively. However, linear regression technique was used to determine the erosion rate. GDS compacts were significantly harder than the native GG and HPMC compacts. GDS matrices exhibited the fastest erosion and drug release in deionised water and phosphate buffer compared with the GG and HPMC. At pH 1.2, GDS exhibited greater swelling than erosion, and drug release was similar to GG and HPMC. This highlights the potential of GDS as a matrix for controlled release similar to HPMC and GG at pH 1.2 but with a more rapid release at pH 6.8. GDS may have wider application in reinforcing compacts with relatively low mechanical strength.
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preformulation studies on Grewia gum as a formulation excipient
2012Co-Authors: Barbara R. ConwayAbstract:Grewia gum is a naturally occurring polysaccharide which has potential as a pharmaceutical excipient. Differential scanning calorimetry and Fourier transform infrared (FT-IR) spectroscopy techniques were used to examine the thermal and molecular behaviours, respectively, of mixtures of Grewia gum with cimetidine, ibuprofen or standard excipients, to assess potential interactions. No disappearance or broadening of the melting endotherm was seen with cimetidine or ibuprofen. Similarly, there was no interaction between Grewia gum and the standard excipients tested. The results obtained using thermal analyses were supported by FT-IR analysis of the material mixtures. Grewia gum is an inert natural polymer which can be used alone or in combination with other excipients in the formulation of pharmaceutical dosage forms.
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Grewia gum 2 mucoadhesive properties of compacts and gels
2011Co-Authors: Elijah I. Nep, Barbara R. ConwayAbstract:Purpose: To compare the mucoadhesive performance of Grewia polysaccharide gum with those of guar gum, carboxymethylcellulose, hydroxypropyl methylcellulose and carbopol 971P. Methods: Grewia polysaccharide gum compacts or gels as well as those of guar gum, carboxymethylcellulose, hydroxypropyl methylcellulose or carbopol 971P were prepared. Texturometric and tensile analysis of the polymer gels and compacts were carried out using a software-controlled penetrometre, TA.XTPlus texture analyzer. The polymer gels were evaluated for hardness, stickiness, work of cohesion and work of adhesion. Furthermore, the detachment force of the polymer compacts from a mucin substrate was evaluated. Results: The work of adhesion of guar gels was significantly greater than that of Grewia gels (p 0.05). Conclusion: Grewia polysaccharide gum demonstrated good mucoadhesive properties, comparable to those of carbopol 971P, carboxymethylcellulose, guar gum and hydroxypropyl methylcellulose, and therefore, should be suitable for the formulation of retentive drug delivery devices.
Elijah I. Nep - One of the best experts on this subject based on the ideXlab platform.
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mechanical and release behaviour of theophylline from matrix tablets containing psyllium powder in combination with Grewia polysaccharides
2020Co-Authors: Elijah I. Nep, Barbara R. Conway, Alan Smith, N Kaur, Seham Shaboun, Adeola O Adebisi, Kofi AsareaddoAbstract:Abstract This study was aimed at investigating the effect of Grewia polysaccharides on the mechanical and release properties of tablet matrices containing binary mixtures of the polysaccharide with psyllium. Two grades of Grewia polysaccharides (GG and GDS) were extracted and binary mixtures of the polysaccharides with psyllium were formulated into tablet matrices containing theophylline as the model drug. The true, bulk and tapped densities, Carr’s compressibility index of the powders and binary composites were determined before tablet compression. Tablet properties (hardness, porosity, and drug release from the matrices) were investigated. The dissolution test was carried out in 0.1 M HCl (pH 1.2) and phosphate buffer (pH 6.8). The results show that GG and GDS produced tablets with good mechanical strength (108.33 N and 95.70 N, respectively) while psyllium produced softer tablets (7.13 N). The combination of psyllium and Grewia polysaccharides in the matrices resulted in a significant increase in the mechanical strength of the matrices when compared to matrices containing psyllium alone as the matrix former. The results also showed that GG and GDS reduced the dissolution rate and effectively eliminated the burst release of theophylline from the psyllium matrices at both pHs. The matrices of GG or GDS and the binary mixtures conform to non-Fickian anomalous diffusion with n > 0.45. When overcoming the burst release of drug from matrices such as psyllium, Grewia polysaccharides may provide an effective reduction and a more sustained drug release from such matrices.
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investigating potential wound healing properties of polysaccharides extracted from Grewia mollis juss and hoheria populnea a cunn malvaceae
2019Co-Authors: Nicholas Pearman, Elijah I. Nep, Samuel R Moxon, Susan M Carnachan, Megan E Cooke, Ian M Sims, Gordon A Morris, Alan SmithAbstract:Abstract The Malvaceae family is a group of flowering plants that include approximately 244 genera, and 4225 species. Grewia mollis, and Hoheria populnea (lacebark), are examples of the Malvaceae family that are used in traditional medicine. For this study polysaccharide samples were extracted from the inner bark of Grewia mollis (unmodified (GG) and destarched Grewia gum (GGDS)) and from the leaves of Hoheria populnea (lacebark polysaccharide (LB)). Wound healing properties of Grewia gum and lacebark polysaccharides were investigated using 3T3 fibroblast cells cultured in supplemented DMEM. Deposition of collagen using van Gieson's stain, expression of the COL1A1 gene which encodes type I collagen using quantitative PCR, and chemotaxis using a scratch plate assay were analysed following treatment of cells with the test polysaccharides. Quantitative PCR results indicated that all three polysaccharides increased the levels of COL1A1 mRNA, with GG showing the greatest fold change. Histological staining also indicated that the fibroblasts treated with GG deposited more collagen than control cells. Additionally, scratch assay data indicated that simulated cell ‘wounds’ treated with each polysaccharide showed increased wound closure rate over a 36 h period post treatment, with GG exhibiting the greatest effect on wound closure. Analysis of the Malvaceae derived polysaccharides indicates that they could have a positive effect on mechanisms that are integral to wound healing, potentially providing greater scientific understanding behind their use in traditional medicine.
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the influence of hydroalcoholic media on the performance of Grewia polysaccharide in sustained release tablets
2017Co-Authors: Elijah I. Nep, Barbara R. Conway, Alan Smith, Adeola O Adebisi, Mohammed H Mahdi, C Dawson, Karl Walton, Paul J Bills, Kofi AsareaddoAbstract:Abstract Co-administration of drugs with alcohol can affect the plasma concentration of drugs in patients. It is also known that the excipients used in the formulation of drugs may not always be resistant to alcohol. This study evaluates effect of varying alcohol concentrations on theophylline release from two grades of Grewia mollis polysaccharides. X-ray microtomography showed that native polysaccharide formulation compacts were not homogenous after the mixing process resulting in its failure in swelling studies. Removal of starch from the native polysaccharide resulted in homogenous formulation compacts resistant to damage in high alcoholic media in pH 6.8 (40%v/v absolute ethanol). Destarched polymer compacts had a significantly higher hardness (375 N) than that of the native polysaccharide (82 N) and HPMC K4 M (146 N). Dissolution studies showed similarity at all levels of alcohol tested ( f 2 = 57–91) in simulated gastric media (pH 1.2). The dissolution profiles in the simulated intestinal fluids were also similar ( f 2 = 60–94), with the exception of the native polysaccharide in pH 6.8 (40%v/v absolute ethanol) ( f 2 = 43). This work highlights the properties of Grewia polysaccharide as a matrix former that can resist high alcoholic effects therefore; it may be suitable as an alternative to some of the commercially available matrix formers with wider applications for drug delivery as a cheaper alternative in the developing world.
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evaluation of some important physicochemical properties of starch free Grewia gum
2016Co-Authors: Elijah I. Nep, Ian M Sims, Gordon A Morris, Vassilis Kontogiorgos, Alan SmithAbstract:Abstract Gums obtained by extraction from the inner bark of stems can be found in association with starch, which must be digested in order to obtain a refined polysaccharide isolate. In the present study, Grewia gum obtained from the inner bark of the stems of Grewia mollis was shown to co-exist with starch and the effect of starch digestion on the physicochemical properties of the resultant polysaccharide was evaluated. The gum was extracted by maceration of the inner bark in deionised water and isolated by a combination of filtration, centrifugation and finally precipitation with absolute ethanol to produce the crude Grewia gum extract (GG). The presence and content of starch in the gum sample was determined followed by enzymatic digestion of the starch using α-amylase (Termamyl 120L) to give a starch-free extract (GGDS). Physicochemical properties of the extracts such as total carbohydrates, total protein, differential sugar composition, NMR, intrinsic viscosity and rheological behaviour of the samples were evaluated. The GG extract had total carbohydrate content of ∼60% out of which 11.8% was starch, and a protein content of 2.3%. Samples also contained galacturonic and glucuronic acid which were highly acetylated. Both samples had a higher proportion of galacturonic acid than glucuronic acid and contained rhamnose, arabinose, galactose, glucose and xylose as neutral sugars in varying proportions. Rheological measurements on 2 %w/w dispersions of the extracts show minor differences between both the original extract and the de-starched material but were influenced by changes in pH.
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starch free Grewia gum matrices compaction swelling erosion and drug release behaviour
2015Co-Authors: Elijah I. Nep, Barbara R. Conway, Kofi Asareaddo, Muhammad Usman Ghori, Alan SmithAbstract:Polysaccharides are suitable for application as hydrophilic matrices because of their ability to hydrate and swell upon contact with fluids, forming a gel layer which controls drug release. When extracted from plants, polysaccharides often contain significant quantities of starch that impacts upon their functional properties. This study aimed to evaluate differences in swelling, erosion and drug release from matrix tablets prepared from Grewia gum (GG) and starch-free Grewia gum (GDS) extracted from the stems of Grewia mollis. HPMC was used as a control polymer with theophylline as a model drug. Swelling, erosion, and in-vitro release were performed in deionized water, pH 1.2 and pH 6.8 media. The Vergnaud and Krosmeyer-Peppas model were used for swelling and drug release kinetics, respectively. However, linear regression technique was used to determine the erosion rate. GDS compacts were significantly harder than the native GG and HPMC compacts. GDS matrices exhibited the fastest erosion and drug release in deionised water and phosphate buffer compared with the GG and HPMC. At pH 1.2, GDS exhibited greater swelling than erosion, and drug release was similar to GG and HPMC. This highlights the potential of GDS as a matrix for controlled release similar to HPMC and GG at pH 1.2 but with a more rapid release at pH 6.8. GDS may have wider application in reinforcing compacts with relatively low mechanical strength.
Vijay Kumar Thakur - One of the best experts on this subject based on the ideXlab platform.
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cellulosic Grewia optiva fibres towards chemistry surface engineering and sustainable materials
2021Co-Authors: Ashvinder K Rana, Prasad Potluri, Vijay Kumar ThakurAbstract:Abstract Natural fibres are abundantly available in nature and their properties largely depends on their physical features and chemical composition. The Himalayan Grewia Optiva fibre is one such natural fibre that is extracted by processing “shoots of Grewia optiva tree” (Grewia oppositifolia). The composite materials manufactured by utilizing natural fibres possess remarkable mechanical, thermal, and physico-chemical properties attributing to their chemical composition and structural dimensions. However, further “upgrade in the aforementioned properties of natural fibre-based bio-composites can be accomplished if the interfacial attachment between the fibre and matrix is enhanced”, which can be done by surface functionalization of the fibres. In this review article, the impact of various surface functionalization strategies on mechanical, thermal, chemical resistance, water absorption and, moisture absorption properties of Grewia optiva fibre have been discussed to set up surface functionalization strategies as a viable process in consolidating valuable Grewia optiva fibre for industrial applications. The surface-functionalized Grewia optiva fibres reinforced composites, thus, prompts the development of Grewia optiva fibre as a reliable and suitable sustainable material for manufacturing of different industrial components that will help t in developing green materials for the feasible future.
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graft copolymers of natural fibers for green composites
2014Co-Authors: Vijay Kumar Thakur, Manju Kumari Thakur, Raju Kumar GuptaAbstract:In the present study, free radical induced graft-copolymerization of natural cellulosic polymers (Grewia optiva) has been carried out to develop the novel materials meant for green composites and many other applications. During the graft copolymer synthesis diverse reaction parameters that significantly affect the percentage of grafting were optimized. The structural, thermal and physico-chemical changes in the natural cellulosic polymers based graft copolymers have been ascertained with scanning electron micrography, Fourier transform infrared spectroscopy, thermogravimetric analysis (TGA) and swelling studies. The swelling studies of the grafted cellulosic polymers have been carried out in different solvents to assess the possible applicability of these natural polymers. Green composites were also prepared using raw/grafted cellulosic polymers. It has been found that grafted polymers (Grewia optiva) based green composites gives better tensile properties than the parent natural cellulosic polymers based composites.
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graft copolymerization of methyl acrylate onto cellulosic biofibers synthesis characterization and applications
2012Co-Authors: Vijay Kumar Thakur, A S Singha, Manju Kumari ThakurAbstract:Graft copolymerization of cellulosic biopolymers with synthetic polymers is of enormous interest because of its application in biofiltration, biosorption, biomedical, biocomposites and various other eco-friendly materials. Synthesis of graft copolymers of methyl acrylate onto mercerized Grewia optivabiofibers using ferrous ammonium sulfate–potassium per sulfate as redox initiator in air was carried out. Different reaction parameters such as amount of solvent, monomer concentration, initiator molar ratio, reaction time and reaction temperature were optimized to get the maximum percentage of grafting. The graft copolymers thus formed were characterized by Fourier transform infrared spectroscopy, scanning electron microscopy, thermogravimetric analysis, differential thermal analysis and differential thermogravimetric techniques. A plausible mechanism for explanation of the graft copolymerization reactions pattern shown is offered. The effect of grafting percentage on the physico–chemical properties of raw as well as grafted Grewia optivabiofibers has also been investigated. The graft copolymers have been found to be more moisture resistant and also showed better chemical and thermal resistance. Green polymer composites were also successfully prepared through compression molding technique by using grafted Grewia optivabiofibers as reinforcement.
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evaluation of Grewia optiva fibers as reinforcement in polymer biocomposites
2010Co-Authors: Vijay Kumar Thakur, A S SinghaAbstract:In present communication, synthesis and characterization of Grewia Optiva fiber reinforced Phenol-Formaldehyde (PF) matrix-based polymer composites through compression molded technique have been reported. The work carried out reveals that mechanical properties of the PF resin increases to extensive extent when reinforced with Grewia Optiva fibers. Thermal (TGA/DTA/DTG) and morphological studies (SEM) of polymer composites thus synthesized have also been carried out to access the applications of polymer composite materials in daily life.
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mechanical thermal and morphological properties of Grewia optiva fiber polymer matrix composites
2009Co-Authors: A S Singha, Vijay Kumar ThakurAbstract:This work is concerned with the evaluation of properties of compression molded Grewia Optiva fiber reinforced Resorcinol-Formaldehyde (RF) matrix-based polymer composites. Reinforcing of the RF resin with Grewia Optiva fiber was done in the form of particle size (200 micron). Present work reveals that mechanical properties such as: tensile strength, compressive strength, flexural strength and wear resistance of the RF matrix have been found to increase up to 30% fibre loading (in terms of weight) and then decreases for higher loading. Morphological and thermal studies of the matrix, fibre and particle reinforced (P-Rnf) green composites have also been studied.
Alan Smith - One of the best experts on this subject based on the ideXlab platform.
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mechanical and release behaviour of theophylline from matrix tablets containing psyllium powder in combination with Grewia polysaccharides
2020Co-Authors: Elijah I. Nep, Barbara R. Conway, Alan Smith, N Kaur, Seham Shaboun, Adeola O Adebisi, Kofi AsareaddoAbstract:Abstract This study was aimed at investigating the effect of Grewia polysaccharides on the mechanical and release properties of tablet matrices containing binary mixtures of the polysaccharide with psyllium. Two grades of Grewia polysaccharides (GG and GDS) were extracted and binary mixtures of the polysaccharides with psyllium were formulated into tablet matrices containing theophylline as the model drug. The true, bulk and tapped densities, Carr’s compressibility index of the powders and binary composites were determined before tablet compression. Tablet properties (hardness, porosity, and drug release from the matrices) were investigated. The dissolution test was carried out in 0.1 M HCl (pH 1.2) and phosphate buffer (pH 6.8). The results show that GG and GDS produced tablets with good mechanical strength (108.33 N and 95.70 N, respectively) while psyllium produced softer tablets (7.13 N). The combination of psyllium and Grewia polysaccharides in the matrices resulted in a significant increase in the mechanical strength of the matrices when compared to matrices containing psyllium alone as the matrix former. The results also showed that GG and GDS reduced the dissolution rate and effectively eliminated the burst release of theophylline from the psyllium matrices at both pHs. The matrices of GG or GDS and the binary mixtures conform to non-Fickian anomalous diffusion with n > 0.45. When overcoming the burst release of drug from matrices such as psyllium, Grewia polysaccharides may provide an effective reduction and a more sustained drug release from such matrices.
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investigating potential wound healing properties of polysaccharides extracted from Grewia mollis juss and hoheria populnea a cunn malvaceae
2019Co-Authors: Nicholas Pearman, Elijah I. Nep, Samuel R Moxon, Susan M Carnachan, Megan E Cooke, Ian M Sims, Gordon A Morris, Alan SmithAbstract:Abstract The Malvaceae family is a group of flowering plants that include approximately 244 genera, and 4225 species. Grewia mollis, and Hoheria populnea (lacebark), are examples of the Malvaceae family that are used in traditional medicine. For this study polysaccharide samples were extracted from the inner bark of Grewia mollis (unmodified (GG) and destarched Grewia gum (GGDS)) and from the leaves of Hoheria populnea (lacebark polysaccharide (LB)). Wound healing properties of Grewia gum and lacebark polysaccharides were investigated using 3T3 fibroblast cells cultured in supplemented DMEM. Deposition of collagen using van Gieson's stain, expression of the COL1A1 gene which encodes type I collagen using quantitative PCR, and chemotaxis using a scratch plate assay were analysed following treatment of cells with the test polysaccharides. Quantitative PCR results indicated that all three polysaccharides increased the levels of COL1A1 mRNA, with GG showing the greatest fold change. Histological staining also indicated that the fibroblasts treated with GG deposited more collagen than control cells. Additionally, scratch assay data indicated that simulated cell ‘wounds’ treated with each polysaccharide showed increased wound closure rate over a 36 h period post treatment, with GG exhibiting the greatest effect on wound closure. Analysis of the Malvaceae derived polysaccharides indicates that they could have a positive effect on mechanisms that are integral to wound healing, potentially providing greater scientific understanding behind their use in traditional medicine.
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the influence of hydroalcoholic media on the performance of Grewia polysaccharide in sustained release tablets
2017Co-Authors: Elijah I. Nep, Barbara R. Conway, Alan Smith, Adeola O Adebisi, Mohammed H Mahdi, C Dawson, Karl Walton, Paul J Bills, Kofi AsareaddoAbstract:Abstract Co-administration of drugs with alcohol can affect the plasma concentration of drugs in patients. It is also known that the excipients used in the formulation of drugs may not always be resistant to alcohol. This study evaluates effect of varying alcohol concentrations on theophylline release from two grades of Grewia mollis polysaccharides. X-ray microtomography showed that native polysaccharide formulation compacts were not homogenous after the mixing process resulting in its failure in swelling studies. Removal of starch from the native polysaccharide resulted in homogenous formulation compacts resistant to damage in high alcoholic media in pH 6.8 (40%v/v absolute ethanol). Destarched polymer compacts had a significantly higher hardness (375 N) than that of the native polysaccharide (82 N) and HPMC K4 M (146 N). Dissolution studies showed similarity at all levels of alcohol tested ( f 2 = 57–91) in simulated gastric media (pH 1.2). The dissolution profiles in the simulated intestinal fluids were also similar ( f 2 = 60–94), with the exception of the native polysaccharide in pH 6.8 (40%v/v absolute ethanol) ( f 2 = 43). This work highlights the properties of Grewia polysaccharide as a matrix former that can resist high alcoholic effects therefore; it may be suitable as an alternative to some of the commercially available matrix formers with wider applications for drug delivery as a cheaper alternative in the developing world.
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evaluation of some important physicochemical properties of starch free Grewia gum
2016Co-Authors: Elijah I. Nep, Ian M Sims, Gordon A Morris, Vassilis Kontogiorgos, Alan SmithAbstract:Abstract Gums obtained by extraction from the inner bark of stems can be found in association with starch, which must be digested in order to obtain a refined polysaccharide isolate. In the present study, Grewia gum obtained from the inner bark of the stems of Grewia mollis was shown to co-exist with starch and the effect of starch digestion on the physicochemical properties of the resultant polysaccharide was evaluated. The gum was extracted by maceration of the inner bark in deionised water and isolated by a combination of filtration, centrifugation and finally precipitation with absolute ethanol to produce the crude Grewia gum extract (GG). The presence and content of starch in the gum sample was determined followed by enzymatic digestion of the starch using α-amylase (Termamyl 120L) to give a starch-free extract (GGDS). Physicochemical properties of the extracts such as total carbohydrates, total protein, differential sugar composition, NMR, intrinsic viscosity and rheological behaviour of the samples were evaluated. The GG extract had total carbohydrate content of ∼60% out of which 11.8% was starch, and a protein content of 2.3%. Samples also contained galacturonic and glucuronic acid which were highly acetylated. Both samples had a higher proportion of galacturonic acid than glucuronic acid and contained rhamnose, arabinose, galactose, glucose and xylose as neutral sugars in varying proportions. Rheological measurements on 2 %w/w dispersions of the extracts show minor differences between both the original extract and the de-starched material but were influenced by changes in pH.
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starch free Grewia gum matrices compaction swelling erosion and drug release behaviour
2015Co-Authors: Elijah I. Nep, Barbara R. Conway, Kofi Asareaddo, Muhammad Usman Ghori, Alan SmithAbstract:Polysaccharides are suitable for application as hydrophilic matrices because of their ability to hydrate and swell upon contact with fluids, forming a gel layer which controls drug release. When extracted from plants, polysaccharides often contain significant quantities of starch that impacts upon their functional properties. This study aimed to evaluate differences in swelling, erosion and drug release from matrix tablets prepared from Grewia gum (GG) and starch-free Grewia gum (GDS) extracted from the stems of Grewia mollis. HPMC was used as a control polymer with theophylline as a model drug. Swelling, erosion, and in-vitro release were performed in deionized water, pH 1.2 and pH 6.8 media. The Vergnaud and Krosmeyer-Peppas model were used for swelling and drug release kinetics, respectively. However, linear regression technique was used to determine the erosion rate. GDS compacts were significantly harder than the native GG and HPMC compacts. GDS matrices exhibited the fastest erosion and drug release in deionised water and phosphate buffer compared with the GG and HPMC. At pH 1.2, GDS exhibited greater swelling than erosion, and drug release was similar to GG and HPMC. This highlights the potential of GDS as a matrix for controlled release similar to HPMC and GG at pH 1.2 but with a more rapid release at pH 6.8. GDS may have wider application in reinforcing compacts with relatively low mechanical strength.
A S Singha - One of the best experts on this subject based on the ideXlab platform.
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microwave induced synthesis of graft copolymer of binary vinyl monomer mixtures onto delignified Grewia optiva fiber application in dye removal
2014Co-Authors: Vinod Kumar Gupta, A S Singha, Deepak Pathania, Bhanu Priya, Gaurav SharmaAbstract:Grafting method, through microwave radiation technique is very effective in terms of time consumption, cost effectiveness and environmental friendliness. Via this method, delignified Grewia optiva identified as a waste biomass, was graft copolymerized with methylmethacrylate (MMA) as an principal monomer in a binary mixture of ethyl methacrylate (EMA) and ethyl acrylate (EA) under microwave irradiation (MWR) using ascorbic acid/H2O2 as an initiator system. The concentration of the comonomer was optimized to maximize the graft yield with respect to the primary monomer. Maximum graft yield (86.32%) was found for dGo-poly(MMA-co-EA) binary mixture as compared to other synthesized copolymer. The experimental results inferred that the optimal concentrations for the comonomers to the optimized primary monomer was observed to be 3.19 mol/L×10-1 for EMA and 2.76 mol/L×10-1 for EA. Delignified and graft copolymerized fibre were subjected to evaluation of physicochemical properties such as swelling behaviour and chemical resistance. The synthesized graft copolymers were characterized with Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), thermogravimetric analysis (TGA) and X-ray diffraction techniques. Thermal stability of dGo-poly(MMA-co-EA) was found to be more as compared to the delignified Grewia optiva fibre and other graft copolymers. Although the grafting technique was found to decrease percentage crystallinity and crystallinity index among the graft copolymers but there was significant increase in their acid/base and thermal resistance properties. The grafted samples have been explored for the adsorption of hazardous methylene dye from aqueous system.
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graft copolymerization of methyl acrylate onto cellulosic biofibers synthesis characterization and applications
2012Co-Authors: Vijay Kumar Thakur, A S Singha, Manju Kumari ThakurAbstract:Graft copolymerization of cellulosic biopolymers with synthetic polymers is of enormous interest because of its application in biofiltration, biosorption, biomedical, biocomposites and various other eco-friendly materials. Synthesis of graft copolymers of methyl acrylate onto mercerized Grewia optivabiofibers using ferrous ammonium sulfate–potassium per sulfate as redox initiator in air was carried out. Different reaction parameters such as amount of solvent, monomer concentration, initiator molar ratio, reaction time and reaction temperature were optimized to get the maximum percentage of grafting. The graft copolymers thus formed were characterized by Fourier transform infrared spectroscopy, scanning electron microscopy, thermogravimetric analysis, differential thermal analysis and differential thermogravimetric techniques. A plausible mechanism for explanation of the graft copolymerization reactions pattern shown is offered. The effect of grafting percentage on the physico–chemical properties of raw as well as grafted Grewia optivabiofibers has also been investigated. The graft copolymers have been found to be more moisture resistant and also showed better chemical and thermal resistance. Green polymer composites were also successfully prepared through compression molding technique by using grafted Grewia optivabiofibers as reinforcement.
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evaluation of Grewia optiva fibers as reinforcement in polymer biocomposites
2010Co-Authors: Vijay Kumar Thakur, A S SinghaAbstract:In present communication, synthesis and characterization of Grewia Optiva fiber reinforced Phenol-Formaldehyde (PF) matrix-based polymer composites through compression molded technique have been reported. The work carried out reveals that mechanical properties of the PF resin increases to extensive extent when reinforced with Grewia Optiva fibers. Thermal (TGA/DTA/DTG) and morphological studies (SEM) of polymer composites thus synthesized have also been carried out to access the applications of polymer composite materials in daily life.
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mechanical thermal and morphological properties of Grewia optiva fiber polymer matrix composites
2009Co-Authors: A S Singha, Vijay Kumar ThakurAbstract:This work is concerned with the evaluation of properties of compression molded Grewia Optiva fiber reinforced Resorcinol-Formaldehyde (RF) matrix-based polymer composites. Reinforcing of the RF resin with Grewia Optiva fiber was done in the form of particle size (200 micron). Present work reveals that mechanical properties such as: tensile strength, compressive strength, flexural strength and wear resistance of the RF matrix have been found to increase up to 30% fibre loading (in terms of weight) and then decreases for higher loading. Morphological and thermal studies of the matrix, fibre and particle reinforced (P-Rnf) green composites have also been studied.
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Grewia optiva fiber reinforced novel low cost polymer composites
2009Co-Authors: A S Singha, Vijay Kumar ThakurAbstract:In this research article, the assessment of properties of compression molded Grewia optiva fiber reinforced Urea-Formaldehyde (UF) matrix based polymer composites is reported. Reinforcing of the UF resin with Grewia optiva fiber was accomplished in the particle, short and long fiber reinforcement. Present work reveals that mechanical properties such as: tensile strength, compressive strength and wear resistance of urea - formaldehyde resin increases to a significant extent when reinforced with Grewia optiva fiber. Analysis of results shows that particle reinforcement is more effective as compared to short and long fiber reinforcement. Morphological and Thermal studies of the matrix and fibre reinforced biocomposites have also been carried out
