Continuous Production of Lipase-Catalyzed Biodiesel in a Packed-Bed Reactor: Optimization and Enzyme Reuse Study

An optimal continuous production of biodiesel by methanolysis of soybean oil in a packed-bed reactor was developed using immobilized lipase (Novozym 435) as a catalyst in a tert-butanol solvent system. Response surface methodology (RSM) and Box-Behnken design were employed to evaluate the effects of reaction temperature, flow rate, and substrate molar ratio on the molar conversion of biodiesel. The results showed that flow rate and temperature have significant effects on the percentage of molar conversion. On the basis of ridge max analysis, the optimum conditions were as follows: flow rate 0.1 mL/min, temperature 52.1°C, and substrate molar ratio 1 : 4. The predicted and experimental values of molar conversion were 83.31 ± 2.07% and 82.81 ± .98%, respectively. Furthermore, the continuous process over 30 days showed no appreciable decrease in the molar conversion. The paper demonstrates the applicability of using immobilized lipase and a packed-bed reactor for continuous biodiesel synthesis

Continuous Production of Lipase-Catalyzed Biodiesel in a Packed-Bed Reactor: Optimization and Enzyme Reuse Study

An optimal continuous production of biodiesel by methanolysis of soybean oil in a packed-bed reactor was developed using immobilized lipase (Novozym 435) as a catalyst in a tert-butanol solvent system. Response surface methodology (RSM) and Box-Behnken design were employed to evaluate the effects of reaction temperature, flow rate, and substrate molar ratio on the molar conversion of biodiesel. The results showed that flow rate and temperature have significant effects on the percentage of molar conversion. On the basis of ridge max analysis, the optimum conditions were as follows: flow rate 0.1 mL/min, temperature 52.1 degrees C, and substrate molar ratio 1 : 4. The predicted and experimental values of molar conversion were 83.31 +/- 2.07% and 82.81 +/- 98%, respectively. Furthermore, the continuous process over 30 days showed no appreciable decrease in the molar conversion. The paper demonstrates the applicability of using immobilized lipase and a packed-bed reactor for continuous biodiesel synthesis

Feasibility of corifollitropin alfa/GnRH antagonist protocol combined with GnRH agonist triggering and freeze-all strategy in polycystic ovary syndrome patients

Background/Purpose: The long-acting corifollitropin alfa is comparable to FSH in terms of pregnancy outcomes in normal responders and poor responders. Corifollitropin alfa has never been studied in polycystic ovary syndrome (PCOS) patients because of concerns of excessive ovarian stimulation and ovarian hyperstimulation syndrome (OHSS). The purpose of the study was to evaluate if corifollitropin alfa can be used in PCOS patients. Methods: Forty PCOS patients who were going to undergo in vitro fertilization were enrolled in this study. A single injection of corifollitropin alfa was administered on cycle day 2 or day 3. From stimulation day 8 onwards, daily FSH was administered until the day of final oocyte maturation. Cetrorelix was administered from stimulation day 5 to prevent premature LH surge. Final oocyte maturation was triggered by: acetate. All embryos were cryopreserved and replaced in subsequent cycles. Results: All 40 patients were subjected to oocyte retrieval, and none developed moderate or severe ovarian hyperstimulation syndrome (0%, 95% CI 0–0.088). For each patient, an average of 23.4 (±7.4; 95% CI 21.0–25.7) oocytes were retrieved and a mean of 11.7 (±6.4; 95% CI 9.6–13.8) embryos were frozen. Mean serum estradiol level on the day of GnRHa triggering was 7829.9 pg/ml (±3297; 95% CI 6775–8885). The cumulated ongoing pregnancy rate after 3 frozen-thawed embryo transfers was 75.0% (95% CI 61.6%–88.4%). Conclusion: The results suggest that corifollitropin alfa/GnRH antagonist protocol can be used in PCOS patients, in combination with GnRHa triggering and embryo cryopreservation. Keywords: Corifollitropin alfa, Cryopreservation, GnRH agonist, Polycystic ovary syndrom

Enzymatic synthesis of rose aromatic ester (2-phenylethyl acetate) by lipase

BACKGROUND: 2-Phenylethyl acetate (2-PEAc) is a highly valued natural volatile ester with a rose-like odour that is widely used to add scent or flavour to cosmetics, soaps, foods and drinks. In this study, 2-PEAc was synthesised enzymatically by transesterification of vinyl acetate with 2-phenethyl alcohol catalysed by immobilised lipase (Novozym 435) from Candida antarctica. RESULTS: Response surface methodology and a three-level/three-factor Box–Behnken design were used to evaluate the effects of time, temperature and enzyme amount on the molar conversion % of 2-PEAc. The results showed that temperature was the most important variable. Based on the ridge max analysis results, optimum enzymatic synthesis conditions were predicted as a reaction time of 79 min, a temperature of 57.8 ◦C and an enzyme amount of 122.5 mg. The predicted and experimental yields were 86.4 and 85.4% respectively. CONCLUSION: Three immobilised lipases were screened and 15 reaction conditions were tested in order to find the combination for maximum yield. The optimisation of 2-PEAc synthesis catalysed by Novozym 435 was successfully developed. The kinetic study of this transesterification reaction showed that it followed an ordered ping-pong bi-bimechanism without any inhibition by reactants

Optimization of Lipase-Catalyzed Synthesis of Cetyl Octanoate in Supercritical Carbon Dioxide

Cetyl octanoate, a wax ester of 24 carbons, is widely used in the cosmetic industry as a base oil. The current work focuses on lipase-catalyzed synthesis of cetyl octanoate in supercritical carbon dioxide (SC-CO2) by esterification of cetyl alcohol and octanoic acid. Three immobilized lipases were screened, and 15 reaction conditions were tested in order to find the combination for maximal yield. The results showed that Novozym 435 was the best catalyst for the synthesis, and a reaction time of 20 min was adequate for a maximal yield. Response surface methodology (RSM) with a 3-factor- 3-level Box-Behnken design was employed to evaluate the effects of synthesis parameters, including reaction temperature (35–75 C), pressure (8.27–12.41 MPa), and enzyme amount (5–15% wt of cetyl alcohol). A model for the synthesis was developed and the optimum conditions could be predicted to be reaction pressure of 10.22 MPa, reaction temperature of 63.70 C, and enzyme amount of 11.20%. An experiment was performed under this optimum condition and a yield of 99.5% was obtained. This experimental yield correlated well with the predicted value of yield (97.6%). We concluded that, in a SC-CO2 system, nearly 100% molar conversion of cetyl octanoate could be obtained by immobilized Novozym 435 in a short reaction time (20 min) under the predicted optimal conditions

Tumor cell expression of podoplanin correlates with nodal metastasis in esophageal squamous cell carcinoma

Podoplanin is a mucin-like glycoprotein expressed in the lymphatic endothelium. It has been suggested to play a role in lymphangiogenesis, since podoplanin deficient mice were found to have dilated malfunctioning lymphatic vessels and lymphedema. High podoplanin expression in tumor cells was found to correlate with lymph node metastasis and poor clinical outcome in patients with oral squamous cell carcinoma (SCC). However, the prognostic significance of podoplanin expression in esophageal SCC remains unexplored. Herein, we studied podoplanin expression in 59 patients who underwent surgical resection of esophageal SCC, with 43 of them preceded by preoperative concurrent chemoradiotherapy (CCRT). We found that high podoplanin expression strongly correlated with clinical nodal metastasis (cN1; p=0.0063), which was associated with short survival (p=0.012). However, there was no direct association between high podoplanin expression and short survival. We also found that lymphatic vessel invasion in the resected esophagus was strongly associated with pathological nodal metastasis (pN1; p=0.00092). Our results suggest that podoplanin could also play a role in tumor aggressiveness in esophageal SCC, as well as in oral SCC