Studies on the Chemical Constituents of Microcos Paniculata
|Keywords||Microcos paniculata chemical components flavonoid quality control metal complex|
Microcos paniculata L. is a plant belonging to the Microcos genus of Tiliaceae family and finds use in Chinese medicine for the treatment of common cold, sore throat, dyspepsia and choloplania, etc. It is widely distributed in southern China, and is often used as one of the main ingredients of a variety of cold herbal tea such as "Guangdong tea", etc.In this thesis, phytochemical investigation on the leaves of M. paniculata led to the isolation of 20 compounds. The structures of these compounds were elucidated by extensive spectroscopic analyses. The compounds included four nor-sesquiterpenes:isololiolide (1), abscisic acid (2), (3R, 6R)-3-hydroxy-ionone (3) and (R)-3-hydroxy-β-ionone (4); three organic acids:vanillic acid (5),p-coumaric acid (6), ferulic acid (7); six flavonoid aglycones: isorhamnetin (8), kaempferol (9), quercetin (10), apigenin (11), epicatechin (12), catechin (13); three flavone-C-glycosides:vitexin (14), isovitexin (15), isoviolanthin (16) and four flavone-O-glycosides:isorhamnetin 3-O-β-D-glucopyranoside (17), narcissin (18), kaempferol 3-O-β-D-(6-O-trans-p-coumaroyl) glucopyranoside (19), typhaneoside (20). Among them, compounds 1-7、11-13、19 and 20 were isolated from this plant for the first time.A quantitative HPLC method was established to determine the content of narcissin in the leaves of M. paniculata. A Cosmosil C18-MS-Ⅱcolumn (5μm,4.6×250mm) was used. The mobile phase consisted of acetonitrile and 0.05% acetic acid solution with an isocratic ratio 18:82. The flow rate was 1.0 ml·min-1 and the detection wavelength 256 nm. The content of narcissin in the samples was determined by external reference method. The method was proved to be quick, simple and reproducible. It is quite suitable to be used for determination of narcissin in the leaves of M. paniculata.M. paniculata is rich source of flavonoids. Metal coordination represents a new effective approach for the derivation of flavonoids. Five metal complexes of apigenin were synthesized and their structures were characterized by UV, IR, elemental analysis and ESI-MS.