Jean-Claude Sapis

Analytical methods for monoterpene glycosides in grape and wine. II. Qualitative and quantitative determination of monoterpene glycosides in grape.

Free and glycosidically bound terpenes of five Vitis vinifera grape cultivars (muscat of Alexandria, muscat of Frontignan, muscat of Hamburg, muscat Ottonel and Gewürztraminer) were investigated. The free and bound fractions were separated by selective retention on Amberlite XAD-2 resin. The glycosidic fractions were analysed by gas chromatography and gas chromatography-mass spectrometry using either enzymic hydrolysis and subsequent analysis of the released aglycones or trimethylsilyl (TMS) and trifluoroacetyl derivatives. The known monoterpenyl, benzyl and 2-phenylethyl beta-D-glucopyranosides, beta-rutinosides, 6-O-alpha-L-arabinofuranosyl-beta-D-glucopyranosides and 6-O-beta-D-apiofuranosyl-beta-D-glucopyranosides were determined. A number of other glycosides were detected and the structures of some of them, mainly apiosylglucosides and glucosides with aglycones in higher oxidation state than linalol, were tentatively identified using the mass spectra of their TMS and TFA derivatives and the results obtained from the analysis of their aglycones.

Enzymatic synthesis of monoterpenyl β-D-glucosides by various β-glucosidases

Abstract β-glucosidases from Aspergillus niger, Trichoderma reesei, Candida molischiana , and almond have been shown to catalyze synthesis of β-glucosides of primary monoterpene alcohols, such as geraniol, nerol, and citronellol, using cellobiose as carbohydrate donor. Enzymes had the strongest glucosyl transferase activity for geraniol. Glucosylation of (±)-citronellol was nonselective. Among organic solvents tested, 30% acetone in enzyme assay gave the highest yield in glucoside synthesis. Monoterpene alcohols, such as linalool, α-terpineol, and menthol, were not used as acceptors in transglycosylation reactions.

Multiple forms of glycosidases in an enzyme preparation from Aspergillus niger: Partial characterization of a β-apiosidase

Abstract Chromatofocusing on PBE 94 of a crude enzyme preparation from Aspergillus niger showed the presence of multiple forms of β-apiosidase, β-glucosidase, α-rhamnosidase, and α-arabinofuranosidase. A β-apiofuranosidase from the enzyme preparation was purified 27-fold by gel filtration and ion-exchange chromatography. The molecular mass of the enzyme and the Km value for p-nitrophenyl-β- d -apiofuranoside were 84,000 and 3.3 m m , respectively. The optimum pH and temperature for the enzyme activity were between pH 5.0–6.0 and 50–60°C, respectively. The enzyme was stable up to 50°C and between pH 4.0–7.0. Geranyl, linalyl apiosylglucosides, aroma precursors in grape, and a flavone apiosylglucoside were the substrates for the β-apiosidase.

Hydrolysis of monoterpenyl-β-d-glucosides by cloned β-glucosidases from Bacillus polymyxa

Abstract Two β-glucosidases, encoded by genes designated as bglA and bglB from Bacillus polymyxa , have been studied for the hydrolysis of monoterpenyl (linalool, α-terpineol, geraniol, nerol, and citronellol), benzyl, and 2-phenylethyl β- d -glucosides. β-Glucosidases were produced in Escherichia coli transformant strains carrying the cloned B. polymyxa genes and purified by ion-exchange, gel filtration, and hydrophobic chromatography. Among monoterpenyl glucosides, the highest activity was for geranyl-β- d -glucoside. β-Glucosidase encoded by the bglA gene was more active toward the glucosidic substrates studied than β-glucosidase encoded by the bglB gene. β-glucosides of tertiary alcohols such as linalool and α-terpineol were not substrates for these enzymes.