Chemical constituents of the Vietnamese liverwort Porella densifolia.

From the ether extract of Porella densifolia, the first liverwort collected and chemically investigated in Vietnam, a kaurane diterpenoid, ent-kauren-15-one (1) and two sesquiterpene norpinguisone (2) and norpinguisone methyl ester (3) have been purified. Their structures were elucidated by spectroscopic analysis. In addition, an X-ray crystal structure of norpinguisone was obtained, allowing to determine its stereochemistry. Furthermore, the inhibitory activity of nitric oxide (NO) production in RAW 264.7 cells stimulated by lipopolysaccharide (LPS) of compounds 1-3 was examined with their IC(50) values of 69.4, 45.5 and 1.68 microM, respectively. Copyright (c) 2010 Elsevier B.V. All rights reserved.