Diffractaic acid and usnic acid were identified as the analgesic and antipyretic components of a lichen, Usnea diffracta. Both compounds showed an analgesic effect by the acetic acid-induced writhing and tail-pressure methods in mice. Regarding the effect on normal body temperature and LPS-induced hyperthermia in mice, diffractaic acid showed a significant effect only on the former and usnic acid only on the latter.

Two distinct NADH oxidases, corresponding to H202-forming and H20-forming enzymes were purified to homogeneity from Streptococcus mutans and their basic properties determined. The H202-forming enzyme was a tetramer with a subunit molecular mass of about 56 kDa and required flavin adenine dinucleotide (FAD) for full activity. The enzyme had an isoelectric point of 6 6 and exhibited optimal activity at pH 6-0. The H20-forming enzyme was a monomer with a molecular mass of 50 kDa and activity independent of exogenously added flavin. The enzyme had an isoelectric point of 4.8 and exhibited optimal activity between pH 7.0 and 7-5. Both enzymes oxidized NADH (K, 0.05 and 0.025 mM for the H202-and H20-forming enzyme, respectively) but not NADPH and contained 1 mol of FAD per monomer. Spectra of the oxidized enzymes exhibited maxima at 271,383 and 449 nm for the H,O,-forming enzyme and 271, 375 and 447 nm for the H,O-forming enzyme. Antibodies raised against the H,O,-forming enzyme or the H20-forming enzyme reacted with their corresponding antigen, but did not cross-react. The amino-terminal regions of the two enzymes had completely different amino acid sequences.

Inhibition of tumor promoter-induced Epstein-Barr virus (EBV) activation was screened using tissue culture and thallus extracts of lichens. Usnea longissima ACH. thallus and Cetraria ornata MULL. ARG. tissue culture showed strong inhibitory activity. We identified (+)-usnic acid (1), barbatic acid (2), diffractaic acid (3), 4-O-demethylbarbatic acid (4), and evernic acid (5) as inhibitors of EBV activation from the U. longissima thallus. Of these compounds, (+)-usnic acid exhibited the highest inhibitory activity (IC50 = 1.0 microM).

Usnic acid acts on gram-positive bacteria1} and is used as a skin germicide, but is not industrially produced. It is widely spread in Usneaceae lichens,2) but these lichens are not abundant in nature and their culture is very difficult because their spores are not always obtained in natural habitats, they are almost always sterile, and natural lichen thalli are

Secondary metabolites from Lichen, mainly phenolic compounds, have been analysed and identified using high performance liquid chromatography with a photodiode array detector. Components of lichen thalli were detected by characteristic ultraviolet spectra and relative retention times. Some new minor components have been found in several lichens.