Kazuhito Ogihara

Triterpenes from the leaves of parsonsia laevigata

Abstract A novel taraxerane-type triterpene-diol, in addition to taraxerol and lupeol, was isolated from the leaves of Parsonsia laevigata . Its structure was shown to be (4β)-D-friedoolean- 14-ene-3β,24-diol (taraxer- 14-ene-3β,24-diol) by a combination of chemical and spectroscopic methods.

Pyrrolizidine alkaloids from Messerschmidia argentea

Abstract A novel pyrrolizidine alkaloid, 3′-acetylindicine-N-oxide {[1R-[1α, 7(2R∗,3S∗), 7αβ]]-3- acetoxy-2-hydroxy -2-(1-methylethyl)-butanoic acid (2,3,5,7a-tetrahydro-1-hydroxy-1H-pyrrolizin-7-yl)methyl ester N-oxide}, was isolated from the twigs of Messerschmidia argentea, in addition to 3′-acetylindicine, indicine and its N-oxide. Structures of these alkaloids were determined by spectroscopic methods and from chemical evidence.

Absolute configurations of pittosporatobiraside A and B from Pittosporum tobira

Abstract The absolute configuration at C-12 of pittosporatobiraside A and B isolated from the leaves of Pittosporum tobira was determined to be S on the basis of the exciton chirality of their dibenzoate derivative. The structures of the two glycosides were thus established to be (1 S ,9 S ,10 S ,11 S ,12 S ,14 R ,16 R )-12-[( Z )-2-methyl-1-oxo-2-butenyl]-6,14-dimethyl-2-methylene-9-(1-methylethyl)-15,17-dioxatricyclo[8.7.0.0 11,16 ]heptadec-5-en-13-one and (1 S ,9 S ,10 S ,11 S ,12 S ,14 R ,16 R )-12-(3-methyl-1-oxo-2-butenyl)-6,14-dimethyl-2-methylene-9-(1-methylethyl)-15,17-dioxatricyclo [8.7.0.0 11,16 ]heptadec-5-en-13-one, respectively.

Fragrant and biologically active constituents of the citrus cultivar jyabon

Abstract 1,8-Cineol is probably a key material for the fragrance characteristic of the fruit of jyabon. Further, the peels of this citrus contain psoralen which has pesticidal activity against Unaspis yanonensis (arrowhead scale insect). The flowers contain a large amount of β-myrcene which attracts Oxycetonia jucunda (citrus flower chafer). The composition of essential oil constituents of the leaves is similar to that of Citrus grandis var. anseikan.

Variations in leaf terpenoids with ploidy level in citrus cultivars and hybrids.

Abstract The leaves of six diploid and six tetraploid citrus taxa contain monoterpenes, sesquiterpenes, phytol, β-amyrin and three phytosterols. The total amounts of lower terpenoids and phytosterols per gram fresh weight of leaf decreased with increasing ploidy level. The same trend was apparent when the amounts of the individual terpenoid components were analysed, although the phytosterol composition showed less variation than in the case of the lower terpenoids.