Chemical Constituents of the Leaves of Campanula takesimana (Korean Bellflower) and Their Inhibitory Effects on LPS-induced PGE2 Production.

Campanula takesimana Nakai (Campanulaceae; Korean bellflower) is one of the endemic herbs of Korea. The plant has been used as traditional medicines for treating asthma, tonsillitis, and sore throat in Korea. A hot water extract of the leaves of C. takesimana exhibited a significant inhibitory effect on lipopolysaccharide (LPS)-stimulated prostaglandin E2 (PGE2) production. Repetitive chromatographic separation of the hot water extract led to the isolation of three new neolignan glucosides, campanulalignans A-C (1-3), with 15 known compounds (4-18). The structures of new compounds 1-3 were elucidated by analyzing nuclear magnetic resonance (NMR) spectroscopic data, along with high resolution quadrupole time of flight mass (HR-Q-TOF-MS) spectrometric data. Among the isolates, simplidin (7), 5-hydroxyconiferaldehyde (11), icariside F2 (12), benzyl-α-l-arabinopyranosyl-(1″→6')-β-d-glucopyranoside (13), and kaempferol 3-O-β-d-apiosyl (1→2)-β-d-glucopyranoside (15) were isolated from the Campanulaceae family for the first time. The isolates (1, 2, and 4-18) were assessed for their anti-inflammatory effects on LPS-stimulated PGE2 production on RAW 264.7 cells. 7R,8S-Dihydrodehydrodiconiferyl alcohol (5), 3',4-O-dimethylcedrusin 9-O-β-glucopyranoside (6), pinoresinol di-O-β-d-glucoside (8), ferulic acid (10), 5-hydroxyconiferaldehyde (11), and quercetin (18) showed significant inhibitory effects on LPS-stimulated PGE2 production.