No abstract

Agarwood oil and spikenard extract were examined for their sedative activity using a spontaneous vapor administration system. It was shown that inhalation of agarwood oil vapor sedated mice. The main volatile constituents of the oil were found to be benzylacetone [agarwood oil from a Hong Kong market (1)], or alpha-gurjunene and (+)-calarene [agarwood oil made in Vietnam (2)]. A hexane extract of spikenard contained a lot of calarene, and its vapor inhalation had a sedative effect on mice. Individual principles benzylacetone, calarene, and alpha-gurjunene were administered to mice, which reproduced the result of the corresponding oil or extract. However, the most effective dose of the compounds was lower than their original content in the oil and extract (benzylacetone 0.1%, calarene 0.17%, alpha-gurjunene 1.5%).

The resinous portions of Aquilaria plants, called agarwood, have been used as medicines and incenses. Agarwood contains a great variety of sesquiterpenes, and a study using cultured cells of Aquilaria showed the production of sesquiterpenes (a-guaiene, a-humulene, and d-guaiene) to be induced by treatment with methyl jasmonate (MJ). In this study, the accumulation and production of sesquiterpenes were quantified. The amounts accumulated and produced reached a maximum at 12 h, and the most abundant product was a-humulene at 6 h and d-guaiene after 12 h. However, a headspace analysis of the cells revealed that a-humulene is likely to be volatilized; so overall, the most abundant sesquiterpene in the cells was d-guaiene. A cDNA library from RNA isolated from MJ-treated cells was screened using PCR methodologies to isolate five clones with very similar amino acid sequences. These clones were expressed in Escherichia coli, and enzymatic reactions using farnesyl pyrophosphate revealed that three of the clones yielded the same compounds as extracted from MJ-treated cells, the major product being d-guaiene. These genes and their encoded enzymes are the first sesquiterpene synthases yielding guaiane-type sesquiterpenes as their major products to be reported. Expression of a fourth terpene synthase gene in bacteria resulted in the accumulation of the protein in insoluble forms. Site-directed mutagenesis of the inactive clone and three-dimensional homology modeling suggested that the structure of the N-terminal domain was important in facilitating proper folding of the protein to form a catalytically active structure.

No abstract

Isoprenoids, major secondary metabolites in many organisms, are utilized in various applications. We constructed a model photosynthetic production system for limonene, a volatile isoprenoid, using a unicellular cyanobacterium that expresses the plant limonene synthase. This system produces limonene photosynthetically at a nearly constant rate and that can be efficiently recovered using a gas-stripping method. This production does not affect the growth of the cyanobacteria and is markedly enhanced by overexpression of three enzymes in the intrinsic pathway to provide the precursor of limonene, geranyl pyrophosphate. The photosynthetic production of limonene in our system is more or less sustained from the linear to stationary phase of cyanobacterial growth for up to 1 month.

No abstract

Two new polyprenylated benzophenones, a new polyprenylated phloroglucinol, and six new xanthone derivatives were isolated from the aerial parts of the Uzbekistan medicinal plant Hypericum scabrum. Their structures were elucidated on the basis of spectroscopic evidence. The isolated compounds showed moderate cytotoxicity for human tumor cells.

Agarwood ('Jinkoh' in Japanese) is a famous incense and is used as a sedative, analgesic and digestive in Kampo medicine. From agarwood, characteristic sesquiterpenes [2][3][4][5][6][7][8] and chromone derivatives [9][10][11][12][13][14][15][16] have been isolated. These compounds, together with the pyrolyzation products, constitute a pleasant odor when agarwood is burnt, 17,18) and combinations of these compounds make up various qualities of agarwood. Although the resinous part of agarwood is formed by decay, injury, etc., of the tree of the Aquilaria species (Thymelaeaceae), this process has not been understood in detail. Examination of the chemical constituents of the damaged wood would offer valuable information for understanding the bioorganic process of agarwood formation. In the present paper, we describe the isolation and structure elucidation of four new chromone derivatives (1-4), together with seven known chromones, from the MeOH extract of withered wood of A. sinensis, an original plant of agarwood (Chart 1). Results and DiscussionWithered wood of A. sinensis GILG grown in Taiwan was extracted with MeOH, and the MeOH extract was fractionated to hexane-, AcOEt-and BuOH-soluble fractions. The hexane-soluble fraction was separated by silica gel column chromatography to yield a new 2-(2-phenylethyl)-chromone 1, together with five known compounds: flindersiachromone, 9) AH 3 , 10) AH 4 , 10) AH 5 10) and AH 6 . 10) The AcOEtsoluble fraction was separated by silica gel and reversedphase silica gel column chromatography to yield a new 2-(2-phenylethyl)chromone 2, two new 2-(2-phenylethyl)-5,6,7,8-tetrahydrochromones 3 and 4, and two known dimeric chromones AH 10 11) and AH 14 12) (Chart 1). The structures of the known compounds were confirmed by comparison of the physical and spectral data with those reported.Compound 1 10) except for the carbons of the chromone system. From the heteronuclear multiple bond connectivity (HMBC) spectrum (Fig. 1), the hydroxyl group was located at C-5 because the hydroxyl proton (d H 12.77) and the proton at C-3 (d H 6.11) correlated with the same carbon at C-4a (d C 111.31). The methoxyl group was located at C-6, because the aromatic carbon (d C 144.18) which correlated with the methoxyl protons (d H 3.85) also correlated with the hydroxyl proton (d H 12.77) at C-5. Thus, compound 1 was determined to be 5-hydroxy-6-methoxy-2-(2-phenylethyl)chromone.Compound 2 was obtained as a white powder with the molecular formula of C 17 H 14 O 4 . The presence of a chromone ring was suggested from the UV and IR spectra. The 13 C-NMR spectrum of 2 (Table 2) was very similar to that of AH 3 10) except for the methylenes (C-7Ј, C-8Ј): one of the methylenes was replaced by an oxymethine group (d C 71.37). This was confirmed by the presence of ABX-type signals at d H 3.14 (1H, dd, Jϭ14.3, 4.6 Hz), 3.20 (1H, dd, Jϭ14.3, 8.7 Hz) and d H 5.53 (1H, dd, Jϭ8.7, 4.6 Hz) in the 1 H-NMR (Table 1). The oxymethine group was located at C-7Ј, because the oxymethine proton (d H 5.53) correlated with the ...