Metabolite profile and in vitro activities of Phagnalon saxatile (L.) Cass. relevant to treatment of Alzheimer's disease

The present study describes for the first time the in vitro properties (inhibition of NO production and anticholinesterase) of Phagnalon saxatile (L.) Cass. (Asteraceae). The methanolic extract showed antioxidant activity that was measured by DPPH assay and beta-carotene bleaching test. The same extract inhibited NO production in the murine monocytic macrophage cell line RAW 264.7. Acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) inhibition was assessed by modifications of Ellman's method. Purification of the MeOH extract of P. saxatile allowed the isolation of phenolic compounds. Among them, the compounds that most effectively inhibited lipopolysaccharide-induced NO production were caffeic acid and methylchlorogenic acid, with IC50 values of 7 microg/mL and 12 microg/mL, respectively. Luteolin and 3,5-dicaffeoylquinic acid exhibited the most promising activity against AChE with an IC50 of 25.2 and 54.5 microg/mL, respectively, while caffeic acid and luteolin exhibited higher activity against BChE with an IC50 of 32.2 and 37.2 microg/mL, respectively.

Primary photoreactions of phylloquinone (vitamin K1) and plastoquinone-1 in solution

The photoreactions of electron transport quinones vitamin K1 (1) and plastoquinone-1 (2) were studied by picosecond pump-probe spectroscopy, nanosecond flash photolysis, step-scan FTIR spectroscopy, and by irradiation in glassy solvents at 77 K with optical and EPR detection. In polar solvents, charge transfer from the beta,gamma-double bond to the quinone moiety initiates intramolecular proton transfer from the side chain, k = 2.7 x 10(11) s-1, yielding 1,3-quinone methide diradicals, which establish a metastable equilibrium between the singlet and the triplet state. Subsequent proton transfer through the solvent forms 1,2-quinone methides. In apolar solvents the predominant primary photoreaction is formation of cyclic 'preoxetane' diradicals (kform > 3 x 10(11) s-1, kdecay approximately 1 x 10(9) s-1), which revert to a photostationary E/Z mixture of the starting materials, unless they are trapped by oxygen. The beta,gamma-double bond in the isoprenoid side chain thus provides two efficient deactivation processes, which prevent the intermolecular photoreactions commonly observed with the parent quinones. A combined mechanistic scheme rationalizes the known photoreactions of 1, 2 and related compounds in solution.

Prenylated flavonoids in the roots of yellow lupin

A further investigation of the methanol-soluble compounds in yellow lupin roots has revealed a new diprenylchromone, a new coumaronochromone (lupinalbin H), a new isoflavone 5,7,4'-trihydroxy-8,3'-di-(3,3-dimethylally)isoflavone (isolupalbigenin), and some complex flavanones. The latter compounds have been identified as two known diprenylated flavanones (lonchocarpol A and euchrestaflavanone A), two diasteroisomeric pairs of dihydrofuranoflavanones (lonchocarpols C1 and C2, and lonchocarpols D1 and D2, the structures formerly proposed for lonchocarpols C and D were also reinvestigated), a new furanoflavanone (lupinenol), and three 8-prenylflavanones with an additional (2RS)-hydroxy-3-methyl-3-butenyl side chain. The structures of the latter flavanones were unambiguously identified by spectroscopic (1H NMR) comparison with 6-, 8- and 3'-prenylnaringenins chemically prepared from (2S)-naringenin. The antifungal activity of the prenylated naringenins, and of the various yellow lupin flavanones, was determined by TLC place bioassays using Cladosporium herbarum as the test fungus.