Koichiro Isoi

Variation in the chemical composition of Eucalyptus sideroxylon

Abstract Eucalyptus sideroxylon leaves collected throughout the habitat of this tree were of two classes. The polyphenol aglycones in the leaves collected from different samples of the normal form of the tree were very similar in nature and amount but the composition of the glycosides was generally characteristic of a geographical region. The latter compounds included the 3-glucoside, 3-rhamnoside, 3-rutinoside of quercetin, the 3-rhamnoside and 3-rutinoside of kaempferol; catechin, epicatechin, shikimic, chlorogenic and p -coumarylquinic acids and some unidentified products were also present. Leaves of the second class were characterized by large amounts of stilbenes, chlorogenic and p -coumarylquinic acids and in some cases dihydrokaempferol 3-rhamnoside; several of the polyphenols in the first class were also present. The leaves of the second class were collected from trees recognized as variant forms and in two areas trees of both forms have been found growing close together. Both forms contain leucocyanidin and esters of gallic, ellagic and gentisic acids. A new flavone, 5,4′-dihydroxy-7-methoxy-6,8-dimethylflavone was isolated from a variant sample and the 4′-methoxy derivative was detected in both forms. The wood extractives of both forms were identical and contained resveratrol and another hydroxystilbene and their glucosides. While the composition of the flavonoids in the leaves of different variant forms remains relatively constant the major stilbene in leaves of the second class varies; it can be the 3-glucoside of either 3,4′,5-trihydroxy-, or 3,3′,5-trihydroxy-4′-methoxy- or another hydroxy-stilbene.

Xanthones in cell suspension cultures of Hypericum paturum

Abstract A new xanthone named paxanthone, 9,11-dihydroxy-5-methoxy-3,3-dimethylpyrano[3,2-a]xanthen-12(3H)-one, has been isolated from the callus tissues of Hypericum paturum together with toxyloxanthone B and γ-mangostin. Their structures were elucidated using spectral techniques.

An isopentenylated flavonol from Hypericum japonicum

Abstract A new isopentenylated flavonol, salothranol, from whole plants of Hypericum japonicum was isolated together with the known isojacareubin. Its struc

A flavanonol rhamnoside from Hypericum japonicum

Abstract A new flavanonol (2R,3R)-taxifolin-7-rhamnoside, from whole plant of Hypericum japonicum has been isolated together with the known quercitrin and vincetoxicoside B. Their structures were elucidated using spectral techniques.

Antianaphylactic Effects of the Principal Compounds from the White Petals of Impatiens balsamina L.

Several flavonols and naphthoquinones have been isolated from a 35% ethanol extract (IB) of the white petals of Impatiens balsamina L. The antianaphylactic effects of the principal compounds were investigated using a murine immediately hypersensitivity reaction system induced by hen egg‐white lysozyme (HEL). The active extracts and phenolic compounds in IB were shown to inhibit significantly both the fatal anaphylactic shock and heterologous PCA reaction.

A chromene from Hypericum japonicum

Abstract A new 2,2-dimethyl-3′,7-dihydroxy-6-phenyl-2′,5-chromenecarbolactone was isolated from the whole plant of Hypericum japonicum . Its structure was elucidated by spectral methods and it was named sarolactone.

Alkaloids of Nelumbo nucifera

Abstract The alkaloids of leaves of Nelumbo nucifera Gaertn. were examined using combined GLC-MS. The occurrence of four new alkaloids, dehydroroemerine (XII), dehydronuciferine (XI), dehydroanonaine (XIII) and N-methylisococlaurine (III) were revealed, besides the known roemerine (V), nuciferine (VI), anonaine (VII), pronuciferine (IV), N-nornuciferine (VIII), nornuciferine (IX), amepavine (I) and N-methylcoclaurine (II).

Co-occurrence of prenylated xanthones and their cyclization products in cell suspension cultures of Hypericum patulum

Abstract A new xanthone named paxanthone B, 5,9,11-trihydroxy-3,3-dimethyl-8-(3-methyl-2-butenyl)-3H,12H-pyrano[3,2-a]xanthen-12-one, has been isolated from callus tissues of Hypericum patulum, together with the known garcinone B and 1,3,6,7-tetrahydroxy-8-(3-methyl-2-butenyl)-9H-xanthen-9-one. Their structures were elucidated using spectral techniques.

A dipeptide derivative fromHypericum japonicum

Abstract The structure of a novel peptide analogue saropeptate, N -benzoyl- l -phenylalanyl- l -phenylalaninol acetate, isolated from the whole plant of H. japonicum was elucidated by spectroscopic analysis and its absolute configuration determined by comparison with four synthetic diastereoisomers.

A 2-pyrone derivative from Hypericum japonicum

Abstract A new 2-pyrone derivative, named saropyrone, [2,3,3-trimethyl-6-(3′4′-dihydroxyphenyl)-2,3-dihydro-4-oxo-4 H-furo[3, 2- c ] pyran], has been isol