Enzymatic water extraction of taxifolin from wood sawdust of Larix gmelini (Rupr.) Rupr. and evaluation of its antioxidant activity

An enzyme incubation-water extraction (El-WE) method was developed and optimised for the extraction of the natural antioxidant taxifolin and of the total flavonoids from wood sawdust of Larix gmelini (Rupr.) Rupr. A factorial design and a central composite design approach were used for method optimisation. Optimal conditions were 0.5 mg/ml cellulase and 0.5 mg/ml pectinase, a pH of 5.0, a temperature of 32 degrees C and 18 h incubation time. The flavonoids and taxifolin were extracted in hot water at 50 degrees C for 30 min, with a solid to liquid ratio of 1:20. Under optimised conditions, the yields of taxifolin and total flavonoids increased from 1.06 +/- 0.08 to 1.35 +/- 0.04 mg/g and 4.13 +/- 0.17 to 4.96 +/- 0.29 mg/g, respectively. DPPH and BHT assays revealed that the El-WE samples had 1.8- and 1.68-fold higher antioxidant activities than the controls. SEM results revealed the structural disruption of wood sawdust with enzyme incubation. (C) 2010 Elsevier Ltd. All rights reserved.