Shigeru Arichi

Inhibition of the formation of 5-hydroxy-6,8,11,14-eicosatetraenoic acid from arachidonic acid in polymorphonuclear leukocytes by various coumarins

The effects of various coumarins (i.e. esculetin, daphnetin and fraxetin) on the formation of the 5-lipoxygenase product, 5-HETE, and the cyclooxygenase product, HHT, were studied. Esculetin (6,7-dihydroxycoumarin) was found to inhibit the formation of 5-HETE more strongly than HHT; its concentrations for 50% inhibition (IC50) were 1.46 +/- 1.02 microM for the formation 5-HETE and 57.3 +/- 17.3 microM for the formation of HHT. Daphnetin (7,8-dihydroxycoumarin) and fraxetin (6-methoxy-7,8-dihydroxycoumarin) also inhibited the formation of the 5-lipoxygenase product, 5-HETE, and the cyclooxygenase product, HHT; their IC50 values were, respectively, 6.90 +/- 2.07 microM and 2.57 +/- 0.088 microM for the formation of 5-HETE and 139.0 +/- 30.0 microM and 532.5 +/- 33.0 microM for the formation of HHT. The monohydroxy coumarin derivatives umbelliferone (7-hydroxycoumarin) and scopoletin (6-methoxy-7-hydroxycoumarin) and the coumarin glucosides fraxin (6-methoxy-7,8-dihydroxycoumarin 8-O-D-glucoside) and esculin (6,7-dihydroxycoumarin 6-O-D-glucoside) also inhibited the formation of 5-HETE, though less strongly. 4-Hydroxycoumarin and coumarin had no effect on either 5-lipoxygenase or cyclooxygenase at concentrations of up to 1 mM. Esculetin inhibited the formation of 5-HETE noncompetitively. In contrast, the dimethoxycoumarin fraxidin (6,8-dimethoxy-7-hydroxycoumarin) inhibited the formation of HHT more strongly than the formation of 5-HETE at a concentration of 1 mM.

Effects of glycyrrhizin and glycyrrhetinic acid on growth and melanogenesis in cultured B16 melanoma cells.

The effects of glycyrrhizin (GL) and its aglycone, glycyrrhetinic acid (GA), on the growth and differentiation of mouse melanoma (B16) cells in culture were studied. GA inhibits the growth of B16 melanoma cells, causes morphological alterations and stimulates melanogenesis. GL also resulted in the same changes but only when the concentration was about 20 times more than that needed for GA. When GA was removed after 84 h of treatment, the growth rate recovered slightly, but the doubling time was about twice that of the control. Cytofluorometric analysis showed that the growth inhibition of GA is the result of inhibition of the transfer from G1 to S phase.

Induction of phenotypic reverse transformation by ginsenosides in cultured Morris hepatoma cells

Abstract Ginsenosides (oligoglycosides) extracted from the root of Panax Ginseng, C. A. Meyer, are found to induce the reverse transformation of Morris hepatoma cells (MH 1 C 1 ) in vitro . After 24 subcultures of growth medium containing ginsenoside, MH 1 C 1 cells were morphologically changed. These cells were relatively large and polygonal in shape with abundant fine granular cytoplasm and clear intercellular space, and resembled normal hepatocyte-like cells. These cells reversely transformed, by ginsenosides, showed much less ability to grow in a 0.33% soft agar suspension culture in comparison to control MH 1 C 1 cells, but the doubling time of these cells was 30 hr which is similar to that of original Morris hepatoma cells. In these reversely transformed cells, a remarkable increase in uptake of l- 3 H -ornithine in an arginine deficient medium, an increase of activity of succinate-cytochrome c reductase and a decrease in 5′ -nucleotidase activity were observed.

Protective effect of saikosaponin-d isolated from Bupleurum falcatum L. on CCl4-induced liver injury in the rat

SummaryThe effects of saikosaponin-d extracted from the roots of Bupleurum falcatum L. on carbon tetrachloride-induced hepatic injury were studied in rats. Pretreatment with saikosaponin-d produced a remarkable inhibitory action on acute hepatic injury by CCl4. A significant inhibition of lipid peroxidation induced by an acute dose of CCl4 in the liver of rats pre-treated with saikosaponin-d was also noted.Continuous injection of CCl4 caused liver cirrhosis in rats but the severity of cirrhosis was reduced in rats treated simultaneously with CCl4 and saikosaponin-d.

Effects of baicalein on leukotriene biosynthesis and degranulation in human polymorphonuclear leukocytes

Studies were made on the effects of baicalein (5,6,7-trihydroxyflavone) on leukotrienes B4 and C4 biosyntheses and degranulation induced by calcium ionophore A23187 (A23187) in human polymorphonuclear leukocytes. Baicalein inhibited A23187-induced biosynthesis of leukotrienes B4 and C4 in human polymorphonuclear leukocytes. The concentration of baicalein required for 50% inhibition (IC50) of leukotrienes B4 and C4 formations was 1.46.10(-6) and 6.00.10(-7) M, respectively, using 1.0 microgram/ml of A23187. In addition, baicalein dose-dependently inhibited beta-glucuronidase and lysozyme releases induced by A23187, leukotriene B4 plus cytochalasin B and platelet-activating factor plus cytochalasin B. Furthermore, baicalein was found to inhibit dose-dependently Ca2+ uptake into the cells and Ca2+ mobilization from the intracellular stores.

Effects of saikosaponin-d on aminonucleoside nephrosis in rats

The effects of saikosaponin-d extracted from the roots of Bupleurum falcatum L. on aminonucleoside nephrosis were studied in rats. Urine protein excretion in rats receiving aminonucleoside alone was significantly elevated on the 2nd day after the last injection of aminonucleoside and reached a peak on the 11th day. Urinary protein on the 11th day was reduced by 48 and 46%, respectively in animals treated with saikosaponin-d from the 2nd and 8th day after the last injection of aminonucleoside. Electron microscopically, the degree of abnormality, e.g. loss or fusion of foot processes, in the glomerular epitherial cells was significantly lower in the rats treated with saikosaponin-d after aminonucleoside injection than in the rats treated with aminonucleoside alone. It is concluded that saikosaponin-d prevents the development of proteinuria induced by aminonucleoside in the rat.

Ultrastructural studies of Morris hepatoma cells reversely transformed by ginsenosides

Ginsenosides, which were extracted from Panax ginseng, C. A. Meyer, induced well the development of subcellular organelles in cultured Morris hepatoma cells (MH1C1).

Erythrocyte membrane stabilization by plant saponins and sapogenins.

SummaryEffects of saponins extracted from Bupleuri Radix (saikosaponin) and the corresponding aglycones on hypotonic or hyperthermic hemolysis were investigated.Low concentrations of saikosaponins protect or stabilize rat erythrocytes against both hypotonic and heat-induced hemolysis. Minor modifications of the aglyconic part of the saikosaponin have enormous effects on the membrane stabilizing potency. Saikogenins also protect erythrocytes from hypotonic hemolysis but do not show any prevention of heat-induced hemolysis. It is suggested that saikogenins react with erythrocyte membranes in a quite different manner from saponins and that the existence of the sugar moiety plays an important role in the reaction with membranes as does a slight modification of the molecular structure in the aglyconic part.

Effects of saikosaponin‐d on enhanced CCl4‐hepatotoxicity by phenobarbitone

The effects of saikosaponin‐d extracted from the roots of Bupleurum falcatum L. on increased toxicity of CCl4 and increased activities of microsomal enzymes induced by phenobarbitone have been examined. Saikosaponin‐d showed protection against the CCl4‐hepatotoxicity enhanced by phenobarbitone. It also inhibited increases in the content of cytochrome P450 and NADPH‐cytochrome c reductase activity, which are induced by the phenobarbitone treatment, but the spectral characteristics of P450 were not altered. The rate of microsomal lipid peroxidation by NADPH and CCl4 was significantly lowered in‐vitro in rats pretreated with phenobarbitone and saikosaponin‐d compared with those pretreated with phenobarbitone alone.

Histochemistry : IX. Distribution of saikosaponins in bupleurum falcatum root

Abstract The root of Bupleurum falcatum cultivated in Japan was examined by histological and chemical means in order to clarify the distribution of saikosaponins in the various kinds of tissues and parts of the root. By means of qualitative thin-layer chromatographic—densitometric and quantitative high-performance liquid chromatographic analyses, saikosaponins, bioactive principles in the root, were found to be abundant in the outer phloem layer, especially the pericycle and its neighbouring parenchyma cells in the root. It was also found that the highest level of saikosaponins was detected in thinner root hairs and that the level decreased towards the thicker root head.