Formic acid

Lipopolysaccharide (LPS), 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT), dimethylsufoxide (DMSO) were purchased from Sigma Chemical Co. (St. Louis, Mo, USA). Dulbecco’s modified Eagle’s medium (DMEM) and fetal bovine serum (FBS) were produced by Gibco BRL (Grand Island, NY, USA). Enhanced Bradford protein assay kit was obtained from Beijing Biomed Co. (Beijing, China). Phenylmethylsulfonyl fluoride (PMSF) and the components of the whole cell lysis buffer for Western blot analysis were purchased from Sigma Chemical Co. (St. Louis, MO, USA). The Griess reagent kit was from Beyotime Chemical Co. (Jiang su, china). Mouse PGE₂ ELISA kit was from Blue Gene Biological Technology Co. (Shanghai, China) and TNF-α, IL-1β and IL-6 ELISA kits were from Multi Sciences Biological Technology Co. (Hangzhou, China). Antibodies for iNOS, COX-2, β-actin, phosphor-NF-κB p65, NF-κB p65, phosphor-IκBa, IκBa, phospho-ERK1/2, ERK1/2, phospho-p38, p38, phospho-JNK/SAPK and JNK/SAPK were obtained from Cell Signaling Technology (Danvers, MA, USA). Acetonitrile (HPLC grade) was purchased from Fisher Scientific (Fair Lawn, NJ, USA) and the other solvents such as formic acid (analytical grade) from Tianjin Guangfu Fine Chemical Research Institute (Tianjin, China). All other chemicals used in the experiments were commercial products of reagent grade.

Rheum palmatum L., Coptis chinensis Franch., Curcuma longa L., Lysimachia christinae Hance, Alisma orientale (Sam.) Juzep. and Panax notoginseng (Burk.) F. H. Chen were purchased from Beijing Tongrentang Co., Ltd. (Hefei, China) and authenticated by Doctor Rongchun Han (College of Pharmacy, Anhui University of Chinese Medicine, Hefei, China). All voucher specimens were deposited at the authors' laboratory. The reference standards, including berberine hydrochloride, physcion, emodin, alisol B 23-acetate, quercetin and notoginsenoside R₁, were obtained from the National Institutes for Food and Drug Control (Beijing, China). Chrysophanol, rhein, aloe-emodin and kaempferide were obtained from Beina Chuanglian Biotechnology Research Institute (Beijing, China). Curcumin was isolated in our laboratory with a purity of more than 98% by HPLC, and its structure and molecular weigh have been identified by using several spectral analyses and MS, respectively. Acetonitrile and methanol (LC-MS grade) were purchased from TEDIA (Fairfield, USA). Formic acid was obtained from Tianjin Guangfu Fine Chemical Research Institute (Tianjin, China). Ultrapure water was purified using a Milli-Q water purification system (Millipore, Billerica, MA, USA).