Procyanidin b1

Cinnamtannin B-1 was purchased from Enzo Life Sciences, Inc., (New York, NY, USA). The target-verified inhibitors including LOPAC1280 used in the inhibition assay were obtained from Sigma-Aldrich Corp., (St. Louis, MO, USA). The PI3K and PKC inhibitors (LY294002 and Gö6983, respectively) were purchased from EMD Millipore Corp., (Billerica, MA, USA). The phospholipase C (PLC), lipoxygenase (LOX), and purine inhibitors (U-73343, nordihydroguaiaretic acid, and azathioprine, respectively) were obtained from Sigma-Aldrich Corp., (St. Louis, MO, USA).
The biflavonoids used were procyanidins and biflavonoids from Cupressus and Garcinia [25 ,26 ], which are similar to the procyanidins. Procyanidin A2, procyanidin B1, and cupressuflavone were obtained from Extrasynthese (Genay, France). For the monomeric flavonoids and polyphenols, (+)-catechin was purchased from Nagara Science Co., Ltd., (Gifu, Japan). Genistein was purchased from Sigma-Aldrich Corp., (St. Louis, MO, USA). Caffeic and gallic acids were obtained from LKT Laboratories, Inc., (St. Paul, MN, USA).

All solvents, reagents, and standards used were of analytical grade. Of these, 99.9% acetonitrile, 36.5–38% hydrochloric acid, >98% formic acid, cyanidin 3-O-galactoside chloride, cyanidin 3-O-arabinoside chloride, peonidin 3-O-galactoside chloride, and peonidin 3-O-arabinoside chloride were obtained from Sigma-Aldrich GmbH (Bethesda, MD, USA). Hyperoside, rutin, quercitrin, phloridzin, procyanidin B1, procyanidin B2, and chlorogenic acid standards were purchased from Extrasynthese (Genay, France), reynoutrin, (+)-catechin, and (−)-epicatechin were obtained from Sigma-Aldrich GmbH (Steinheim, Germany), and avicularin, procyanidin C1, and isoquercitrin were purchased from Chromadex (Santa Ana, CA, USA). Additionally, 96% ethanol was obtained from Stumbras AB (Kaunas, Lithuania), and 2,2-diphenyl-1-picrylhydrazyl (DPPH) was purchased from Vaseline-Fabrik Rhenania (Bonn, Germany). Purified deionized water used in the tests was prepared with the Milli-Q^® (Millipore, Bedford, MA, USA) water purification system.

Acetonitrile, water (HPLC), methylene chloride, ethyl acetate, acetone, ethyl ether, albumin standard, 1-chloro-2,4-dinitrobenzene, nicotinamide adenine dinucleotide phosphate (NADPH) and paraffin wax was obtained from Merck (Germany). Streptozotocin (STZ) was obtained from Sigma Chemicals Co (St. Louis, MO, USA). Referent HPLC standards (chlorogenic acid, vanillic acid, p-coumaric acid, rutin, hyperoside, isoquercetin, ellag-ic acid, kaempferol-3-O-glucoside, morin, resveratrol, quercetin, luteolin, kaempferol, gallic acid, cyanidin chloride, cynanidin-3-O-glucoside, cyanidin-3-O-rutinoside, pro-cyanidin B1, protocatechuic acid, protocatechuic acid ethyl ester, p-hydroxybenzoic acid, epicatechin and phloridzin) (HPLC grade, ≥99% purity) were obtained from Extrasynthese (Lyon, France). The other chemicals were purchased from Sigma-Aldrich, Schnelldorf, Germany.