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Ferulic acid (FA) is a component of plant cell walls that has applications in food, cosmetic, and health products, but its applications are limited by its high insolubility. We synthesized water-soluble FA derivatives by esterification of FA with diglycerol (DG) using feruloyl esterase purified from a commercial enzyme preparation produced by Aspergillus niger. The major reaction product, FA-DG1, was determined to be γ-feruloyl-α,α'-DG by NMR and electrospray ionization mass spectrometry analyses. FA-DG1 is a sticky liquid whose water solubility (>980 mg/ml) is dramatically higher than that of FA (0.69 mg/ml). Suitable conditions for esterification of FA with DG were 100 mg of FA in the presence of 1 g of DG and 0.1 ml of 1 M phosphate buffer (pH 6.0) at 50 °C under reduced pressure. Under these conditions, 168 mg of feruloyl DGs (FA-DG1, 2, and 3) was obtained, corresponding to a 95 % conversion rate of FA. We also developed a batch method which resulted in synthesis of 729 mg of feruloyl DGs and 168 mg of diferuloyl DGs from 600 mg of FA and 1 g of DG (corresponding to conversion of 69 % of the FA to feruloyl DGs and 21 % of the FA to diferuloyl DGs). As an anti-oxidant, feruloyl DGs were essentially equal to FA and butyl hydroxytoluene in scavenging 1,1-diphenyl-2-picrylhydrazyl radicals. In contrast, the scavenging abilities of diferuloyl DGs were twice those of feruloyl DGs.

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Glyceryl ferulate was synthesized by the condensation of ferulic acid with glycerol using Pectinase PL "Amano" from Aspergillus niger, which contained ferulic acid esterase, to improve the water-solubility of ferulic acid. The optimum reaction medium was glycerol/0.1 M acetate buffer, pH 4.0, (98:2 v/v). The enzyme immobilized onto Chitopearl BCW3003 exhibited the highest activity among the those immobilized onto various kinds of Chitopearl BCW resins. The optimum temperature for the immobilized enzyme was 50 degrees C, and it could be reused at least five times without a significant loss in activity for the synthesis of glyceryl ferulate in batch reaction. Storage of the reaction mixture at 25 degrees C improved the molar fraction of glyceryl ferulate relative to the dissolved ferulic residues.

Ferulic acids have been found in the cell walls of many plant products including maize bran, 1) sugar cane bagasse,2) wheat bran, 3) sugar beet pulp, 4,5) and spinach. 6) In the three former tissues, ferulic acid is esterified to the C 5 of arabinose in arabinoxylan, a 1,4 D xylan to which L arabinofuranosyl residues are attached at position 2 or 3. In contrast, ferulic acids mainly attach to the C 2 position of 1,5 linked arabinofuranose residues or the C 6 of 1,4 linked galactopyranose residues in the hairy region of pectins of sugar beet and spinach. 7,8) Recently, Levigne et al. demonstrated that ferulic acid is also linked to the C 5 position of arabinofuranose residues in sugar beet pectin by analysis of the structures of feruloylated oligosaccharides obtained by treating sugar beets with a commercial enzyme preparation (Driselase). 9) Furthermore, some ferulic acids exist as dehydrodimers (e.g. 5 5 dehydrodiferulic acid) in the cell walls of several plant species, which are formed through an oxidation reaction catalyzed by peroxidases.10,11) Possible roles of ferulic acid in plant cell walls are to decrease the digestibility of the cell wall by microorganisms 12) and to regulate cell growth 13) by cross linking cell wall polysaccharides.Ferulic acid esterases (FAEs) are enzymes that catalyze the hydrolysis of ester linkages between ferulic acids and sugars or alcohols. The number of studies concerning microbial FAEs has been increasing in the last ten years and many FAEs have been isolated and characterized. In the utilization of agro industrial wastes such as sugar beet pulp, effective degradation of plant cell walls requires FAEs for the release of ferulic acid as well as polysaccharidases such as xylanases 14) and arabinanases. 15) Moreover, ferulic acid has several potential applications: it may be useful as an anti oxidizing agent, 16,17) an anti inflammatory drug, 18,19) and a food preservative that inhibits microbial growth. 20,21) Enzymatic extraction of ferulic acid from industrial wastes has been studied. Penicillium funiculosum FAEB releases 98% of esterified ferulic acid from wheat bran in the presence of xylanase and releases 35% of esterified ferulic acid from sugar beet pulp in the presence of a mixture of endo arabinanase and L arabinofuranosidase. 22) To the best of our knowledge, that releases more ferulic acid from sugar beet pulp than any other enzyme.In this paper we describe the screening of microorganisms that can achieve high yield extraction of free ferulic acid from sugar beet pulp. In addition, we describe the isolation and some of the characteristics of a novel FAE, termed FAE 1, produced by P. chrysogenum 31B. MATERIALS AND METHODS Chemicals and reagents.ResourceQ 6 mL, ResourceS 6 mL, MonoQ HR 5 5, MonoS HR 5 5 and HiLoad 16 60 Superdex 75 columns were purchased from Amersham Biosciences. All other chemicals were from Wako Pure Chemical Industries, Ltd. (Osaka) unless otherwise stated, and were of certified reagent grade.Organism and cultivation conditions. The microorganisms...