Iwao Miura

Constitution of two coloring matters in the flower petals of Carthamus Tinctorius L.

Abstract Structures of the safflower red pigment carthamin and the yellow pigment safflor yellow A are shown to be expressed by 3 and 4 respectively, mainly on the basis of spectroscopic evidence.

Drimane-type sesqui- and norsesquiterpenoids from polygonum hydropiper

Abstract Polygonic acid, which shows weak anticomplement activity, has been isolated from leaves of Polygonum hydropiper together with four drimane-type sesquiterpenes, 11-ethoxycinnamolide, polygodial acetal, valdiviolide and fuegin and two drimane-type norsesquiterpenes, isopolygonal and polygonone.

Phthalides from the rhizome of Ligusticum wallichii

Abstract Three phthalides, 3-butylidene-7-hydroxyphthalide, and cis and trans -6,7-dihydroxyligustilides, along with a dimeric phthalide wallichilide have been isolated from the hot water extract of the rhizome of Ligusticum wallichii . Their structures were established mainly on the basis of spectroscopic data. 3-Butyl-4,5-dihydro-3-hydroxy phthalide and adenosine were identified as active principles of the extract which are responsible for increase of coronary blood flow in the dog heart.

Jinkohol, a prezizane sesquiterpene alcohol from agarwood

Abstract A new tricyclic sesquiterpene, jinkohol, has been isolated from an agarwood ( Aquillaria sp.) which is different from that obtained from Aquillaria agallocha . Its structure was shown to be 2β-hydroxy-(+)-prezizane by spectroscopic methods and by chemical transformation. The two kinds of agarwood are readily identified from their sesquiterpene components.

Isolation, structure and synthesis of maesanin, a host defense stimulant from an African medicinal platn maesa lanceolata

Abstract The isolation, characterization and an efficient synthesis of maesanin 1 , a host defense stimulant isolated from an African medicinal plant Maesa lanceolata is reported.

Sesquiterpenoids in two different kinds of agarwood

Abstract Sesquiterpenoids of an agarwood originating from Aquilaria agallocha and of the other kind of agarwood (Aquilaria sp.; probably Aquilaria malaccensis) were investigated by a combination of GLC and GC/MS. The differences in sesquiterpene composition between the two kinds of agarwood are discussed.

A first total synthesis of Germacrone by intramolecular alkylation of protected cyanohydrin

Abstract A total synthesis of Germacrone by the intramolecular alkylation of a carbanion generated from protected cyanohydrin is presented.

Azedarachol, a steroid ester antifeedant from Melia azedarach var. japonica

Abstract A new steroid ester, azedarachol, from the root bark of Melia azedarach has been identified as an antifeedant against a Japanese insect pest and the structure has been assigned as 2α,3α,16β-trihydroxy-5α-pregnane 20 R -methacrylate.

Observation of fatigue unrelated to gross energy reserve of skeletal muscle during tetanic contraction ― an application of 31P-MRS

The mechanism of muscle fatigue was studied by 31P-MRS. During tetanic contraction for 2 minutes(min), the tension measured with a strain gauge and Phosphocreatine(PCr)/Inorganic phosphate(Pi)+ Phosphomonoester(PME) ratio decreased to 31.5 +/- 4.4% of the control value and 0.6 +/- 0.1, respectively. The intracellular pH(pH) also decreased to 6.62 +/- 0.04. Toward the end of the stimulation, the tension decreased to 25.3 +/- 1.9% of the control value. However, during 20min stimulation, the PCr/(Pi+PME) ratio increased to 2.5 +/- 0.5 and the pH to 6.91 +/- 0.04. These results show that muscular fatigue is ascribable not to a decreased level of high energy metabolites required for actomyosin ATPase, but to an increase in the threshold intensity of excitation in excitation-contraction coupling.

Aristoloside, an aristolochic acid derivative from stems of Aristolochia manshuriensis

Abstract Aristoloside, a new companion aristolochic acid derivative isolated from stems of Aristolochia manshuriensis has been shown to be 6- O -β- d -glucopyranoside of aristolochic acid-D on chemical and physicochemical evidence. Three known acids, aristolochic acids I, IV (both as their corresponding methyl esters), and -D have also been characterized from stems of the plant.