Studies on the chemical constituents and anti-inflammatory activities from Aquilaria sinensis

Aquilaria sinensis (Lour.) Gilg. (Thymelaeaceae) is an evergreen tree (6 to 20 m tall) and endemic to China. The balm (resin) produced and accumulated from the wood is used as a valuable Chinese medicine called “Chen Xiang”. According to Chinese medicinal literature, the resin can be extracted in large quantities by natural fungal infection or by external wounding. In our studies on the anti-inflammatory constituents of Formosan plants, many species have been screened for in vitro inhibitory activity on neutrophil pro-inflammatory responses, and Aquilaria sinensis has been found to be an active species. Investigation on EtOAc-soluble fraction of the pericarp of Aquilaria sinensis has led to the isolation of a new flavonoid, aquilasinin (1), along with 15 known compounds, 5-hydroxy-7,3′,4′-trimethoxyflavone (2), velutin (3), pilloin (4), apigenin 7,4′-dimethyl ether (5), genkwanin (6), β-sitostenone (7), 3β-hydroxystigmast-5-en-7-one (8), 6β-hydroxystigmast-4-en-3-one (9), mixture of β-sitosterol (10) and stigmasterol (11), ergosterol peroxide (12), friedelan-3-one (13), epi-friedelinol (14), α-tocopheryl quinone (15), and myristic acid (16). The structure of new compound 1 was determined through spectral analyses including extensive 2D NMR data. Among the isolates, velutin (3), pilloin (4), and β-sitostenone (7) exhibited potent inhibition against lipopolysaccharide (LPS)-induced NF-κB production by macrophages with IC50 values of 23.36, 25.58, and 11.51µM, respectively.