Manabu Hikichi

Flavonoids from the cultured cells of Glycyrrhiza echinata

Abstract Constituents of the cultured cells of Glycyrrhiza echinata have been investigated. Echinatin (4,4′-dihydroxy-2-methoxychalcone), a biosynthetically unique retrochalcone, and licodione (1-(2,4-dihydroxyphenyl)-3-(4-hydroxyphenyl)-1,3-propanedione), a dibezoylmethane derivative, which is the possible precursor of echinatin, were obtained. The structures were determined by spectroscopic methods and syntheses. 1H NMR of licodione revealed new features in chemical shifts of protons of diketonic and keto—enolic forms. 7,4′-Dihydroxyflavone, two of its prenyl derivatives and formononetin were also isolated. A discussion on retrochalcone biosynthesis is presented.

Alkaloids and triterpenoids of Symphytum officinale

Abstract Alkaloids, symphytine and echimidine, triterpenoids, isobauerenol, and phytosterols, β-sitosterol, have been isolated from the roots of Symphytum officinale (Boraginaceae). The structure of symphytine was also determined as 7-tiglylretronecine viridiflorate (I), and is the first isolated pyrrolizidine alkaloids with tiglic acid.

Ligularidine, a new pyrrolizidine alkaloid from Ligularia dentata

Abstract The structure of a new macrocyclic pyrrolizidine alkaloid, ligularidine(1), having significantly high mutagenic activity was elucidated and the configurations of the necic acid and its enantiomer reported by Edwards2 were also determined.