Butanol

The SCFA concentrations in serum were determined using the acid alcohol methods previously described [34 (link)]. The serum was mixed with an equal volume of butanol (DUKSAN, Seoul, Korea), and HCl was added. The mixture was separated by centrifugation at 15,000 rpm for 15 min at 4 °C and filtered through a 0.45 μm microporous filter. Short-chain fatty acids in the filtrates were detected by gas chromatography (GC, Clarus 680 GAS, PerkinElmer) using an Elite-FFAP 30 m × 0.25 mm × 0.25 μm capillary column, with helium as the carrier gas at a flow rate of 1 mL/min, as previously described [34 (link)].

Ethyl acetate (EA, extra pure grade), dichloromethane (DCM, extra pure grade), methanol (MeOH, extra pure grade), hexanes (extra pure grade) and butanol (extra pure grade) were purchased from Duksan pure chemicals Co. (Ansan, Korea). Acetonitrile (reagent grade), water (reagent grade) and methanol (reagent grade) were purchased from J.T.Baker (Phillipsburg, NJ, USA). Acetone-d6 (deuteration degree min. 99.9%) and dimethyl sulfoxide- d₆ (deuteration degree min. 99.8%) for NMR spectroscopy were purchased from Merck (Darmstadt, Germany). Trifluoroacetic acid (TFA), 1,1-diphenyl-2-picryl hydrazyl (DPPH), 2,2-azino-bis-(3-ethylbenzothiazoline-6-sulfonic acid), and diammonium salt (ABTS+) were purchased from Sigma-Aldrich (St Louis, MO, USA).