Melt solidification technique: Incorporation of higher wax content in ibuprofen beads

The purpose of this study was to achieve incorporation of a higher amount of wax during the preparation of ibuprofen beads by a melt solidification technique for better integrity and prolonged drug release by using a combination of waxes. A mixture of cetyl alcohol (CA) and palmitic acid (PA) was used to improve the matrix integrity and drug release. The effect of variables such as CA, PA, and speed of agitation were studied using 3³ factorial design. Yield, crushing strength, and drug release were analyzed using response surface methodology. The in vitro dissolution test did not show any significant improvement in the drug release. Scanning electron microscopy (SEM) showed that beads were spherical with a smooth surface, but after dissolution became rough and porous. Differential scanning calorimetry (DSC) studies showed that different solidification and erosion properties of waxes are responsible for the inability of waxes to retard drug release even at higher concentration.     

Studies on Formulation Development of Mucoadhesive Sustained Release Itraconazole Tablet Using Response Surface Methodology

The purpose of this research was to prepare and evaluate sustained release mucoadhesive tablets of Itraconazole. It is practically insoluble in aqueous fluids hence its solid dispersion with Eudragit E100 was prepared by spray drying. This was formulated in matrix of hydrophilic mucoadhesive polymers Carbopol 934P (CP) and Methocel K4M (HPMC). The formulation was optimized using a 3² factorial design. Amounts of CP and HPMC were taken as formulation variables for optimizing response variables i.e. mucoadhesion and dissolution parameters. The optimized mucoadhesive formulation was orally administered to albino rabbits, and blood samples collected were used to determine pharmacokinetic parameters. The solid dispersion markedly enhanced the dissolution rate of itraconazole. The bioadhesive strength of formulation was found to vary linearly with increasing amount of both polymers. Formulations exhibited drug release fitting Peppas model with value of n ranging from 0.61 to 1.18. Optimum combination of polymers was arrived at which provided adequate bioadhesive strength and fairly regulated release profile. The experimental and predicted results for optimum formulations were found to be in close agreement. The formulation showed C _max 1898 ± 75.23 ng/ml, t _max of the formulation was 2 h and AUC was observed to be 28604.9 ng h/ml     

Optimization of a medium for enhancing nicotine biodegradation by Ochrobactrum intermedium DN2

AIMS: To optimize a medium for nicotine degradation by Ochrobactrum intermedium DN2 in presence of yeast extract, glucose and Tween 80 using response surface methodology (RSM). METHODS AND RESULTS: In this study, the effects of yeast extract, glucose and Tween 80 on nicotine degradation were investigated in flasks using a novel nicotine-degrading bacterium, O. intermedium DN2. A full factorial central composite design was applied in the design of experiments and in the analysis of the experimental data. The results showed that the most significant variable influencing nicotine degradation was yeast extract, followed by glucose, and then Tween 80. Moreover these three factors interacted with each other and combined to produce positive effects on nicotine degradation. The experimental data also allowed the development of an empirical model (P < 0.0001) describing the inter-relationship between independent and dependent variables. By solving the regression equation, the optimal values of the variables were determined as: yeast extracts 0.094%, glucose 0.101% and Tween 80 0.080%. Using the medium obtained, about 1,220 mg l(-1) of nicotine was degraded (95.55%) within 10 h at the specific biodegradation of 116.59 mg l(-1) h(-1) in 30-l bioreactor containing 25-l tobacco extract. CONCLUSIONS: An optimal medium of nicotine degradation by the strain DN2 was obtained. SIGNIFICANCE AND IMPACT OF THE STUDY: RSM proved to be reliable in developing the model, optimizing factors and analysing interaction effects. The results provide better understanding on the interactions between yeast extract, glucose and Tween 80 for nicotine biodegradation.     

Response surface methodology for optimizing the fermentation medium of Clostridium butyricum

AIMS: Strains of Clostridium butyricum have been increasingly used as probiotics for both animals and humans. The aim of this study was to develop a growth medium for cultivating C. butyricum ZJUCB using a statistical methodology. METHODS AND RESULTS: Response surface methodology (RSM) was used to evaluate the effects of variables, namely the concentrations of the glucose, pectin, soyabean cake extract, casein, corn steep flour, ammonium sulphate, sodium bicarbonate and the medium initial pH. A fractional factorial design was applied to study the main factors that affected the growth of a probiotic strain of C. butyricum currently preserved in our lab and the central composite experimental design was adopted to derive a statistical model for optimizing the composition of the fermentation medium. The experimental results showed that the optimum fermentation medium for the growth of C. butyricum was composed of 2% glucose (w/v), 0.5% pectin (w/v), 0.2% casein (w/v), 3.98% soyabean cake extract, 0.1% (NH4)2SO4 (w/v), 0.124% NaHCO3 (w/v), 0.37% corn steep flour (w/v), 0.02% MnSO4 H2O (w/v), 0.02% MgSO4 7H2O (w/v) and 0.002% CaCl2 (w/v) at pH 7.5. CONCLUSIONS: After incubating 24 h in the optimum fermentation medium, the populations of the viable organisms were estimated to be 10(9) CFU ml(-1). In the present study, we report the optimization of a growth medium that produced increased yields using statistical approach. SIGNIFICANCE AND IMPACT OF THE STUDY: The use of bacteria as a probiotic is showing increasing potential. The development of a growth medium that has a high yield is an obvious need, and the approach to optimizing a growth medium is innovative.     

Utilisation of response surface methodology to optimise the culture medium for Bacillus thuringiensis subsp. israelensis

Bacillus thuringiensis israelensis (Bti) is a sporulating Gram-positive bacterium that produces protein crystals with insecticide activity against Diptera. The aim of the present work was to optimise the culture medium for this bacterium, based on mathematical and statistical concepts (factorial designs and response surface methodology). The variables studied were carbon and nitrogen source concentrations. The main response analysed was toxicity, evaluated by means of bioassay with Aedes aegypti. The nutrient sources were first selected and then optimised. Ground Bombyx mori pupae, ammonium sulphate and glucose were the most suitable sources of organic nitrogen, inorganic nitrogen and organic carbon, respectively. The toxicity of optimised medium (LC₅₀ = 0.703 ppm, v/v) was higher than that the medium used as reference (LC₅₀ = 3.01 ppm, v/v), which is commonly used in the laboratory culture of Bti. Besides, the optimised medium showed a cost 7.36 times less than that of an alternative medium, based on soybean flour and sugarcane molasses. Factorial design and response surface methodology were effective methods for culture medium optimisation. The results will contribute to the development of local production and utilisation of agroindustrial waste locally.     

Evaluation of simple enzyme kinetics by response surface modelling

The activity of a horse liver alcohol dehydrogenase catalysed reduction of cyclohexanone was investigated by using a central composite circumscribed design in which two parameters (pH and cyclohexanone concentration) were varied. By log transformation of the substrate concentration an adequate model could be obtained from which reliable kinetic constants and pH profiles were determined.     

响应面法优化黑土豆色素提取工艺研究

以黑土豆为原料提取色素,在乙醇浓度、回流温度、回流时间和料液比四个单因素实验基础上,通过响应面法优化提取条件,利用 Box-Benhnken 设计模型,研究四个自变量之间的影响.结果表明,得到最佳提取工艺为回流温度47℃,回流时间47．5 min,料液比1∶90,乙醇浓度42．5％.在此条件下,理论上测得黑土豆中色素的吸光度值为0．413,实验测得黑土豆中色素的吸光度值为0．416,理论值与实验值的相对误差为0．726％.该提取工艺简便、具有较高的重现性和可行性.     

Liposomal formulation for co-delivery of paclitaxel and lapatinib,preparation, characterization and optimization

Paclitaxel (PTX) is one of the most promising natural anticancer agents with a wide therapeutic range which is limited by its hydrophobic nature, low therapeutic index and more importantly, the emergence of multidrug resistance (MDR). Lapatinib (LPT) is a dual tyrosine kinase inhibitor with a significant potential to inhibit p-glycoproteins which form one of the main groups of proteins responsible for efflux pump mediated MDR. To overcome the PTX related MDR, a novel liposomal formulation was optimized for co-delivery of PTX and LPT by applying the D-optimal response surface methodology. The encapsulation efficiency (EE%) of the optimized formulation for LPT and PTX was 52?±?3% and 68?±?5, respectively. The optimized formulation showed a narrow size distribution with the average of 235?±?12?nm. The transmission electron microscopy image showed that liposomes were round in shape and discrete. The release profile exhibited 93% and 71% drug release for PTX and LPT after 40?h in the sink condition. The differential scanning calorimetry analysis indicated the conversion of both drugs from crystalline state to molecular state in the optimized lyophilized formulation. The cytotoxicity of the prepared formulation was studied against 4T1 murine mammary cells. The liposomal formulation showed better cytotoxicity in comparison to the binary mixture of free drugs.     

Optimization and kinetic study of immobilized lipase-catalyzed synthesis of ethyl lactate

Abstract

Enzymatic synthesis of ethyl lactate catalyzed by immobilized lipase has been investigated. The reaction variables (including the molar ratio of ethanol to acid, total substrate amount, temperature, reaction time and rotation speed) were selected in accordance with the Plackett–Burman design and were further optimized via response surface methodology. The molar ratio of ethanol to acid, total substrate amount and reaction time were screened out as significant variables for the optimization study. A 20-run, full-factorial, central composite design was used to construct the statistical model and the optimal conditions obtained were as follows: molar ratio of ethanol to acid of 8.3:1, total substrate amount of 0.4 g, reaction time of 26.87 h with temperature of 55°C and rotation speed of 150 rpm. Under the optimal conditions, the yield of ethyl lactate was up to 24.32%; close to the 25.13% obtained using the commercial lipase, Novozym 435. Due to the low cost and simple immobilization process, the lipase prepared in the present work could have great potential in enzymatic applications. Additionally, a kinetic model with inhibition by both ethanol and lactic acid following a ping-pong bi-bi mechanism was proposed.     

Optimization and characterization of rhamnolipid production by Pseudomonas aeruginosa NY3 using waste frying oil as the sole carbon

Yield and cost are two major factors limiting the widespread use of rhamnolipids (RLs). In the present study, waste frying oil (WFO) was used as the sole carbon source to produce environmentally friendly RLs by Pseudomonas aeruginosa NY3. The Plackett–Burman design (PBD) and Box–Behnken design (BBD) methods were used to maximize the production yield of RL. The PBD results showed that the concentrations of NaNO₃, Na₂HPO₄, and trace elements were the key factors affecting the yield of RL. Furthermore, the BBD results showed that at NaNO₃, Na₂HPO₄, and trace elements concentrations were 4.95, 0.66, and 0.64 mL/L, respectively, the average RL yield reached 9.15 ± 0.52 g/L, 1.58-fold higher than that observed before optimization. Fourier transform infrared spectroscopy (FTIR) and liquid chromatography-ion trap-time of flight mass spectrometry (LCMS-IT-TOF) were used to elucidate the diversity of RL congeners. The results showed that, after optimization, the RL congener diversity increased, and the major RL constituent was converted from di-RLs (64.04%) to mono-RLs (60.44%). These results suggested that the concentrations of the components contained in the culture medium of P. aeruginosa NY3 influenced not only the yield of RL, but also its congener distribution.     

重组巴斯德毕赤酵母发酵生产内切几丁质酶的培养条件优化

探讨重组巴斯德毕赤酵母发酵生产内切几丁质酶的最适培养条件,以期获得最佳的内切几丁质酶活力。以内切几丁质酶活力为指标,通过部分因子试验设计以及响应面法优化确定重组巴斯德毕赤酵母高产内切几丁质酶的最适培养条件。部分因子试验设计筛选的影响重组巴斯德毕赤酵母高产内切几丁质酶的3个关键因子为甲醇、油酸和吐温-80。响应面法优化的上述3个关键因子的最佳浓度分别为0.71%、0.086%和0.31%。重组巴斯德毕赤酵母发酵生产内切几丁质酶的最适培养条件为：酵母膏1%、酵母氮碱（YNB）1.34%、蛋白胨2%、甲醇0.71%、油酸0.086%、吐温-80 0.31%、PTM₁ 0.8%、pH 6.0。在上述培养条件下,重组巴斯德毕赤酵母产内切几丁质酶的活力高达30.92U/mL。与未优化前相比,酶活力提高了1.44倍。研究结果为内切几丁质酶的产业化生产和应用奠定了良好基础。     

Response surface methodology for optimization and characterization of limonene-based coenzyme Q10 self-nanoemulsified capsule dosage form

The aim of this study was to systematically obtain a model of factors that would yield an optimized self-nanoemulsified capsule dosage form (SNCDF) of a highly lipophilic model compound, Coenzyme Q10 (CoQ). Independent variables such as amount of R-(+)-limonene (X ₁), surfactant (X ₂), and cosurfactant (X ₃), were optimized using a 3-factor, 3-level Box-Behnken statistical design. The dependent variables selected were cumulative percentage of drug released after 5 minutes (Y ₁) with constraints on drug release in 15 minutes (Y ₂), turbidity (Y ₃), particle size (Y ₄), and zeta potential (Y ₅). A mathematical relationship obtained,Y ₁=78.503+6.058X ₁ +13.738X ₂+5.986X ₃−25.831X ₁ ² +9.12X ₁X₂−26.03X ₁X₃−38.67X ₂ ² +11.02X ₂X₃−15.55X ₃ ³ (r ²=0.97), explained the main and quadratic effects, and the interaction of factors that affected the drug release. Response surface methodology (RSM) predicted the levels of factorsX ₁,X ₂, andX ₃ (0.0344, 0.216, and 0.240, respectively), for a maximized response ofY ₁ with constraints of >90% release onY ₂. The observed and predicted values ofY ₁ were in close agreement. In conclusion, the Box-Behnken experimental design allowed us to obtain SNCDF with rapid (>90%) drug release within 5 minutes with desirable properties of low turbidity and particle size.     

Sequential Statistical Improvement of the Liquid Cultivation of Helicobacter pylori

Background: Colonization of the gastric mucosa by Helicobacter pylori is one of the most important causes of acute and chronic gastric pathologies in humans. Achieving the growth of H. pylori in liquid media is of great importance in the development of clinical studies. In this study, we developed a sequential optimization strategy based on statistical models to improve the conditions of liquid culture of H. pylori. Materials and Methods: Four statistical models were sequentially used. First, a Box‐Behnken design was used to select the best process conditions (shaking speed, inoculum concentration, and final volume of culture). Secondly, a general factorial design was used to evaluate the influence of adding gel blocks or gel beads (shape and composition). Then a D‐optimal reduce design was carried out to allow the selection of the most influential factors in increasing the cell concentration (culture media components). Finally, another Box‐Behnken design was used to optimize the concentration of the culture media components previously selected. Results: After 12 hours of liquid culture a concentration of 25 × 10⁸ cells per mL (9.4 log₁₀ cells per mL) of H. pylori was obtained, compared with a predicted 32 × 10⁸ (9.5 log₁₀ cells per mL), which means between 1 and 5 log₁₀ units higher than some previous reports. Conclusions: The sequential statistical approach increased the planktonic H. pylori cell culture. The final culture media and conditions were: Brain Heart Infusion, blood agarose (1.5% w/v), lamb’s blood (3.18% v/v), DENT (0.11% v/v), and Vitox (0.52% v/v) at 60 rpm and 37 °C with filtered CO₂ (5% v/v) bubbled directly into the culture media in a final volume of 76.22 mL.     

产酸克雷伯氏杆菌发酵产2，3-丁二醇的培养基优化

采用不同设计方法相结合的策略对耐高糖产酸克雷伯氏杆菌（Klebsiella oxytoca）ME—UD-3-4发酵产2,3-丁二醇的培养基进行优化。首先在单因素实验的基础上采用Plackett—Burrnan设计法对影响ME—UD-3-4发酵产2,3-丁二醇的相关因素进行研究,筛选到3种有显著效应的因素（P〈0．05）：葡萄糖、玉米浆和MgSO4·7H2O。然后利用响应曲面法（Response Surface Methodology,RSM）对这3种因素的最佳水平范围进一步探讨;对得到的回归模型进行分析,得最佳条件（g／L）：葡萄糖220、玉米浆19和MgSO4·7H2O 0．4;在最佳条件下,发酵80h,2,3-丁二醇产量从原来的57．3 g／L提高到86．1 g／L,生产强度由0．72g／（L·h）提高到1．08g/（L·h）。     

基于响应面法优化匍枝根霉TP-02液态发酵纤维素酶条件

利用Plackett-Burman设计法(Plackett-Burman,PB),对影响根霉TP-02液态发酵产纤维素酶的8个因子进行了筛选,结果表明,影响该菌发酵产纤维素酶的主要因子为麸皮与稻草的比例、槐糖、Tween 80。利用最陡爬坡试验逼近最大响应区域,在此基础上,采用响应面法(ResponseSurface Methodology,RSM)对这3个因子的影响进行研究,得出纤维素酶产量的数学模型,通过对二次多项回归方程求解,得到3个因子的最优用量:麸皮稻草比例为:3.7:1,槐糖量为:0.62%,Tween 80为0.68 g/L,在优化后的条件下培养96 h,纤维素酶滤纸酶活可达到8.13 IU/mL比优化前提高了38.97%。     

响应面优化产琥珀酸放线杆菌生产丁二酸

丁二酸是一种重要的C4化合物平台,可以合成一系列重要化合物。文中对产琥珀酸放线杆菌Actinobacillus succinogenes GXAS137发酵生产丁二酸培养基成分进行优化。通过单因素和Plackett-Burman试验设计筛选出影响丁二酸发酵的重要参数,采用最陡爬坡实验逼近最大丁二酸生产区域后,利用Box-Behnken设计确定重要参数的最佳水平。筛选结果表明,影响丁二酸产量的重要参数是葡萄糖、酵母提取物和碱式碳酸镁浓度。最佳条件为(g/L)：葡萄糖70.00,酵母提取物9.20,碱式碳酸镁58.10。优化后丁二酸产量达到47.64 g/L。与初始条件 (36.89 g/L) 相比,丁二酸浓度提高了30 %。在最佳工艺条件下得到的试验结果与模型预测值很吻合,说明建立的模型是有效的。     

白木通种子油的理化特性及制备生物柴油的研究

以白木通种子为实验材料,索氏提取法提取种子油,GC-MS测定脂肪酸组成,国标法测定理化性质,运用响应面法对碱催化白木通种子油酯交换制备生物柴油工艺进行优化。结果表明:白木通种子油含有5种脂肪酸,其中油酸含量最高,硬脂酸次之。白木通种子油的得率、含水量、碘值、酸值、皂化值、过氧化值、凝固点、闪点和冷滤点分别为32.76%、0.36%、67.89 g/100 g、8.85 mg KOH/g、235.03 mg KOH/g、47.08 mmol/kg、-12℃、215℃和-7℃。优化的生物柴油制备工艺为:反应时间80 min,醇油摩尔比6.7∶1,催化剂用量1.3%(按反应体系总质量计算)。白木通种子含油率高,可作为藤本油料作物开发利用。     

工业纤维素诱导里氏木霉RUT C-30产葡聚糖酶的条件

为了研究工业纤维素诱导里氏木霉RUT C-30产葡聚糖酶的最佳条件,根据单因素实验结果,以工业纤维素、(NH4)2SO4和生物素为实验因素,滤纸酶活为响应值,进行中心组合设计,建立一个二次多项式数学模型,进行响应面优化,寻找最优产酶结果.经过优化,选出工业纤维素、(NH4)2SO4和生物素的添加量分别为39.485 g/L、6.232 g/L和249.872 μg/L,最高的滤纸比酶活为6.298 U/mL,实验验证,滤纸比酶活为6.118 U/mL,与预测值相差了2.86%.     

Biodegradation of Kerosene by Aspergillus flavus Using Statistical Experimental Designs

The ability of different local fungal isolates to degrade kerosene in liquid medium was studied. The results showed that the percent of kerosene degradation varied among the different tested fungi and that 60–96% of kerosene was degraded after 7 days in the presence of 0.2% (v/v) of Tween 80. The absence of the surfactant led to about 28.34% decrease of biodegradation. The degradation of 2% (v/v) of kerosene by the most efficient fungus (Aspergillus flavus) was significantly influenced by the incubation period and the composition of culture medium. Statistical experimental designs were used to optimize the process of kerosene degradation by the fungus. Under optimized medium compositions and culture conditions, A. flavus degraded kerosene (100%) after 111.3 h of incubation. Optimal conditions obtained in this work provided a solid foundation for further use of A. flavus in treatment of kerosene-polluted soil. The optimized conditions were applied to bioremediate 2.5% (v/w) kerosene-polluted soil by A. flavus, and the fungus efficiently degraded kerosene after 35 days of incubation.     

Isolation and characterization of Aspergillus sp. for the production of extracellular polysaccharides by response surface methodology

In this study, Aspergillus sp. was isolated for the production of extracellular polysaccharide. The process parameters were initially optimized by traditional methods. The cheap substrate, wheat bran was used for the production of extracellular polysaccharide in solid state fermentation. Supplementation of (1%, w/w) maltose, gelatin enhanced EPS production (5.36?mg/g). The salts such as, Cu²⁺ (4.9?mg/g), Ca²⁺ (3.5?mg/g), Zn²⁺ (2.9?mg/g), Mn²⁺ (3.4?mg/g) and Mg²⁺ (1.8?mg/g) stimulated EPS production. In two level full factorial experimental designs, the EPS yield varied from 3.18 to 11.65?mg/g wheat bran substrate with various combinations of the components supplemented with wheat bran substrate. Among these selected factors in central composite design, maltose significantly influenced on extracellular polysaccharide production.