Identification of bitter components from Pamp.

Identification of bitter components from the aerial parts of Pamp. was performed to search for a method to eliminate the bitter taste from products. The aerial parts of were extracted in an aqueous EtOH solution, and the obtained extracts were partitioned into essential-oil, flavonoid-rich, -BuOH, and aqueous fractions. Two purified bitter sesquiterpenoids were identified through repeated column chromatography of the bitterest fraction, the flavonoid-rich fraction, through an activity-guided fractionation method. The compounds were identified to be 1α,6α,8α-trihydroxy-5α,7βH-guaia-3,9,11(13)-trien-12-oic acid and artecalin, respectively, based on the interpretation of NMR, MS, and IR spectroscopic data. Both compounds were 50 times bitterer than caffeine and had similar bitterness to quinine HCl. Neither eupatilin nor jaceosidin, the major active components of , showed any bitterness.