Toshiyuki Fukuda

Antioxidative polyphenols from walnuts (Juglans regia L.).

Three hydrolyzable tannins, glansrins A-C, together with adenosine, adenine, and 13 known tannins were isolated from the n-BuOH extract of walnuts (the seeds of Juglans regia L.). Glansrins A-C were characterized as ellagitannins with a tergalloyl group, or related polyphenolic acyl group, based on spectral and chemical evidence. The 14 walnut polyphenols had superoxide dismutase (SOD)-like activity with EC(50) 21.4-190 microM and a remarkable radical scavenging effect against 1,1-diphenyl-2-picrylhydrazyl (DPPH) (EC(50) 0.34-4.72 microM).

甘草のフェノール性成分(第4報)甘草のフェノール性成分と基原植物の関係, 並びに各種甘草エキスのXanthine Oxidase及びMonoamine Oxidaseに対する阻害効果

The roots and/or rhizomes of Glychyrrhiza uralensis, G. glabra and G. inflata, and commercial licorice specimens from various regions or countries were analyzed by high-performance liquid chromatography (HPLC), and classified into three types based on their phenolic constituents. i) Type A: The roots and rhizomes of G. uralensis, commercial licorice specimens from northwestern region of China (Seihoku-kanzo) and from northeastern region of China (Tohoku-kanzo) in Japanese markets, and also several licorice specimens from Chinese markets. They contain licopyranocoumarin (6), glycycoumarin (7) and/or licocoumarone (8), which were not found in G. glabra and G. inflata. ii) Type B: The root and rhizome of G. glabra, and the licorice specimens imported from the Soviet Union and Afghanistan. They contain glabridin (9) and glabrene (10), which were not found in the samples of the other two Glycyrrhiza species. A root sample of Glycyrrhiza species from Turkey also contains 9 and 10. iii) Type C: The root sample of G. inflata. They contain licochalcones A (11) and B (12), which were not found in the samples of the other two Glycyrrhiza species. Commercial licorice specimens obtained in Japan, which were imported from Sinkiang of China (Shinkyo-kanzo), and some licorice specimens obtained from Chinese markets, have also been found to contain 11 and 12. The phenolics 6-12, characteristic constituents of types A, B or C, were not found in a specimen of cortex-free licorice from a Japanese market (kawasari-kanzo). Extracts of some licorice specimens of types A and B, and all of the licorice specimens of type C inhibited 40-56% of the xanthine oxidase activity at the concentration of 30 micrograms/ml. Extracts of some licorice specimens of types A and B also showed inhibitory effects on monoamine oxidase (44-64% inhibition, at the concentration of 30 micrograms/ml), which were slightly weaker than that of harmane hydrochloride.

Effect of Polyphenol-Rich Extract from Walnut on Diet-Induced Hypertriglyceridemia in Mice via Enhancement of Fatty Acid Oxidation in the Liver

The kernel pellicles of walnut are rich in ellagitannins with antioxidative activity. A polyphenol-rich extract from walnuts (WP, 45% polyphenol) was prepared and evaluated for its hypolipidemic effect in high fat diet fed mice. Oral administration of WP (100 and 200 mg/kg) significantly reduced liver weight and liver and serum triglycerides (TG). Hepatic beta-oxidation in cytosol, including peroxisome, was enhanced by WP (50-200 mg/kg). mRNA expressions of hepatic peroxisome proliferator-activated receptor (PPAR) alpha and acyl coenzyme A oxidase (ACOX) 1 were enhanced by WP (50-200 mg/kg). With respect to the hypotriglyceridemic mechanism of WP, it suppressed neither olive oil induced serum TG elevation in mice nor oleic acid induced TG accumulation in HepG2 cells. On the other hand, mRNA expressions of PPARalpha, ACOX1, and carnitine palmitoyltransferase (CPT) 1A in HepG2 cells were significantly enhanced by addition of WP (100 microg/mL). Moreover, tellimagrandin I, a polyphenolic constituent in WP, enhanced ACOX1 expression at 1-100 microg/mL. In conclusion, WP was found to possess hypotriglyceridemic activity via enhancement of peroxisomal fatty acid beta-oxidation in the liver. These results suggest that tellimagrandin I is involved in the hypotriglyceridemic mechanism of WP.

Fractionation of Pharmacologically Active Plant Polyphenols by Centrifugal Partition Chromatography

Abstract Centrifugal partition chromatography (CPC) has been applied to the preparative fractionation of pharmacologically active polyphenols contained in the crude extracts from three medicinal plants. 1) (-)-Epigallocatechin gallate, the main component of tea polyphenols, which inhibits tumor promotion, 2) oligomeric hydrolyzable tannins, having host-mediated anti-tumor activity and antiviral activity, contained in Woodfordia fruticosa flower, 3) polyphenolic components of licorice, having anti-HIV activity. The results obtained with cartridges of medium volume and of small volume were compared during the fractionation of tea polyphenols.