Metabolic Transformation of Gentiopicrin, a Liver Protective Active Ingredient, Based on Intestinal Bacteria

Gentiopicrin, the main component of the famous Chinese patent medicine Long Dan Xie Gan Wan, has the characteristics of fast absorption in vivo and low bioavailability. Intestinal bacteria play an important role in the absorption and pharmacokinetics of oral drugs. In this study, the metabolic transformation of gentiopicrin by intestinal bacteria was examined. High-performance liquid chromatography coupled with ion trap time-of-flight mass spectrometry (LC/MSn-IT-TOF) and nuclear magnetic resonance (NMR) were used, and six metabolites were identified, including reduction products (G-M1, G-M2, G-M4, and G-M6), a hydrolytic product (G-M3), and a dehydration product (G-M5) of gentiopicrin aglycone after hydrolysis, reduction, and dehydration reactions were performed by the intestinal flora. This is the first time that chiral metabolites of gentiopicrin (G-M1 and G-M2) were found in this study. In addition, the precursors of glucuronic acid conjugates previously reported in vivo may have come from the intestinal bacterial metabolites G-M1, G-M2, and G-M3. In addition, the metabolic transformation of gentiopicrin in liver microsomes was studied in vitro, and it was found that gentiopicrin did not undergo metabolic transformation under the action of liver microsomes. It is suggested that gentiopicroside may be metabolized in the intestine. This study provides both new insight regarding the investigation of effective substances and an exploration of the pharmacodynamic and toxicological properties of gentiopicrin.

Separation and Analysis of Oxygen-Containing Compounds in a Shaanxi Middle/Low-Temperature Coal Tar

A middle/low-temperature coal tar (M/LTCT) was obtained from a low-temperature carbonization plant in Shaanxi, China. The M/LTCT was separated into light components and coal tar pitch through extraction. A series of alkanes, aromatic hydrocarbons, oxygen-containing arenes (OCAs), and nitrogen-containing arenes were fractionated from light components by medium-pressure preparative chromatography with gradient elution using petroleum ether and ethyl acetate. They were analyzed using a gas chromatography-mass spectrometer (GC-MS) and a Fourier transform infrared spectrometer. The OCAs were analyzed by a Fourier transform Orbitrap MS (quadrupole exactive Orbitrap mass spectrometer), and the molecular distribution of the O ₁-O ₆ species was studied. OCAs are mainly oxygen-containing aromatic compounds, including aromatic phenols, furans, alkoxy aromatic hydrocarbons, aromatic ethers, aromatic aldehydes, aromatic ketones, and aromatic acids. The position of the oxygen atom on the aromatic ring and the condensation form of the aromatic ring are studied.