Study On The Chemical Constituents Of Conyza Canadensis And Laggera Pterodonta

Conyza canadnsis is a medicinal herb widely distributed in many districts of China; possessing the functions of removing heat and detoxification. However, there is paucity of information on the chemical constituents and biological activities of C. canadnsis. Laggera pterdonta is a medicinal herb distributed mainly in southern China for the treatment of respiratory infections and inflammations in folk. Pharmacological researches indicate that L. pterdonta possess antibacterial, anti-inflammation, and antitumor activities. The chemical constituents of L. pterdonta mainly include eudesmane sesquiterpenes and flavonoids, however, fewer reports are related to its active constituents. The objectives of this thesis are to isolate and identify the chemical constituents of these two herbs, and then screen the possible biological activities of the isolated compounds.The ethanol extracts of C. canadnsis and L. pterodonta were isolated by column chromatogramphies on silica gel, ODS, and sephadex LH-20 columns, respectively, to afford 21 compounds. The structures of the isolated compounds were identified by chemical reactions and spectroscopic analysis. As a result,9 compounds including pryomeconic acid-3-O-β-D-glucopyranoside-6'-(O-4"-hydroxybenzoate) (1),pryome conicacid-3-O-β-D-glucopyranoside-6'-(O-4"-hydroxy-3",5"-dimethoxybenzoate) (2),pyromeconic acid-3-O-β-D-glucopyranoside-3'-(O-β-D-glucopyranoside)-6'-(O-4"-hydroxybanzoate) (3),Eugenylβ-Psd (4), scutellarin (5), luteolin-7-O-β-D-glucuronide (6), quercetin (7), quercetin-3-O-β-D-glucopyranoside (8), and luteolin (9) were obtained from C. canadnsis. Other 12 compounds including artemitin (10), 3,5-dihydroxy-3',4',6,7-tetramethoxyflavone (11),5,6,4'-trihydroxy-3,7-dimethoxy flavone (12), chrysosplenol D (13), quercetin (14), quercetin-3-O-β-D-galactopyranoside (15), patuletin (16), tamarixetin (17), patuletin-3-O-β-D-glucopyranoside (18), helichrysoside (19),4',5,7-trihydroxy-6-methoxyflavone-3-O-β-D-rutinoside (20) and kaempferol-5-O-β-D-glucopyranoside (21) were isolated from L. pterodonta. Among these compounds,3 is a new compound,1-4,6,8 and 9 were isolated from C. canadnsis for the first time, and 11,12,15-21 were isolated from L. pterodonta for the first time.The cytotoxicity on the normal cells and antiproliferative effect on tumor cells were tested by MTT assay. The results of MTT assay showed 5,7,3',4'-tetramethoxy-3-hydroxyflavone and chrysosplenetin B inhibited growth of A549 and Hela cells significantly with a dose dependent mode, while exhibited lower cytotoxicity to the two normal cells,Vero and EVC304. The antibacterial activity of three pyromeconic acids was tested by broth dilution method. The result indicated that 1,2, and 3 were invalid on two bacteria, Escherichia coli and Staphyloccocus aureus.