Tsutomu Nakanishi

Antimicrobial alkaloids from Zanthoxylum tetraspermum and caudatum.

Two benzophenanthrene alkaloids, 8-acetonyldihydronitidine and 8-acetonyldihydroavicine were isolated from Zanthoxylum tetraspermum stem bark along with liriodenine, sesamin, lichexanthone and (+)-piperitol-gamma,gamma-dimethylallylether. The species endemic to Sri Lanka, Z. caudatum, contained sesamin, savinin, liriodenine, decarine and 8-O-desmethyl-N-nornitidine. 8-Acetonyldihydronitidine and 8-acetonyldihydroavicine showed significant antibacterial activity while the former along with liriodenine was strongly antifungal. Savinin exhibited potent spermicidal activity. Both savinin and sesamin exhibited significant insecticidal activity.

Three fragrant sesquiterpenes of agarwood

Abstract Three fragrant sesquiterpenes have been isolated as major constituents from the wood of Aquilaria malaccensis and identified as α-agarofuran, (−)-10-epi-γ-eudesmol and oxo-agarospirol.

New Neolignan and Phenylpropanoid Glycosides in Juniperus communis var. depressa

Two new neolignan glucosides (junipercomnosides C and D) and two new phenypropanoid glycosides (junipercomnosides E and F) were isolated from aerial parts of Juniperus communis var. depressa along with seven known phenylpropanoid glycosides. The structures of the isolated compounds were determined by spectral analysis, in particular by the detailed analysis of 2D NMR and CD spectra.

Jinkoh-eremol and jinkohol II, two new sesquiterpene alcohols from agarwood

From an agarwood (Aquilaria sp.; probably Aquilaria malaccensis Benth.) which is different from that obtained from Aquilaria agallocha Roxb., two new sesquiterpene alcohols, which we have named jinkoh-eremol (3) and jinkohol II (5), have been isolated, together with agarospirol (1), kusunol (2), and jinkohol (4), as major sesquiterpene constituents and their structures have been established.

New Luteolin 3'-O-Acylated Rhamnosides from Leaves of Bursera graveolens

Three new luteolin 3-O-rhamnopyranosides with an acetyl and/or a p-coumaroyl groups were isolated from leaves of Bursera graveolens along with five known flavonol glycosides, β-sitosterol 3-O-β-glucopyranoside and α-amyrin. The structures of the isolated compounds were determined by spectroscopic analysis. Their inhibitory activities for the Maillard reaction were also investigated.

Flavonol glycosides in two Diospyros plants and their radical scavenging activity

Methanol extracts of leaves of Diospyros glaucifolia and D. kaki were showed the scavenging activity of 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical. Chromatographical separation and purification of methanol extracts resulted in isolation of three new flavonol glycosides [2-(E)-p-coumaroylmyricitrin (3), 3-(E)-p-coumaroylmyricitrin (4) and mearsetin 3-O-β-glucronopyranoside (11)] along with known phenolic compounds. These structures were determined by means of spectroscopic analysis. The scavenging activities of DPPH radical of the isolated compounds were examined.

Synthetic uses of steroidal ring B diene protection: 22,23-dihydroergosterol

Protection of the ring B diene system of ergosterol by (i) a two-step addition of the elements of water across the 5,6-double bond, (ii) formation of the 4-phenyl-1,2,4-triazoline-3,5-dione adduct, or (iii) formation of the iron tricarbonyl adduct by treatment with p-methoxybenzylideneacetonetricarbonyliron, allowed selective reduction of the 22,23-double bond by catalytic or, as appropriate, ionic hydrogenation. Regeneration of the 5,7-diene system in each case gave a high yield of 22,23-dihydroergosterol.

ろ紙クロマトグラフィーにより食用青色1号(ブリリアントブルーFCF)アルミニウムレーキから検出された付随色素の構造

One of eight Food Blue No. 1 aluminum lakes (B-1Als) used in the official inspection of coal-tar colors in fiscal year 1999 had a violet sub-spot during paper chromatography and was rejected. To clarify the orgin of the sub-spot, the violet subsidiary color (Sub-V) was isolated from the sample. On the basis of NMR and MS analyses and ion chromatography, the structure of the subsidiary color was elucidated to be 2-[[4-[N-ethyl-N-(3- sulfophenylmethyl)amino]phenyl][4-hydroxyphenyl]methylio]benzenesulfonic acid. The relative content of Sub-V to that of m,m-B-1 in the rejected sample was determined to be 39.5% by HPLC. The relative contents in other submitted samples of B-1Al were in the range of 1.1-3.6%.