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  Citation statistics : Table of Contents
   2015| May-August  | Volume 14 | Issue 2  
    Online since July 21, 2015

 
 
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ORIGINAL ARTICLES
Improvement in bacterial cellulose production using Gluconacetobacter xylinus ATCC 10245 and characterization of the cellulose pellicles produced
Nagwa A Atwa, Ahmed I El-Diwany, Houssni El-Saied, Altaf H Basta
May-August 2015, 14(2):123-129
DOI:10.4103/1687-4315.161286  
Aim This paper deals with the improvement in bacterial cellulose (BC) production by Gluconacetobacter xylinus ATCC 10245 cultivated under shaking condition. Materials and methods The study was performed using two different approaches. First, through the addition of some thickening agents to the fermentation medium; second, by applying a two-stage fermentation process in which cells of G. xylinus were grown under two successive static and shaking conditions. During the first fermentation stage, the experimental microorganism was cultivated under static condition to produce thick, leather-like, white BC pellicles on which the bacterial cells were firmly adhered. However, during the second fermentation stage, these pellicles were reused to inoculate fresh, more economic medium, and incubated under shaking condition. Results The results showed that the addition of sodium alginate at a concentration of 0.4 g/l resulted in a BC production of 8.25 g/l compared with only 1.7 g/l obtained using the control medium without thickeners under similar shaking condition. The second method resulted in a substantial increase in the produced BC pellicle up to about 16.9 g/l. Further increase in the weight of the BC gels was obtained by adopting a repeated batch cultivation method during the second fermentation stage. After seven successive repeated batches, which extended for 56 days, the total BC mass reached 81.25 g/l. The properties of some BC pellicles were studied using thermogravimetric analyses and then compared with those of cotton linter. Conclusion The results showed that these two methods are very promising for BC production on a large scale.
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Comparative studies of free and immobilized phytase, produced by Penicillium purpurogenu GE1, using grafted alginate/carrageenan beads
Ghada EA Awad, Mona A Esawy, Eman W El-Gammal, Hanan Mostafa Ahmed, Magdy M Elnashar, Nagwa A Atwa
May-August 2015, 14(2):87-93
DOI:10.4103/1687-4315.161268  
Aim The aim of the study was to immobilize the phytase enzyme produced by Penicillium purpurogenu GE1 on grafted alginate/carrageenan beads and study the properties of the immobilized enzyme in comparison with free ones. Materials and methods The immobilization conditions were first optimized and then the optimum conditions of temperature and pH for the maximum activity of the immobilized and free enzyme were studied and compared. The stabilities of both immobilized and free phytase at moderate and low temperatures of 50 and 4°C, as well as their stability at the acidic pH of 4, were also studied. Finally, the activity of the immobilized enzyme was monitored over 20 successive repeated batches. Results The maximum loading capacity was obtained after 20 h at the enzyme/acetate buffer dilution ratio of 1 : 2. The optimum temperature and pH of the immobilized enzyme, as compared with free state, were found to have shifted from 37 to 45°C and from pH 5.5 to 4, respectively. Moreover, the results also proved that when phytase in both immobilized and free states was subjected to an acidic pH of 4 for 45 min, or to a moderately high temperature of 50°C for 60 min, the activity of the former remained stable, whereas that of the latter showed substantial losses. In contrast, at the refrigerator shelf temperature of 4°C, dry and wet immobilized forms retained 100% activity for 12 weeks, whereas that of the free enzyme was completely lost within a shorter period of 4 weeks. Furthermore, the activity of the phytase enzyme immobilized on gel beads was maintained at the 100% level for more than 12 repeated batch utilizations of the beads. Conclusion The results revealed that the physiological parameters of the immobilized enzyme were greatly improved compared with the free state. Further, the activity of the phytase enzyme immobilized on gel beads was maintained at the 100% level for more than 12 repeated batch cultivations of the beads.
  4 1,465 280
REVIEW ARTICLE
Interpenetrating polymer network-based drug delivery systems: emerging applications and recent patents
Gupta Somya, Parvez Nayyar, Bhandari Akanksha, Sharma Pramod Kumar
May-August 2015, 14(2):75-86
DOI:10.4103/1687-4315.161266  
Interpenetrating polymer network (IPN) systems use novel polymers that are synthesized by the interlacing of two independent polymers in a cross-linked form. For successful preparation of such IPN systems, at least one of the participating polymers should be synthesized/cross-linked in the immediate presence of the other. The polymers used to fabricate an IPN system are independently cross-linked or cross-linked to each other. They can be prepared by selective combination of the starting polymers to tailor the final product based on the ultimately desired characteristics. The nontoxic nature and biodegradability of natural polymers can thus be combined with the robustness and strength offered by the synthetic polymers by fabricating their IPN systems. The present review aims to summarize the IPN systems in terms of their advantages, disadvantages, and different drug delivery systems based on these polymers and their numerous biomedical applications. This review includes a detailed study of the recent publications and patents describing the use of IPNs in different spheres/formulations.
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ORIGINAL ARTICLES
Semisolid state fermentation: effects of beet sugar root : peptone ratio on erythromycin production by Saccharopolyspora erythraea NCIMB 12462
Mohamed AM Farid, Hoda MA Shata, Azza M Noor El-Deen, Nayera AM Abdelwahed
May-August 2015, 14(2):94-102
DOI:10.4103/1687-4315.161280  
Background and objectives Erythromycin, a prominent member of the macrolide antibiotics, is commercially produced by submerged fermentation. However, this process requires high energy expenditures. The objective of the present work was to improve and optimize the cultural conditions of Saccharopolyspora erythraea NCIMB 12462 grown under semisolid state fermentation, with less energy requirements, less waste water generation, and easier product recovery, for the production of erythromycin using beet sugar root (BSR) and peptone. Materials and methods Chemical analysis of BSR was carried out according to the guidelines of AOAC and using high-performance liquid chromatographic. The concentration of erythromycin was measured using the agar diffusion bioassay method. Evaluation of different nitrogen sources for erythromycin production was carried out and the effect of different BSR : peptone ratio on erythromycin production was determined. The impact of initial moisture content (75-88%), size of inoculum, sodium chloride and calcium carbonate concentrations, and incubation period (1-12 days) on erythromycin production using solid state fermentation by S. erythraea NCIMB 12462 was evaluated. Results and discussion Optimization of environmental and culture parameters, concentration of nitrogen sources (ammonium sulfate, yeast extract, and peptone), BSR/peptone ratio, inoculum size, moisture content, and incubation time exhibited a significant increase in erythromycin production compared with the production before optimization. The concentration of erythromycin in optimized medium was 735.65 ± 8.58 μg/g dry BSR (1.36 times more than that of the control medium). The optimal conditions for erythromycin production using solid state fermentation for BSR were a initial moisture level of 77.78%, inoculum size of 2 × 10 6 -2 × 10 7 spores/10 g dry BSR, incubation period of 10 days, and peptone at a concentration of 0.8 g/100 g BSR.
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Synthesis and evaluation of neuropharmacological profile of isatin-3-[ N2 -(2-benzalaminothiazol-4-yl)] hydrazones
Venkateshwar Rao Jupally, Venkateshwarlu Eggadi, Sharavana Bhava Bandaru Sheshagiri, Umasankar Kulandaivelu
May-August 2015, 14(2):130-138
DOI:10.4103/1687-4315.161287  
Background and objective Isatin and its derivatives are versatile lead molecule for potential bioactive agents and are reported to possess a wide spectrum of activities such as central nervous system (CNS), antibacterial, antifungal, anticonvulsant, anti-HIV, antidepressant, anti-inflammatory, etc. In this study, we evaluated neuropharmacological profile of isatin-3-[N2 -(2-benzalaminothiazol-4-yl)] hydrazone derivatives using well-defined preclinical models. Materials and methods The isatin-3-[N2 -(2-benzalaminothiazol-4-yl)] hydrazone derivatives ( Va-Vj ) were synthesized and characterized using spectral data. Neuropharmacological profile of Va-Vj (10 and 100 mg/kg, orally) was investigated by gross behavioural profile, hole board, locomotor activity, hypnotic activity, forced swim test, tail suspension test and rota rod test in mice. Imipramine (10 mg/kg) and diazepam (2 mg/kg) were used as standard for antidepressant and sedative as well as a hypnotic drug, respectively. Results and conclusion Isatin derivatives showed dose-dependent neuropharmacological action on the CNS, such as anxiolytic, sedative, hypnotic and depressant action. Among all the derivatives, halogen-substituted compounds ( Vh and Vi ) at 100 mg/kg showed significant (P < 0.001) action when compared with the control group (0.1% sodium carboxy methylcellulose (CMC)), and other substituted isatin derivatives Va, Vb, Vc, Vd, Ve, Vf, Vg and Vj also proved to possess a significant (P < 0.05) action at 100 mg/kg compared with the control group. From these results, we concluded that Va-Vj compounds possessed a wide range of CNS activities.
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Comparison of enhancement of transdermal permeability of Carvedilol through physical and chemical methods
Sriram Pavani, Yamsani S Kumar, Yamsani M Rao
May-August 2015, 14(2):103-108
DOI:10.4103/1687-4315.161282  
Background The aim of the study was to overcome the difficulties raised in oral therapy; there is a need for the development of new drug delivery system that will improve the therapeutic efficacy. Because of its low dose and extensive hepatic metabolism, Carvedilol is a suitable candidate for transdermal administration. Objective The ultimate aim of this study was to administer Carvedilol through a transdermal patch and to evaluate by chemical method and iontophoresis by means of in-vitro drug release and ex-vivo permeation studies. Materials and methods The matrix type transdermal patches were prepared by solvent evaporation technique. Various formulations composed of hydroxypropyl methylcellulose (HPMC E15), Eudragit (ERL 100) in different ratios were prepared. All formulations consist of 15% v/w of dibutyl phthalate as plasticizer. Results and conclusion The prepared patches were characterized for various physicochemical parameters. The penetration-enhancing mechanism of iontophoresis was found to increase solvent flow through electro-osmosis and pore enlargement in the skin barrier, together with enhancement of electrochemical potential difference across the skin. The effect of chemical enhancer d-limonene and iontophoretic transdermal transport of drug using a current density of 1 mA/cm 2 was investigated. Increasing the applied current density from 0.5 to 1 mA/cm 2 resulted in a 2.2-fold increase in iontophoretic flux. Results demonstrated that iontophoresis exhibited a great ability to enhance the flux of drug in comparison with the chemical method. The optimized formulations F2 and F3 containing 8% d-limonene as chemical enhancer showed maximum skin permeation, 979.45 ± 3.16 and 900.57 ± 2.8 μg/cm 2 , respectively, whereas formulations F9 and F10 with iontophoresis showed the skin permeation, 1048.7 ± 3.8 and 1476.7.7 ± 4.8 μg/cm 2 , respectively, and obtained flux greater than F2.
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Physiological studies on a locally isolated rhamnolipid producer, Pseudomonas strain
Nagwa A Atwa
May-August 2015, 14(2):109-116
DOI:10.4103/1687-4315.161283  
Aim Bacterial strains were isolated from different soil samples and evaluated for their ability to produce biosurfactants. Preliminary identification was made of the selected strain Kh4, as well as of the type of produced biosurfactant. Finally, the most optimum conditions for improving growth and the percentage of reduction in the culture surface tension (ST) were investigated. Materials and methods The genus of the selected strain was preliminarily identified on the basis of some biological tests and characterized pigmentation on a specific medium. Rhamnolipid production was confirmed using both Siegmund Wagner and Dubois methods as well as thin-layer chromatography. Quantitative measurements of the ST of cell-free supernatants were determined using the Du Nouy ring method in order to estimate the amount of biosurfactant produced. Cultivation conditions were studied on the basis of both flask and 7 l stirred tank bioreactor levels. Results A total of 66 bacterial strains were isolated from Egyptian soil and assessed for biosurfactant productivity. The selected isolate, preliminarily identified as a Pseudomonas spp., has the ability to produce rhamnolipid and hence to decrease the ST of the fermentation medium from 60 to about 35 mN/m. The optimum fermentation medium, used for the growth and maximum decrease in ST, was determined. Some physiological parameters such as the initial pH, incubation temperature, and time were also studied. Furthermore, the effect of pH control during the fermentation production of rhamnolipid in a 7 l stirred bioreactor was also studied. Accordingly, a maximum decrease in the ST of the cell-free culture medium of 32 mN/m was reached, confirming the production of a satisfactory level of rhamnolipid biosurfactant. Conclusion These results qualified the locally isolated Pseudomonas spp. Kh4 for use in the bioremediation of hydrocarbon-contaminated sites as well as in petroleum industries.
  - 1,247 170
Evaluation of phenolic extract of licorice roots in diets of Nile tilapia (Oreochromis niloticus)
Amani M.D. El Mesallamy, Hany I El-Marakby, Ahmed MA Souleman, Fatma S Abd El-Naby
May-August 2015, 14(2):117-122
DOI:10.4103/1687-4315.161285  
Aims The aims of this study were to evaluate the effect of methanolic extract of licorice roots (MELRs) as a feed additive on the growth performance, feed utilization, and innate immunity of Nile tilapia (Oreochromis niloticus), and to screen the phenolic compounds contained in the different MELRs through reverse-phase high-performance liquid chromatography (HPLC). Background Licorice is doubtless one of the most popular medicinal plants, with its roots being the most used part. Particularly, the species Glycyrrhiza glabra L. has well-known therapeutic properties, which have been documented since the Egyptian age. Materials and methods MELR was prepared as follows: in a typical experiment, 500 g of the plant was dried at room temperature. The dried plant was defatted separately with n-hexane in a Soxhlet apparatus for 15 h. The plant residue was then extracted with methanol in a Soxhlet apparatus for 20 h. The obtained data were analyzed using one-way procedure SPSS according to the following model: Yij = μ+Ti +eij , where μ is the over mean, Ti is the fixed effect of the rocket supplementation (1…4), and eij is random error. The differences between the experimental groups were determined using Duncan's multiple range test. Results and discussion Screening the phenolic compounds contained in the different MELR achieved through reverse-phase HPLC analysis showed 21 phenolic and flavonoid compounds. The MELR supplementation enhanced fish growth compared with the control diet, and the highest fish performance was obtained at 0.04% MELR level. Supplementation with MELR was found to have an antibacterial activity antagonistic to pathogenic bacteria Aeromonas jandaei infection in fish. It is recommended that 0.04% MELR be used as a feed additive for Nile tilapia to enhance its growth performance, health, and innate immunity. Conclusion This study was carried out to evaluate the effect of MELRs as a feed additive on the growth performance, feed utilization, and innate immunity of Nile tilapia. MELR enhances fish growth rate, feed utilization, and innate immunity. The highest fish growth was obtained when fish were fed a diet containing 0.04% extract.
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