The ethyl acetate fraction of Catalpa ovata (Bigoniaceae) exhibited a strong inhibitory effect on NO production in lipopolysaccharide-induced BV2 microglia cells. Recently, LC-QTOF MS/MS spectrometry has been used extensively to identify compounds in crude extracts without the need for separation; this hyphenated technique also provides information on the molecular weight and type of the compounds of interest [1,2]. We tried to identify the active constituents of C. ovata by using LC-MS coupled with a cell-based assay. A new iridoid compound, 6-O-trans-feruloyl-3α-hydroxy-7-deoxyrehamaglutin A (4), and nine known compounds were isolated from the extracts of C. ovata by repeated column chromatography. Compounds 1-3, and 5–10 were identified as p-hydroxybenzoic acid (1), arillatose B (2), p-hydroxyphenylferulate (3), 6-O-(E)-feruloyl-α-glucopyranoside (5), 1-O-p-coumaroyl-β-D-glucopyranose (6), 6-O-caffeoyl-β-D-glucose (7), minecoside (8), catalposide (9), and 6-O-trans-feruloyl-5,7-bisdeoxycynanchoside (10) through comparison of the 1H-NMR, 13C-NMR, and MS data with reference spectra. Among them, compounds 3, 4, 5, 7, and 8 significantly attenuated lipopolysaccharide-stimulated NO production in BV2 cells. Our results indicate that time-dependent LC-MS coupled with a cell-based NO production inhibitory assay successfully predicted active compounds without a time-consuming isolation process.
References
[1] Li D, Wang T, Guo Y, Hu Y, Yu B, Qi J. J Chromatogr A. 2015; 1425: 106-115
[2] Shin H, Park Y, Jeon YH, Yan X-T, Lee KY. Biosci Biotechnol Biochem. 2018; 82: 15-21