Adsorption of methylene blue onto treated activated carbon

The potential feasibility of treated and untreated activated carbon for removal of methylene blue from aqueous solution was investigated. The effects of various experimental parameters such as contact time, solution pH and adsorbent dosage were investigated. The extent of methylene blue removal increased with the increased in contact time, solution pH and amount of adsorbent used. Adsorption data was better fitted to the Langmuir isotherm. The results in this study indicated that the treated activated carbon was an attractive candidate for removing organic dye of methylene blue which shows great reduction of colour while reducing the time contact to achieve equilibrium

Enzymatic synthesis of betulinic acid ester as an anticancer agent: optimization study

Immobilized Candida antarctica lipase, Novozym 435, was used to catalyze the esterification reaction between betulinic acid and phthalic anhydride to synthesize 3-O-phthalyl betulinic acid in n-hexane/chloroform. Response surface methodology based on a five-level, four-variable central composite rotatable design was employed to evaluate the effects of synthesis parameters such as reaction time, reaction temperature, enzyme amount and substrate molar ratio on the yield of ester. Based on the response surface model, the optimal enzymatic synthesis conditions were predicted to be: reaction time 20.3 h, reaction temperature 53.9°C, enzyme amount 145.6 mg, betulinic acid to phthalic anhydride molar ratio 1:1.11. The predicted yield was 65.8% and the actual yield was 64.7%

Solubility of Betulinic Acid in Microemulsion System:(Part 2).

Microemulsion has been reported to be an alternative carrier for poor solubility of the compounds in aqueous media. Microemulsion is a stable isotropic liquid mixture of oil, water, surfactant, with or without the combination of a co-surfactant. In this work, the microemulsion was designed by constructing a ternary phase diagram using sodium dodecyl sulphate (SDS) as the surfactant, water as the aqueous media and the carboxylic acids and esters as the co-surfactant. After designing the microemulsion, and constructing the phase diagram, the known isotropic regions were reformulated. Betulinic acid was then solubilized in the isotropic region. For the system containing carboxylic acid, the acetic acid system offered the largest isotropic region and it was found that the microemulsion system obtained was suitable for dissolving betulinic acid. The concentration of betulinic acid dissolved in this system was directly proportional to the percentage of surfactant but inversely proportional to the water percentage

Spectroscopic data of 3-O-acetyl-betulinic acid: an antitumor reagent

In this paper, the spectroscopic data of the 3-O-acetyl betulinic acid is reported. This compound was prepared by enzymatic reaction of betulinic acid and acetic anhydride in the presence of lipase from Candida antarctica (Novozem® 435) at 54oC for 20 h in 79.3 % yield

Anticancer activity of 3-O-acylated betulinic acid derivative obtained by enzymatic synthesis

An easy and efficient strategy to prepare betulinic acid esters with various anhydrides was used by the enzymatic synthesis method. It involves lipase-catalyzed acylation of betulinic acid with anhydrides as acylating agents in organic solvent. Lipase from Candida antarctica immobilized on an acrylic resin (Novozym 435) was employed as a biocatalyst. Several 3-O-acyl-betulinic acid derivatives were successfully obtained by this procedure. The anticancer activity of betulinic acid and its 3-O-acylated derivatives were then evaluated in vitro against human lung carcinoma (A549) and human ovarian (CAOV3) cancer cell lines. 3-O-glutaryl-betulinic acid, 3-O-acetyl-betulinic acid, and 3-O-succinyl-betulinic acid showed IC(50)<10 microg/ml against A549 cancer cell line tested and showed better cytotoxicity than betulinic acid. In an ovarian cancer cell line, all betulinic acid derivatives prepared showed weaker cytotoxicity than betulinic acid

Artificial neural network modeling studies to predict the yield of enzymatic synthesis of betulinic acid ester

3β-O-phthalic ester of betulinic acid was synthesized from reaction of betulinic acid and phthalic anhydride using lipase as biocatalyst. This ester has clinical potential as an anticancer agent. In this study, artificial neural network (ANN) analysis of Candida antarctica lipase (Novozym 435) -catalyzed esterification of betulinic acid with phthalic anhydride was carried out. A multilayer feed-forward neural network trained with an error back-propagation algorithm was incorporated for developing a predictive model. The input parameters of the model are reaction time, reaction temperature, enzyme amount and substrate molar ratio while the percentage isolated yield of ester is the output. Four different training algorithms, belonging to two classes, namely gradient descent and Levenberg-Marquardt (LM), were used to train ANN. The paper makes a robust comparison of the performances of the above four algorithms employing standard statistical indices. The results showed that the quick propagation algorithm (QP) with 4-9-1 arrangement gave the best performances. The root mean squared error (RMSE), coefficient of determination (R2) and absolute average deviation (AAD) between the actual and predicted yields were determined as 0.0335, 0.9999 and 0.0647 for training set, 0.6279, 0.9961 and 1.4478 for testing set and 0.6626, 0.9488 and 1.0205 for validation set using quick propagation algorithm (QP)

Recent development of amino acids and peptides in metal ions detection: an overview

Little work has been reported on the development of solid state metal ion sensor based on the use of amino acids and peptides. This review covers literature on the use of amino acids and peptides (short peptide, oligopeptide and cyclic peptide) as a recognition molecule for metal detection system. Amino acids and peptides offer a high degree of selectivity, good limit of detection and high sensitivity towards detection of metal ion

Optimization of enzymatic synthesis of 3-O-β-D-glucopyranoside betulinic acid by Novozyme-435

The enzymatic synthesis of 3-O-β-D-glucopyranoside betulinic acid using Novozyme-435 as a catalyst was studied. The effects of various parameters such as reaction temperature, reaction time and amount of enzymes were investigated. The optimum reaction conditions for the synthesis of 3-O-β-D-glucopyranoside betulinic acid was obtained using 30.67 h, 54.30°C and 180 mg of enzymes using betulinic acid (0.05 mmol) and glucose (0. 1 mmol) respectively. The actual percentage yield under these conditions was 88.69 % and the predicted value was 89.05 %

Lipase-catalyzed esterification of betulinic acid using phthalic anhydride in organic solvent media: study of reaction parameters

The lipase from Candida antarctica immobilized on an acrylic resin (Novozym 435) was employed for the catalytic reaction of betulinic acid and phthalic anhydride. The influence of different reaction parameters, such as effect of single and mixed solvents, substrate molar ratio, reaction time, temperature, amount of enzyme, effect of inorganic bases and effect of substrate support were investigated and optimized. Optimum conditions to produce 3-O-phthalyl- betulinic acid were observed at reaction time; 24 h, temperature; 55°C, amount of enzyme; 176 mg, substrate molar ratio (betulinic acid: phthalic anhydride, 1:1), inorganic base of K2CO3, amount of celite; 170 mg in 1:1 mixture of chloroform and n-hexane as solvent. At optimum conditions, it gave 61.8% of 3-O-phthalyl- betulinic acid