Inhibitory effects of the lichen metabolite lobaric acid on arachidonate metabolism in vitro.

An extract containing phenolic constituents of the lichen Stereocaulon alpinum was shown to exhibit potent in vitro inhibitory effects on arachidonate 5-lipoxygenase from porcine leucocytes. The active component has been identified as the orcinol depsidone lobaric acid (1), which shows dose-dependent inhibitory effects on the enzyme, with an IC(50) value of 7.3 μM.

In vitro inhibition of 5-lipoxygenase by protolichesterinic acid from Cetraria islandica.

The aliphatic α-methylene-γ-lactone (+)-protolichesterinic acid (1), isolated from Cetraria islandica, has been shown to exhibit inhibitory effects on the enzyme 5-lipoxygenase in an in vitro assay in which porcine leucocytes are used as a source of the enzyme system. The isomeric compounds (+)-lichesterinic acid (2) and (-)-lichesterinic acid (4), prepared from (+)-protolichesterinic- and (-)-allo-protolichesterinic acids, respectively, exhibited anti-5-lipoxygenase activity of the same order of magnitude. (+)-Methyl lichesterinate (3) was, however, inactive.

Anti-inflammatory active polyacetylenes from Bidens campylotheca.

The n-hexane extract of Bidens campylotheca Schultz Bip. ssp campylotheca (Compositae) showed significant in vitro inhibition of cyclooxygenase (CO) and 5-lipoxygenase (5-LO). Five polyacetylenes, heptadeca-2E,8E,10E,16-tetraene-4,6-diyne (1), heptadeca-2E,8Z,10E,16-tetraene-4,6-diyne (2), heptadeca-2E,8E,16-triene-4,6-diyne-10-ol (3), safynol (5) and, as a new compound, safynol-2-O-isobutyrate (4) could be isolated and their structures elucidated mainly by UV, MS, NMR, and COSY-NMR.

In vitro inhibition of cyclooxygenase and 5-lipoxygenase by alkamides from Echinacea and Achillea species.

Polyunsaturated alkamides isolated from Achillea species, Echinacea angustifolia DC., Anacyclus pyrethrum (L.) Link, and Aaronsohnia pubescens (Desf.