Yukihiro Asaka

Perseapicroside A, hexanorcucurbitacin-type glucopyranoside from Persea mexicana.

Abstract Perseapicroside A, a new bitter hexanorcucurbitacin-type glucoside isolated from Persea mexicana , has been assigned the structure 2,3,16-trihydroxy- 4,4,9,14-tetramethyl-19-norpregn-5-ene-11,20-dione on the basis of detailed spectrsocopic analysis.

Clerodane diterpenoids from the roots of Portulaca pilosa

Abstract Three trans-clerodane diterpenoids, pilosanol A, B and C, the last compound being a glucoside, have been isolated from the roots of Portulaca pilosa. They show a marked contrast in skeletal type with the constituents of aerial part. Evolutionary changes in the biosynthetic abilities of Portulaca species is discussed.

A diterpenoid from Portulaca pilosa

A new diterpenoid, pilosanone C, having a bicyclo[5.4.0]undecane skeleton, has been isolated from the aerial parts of Portulaca pilosa. Its structure was elucidated on the basis of spectral studies. Its biosynthesis and implication in chemosystematic evolution is discussed.

Relationship between lipophilicity, bitterness and structure of phenyl β-d-glucopyranosides

Abstract The relationship between lipophilicity, structure and bitterness of phenyl β- d -glucopyranosides and their methyl ether derivatives was examined quantitatively using lipophilic and STERIMOL parameters, and selected indicator variables to assess position-specific substituent effects. The results indicate that the partial lipophilicity of the methoxyl groups is different for each substituent position of the glucose moiety and that the lipophilicity of a methoxyl group at position 2 is the largest. The results also show that the bitterness of phenyl β- d -glucopyranosides is determined primarily by the presence or absence of the methoxyl group at position 2 of the glucose moiety, not by the lipophilicity of the entire molecule.