Efficient solvent extraction of antioxidant-rich extract from a tropical diatom,Chaetoceros calcitrans (Paulsen) Takano 1968

Objective:To compare thein vitro antioxidant capacity of a diatom,Chaetoceros calcitrans (C. calcitrans) extracted using six types of solvents. Methods:Each extract was evaluated in terms of extraction yield, total carotenoid, fucoxanthin content, total phenolic and antioxidant capacities (DPPH? andABTS?+ scavenging activity and iron chelating activity). Results: The methanol extract exhibited the highest yield [(22.71 ± 0.96) g/100 g dry weight (DW)], total carotenoid [(4.46 ± 0.36) mg/g DW], total phenolic [(2.49 ± 0.08) mg gallic acid equivalents/g DW] and second highest fucoxanthin content [(2.08 ± 0.03) mg fucoxanthin/g DW] as compared to other solvent extracts. Methanolic extract also exhibited significantly higher (P Conclusions: Methanol was the recommended solvent for the production of antioxidant rich extract fromC. calcitrans. Both carotenoids and phenolic acids were found to be positively correlated to the antioxidant capacities ofC. calcitrans. Lead bioactives confirmed by subsequent high performance liquid chromatography studies were fucoxanthin, gallic acid and protocatechuic acid.

Lipase production and growth modeling of a novel thermophilic bacterium: aneurinibacillus thermoaerophilus strain AFNA

Aneurinibacillus thermoaerophilus strain AFNA as a novel isolated extracellular thermostable organic solvent tolerant lipase producing bacterium was employed in the present study. The lipase production of strain AFNA and its correlation with bacterial growth was studied via a modeling assessment by response surface methodology (RSM) and artificial neural network (ANN) techniques. The best achieved models were multilayer full feed forward incremental back propagation network and modified cubic response surface model (mRSM) using backward elimination. The highest lipase specific activity (13.1 Umg-1) and bacterial growth (OD600 = 3.0) were obtained at technically similar: growth temperature (53 and 53ºC), inoculum size (2.6 and 3.0 percent), agitation rate (118 and 115 rpm) and initial pH (7.0 and 7.2) but different medium volume (139 and 87 ml) and incubation period (48 and 38 hrs), respectively. In addition, the importance of effective parameters on the bacterial growth and lipase production was studied where pH and inoculum size were the most and the least effective factors, respectively. Significant correlation between lipase production and bacterial growth was observed when Bivariate correlation was employed to analyse the data. As a conclusion, lipase production was the result of a synergistic combination of effective parameters interactions and these parameters were in equilibrium.

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

3 beta-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).

High performance enzymatic synthesis of oleyl oleate using immobilised lipase from Candida antartica

High performance enzymatic synthesis of oleyl oleate, a liquid wax ester was carried out by lipase-catalysed esterification of oleic acid and oleyl alcohol. Various reaction parameters were optimised to obtain high yield of oleyl oleate. The optimum condition to produce oleyl oleate was reaction time; 5 min, organic solvents of log P is greater than or equal to 3.5, temperature; 40-50 ºC, amount of enzyme; 0.2-0.4 g and molar ratio of oleyl alcohol to oleic acid; 2:1. The operational stability of enzyme was maintained at >90 percent yield up to 9 cycles. Analysis of the yield of the product showed that at optimum conditions, >95 percent liquid wax esters were produced.