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• W1011659317 abstract "In this study, 3-O-acyl-betulinic acid derivatives were synthesized by the reaction ofbetulinic acid with various anhydrides using lipase as a biocatalyst in organic solvents.The reaction between betulinic acid and phthalic anhydride was chosen as the modelreaction for optimization studies. The immobilized lipase from Candida antarctica(Novozym 435) was selected as a biocatalyst. The effects of different reactionparameters were investigated and optimized in the model reaction using one-variable-ata-time technique for the first time. Optimum conditions to produce 3-O-phthalylbetulinicacid up to 61.8% were observed at a reaction time of 24 hours; amount ofenzyme, 176 mg; betulinic acid to phthalic anhydride molar ratio of 1:1; amount ofcelite, 170 mg and 6 mg of K2CO3 in a mixture of n-hexane-chloroform (1:1, v/v) asorganic solvent at 55'C.The response surface methodology (RSM), based on a five-level, four-variable centralcomposite rotatable design (CCRD), was employed to evaluate the effects of synthesis parameters of the model reaction. Using the RSM analysis, it was observed that themaximum yield of 3-O-phthalyl-betulinic acid (65.8%) could be obtained using 145.6mg of enzyme, reaction temperature of 53.9°C, reaction time of 20.3 hours and betulinicacid to phthalic anhydride molar ratio of 1:1.11. The actual experimental value obtainedwas at 64.7%.Artificial neural network (ANN) was successfully developed to model and predict theenzymatic synthesis of 3-O-phthalyl-betulinic acid. The network consists of an inputlayer, a hidden layer and an output layer. Inputs for the network were reaction time,reaction temperature, enzyme amount and substrate molar ratio, while the output waspercentage isolated yield of ester. Four different training algorithms, belonging to twoclasses, namely gradient descent and Levenberg-Marquardt, were used to train ANN.The best results were obtained from the quick propagation algorithm (QP) with 4-9-1topology. Based on the ANN analysis, the optimal conditions to obtain the highest yieldwere 148.3 mg enzyme, reaction temperature of 53.1°C, reaction time of 20.3 hours andbetulinic acid to phthalic anhydride molar ratio of 1:1.24. The predicted and actualyields were 64.9 and 64.3%, respectively. In this work, the ANN and RSM analysis wereinvestigated on the enzymatic synthesis of 3-O-phthalyl-betulinic acid for the first time.Finally, several betulinic acid esters (compounds 57-66) were synthesized using theoptimal operation conditions which were obtained by the RSM technique. Esterificationof betulinic acid with various anhydrides was performed at 54oC in a mixture of n-hexane-chloroform (1:1, v/v) for 20.3 hours, catalyzed by Novozym 435, gave 24.7 to79.3% yield. Five new compounds (58, 62, 64, 65 and 66) were synthesized for the firsttime in the present study. In brief, the anti-cancer activity of betulinic acid (1) and its 3-O-acylated derivatives(compounds 57-66) were evaluated against human lung carcinoma (A549) and humanovarian (CAOV3) cancer cell lines. In particular, compounds (59), (61) and (63) werefound to show IC50 < 10 μg/ml against A549 cancer cell line tested and showed bettercytotoxicity than betulinic acid. In the ovarian cancer cell line, all betulinic acidderivatives prepared revealed weaker cytotoxicity than betulinic acid." @default.
• W1011659317 created "2016-06-24" @default.
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• W1011659317 date "2010-02-01" @default.
• W1011659317 modified "2023-09-24" @default.
• W1011659317 title "Enzymatic Synthesis of 3-O-Acylbetulinic Acid Derivatives and Prediction of Acylation Using Response Surface Methodology and Artificial Neural Network Analyses" @default.
• W1011659317 hasPublicationYear "2010" @default.
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