Yarrow, Achillea millefolium L., is one of the commonest weeds of the Compositae family. Cases of allergic contact dermatitis have been described since 1899. Although 10 sesquiterpene lactones (SL) and 3 polyines have previously been identified, the sensitizers of yarrow have escaped detection. A reinvestigation of short ether extracts of yarrow revealed the presence of 5 unsaturated hitherto unknown guaianolides of peroxide character. The main SL, identified as a strong sensitizer in guinea pig sensitization experiments, was named alpha-peroxyachifolid. The minor SL also contribute marginally to the sensitizing capacity, while other known yarrow constituents like dehydromatricaria ester and pontica epoxide appear to play no role. A 5-year follow-up (1985-1990) of Compositae-sensitive patients showed that more than 50% reacted when tested with a short ether extract of yarrow. Exacerbation of the patch test sites by irradiation with UV light was never observed.
1. Fatty acid synthesis from [2-(14)C]acetate by Chlorella vulgaris cells grown and incubated in the dark is limited almost entirely to the production of saturated and monoenoic acids. 2. In light-incubated cells, both saturated and polyunsaturated fatty acids are rapidly synthesized. 3. Two groups of lipids can be distinguished in both dark- and light-incubated cells. The first group, consisting of phosphatidyl-glycerol, monogalactosyl diglyceride, lecithin and neutral glyceride, has a very high turnover rate for certain fatty acids. The second group, consisting of digalactosyl diglyceride, sulpholipid, phosphatidylethanolamine and phosphatidylinositol, has a slow turnover of fatty acids. 4. The lipids with rapid fatty acid turnover may be involved in the sequences of saturated and unsaturated fatty acid synthesis. A classification of lipids is made on the basis of their suggested functions.
Among the numerous components of essential oils, especially the substituted phenols were found to prevent the growth of bacteria and fungi (1) and inhibit energy metabolism catalyzed by isolated cell membranes (2). The effective final concentrations applied were in the range of 0.02 to 5mM.We have established chemical test systems in vitro which would allow us to evaluate essential oil components in regard to their capacity to scavange oxygen radicals. The latter were generated in the reaction vessel from hydrogen peroxide or p-cumene hydroperoxide as the 0H or p-cumene-0 moiety, respectively. Since linolenic acid served as the substrate, oxygen radicals derived from this component were also present (3). In addition, the isolated essential oll components were tested to determine whether they might influence a soybean lipoxygenase reaction rate (4).Among the numerous compounds tested, again the substituted phenolic essential oil components revealed the most potent capacity to scavange oxygen radicals. 1.4 to 6.5mM final concentrations of, e.g., thymol, carvacrol, eugenol, or isoeugenol caused rather strong oxygen scavanging activities.The similar substituted phenolic compounds likewise represent those components which preferentially decreased the soybean lipoxygenase turnover. Final concentrations in the range of 0.5 to 2.3mM were required to cause a 50% inhibition rate.It has been reported earlier (5) that simllar components decreased a cyclooxygenase reaction. As in the case of cyclooxygenase, it has been demonstrated for the soybean lipoxygenase (6) that on the addition of arachidonic acid, both the enzymes catalyzed the production of prostaglandin F2.
From flower heads of Achillea nobilis two chrysanthemol derivatives (1, 2), tanaparthin-beta-peroxide (3), and 5-hydroxy-3,6,7,4'-tetramethoxyflavone (4) were isolated by repeated column chromatography and HPLC. Structure elucidation has been performed by means of MS, 1H-NMR, 13C-NMR, and 2D-NMR experiments.
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