Elsevier

Fitoterapia

Volume 98, October 2014, Pages 117-123
Fitoterapia

2-(2-Phenylethyl)chromone derivatives from Chinese agarwood induced by artificial holing

https://doi.org/10.1016/j.fitote.2014.07.011Get rights and content

Abstract

Three new 2-(2-phenylethyl)chromone derivatives (13), together with thirteen known ones (416), were isolated from the EtOAc extract of Chinese agarwood induced by artificial holing, originating from Aquilaria sinensis (Lour.) Gilg (Thymelaeaceae). The chemical structures of the new compounds were identified by spectroscopic techniques (UV, IR, MS, 1D and 2D NMR). Compounds 1, 6, 15 and 16 exhibited inhibitory effects on Staphylococcus aureus, and compounds 15 and 16 showed inhibitory effects on Ralstonia solanacearum. Compounds 13, 7, 9, 11, 12, 15 and 16 exhibited acetylcholinesterase inhibitory activity. A possible biogenetic pathway of compounds 116 was proposed to show the relationships between diepoxy-tetrahydro-2-(2-phenylethyl)chromones, epoxy-tetrahydro-2-(2-phenylethyl) chromones, tetrahydro-2-(2-phenylethyl)chromones, and 2-(2-phenylethyl)chromones of the flidersia type, the four main types of 2-(2-phenylethyl)chromones found in agarwood, on the basis of their appearances in different stage of agarwood formation.

Graphical abstract

The structures of three new compounds and the sample of Chinese agarwood induced by artificial holing.

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Introduction

Agarwood, the fragrant resinous wood obtained from certain trees of Aquilaria species (Thymelaeaceae), also called eaglewood, gaharu, kanankoh, kyara, jinkoh or chen xiang in different cultures, could be used as incense and traditional medicine [1]. According to the review of Naef R, agarwood possesses a panoply of effects such as aphrodisiac, sedative, cardiatonic and carminative, and to relieve gastric problems, coughs, rheumatism and high fever [2]. Agarwood cannot be generated in normal wood tissues, but might be formed when the Aquilaria plants were injured by natural or artificial effects, such as lighting striking, burning, microbial invasions, holing, cutting, and artificial fungus inoculation [1]. Phytochemical research showed that sesquiterpenoids and 2-(2-phenylethyl)chromone derivatives were identified from several sorts of agarwood [2], [3]. As agarwood has become more and more popular in the international market [4], [5], [6], [7], great efforts were under way to cultivate Aquilaria trees and to afford agarwood by artificial methods in recent years, to meet the demand for agarwood in the form of medicine, incense stick or oil.

Previous studies on Chinese agarwood originating from Aquilaria sinensis were mostly concentrated on the wild ones, and researchers have reported various sesquiterpenoids together with 2-(2-phenylethyl)chromone derivatives [2], [3]. To identify the chemical components of Chinese agarwood induced by artificial holing, as well as afford valuable information for understanding the bioorganic process of agarwood formation, the chemical constituents of Chinese agarwood induced by artificial holing from A. sinensis were investigated in this study. This paper described the isolation, the structure elucidation, the antibacterial activity and AChE inhibitory activity of three new 2-(2-phenylethy)chromone derivatives (13), together with thirteen known ones (416) from Chinese agarwood induced by artificial holing of A. sinensis.

Section snippets

General

1D and 2D NMR experiments were recorded on a Bruker AV III spectrometer (for 1H NMR at 500 MHz and 13C NMR at 125 MHz) using TMS as the internal standard. HRMS were acquired using an API Qstar Pulsar mass spectrometer (Bruker, Germany). Optical rotations were measured on a Rudolph Autopol III polarimeter (Rudolph, Flanders, America). IR spectra were performed on a Nicolet 380 FT-IR spectrometer (Thermo, America). UV spectra were recorded on a Shimadzu UV-2550 spectrometer (Beckman, America). HPLC

Results and discussion

Three new 2-(2-phenylethyl)chromone derivatives (13), together with thirteen known ones (416), were isolated from the EtOAc extract of Chinese agarwood induced by artificial holing originating from A. sinensis (Fig. 1). The thirteen known 2-(2-phenylethy)chromone derivatives were identified as rel-(1aR,2R,3R,7bS)-1a,2,3,7b-tetrahydro-2,3-dihydroxy-5-(2-phenylethyl)-7H-oxireno[f][1]benzopyran-7-one (4) [11],

Acknowledgements

This work was financially supported by the National Support Science and Technology Subject (2013BAI11B04), Major Technology Project of Hainan Province (ZDZX2013013; ZDZX2013023-1) and Natural Science Foundation of Hainan Province (313080).

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    These authors contributed equally to this work.

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