L tyr

BA standards (tyramine hydrochloride, 2-phenylethylamine hydrochloride, putrescine dihydrochloride, cadaverine dihydrochloride, histamine dihydrochloride, tryptamine hydrochloride, spermidine trihydrochloride) and amino acid standards (L-Asp, L-Glu, L-Ser, L-Gly, L-His, L-Thr, L-Arg, γ-aminobutyric acid [GABA], L-Ala, L-Pro, L-Tyr, L-Val, L-Met, L-Iso, L-Leu, L-Phe, L-Trp, and L-Lys) were all purchased from Sigma-Aldrich Chemical Co. (St. Louis, MO, USA). Dansyl chloride, perchloric acid, sodium hydrogen carbonate, potassium dichromate, and silver nitrate were purchased from Daejung Chemical Co. (Siheung, Korea). Distilled water, acetone, and acetonitrile (HPLC grade) were purchased from Tedia Co. (Fairfield, OH, USA).

Velvet antlers (Cervus elaphus Linnaeus) were obtained from male red deer that were bred at the Daxing’an Mountain range (Heilongjiang, China). Samples were freeze-dried, homogenized, and stored at 4°C. Pepsin (EC 3.4.23.1, ≥ 2500 U/mg), pancreatin (8× USP specifications), LPS, protease inhibitors cocktail, Sephadex G-15, 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT), and L-Tyr were purchased from Sigma–Aldrich (Shanghai, China). Murine macrophage cell line RAW 264.7 (ATCC TIB-71) was purchased from Cell Culture Center of Institute of Basic Medical Sciences Chinese Academy of Medical Sciences (Beijing, China). Dulbecco’s modified Eagle’s medium and fetal bovine serum were purchased from Gibco BRL (Grand Island, NY, USA). Penicillin–streptomycin and NO Assay kit were purchased from Beyotime Biotechnology (Shanghai, China). HPLC-grade acetonitrile was purchased from Mallinckrodt Baker (Phillipsburg, NJ, USA). All other chemicals were of analytical grade unless otherwise mentioned.