Effects of various ginseng saponins on 5-hydroxytryptamine release and aggregation in human platelets.

The effects of various ginseng saponins isolated from red ginseng roots, on aggregation and 5-hydroxytryptamine release (5-HT) human platelets have been investigated. Among the six saponins tested, only ginsenoside Rg1 inhibited adrenaline- and thrombin-induced platelet aggregation and 5-HT release dose-dependently, at concentrations of 5 to 500 micrograms ML-1. Ginsenoside Rg1 had no effect on adrenaline- and thrombin-induced arachidonic acid release and diacylglycerol production. But it did reduce the elevation of cytosolic free calcium concentration (Ca2+)i shown in the second phase induced by adrenaline and thrombin, at concentrations of 10 to 500 micrograms mL-1. Those data suggest that the inhibitory effects of ginsenoside Rg1 on 5-HT release from, and aggregation of, platelets might be due to the reduction of (Ca2+)i elevation at the second phase induced by adrenaline and thrombin. The results suggest that ginsenoside Rg1 in red ginseng roots may be active as a drug in the treatment of artheroscleorosis and thrombosis.

[Ginsenoside-Rb1 as a suppressor in central modulation of feeding in the rat].

Ginsenosides, the main component of Panax ginseng root, have been reported to show several pharmacological actions on the peripheral metabolism of glucose and lipid and on endocrine secretion. The present study aimed to clarify the effects of ginsenoside-Rb1 on feeding behavior and endogenous chemical substances. Rb1 infusion into the rat third cerebroventricle was started at 1930 hr, and ingestive behavior was recorded in a soundproof room illuminated daily from 0800 to 2000 hr. Rb1 at doses of 0.05, 0.10 and 0.20 mumol potently decreased food intake dose-dependently during the first dark period after infusion. Analysis of meal patterns revealed that the suppressive effect was due to decreasing meal size, but not to postprandial intermeal interval and eating speed. Drinking episodes decreased concomitantly with feeding suppression only at the highest dose of 0.20 mumol. Ambulatory activity was not affected in the doses tested. Infusion of Rb1 increased plasma glucose, leaving insulin unaffected. Microinjection of 0.01 mumol Rb1 into the hypothalamic ventromedial nucleus (VMH) decreased food intake, but injection into the lateral hypothalamic area did not. Taking these data together, Rb1 was found to have a suppressive effect on feeding partly through the VMH.

Alterations in the glomerulus in aminonucleoside nephrosis in analbuminemic rats.

Whether obliteration of glomerular epithelial foot processes and increases in urinary N-acetyl-beta-D-glucosaminidase (NAG) activity are the consequence or the cause of proteinuria after administrations of the aminonucleoside of puromycin was examined using Nagase analbuminemic rats. The administration of puromycin aminonucleoside to Nagase analbuminemic rats did not induce proteinuria. However, the increase in urinary NAG activity and the degree of abnormality of foot processes in the glomerular cells were similar to those in control Sprague-Dawley rats. These findings suggest that NAG excretion and the morphological alterations of epithelial cells in nephrosis are not the consequence of massive proteinuria.

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 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.

Biopharmaceutical studies on crude drug preparations. I: Permeation of paeonol in a decoction and dry extract of Paeonia suffruticosa root cortex using an absorption simulator.

The permeation behavior of paeonol, one active constituent of a crude Chinese drug called Moutan Cortex, through an artificial gastric lipid barrier was examined in vitro using an absorption simulator in order to clarify how the administered form influenced the bioavailability of paeonol from a crude preparation. Paeonol concentrations were determined by a high-performance liquid chromatographic method developed during this study. Paeonol showed greater permeation from artificial gastric juice into artificial plasma when it was applied as a decoction or freeze-dried extract of Moutan Cortex than when applied as purified paeonol alone.

[Basic studies on chemotherapy of brain tumors by means of liposomes: affinity of sulfatide-inserted liposomes to human glioma cells].

In order to utilize liposomes for the treatment of brain tumors, we examined the interaction between the cells and the liposomes prepared from phosphatidylcholine, cholesterol, and sulfatide (molar ratio, 7:2:1), which were able to deliver the encapsulated materials into the brain through the blood-brain barrier. With a variety of human cell lines, the incorporation of the liposomes and the release of the liposomal contents into cells were studied by spectrofluorometry and flow cytometry by use of encapsulated 6-carboxy-fluorescein. It was found that the amounts of liposomes incorporated into cells were dependent on the dose of liposomes and type of cells. At the same concentration of liposomes, the highest incorporation was found for glioma cells, which was further confirmed by electron microscopy with ferritin-containing liposomes. These results indicate that the liposomes composed of sulfatide, phosphatidylcholine and cholesterol have a high affinity for human glioma cells and should be useful for the chemotherapy of glioma when antitumor drugs are encapsulated into them.

Inhibitory effects of various flavonoids isolated from leaves of persimmon on angiotensin-converting enzyme activity.

The leaves of the persimmon Diospyros kaki, have been traditionally used for treatment of hypertensive diseases in Japan. We have studied the inhibitory effects of four flavonoids isolated from the leaves of the persimmon on angiotensin-converting enzyme activity. The four flavonoids astragalin [1], kaempferol-3-O-(2"-O-galloyl)-glucoside [2], isoquercitrin [3], and quercetin-3-O-(2"-O-galloyl)-glucoside [4] inhibited the angiotensin-converting enzyme activity in a dose-dependent fashion. Compounds 1-4 produced 67%, 53%, 33%, and 48% inhibition at a concentration of 300 micrograms/ml, respectively. The 50% inhibitory concentrations (IC50) of 1 and 2 for the angiotensin-converting enzyme were 180 micrograms/ml and 280 micrograms/ml, respectively. On the other hand, 2 and 4 were shown to have tannin activities, but 1 and 3 had no tannin activities. These results suggest that there is no relationship between the inhibition for angiotensin converting enzyme activity and the tannin activity for the four flavonoids.

Plant-glycoside modulation of cell surface related to control of differentiation in cultured B16 melanoma cells.

We have shown that the ginsenosides Rh1 and Rh2, which are plant glycosides with a dammarane skeleton resembling a steroid skeleton as an aglycone, control the phenotypic expression of mouse B16 melanoma cells in different ways. The effects of Rh1 and Rh2 on the cell surface were studied to clarify the relationship between the control of phenotypic expression and modification of the cell surface in B16 melanoma cells. Rh2, which has the capacity to inhibit the growth of and to stimulate melanogenesis in B16 melanoma cells, causes flattening of the cells cultured in a collagen gel, leading to organized, nonoverlapping monolayers. Cell-to-cell adhesiveness and cell-to-substrate adhesiveness were markedly increased in the B16 melanoma cells treated with Rh2. In Rh2-treated cells, the binding of peanut agglutinin on the cell surface was also increased, whereas no marked changes were observed in the binding of concanavalin A or wheat germ agglutinin. In contrast, Rh1, which showed no effect on cell growth, but did stimulate melanogenesis, did not cause morphological changes of the cells and exerted no effect on cell adhesiveness or cell surface lectin binding. 1,6-Diphenyl-1,3,5-hexatriene polarization values markedly decreased in cells treated with either Rh1 or Rh2. Rh2 was found to be incorporated in the lipid fraction of the B16 melanoma cell membrane. In contrast, Rh1 was not detected in the lipid fraction of B16 melanoma cells. However, novel lipid components were found.

Studies on the activities of tannins and related compounds, X. Effects of caffeetannins and related compounds on arachidonate metabolism in human polymorphonuclear leukocytes.

As part of a series of biological examinations of various tannins and related compounds, the present paper reports the effects of caffeetannins and related compounds isolated from medicinal plants on arachidonate metabolism in human peripheral polymorphonuclear leukocytes (PMN-L). The formation of leukotriene B4 (LTB4) induced by calcium ionophore A 23187 (A 23187) in human PMN-L was inhibited by 3,5-, 4,5-, and 3,4-di-O-caffeoylquinic acid, caffeoylmalic acid, caffeoyltartric acid, rosmarinic acid, and caffeic acid. Rosmarinic acid strongly inhibited the formation of 5-hydroxy-6,8,11,14-eicosatetraenoic acid (5-HETE) and LTB4 (5-lipoxygenase products) at concentrations of 10(-5)-10(-3) M. On the other hand, the formation of prostaglandin E2 (PGE2) was enhanced in a concentration-dependent fashion by caffeic acid, caffeoylmalic acid, caffeoyltartaric acid, and 3,4-di-O-caffeoylquinic acid. On the basis of experimental results, it seems likely that caffeoyl derivatives could be developed as therapeutic drugs for treatment of allergic inflammation such as asthma.