4 hydroxyphenyl acetate

Restriction enzymes, DNA polymerase, T4 polynucleotide kinase, and T4 DNA ligase were purchased from Takara Bio, Inc. (Dalian, China). Hieff Clone^TM Plus Multi One Step Cloning Kit was purchased from YEASEN Biotechnology Co., Ltd. (Shanghai, China). Oligonucleotides were purchased from Life Technologies (Shanghai, China). 4-Hydroxyphenylacetate, tyrosine, tyrosol, hydroxytyrosol, tyramine, dopamine, 3,4-DHPAA, 4HPAA, sodium periodate, dansylcholoride, and NADH were all purchased from Sigma-Aldrich (St. Louis, USA).
Escherichia coli strain MC1061, BL21(DE3), and BW25113 were used for cloning, protein overexpression, and hydroxytyrosol biosynthesis, respectively. Strains were grown at 37 °C. Kanamycin (50 μg/mL) were supplemented when necessary. Hydroxytyrosol biosynthesis was performed in yeast extract M9Y medium (M9 minimal salts (Becton, Dickinson and Company), 1% (w/v) glucose, 5 mM MgSO₄, 0.1 mM CaCl₂ supplemented with 0.025% (w/v) of yeast extract)^{14 (link)}, while other cultures were done in Luria-Bertani (LB) medium if not specially indicated.

Solvents of HPLC grade were purchased from Carlo Erba Reagents (Milan, Italy), while solvents of analytical grade were obtained from VWR International s.r.l. (Milan, Italy). Acarbose was purchased from Serva (Heidelberg, Germany). Folin-Ciocalteu reagent, Tween 20, ascorbic acid, butylated hydroxytoluene (BHT), sulphuric acid, sodium carbonate, propyl gallate, 2,2-diphenyl-1-picrylhydrazyl (DPPH), tripyridyltriazine (TPTZ), 2,2′-azino-bis (3-ethylbenzothiazoline-6-sulfonic) acid (ABTS) solution, β-carotene, linoleic acid, orlistat, 4-nitrophenyl octanoate (NPC), maltose, α-amylase from porcine pancreas, α-glucosidase from Saccharomyces cerevisiae, o-dianisidine dihydrochloride, 4-nitrophenyl octanoate (NPC), porcine pancreatic lipase, peroxidase/glucose oxidase (PGO), hydroxytyrosol, tyrosol, 4-hydroxyphenyl acetate, vanillic acid, caffeic acid, p-coumaric acid, ferulic acid, verbascoside, luteolin, and oleuropein were purchased from Sigma-Aldrich S.p.a. (Milan, Italy).

Solvents of analytical grade were obtained from VWR International s.r.l. (Milan, Italy), solvents of HPLC grade were purchased from Carlo Erba Reagents (Milan, Italy). Acarbose was obtained from Serva (Heidelberg, Germany). Tween 20, ascorbic acid, Folin-Ciocalteu reagent, butylated hydroxytoluene (BHT), sulfuric acid, sodium carbonate, orlistat, 4-nitrophenyl octanoate (NPC), propyl gallate, 2,2-diphenyl-1-picrylhydrazyl (DPPH), β-carotene, tripyridyl triazine (TPTZ), 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonic) acid (ABTS) solution, maltose, vanillic acid, linoleic acid, 4-nitrophenyl octanoate (NPC), α-amylase from porcine pancreas, porcine pancreatic lipase, α-glucosidase from Saccharomyces cerevisiae, o-dianisidine dihydrochloride, peroxidase/glucose oxidase (PGO), caffeic acid, hydroxytyrosol, verbascoside, tyrosol, 4-hydroxyphenyl acetate, p-coumaric acid, ferulic acid, and oleuropein were purchased from Sigma-Aldrich S.p.a. (Milan, Italy).