Four New 2-(2-Phenylethyl)chromone Derivatives from Withered Wood of Aquilaria sinensis

Abstract

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 ...

Production of agarwood fragrant constituents in Aquilaria calli and cell suspension cultures

“…The conditions for the HPLC were as follows: the column was a YMC-Pack ODS/R, 10 mm, 120Å, 250ϫ4.6 mm I.D., the detection was carried out at 254 nm, the solvent was MeOH in water with a gradient from 37% (0 min) to 100% (30 min) MeOH, the flow rate was 1 ml min Ϫ1 , and the injection volume was 3 ml. Peaks were identified by comparing retention times with those of standard samples which were isolated from the extract of withered or artificially wounded wood of Aquilaria and identified by 1 H-NMR and 13 C-NMR (Yagura T et al 2003(Yagura T et al , 2005, and were quantified by calculating according to the calibration curve of the samples. AH 3 , AH 4 , AH 5 , and AH 6 in calli were also analyzed by LC-MS to confirm their structures.…”

Bioactive Chromone Derivatives – Structural Diversity

“…(11)) [75] showed to be a promising candidate for the treatment of psychosis. Studies carried out on 2-(2-phenylethyl)chromones [74,81,82] allowed to conclude that those derivatives comprising a 5-OH substituent and a phenylethyl moiety at position 2 (Fig. (12)) display a significant protective effect against glutamate-induced neurotoxicity, already for a 10 μM concentration.…”

“…rheumatoid arthritis). Phenylethylchromones (with different hydroxyl and methoxyl substitutions [82]), in turn, have shown remarkable effects, namely at the central nervous system -5-hydroxy-2-(2-phenylethyl)chromone, for instance, acts as a neuroprotector against glutamate-induced neurotoxicity [74,81]. Eugenitol (2,8-dimethyl-5,7-dihydroxy-chromone) and eugenitine (2,6-dimethyl-5-hydroxy-7-methoxy-chromone), which are important constituents of clove oil, were reported to behave as carcinogenesis inhibitors thanks to their remarkable antioxidant capacity.…”

Quantitative Prediction of Agarotetrol in Chinese Eaglewood Using Near Infrared Spectroscopy

“…Gilg), which is formed by the decomposition of fungi in an anaerobic environment (Jalaluddin 1977;Qi 1995), is widely distributed in southern China, Indonesia, Malaysia, and other tropical areas (Yagura et al 2003;Naef 2011). It has become famous and popular for its versatile uses in sedatives, and its analgesic and digestive properties (Yagura et al 2003;Chen et al 2012).…”