Simultaneous determination of twenty-five compounds with anti-inflammatory activity in Spatholobi Caulis by using an optimized UFLC-MS/MS method: An application to pharmacokinetic study

As a kind of commonly used Traditional Chinese Medicine in clinical, Spatholobi Caulis (SPC) contains a wide variety of bioactive compounds, including protocatechuate (1), nicotinic acid (2), p-hydroxybenzoic acid (3), salicylic acid (4), 6,9-dihydroxy megastigma-4,7-dien-3-one (5), 8,9-dihydroxy megastigma-4,6-dien-3-one (6), daidzin (7), genistin (8), isolariciresinol (9), ononin (10), 4′,8-dimethoxy-7-O-β-d-glucopyranosyl isoflavone (11), 3′-methoxydaidzein (12), odoratin (13), spasuberol A (14), (+)-pinoresinol (15), 4-hydroxy-3-methoxy cinnamic acid methyl ester (16), (+)-epipinoresinol (17), calycosin (18), 8-O-methylretusin (19), formononetin sodium (20), formononetin (21), biochanin A (22), butesuperin A (23), homovanillyl-4-oxo-nonanoate (24) and (6aR,11aR)-maackiain (25). The pharmacokinetic characteristics of these twenty-five compounds in rat plasma were quantitatively and simultaneously studied using a fast, sensitive and precise ultra fast liquid chromatography combined with electrospray ionization triple quadrupole tandem mass spectrometry (UFLC-MS/MS) method after oral administration of aqueous extract of SPC to rats. The mobile phase consists of acetonitrile and 0.5 mM ammonium acetate in water, and these compounds were well separated at a gradient elution program with flow rate of 0.35 mL/min. Carbamazepine was employed as the internal standard (IS) and all samples were precipitated with MeOH-ACN (2:1, v/v). The analytical method has been proved to be good linearity (R2 ≥ 0.9957), precise, accurate, stable, recovery and matrix effect, which applicated becomingly to study the pharmacokinetic processes of these compounds in rat plasma. In addition, these twenty-five compounds exhibited anti-inflammatory activity on the inflammatory model of NO over production in RAW264.7 cells stimulated by lipopolysaccharide (LPS). Isoflavones, especially compounds 20-22 (The IC50 of which were 22.75 μM, 21.11 μM and 48.29 μM, respectively.) might be the important constituents for anti-inflammatory activity of SPC. This study provides reference values for the clinical application, in-depth study on new dosage forms and pharmacological activities of SPC.