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Acetylcholinesterase (AChE) inhibitory activity-guided fractionation of Angelica gigas led to isolation and identification of a new coumarin, peucedanone (12), and isolation of 11 known coumarins. Among them, decursinol (1) represented the highest inhibitory activity toward AChE in vitro. The correlation of the inhibitory activities of the coumarins toward AChE with their chemical structures was studied.

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An 80% methanolic extract of Rhus verniciflua Stokes bark showed significant anti-viral activity against fish pathogenic infectious hematopoietic necrosis virus (IHNV) and viral hemorrhagic septicemia virus (VHSV) in a cell-based assay measuring virus-induced cytopathic effect (CPE). Activity-guided fractionation and isolation for the 80% methanolic extract of R. verniciflua yielded the most active ethyl acetate fraction, and methyl gallate (1) and four flavonoids: fustin (2), fisetin (3), butin (4) and sulfuretin (5). Among them, fisetin (3) exhibited high antiviral activities against both IHNV and VHSV showing EC(50) values of 27.1 and 33.3 μM with selective indices (SI = CC(50)/EC(50)) more than 15, respectively. Fustin (2) and sulfuretin (5) displayed significant antiviral activities showing EC50 values of 91.2-197.3 μM against IHNV and VHSV. In addition, the antiviral activity of fisetin against IHNV and VHSV occurred up to 5 hr post-infection and was not associated with direct virucidal effects in a timed addition study using a plaque reduction assay. These results suggested that the bark of R. verniciflua and isolated flavonoids have significant anti-viral activity against IHNV and VHSV, and also have potential to be used as anti-viral therapeutics against fish viral diseases.

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