3 hydroxybenzyl alcohol

All chemicals including gallic acid, Folin-Ciocalteu reagent, sodium carbonate (Na₂CO₃), hydrogen peroxide (H₂O₂), sulfuric acid (H₂SO₄), xylenol orange, Iron(II) sulphate (FeSO₄), butylated hydroxytoluene (BHT), tris(hydroxymethyl)aminomethane (Tris), glycine, citrate, urea, hydrochloric acid (HCl), Trolox, bathocuproinedisulfonic acid sodium salt (BCS), copper(II) chloride (CuCl₂), methanol, formic acid, acetonitrile, l-histidine, (S)-dihydroorotate, shikimate, 4-pyridoxate, 3-hydroxybenzyl alcohol, 2,5-dihydroxybenzoate, 3-hydroxybenzaldehyde, trans-cinnamate, estradiol-17α, deoxycholate, retinoate, oleic acid, and heptadecanoate were of analytical grade and from Sigma-Aldrich (St. Louis, MO, USA). 96 well plates were from Greiner UV-Star (Greiner Bio-One, Frickenhausen, Germany).
Tris-glycine-urea buffer pH 7 contained 0.086 M Tris, 0.09 M glycine, 4 mM citrate, and 8 M urea, adjusted to pH 7 using 2 M HCl. Ferrous ion oxidation-xylenol orange (FOX) reagent contained 25 mM H₂SO₄ containing 0.1 mM xylenol orange, 0.25 mM FeSO₄, and 4 mM BHT in 90% methanol.

Analytical standards of 2,5-dihydroxybenzaldehyde (compound 2; 98% purity), m-cresol (3; 99% purity), 3-hydroxybenzyl alcohol (4; 99% purity), toluquinol (5; ≥98% purity), 3-hydroxybenzaldehyde (6; ≥99% purity), 3-hydroxybenzoic acid (7; 99% purity), 2,5-dihydroxybenzoic acid (8; 98% purity), 2,4-dihydroxybenzaldehyde (10; 98% purity), 3,4-dihydroxybenzaldehyde (11; 97% purity), 3,5-dihydroxybenzaldehyde (12; 98% purity), 2-hydroxybenzaldehyde (13; 98% purity), and 4-hydroxybenzaldehyde (14; 98% purity) were procured from Sigma-Aldrich, Seoul, Korea. Methanol, acetone, and water used for the following experiments were of high-performance liquid chromatography (HPLC) grade.

4-Hydroxy-3,5-dimethoxybenzyl alcohol was from Alfa Aesar (Haverhill, MA, USA). 4-n-Butylphenol and 4-n-nonylphenol were from Lancaster Synthesis (Haverhill, MA, USA). Ferrous sulphate heptahydrate was from Merck (Burlington, MA, USA). 4-Allylphenol (chavicol) was from Quest International (Naarden, The Netherlands). 4-Allylphenol-2,6-dimethoxyphenol, 4-allyl-2-methoxyphenol (eugenol), 4-(aminomethyl)-2-methoxyphenol hydrochloride (vanillyl amine), 4-sec-butylphenol, 4-cyclohexylphenol, 4-cyclopentylphenol, 4-ethylphenol, 4-n-hexylphenol, 2-hydroxy-benzyl alcohol, 3-hydroxybenzyl alcohol, 4-hydroxybenzyl alcohol, 4-hydroxy-2-methoxybenzyl alcohol, 4-hydroxy-3-methoxybenzyl alcohol (vanillyl alcohol), 5-indanol, 4-isopropylphenol, 2-methoxy-4-methylphenol (para-creosol), 4-methylphenol (para-cresol), 4-n-pentylphenol, 4-n-propylphenol, 5,6,7,8-tetrahydronaphthol and xylenol orange tetrasodium salt were from Sigma-Aldrich (St. Louis, MO, USA). All other chemicals were from commercial sources and of the purest grade available. The pJ404-His-VAO and pBAD-EUGO-His plasmids were a kind gift from Prof. Dr. Marco Fraaije (University of Groningen).