Octyl gallate

Acetonitrile (ACN) LCMS-grade solvent was purchased from Merck (Darmstadt, Germany). Highly purified water was prepared with a Millipore Milli-Q Plus water purification system. Octyl gallate, analytical standard, was purchased from Sigma, Rehovot, Israel.

Curcumin, Gallic acid, Sodium gallate, Ethyl gallate, Octyl gallate, Catechin, Catechin gallate, EpigalloCatechin, EpigalloCatechin gallate, Metformin, Testosterone, L-Arginine and insulin were purchased from Sigma.
Osteocalcin was purified from bovine tibial bone extracts [24 (link)]. Briefly, cortical bone was obtained from the central section of the tibia of freshly slaughtered bovine from Piggly Wiggly (Memphis, TN). Bone samples were freed of marrow and connective tissue, ground to a particle size that passed through a 210-μm sieve, and washed with several changes of water for 24 hr at 4 °C. The bone was then dialyzed against several changes of 0.5 M EDTA, pH 8, at 4 °C for 8–10 days. The soluble fraction inside the dialysis sack was collected by centrifugation, dialyzed exhaustively against 5 mM NH4HCO3, and lyophilized. After gel filtration on Sephadex G-100, peak fractions containing the osteocalcin were lyophilized and then chromatographed on a 2 X 50 cm column of DEAE-Sephadex A25 at 25 °C with a linear gradient in 0.1 M Tris-HCI, pH 8.0, from 0 to 0.75 M NaCl. Decarboxylated osteocalcin was produced by treating osteocalcin in vacuo at 110 °C [25 (link)]. The purity and decarboxylation state were confirmed by native gel electrophoresis, or by blotting followed by reaction with DBS staining for γ-carboxyglutamic acid [26 (link)].

The polymers used for the study were biodegradable aliphatic polyesters: PLA and polymer P(3,4HB) 2001 from the PHA group of polymers. PLA (IngeoTM Biopolymer 4043D PLA) was bought from Nature WorksTM (Minnetonka, MN, USA) and had the following properties: T_g = 55–60 °C, T_m = 145–160 °C, and Melt Flow Index MFI = 6 g/10 min; PLA contained 4.8 % D-lactide and had an average molecular weight (M_w) of 200 kDa. PHA was obtained from Simag Holdings LTD (Hong Kong, China) and had the following properties: P(3,4HB) containing 12 mol % 4-hydroxybutyrate, average M_w of approximately 520 kDa, MVR = 15–20 g/10 min, (assay conditions: temperature 170 °C, nominal load 2.16 kg), and density of 1.25 g/cm³. The configuration of the 3HB component in the copolymer was R-3HB.
Gallates (ethyl gallate M_w = 198.17 g/mol, antioxidant, ≥96.0% (HPLC); propyl gallate M_w = 212.20 g/mol, antioxidant, ≥98.0% (HPLC); octyl gallate M_w = 282.33 g/mol, antioxidant, ≥99.0% (HPLC), and lauryl gallate M_w = 338.44 g/mol, antioxidant, ≥99.0% (HPLC)) were obtained from Sigma Aldrich (Steinheim, Germany). Figure 1 shows the structural formulas of the polymers and gallates used.