Hidemichi Mitome

Location of functional groups in mycobacterial meromycolate chains; the recognition of new structural principles in mycolic acids.

Mycobacterial alpha-, methoxy- and keto-mycolic acid methyl esters were separated by argentation chromatography into mycolates with no double bond, with one trans double bond or with one cis double bond. Meromycolic acids were prepared from each methyl mycolate fraction by pyrolysis, followed by silver oxide oxidation, and analysed by high-energy collision-induced dissociation/fast atom bombardment MS to reveal the exact locations of the functional groups within the meromycolate chain. The locations of cis and trans double bonds, cis and trans cyclopropane rings, methoxy and keto groups, and methyl branches within the meromycolate chain were determined from their characteristic fragment ion profiles, and the structures of the meromycolic acids, including those with three functional groups extracted from Mycobacterium tuberculosis H37Ra, Mycobacterium bovis BCG and Mycobacterium microti, were established. Meromycolic acids with one cis double bond were structurally closely related to those with one cis cyclopropane ring, whereas the meromycolic acids with one trans cyclopropane ring were closely related to the corresponding meromycolic acids with one cis cyclopropane ring. A close relationship between methoxy- and keto-meromycolic acids was also implied. The relationship between the meromycolic acids with a trans double bond and the other meromycolic acids was not clearly revealed, and they did not appear to be immediate substrates for trans cyclopropanation.

N1-aminopropylagmatine, a new polyamine produced as a key intermediate in polyamine biosynthesis of an extreme thermophile, Thermus thermophilus.

In the extreme thermophile Thermus thermophilus, a disruption mutant of a gene homologous to speB (coding for agmatinase = agmatine ureohydrolase) accumulated N1-aminopropylagmatine (N8-amidino-1,8-diamino-4-azaoctane, N8-amidinospermidine), a new compound, whereas all other polyamines produced by the wild-type strain were absent from the cells. Double disruption of speB and speE (polyamine aminopropyltransferase) resulted in the disappearance of N1-aminopropylagmatine and the accumulation of agmatine. These results suggested the following. 1) N1-Aminopropylagmatine is produced from agmatine by the action of an enzyme coded by speE. 2) N1-Aminopropylagmatine is a metabolic intermediate in the biosynthesis of unique polyamines found in the thermophile. 3) N1-Aminopropylagmatine is a substrate of the SpeB homolog. They further suggest a new biosynthetic pathway in T. thermophilus, by which polyamines are formed from agmatine via N1-aminopropylagmatine. To confirm our speculation, we purified the expression product of the speB homolog and confirmed that the enzyme hydrolyzes N1-aminopropylagmatine to spermidine but does not act on agmatine.

1H NMR-based metabonomic analysis of urine from young spontaneously hypertensive rats

Spontaneously hypertensive rats (SHR) and their substrains are a useful model for studying essential hypertension which is a complex, polygenic, and multifactorial disorder. Their genetic and metabolic features are of great interest because they may provide insights into the mechanism of blood pressure regulation. We have compared urinary metabolic profiles of young SHR with those of their age-matched normotensive controls, Wistar Kyoto rats, using (1)H NMR-based metabonomics. Principal components analysis was applied to the NMR spectral data after data-reduced and normalized by the total integral or the creatinine integral. Consequently, a clear separation of urine samples between the two strains was observed in the principal components scores plot. The loadings plot from the data normalized by the creatinine integral showed that many metabolites such as citrate, alpha-ketoglutarate, and hippurate contributed to the separation, and the urinary levels of most metabolites used in this study, including these three, were lower in SHR than in Wistar Kyoto rats. These metabolic changes may be concerned with blood pressure regulation in SHR, although a relation to other strain differences cannot be ruled out. The present study suggests the usefulness of a (1)H NMR-based metabonomic approach using SHR in the field of hypertension research.

Aragusterol a: A potent antitumor marine steroid from the okinawan sponge of the genus, Xestospongia

Abstract Aragusterol A, a new marine steroid possessing potent antitumor activity, was isolated from the Okinawan sponge of the genus Xestospongia and its structure was determined by spectroscopic analysis and chemical evidence. The compound strongly inhibited the cell proliferation of KB, HeLaS3, P388 and LoVo cells in vitro , and also showed potent in vivo antitumor activity toward P388 in mice and L1210 in mice.

Aragusterols E-H, new 26,27-cyclosterols from the Okinawan marine sponge of the genus Xestospongia and absolute configurations of xestokerols A and B

Abstract New 26, 27-cyclosterols, aragusterols E-H, were isolated from the Okinawan marine sponge of the genus Xestospongia . Their structures were determined by spectroscopic measurement and chemical conversion. The absolute configurations of xestokerols A and B were determined by chemical conversion.

A PHENOLIC CINNAMATE DIMER FROM PSORALEA PLICATA

Abstract Caryophyllene oxide, α-tocopherol, Z and E -werneria chromenes, two furanocoumarins, bakuchicin and psoralen, in addition to plicatin-B, lupeol and stigmasterol, have been isolated from the hexane-soluble extract of the aerial parts of Psoralea plicata . Plicatin-A, 3-(-3-methyl-2,3-epoxybutyl)- p -coumaric acid methyl ester and a new dimer, α- diplicatin B, were isolated from the ethyl acetate-soluble fraction. From the butanol-soluble matter, roseoside A, daidzin, isopsoralic acid- O -gluco-pyranosyl and isovitexin were isolated. Most of these compounds have been isolated from this species for the first time, although known from other plant sources.

Total synthesis of marine diterpenoid stolonidiol

Abstract Marine dolabellane diterpenoid stolonidiol was synthesized from l -ascorbic acid. The method for this total synthesis involves formation of the bicyclo[2.2.1]heptane derivative using a diastereoselective sequential Michael reaction, formation of cyclopentane derivative by the retro-aldol reaction and construction of an 11-membered carbocyclic ring through the intramolecular Horner–Wadsworth–Emmons reaction.

Total synthesis of marine diterpenoid kalihinene X

Abstract Total synthesis of marine diterpenoid kalihinene X was achieved. This total synthesis involves regioselective coupling reaction of carbanion of alkyl sulfone with epoxyalcohol and construction of cis-decalin ring by intramolecular Diels–Alder reaction. The absolute configuration of kalihinene X could be determined by this total synthesis.

Pregnene derivatives from Solenostemma argel leaves

Two new pregnene derivatives 14beta-15alpha-dihydroxy-delta4pregnene-3,20 dione and 3beta-14beta,15alpha-16alpha hydroxy-20-oxo-delta5pregnene-tetra-ol, in addition to alpha- and beta-amyrin and beta-sitosterol, were isolated from Solenostemma argel leaves. The structures were established by extensive spectral analysis as well as comparison with reference materials.

A metabonomic study of biochemical changes characteristic of genetically hypertensive rats based on 1 H NMR spectroscopic urinalysis

Spontaneously hypertensive rats (SHR) provide a simple model for studying essential hypertension. Their genetic and metabolic features are of great interest because they may provide insights into the pathophysiological processes underlying essential hypertension. We have thus investigated the metabolic characteristics of SHR at various ages, covering the prehypertensive stage and the developmental phase of hypertension, using a 1H nuclear magnetic resonance (NMR)-based metabonomic approach. Twenty-four-hour urine samples from the SHR and their age-matched normotensive control, Wistar–Kyoto rats, were analyzed using 1H NMR spectroscopy, and the spectral data were subjected to principal components analysis (PCA) to find metabolic differences between the two strains. Consequently, it was possible to separate the urine samples between the two strains at any age ranging from 4 to 20 weeks in the principal component scores plots. The major spectral regions and signals (metabolites) contributing to the separation were picked up based on the loadings. Subsequently, the urinary excreted levels of metabolites highlighted by the PCA were compared based on the signal intensities corrected by urine volume and body weight. These investigations revealed the major metabolic changes characteristic of the SHR, which included differences in citrate, α-ketoglutarate, succinate, hippurate, phenylacetylglycine, p-cresol glucuronide, creatine, taurine, medium-chain dicarboxylates (tentative), unknown (δ 3.11), and the regions at 3.60, 3.64, 3.68 and 3.88 p.p.m. The results supported the occurrence of metabolic acidosis in the SHR in the period of prehypertension as well as rapidly rising blood pressure. In addition, the intestinal microfloral populations in the SHR were suggested to be altered in the developmental phase of hypertension.