Radical and Superoxide Scavenging Activities of Matairesinol and Oxidized Matairesinol

The radical and superoxide scavenging activities of oxidized matairesinols were examined. It could be assumed that the free benzylic position was important for higher radical scavenging activity. The different level of activity was observed between 7′-oxomatairesinol (Mat 2) and 7-oxomatairesinol (Mat 3). The activity of 8-hydroxymatairesinol was lower than that of matairesinol (Mat 1). The superoxide scavenging activity of the oxidized matairesinols was also demonstrated for the first time. It is assumed that the pKa value of phenol in the oxidized matairesinols affected this activity.     

Reactivity of bacterial and fungal laccases with lignin under alkaline conditions

The ability of Streptomyces ipomoea laccase to polymerize secoisolariciresinol lignan and technical lignins was assessed. The reactivity of S. ipomoea laccase was also compared to that of low redox fungal laccase from Melanocarpus albomyces using low molecular mass p-coumaric, ferulic and sinapic acid as well as natural (acetosyringone) and synthetic 2,2,6,6-tetramethylpiperidine 1-oxyl (TEMPO) mediators as substrates. Oxygen consumption measurement, MALDI-TOF MS and SEC were used to follow the enzymatic reactions at pH 7, 8, 9 and 10 at 30 °C and 50 °C. Polymerization of lignins and lignan by S. ipomoea laccase under alkaline reaction conditions was observed, and was enhanced in the presence of acetosyringone almost to the level obtained with M. albomyces laccase without mediator. Reactivities of the enzymes towards acetosyringone and TEMPO were similar, suggesting exploitation of the compounds and low redox laccase in lignin valorization under alkaline conditions. The results have scientific impact on basic research of laccases.     

Effect of Benzylic Oxygen on the Cytotoxic Activity for Colon 26 Cell Line of Phenolic Lignans

The cytotoxic activity for colon 26 cell line of matairesinol, oxidized matairesinol, 9,9′-epoxylignan and oxidized 9,9′-epoxylignan were examined. (?)-Matairesinol (Mat 1) showed greatest cytotoxic activity (LC₅₀=9 μg/ml) of the lactone-type lignans. 7,7′-Oxomatairesinol having same steric configuration as that of (?)-matairesinol showed greater activity (LC₅₀=25 μg/ml) than hydroxy or mono-oxomatairesinol. The activities of 9,9′-epoxylignan and 7,7′-oxo-9,9′-epoxylignan having same steric configurations as (?)-matairesinol were weaker than that of corresponding matairesinols. Different activity levels were observed between enantiomers.     

Investigation on the Toxin Production by Several Blast Fungus Strains and Isolation of Tenuazonic Acid as a Novel Toxin

A survey of the toxin production by several strains of blast fungus was carried out. Among the strains tested only one strain, C₁(THU 69-03) produced α-picolinic acid with good yield and other strains produced neither α-picolinic acid nor piricularin. On the other hand, tenuazonic acid and its Fe-cbelate compound were isolated as novel blast fungus toxins from the surface culture brothes of these strains, but they could not be isolated from the shaking culture brothes. The phytotoxic effect of tenuazonic acid on rice plants in regard to varietal difference was also studied.     

Inhibition of the Discoloration of Yellowtail Dark Muscle by Lignan

The inhibitory effect of (?)-, (+)-matairesinol and (?)-, (+)-secoisolariciresinol on the discoloration of dark muscle (chiai in Japanese) of two-year-old yellowtail (hamachi in Japanese) was evaluated by measuring the X and a^* values. (?)-Matairesinol was most effective for retaining the red color of dark muscle in this experiment.     

IgE-Suppressive Activity of (−)-Matairesinol and Its Structure-Activity Relationship

The IgE-suppressive activity of (?)-matairesinol is demonstrated, and the structure-activity relationship of (?)-matairesinol clarified. 3′,4-Dihydroxy-3,4′-dimethoxylignano-9,9′-lactone showed higher IgE-suppressive activity than (?)-matairesinol without any cytotoxic activity. Some derivatives bearing a longer and more bulky alkoxy group at the 3 or 4 position showed IgE-accelerative activity.