Identification of Metabolites of Turmeric Extract in Rats by UPLC-Q-Extractive Orbitrap MS

Turmeric extract is a β-diketone polyphenol extract isolated from the Curcuma longa L, a plant of the genus Curcuma of the Zingberaceae family. It mainly includes curcumin (CUR), demethoxycurcumin (DMC), and bisdemethoxycurcumin (BDMC). It is a commonly used food, natural pigment and cosmetic additive, which has various pharmacological activities, such as hypolipidemia, antioxidant, anti-inflammation, antiviral and anti-Alzheimer's disease. However, poor stability and low bioavailability limit the clinical application of curcuminoids. Curcumin hydrogenated metabolites also have pharmacological activity, and they are more stable and bioavailable than curcumin. The metabolites of curcuminoids (CUR, DMC and BDMC) in turmeric extract in rats were identified. Turmeric extract was suspended in 0.5% carboxymethlcellulose sodium (CMC-Na). Healthy male Sprague Dawley (SD) rats in drug group were gavaged with a single dose of 1 703 mg/kg turmeric extract (approximately 480 mg/kg curcuminoids), and the rats in control group were given equal volume of 0.5% CMC-Na solution. And then, plasma at different time points was collected after oral gavage. Urine, faeces and bile were collected after oral gavage in rats within 12 h. Plasma were prepared by protein precipitation method, the urine, faeces and bile were extracted by methanol. The biological samples of faeces, urine, bile and plasma were analyzed by ultra high per-formance liquid chromatography-quadrupole extractive orbitrap mass spectrometry (UPLC-Q-Extractive MS) in negative ion mode. The accurate molecular weight, primary and secondary mass spectrometry information of metabolites in faeces, urine, bile and plasma were identified. As a result, a total of 59 metabolites (B1-W12) were identified. B3, B7, B8, B11, B12, B13, C3, D3, D5, D8, D10, W1, W2, W4, W5, W7 and W10 were new metabolites. W3/W6, W11/W12 and W12 were firstly found in plasma, faces and urine, respectively. The results showed that the main metabolic pathways of curcumin were glucuronidation, sulfation, reductive hydrogenation, oxidation, reduction, hydroxylation, dehydroxylation and their composite reactions. This method can provide a theoretical basis for the later screening of active metabolites of curcumin compounds.