Tadashi Kageura

Effects of sesquiterpenes and amino acid–sesquiterpene conjugates from the roots of Saussurea lappa on inducible nitric oxide synthase and heat shock protein in lipopolysaccharide-activated macrophages

The methanolic extract of the roots of Saussurea lappa CLARKE, a Chinese medicinal herb Saussureae Radix, was found to inhibit nitric oxide (NO) production in lipopolysaccharide (LPS)-activated mouse peritoneal macrophages. Among the constituents from the methanolic extract, two sesquiterpene lactones (costunolide and dehydrocostus lactone) and two amino acid-sesquiterpene conjugates (saussureamines A and B) potently inhibited LPS-induced NO production (IC(50)=1.2-2.8 microM). Saussureamines A and B in addition to costunolide and dehydrocostus lactone did not inhibit iNOS enzyme activity, but they inhibited both induction of inducible NO synthase and activation of nuclear factor-kappaB in accordance with induction of heat shock protein 72.

Effects of sesquiterpenes and triterpenes from the rhizome of Alisma orientale on nitric oxide production in lipopolysaccharide-activated macrophages: absolute stereostructures of alismaketones-B 23-acetate and -C 23-acetate.

The methanolic extract from a Chinese herbal medicine, the rhizome of Alisma orientale, was found to exhibit inhibitory activity of nitric oxide (NO) production in lipopolysaccharide (LPS)activated macrophages. Novel triterpenes, alismaketones-B 23-acetate and -C 23-acetate, were isolated from the active extract together with eight sesquiterpenes and eighteen protostane-type triterpenes. The absolute stereostructures of new triterpenes were characterized on the basis of chemical and physicochemical evidence, which included the chemical correlations with known triterpenes. The guaiane-type sesquiterpenes (alismol, orientalols A and C) and protostane- and seco-protostane-types triterpenes (alisols C monoacetate, E-23-acetate, F, H, I, L-23-acetate, and M-23-acetate, alismaketones-B 23-acetate and -C 23-acetate, alismalactone 23-acetate, and 3-methylalismalactone 23-acetate) inhibited LPS-induced NO production (IC50 = 8.4-68 microM). Other triterpenes (alisols A, A monoacetate, B, B monoacetate, E, G, K-23-acetate, and N-23-acetate and 11-deoxyalisol B) also showed the potent inhibitory activity, but they showed cytotoxic effects more than 30 microM (MTT assay). In addition, alismol and alisol F were found to suppress iNOS induction.

Hepatoprotective and nitric oxide production inhibitory activities of coumarin and polyacetylene constituents from the roots of Angelica furcijuga

The methanolic extract from the roots of Angelica furcijuga KITAGAWA was found to exhibit protective effects on liver injury induced by D-galactosamine (D-GalN) and lipopolysaccharide (LPS). From the methanolic extract, seventeen coumarins, two phenylpropanoids, and two polyacetylenes were isolated and examined their in vitro and in vivo hepatoprotective effects and inhibitory activity of NO production in macrophages. A acylated khellactone, isoepoxypteryxin, showed protective activity against D-GalN-induced cytotoxicity in primary cultured rat hepatocytes. On the other hand, six acylated khellactones (hyuganins A, B, C, and D, anomalin, isopteryxin) and two polyacetylenes [(-)-falcarinol and falcarindiol] strongly inhibited NO production induced by LPS in cultured mouse peritoneal macrophages, and also other acylated khellactones (isoepoxypteryxin, pteryxin, and suksdorfin) and a coumarin glycosides (praeroside II) were found to show the activity. By comparison of the inhibitory activities for acylated khellactones with those for other coumarins, acyl groups were found to be essential to exerting potent activity.

Absolute Stereostructures and Syntheses of Saussureamines A, B, C, D and E, Amino Acid–Sesquiterpene Conjugates with Gastroprotective Effect, from the Roots of Saussurea lappa

Abstract From the methanolic extract of the dried roots of Saussurea lappa Clarke, Saussureae Radix, five amino acid–sesquiterpene conjugates, saussureamines A, B, C, D and E, were isolated together with a lignan glycoside, (−)-massoniresinol 4″- O -β- d -glucopyranoside. Their stereostructures were determined on the basis of chemical and physicochemical evidence. In addition, saussureamines and the related amino acid–sesquiterpene conjugates were synthesized using a Michael type addition reaction of amino acid to the α-methylene-γ-lactone moiety of sesquiterpenes. Saussureamines A, B and C, costunolide and dehydrocostus lactone showed a gastroprotective effect on acidified ethanol-induced gastric mucosal lesions in rats. Saussureamines A also exhibited an inhibitory effect on gastric mucosal lesions induced by water-immersion stress in mice.

Different effects of cell‐permeable ceramide analogs on platelet activation

The effects of cell‐permeable ceramide analogs on platelet responses induced by agonists were investigated. When washed rabbit platelets were pretreated with ceramide and then stimulated with thrombin or U46619, C2‐ceramide (N‐acetylsphingosine) dose‐dependently inhibited the aggregation and arachidonic acid liberation, whereas C6‐ceramide (N‐hexanoylsphingosine) and C8‐ceramide (N‐octanoylsphingosine) enhanced these responses. Furthermore, C6‐ceramide, but not C2‐ceramide, enhanced the increase in and prevented the progressive decrease in cytoplasmic free Ca2+ concentration induced by U46619. On the other hand, treatment with sphingomyelinase potentiated the aggregation in response to U46619. These results indicate that the effects of cell‐permeable ceramide analogs on platelet activation vary with N‐acyl chain length.

Sphingosine Enhances Arachidonic Acid Liberation in Response to U46619 through an Increase in Phospholipase A2 Activity in Rabbit Platelets.

Treatment of rabbit platelets for 1 min with 10-15 microM sphingosine enhanced arachidonic acid liberation after stimulation with U46619, although sphingosine or U46619 alone elicited little liberation of the lipid. Thrombin-induced arachidonic acid liberation was not influenced by sphingosine up to 10 microM, and was suppressed at concentrations higher than 20 microM. Sphingosine also promoted lysophosphatidylcholine formation in response to U46619, indicating that sphingosine caused an increase in hydrolytic action of phospholipase A2 (PLA2). The enhancing effect of sphingosine on arachidonic acid liberation decreased with increases in pretreatment time, accompanied by the conversion of sphingosine to sphingosine-1-phosphate. Of various sphingosine derivatives examined, sphingosine-1-phosphate, N,N-dimethylsphingosine, and N-acetylsphingosine (C2-ceramide) showed little enhancing effect on arachidonic acid liberation. Sphingosine increased cytosolic PLA2 activity in response to U46619 with enhancement of mitogen-activated protein kinase activity. These results indicate that sphingosine potentiates the transduction process of stimulus-PLA2 activation, resulting in enhancement of arachidonic acid liberation.