6 g, K2HPO4 1.85 g, 1% (v/v) reducing solution (30 g/l check details L-aminothiopropionic acid and Akt inhibitor 30 g/l sodium hyposulfite, dissolved in PBS), and 1 g NH4Cl. Medium C was the same as medium B except the absence of any nitrogen source. Culture was conducted as follows: 0.3 g of defatted flaxseeds was added into each of tubes containing either medium A, B or C (3 ml), which were then sealed with liquid paraffin and autoclaved at 121°C for 15 min. Into the medium, 0.3 g of fresh human feces was added and incubated at 37°C for 72
h. Supernatant of the cultures was then inspected for the appearance of END. Collection and processing of fecal samples Initially, fresh fecal specimens (ca. 4.0 g each), obtained from 28 healthy young subjects (fourteen females and fourteen males, 22-33 years old), were suspended in 20 ml sterile phosphate buffer saline (PBS, 2.6 g l-1 KH2PO4, 1.85 g l-1 K2HPO4, PH 7.4) and 2 ml such fecal suspension was transferred to 20 ml medium, followed by incubation at 37°C for 36 h. During the fecal collection and culture preparation, no strictly anaerobic techniques or instruments were used. The fecal specimen that we used for END production was from a 33 years old female. High-performance liquid chromatography
(HPLC) The HPLC system consisted of Agilent 1200 series HPLC selleck screening library apparatus (Agilent Technologies, USA), including high-pressure binary-gradient solvent-delivery pump, DAD detector, autosampler, thermostat column compartment and chemstation (9.01 edition). Niclosamide Zorbax SB-C18 column (4.6 mm × 250 mm, 5 μm) was used to analyze all of the samples. Mobile phase consisted of
water (A) and acetonitrile (B) in a linear gradient change from 100% A to 50% A and 50% B in 30 min. Detection wavelength was 280 nm, and the temperature of the column oven was 25°C with a flow rate of 1.0 ml min-1. Calibration of the END and SECO curves The stock solutions of END standard (1.98 mg ml-1) and SECO standard (175.5 μg ml-1) were prepared by accurately weighing and transferring each of them into a volumetric flask (1 ml) and dissolving it in methanol. Solutions for END calibration (0.0198 ~ 1.98 mg ml-1) and SECO calibration (175.5 ~ 2.74 μg ml-1) were prepared by dilution of the stock solutions with methanol, with six dilution series being analyzed (1.98, 0.99, 0.396, 0.198, 0.099, 0.0198 mg ml-1) for END calibration and seven dilution series being analyzed (175.5, 87.75, 43.86, 21.94, 10.97, 5.48, 2.74 μg ml-1) for SECO calibration. For each calibration curve, independent dilutions were analyzed. The calibration equation of END was obtained by plotting HPLC peak areas (Y) versus the concentration of calibrators (X, mg ml-1), which was as follows: Y = 4433.46 X + 63.86 (R2 = 0.9999), with a good linearity over the range from 0.0198 mg ml-1 to 1.