Robert Anton

Suppression of Azoxymethane-Induced Preneoplastic Lesions and Inhibition of Cyclooxygenase-2 Activity in the Colonic Mucosa of Rats Drinking a Crude Green Tea Extract

We determined the effects of a crude green tea extract given as drinking fluid on the promotion/progression phase of colon carcinogenesis in rats after induction of the neoplastic process by azoxymethane. Adult Wistar rats were given azoxymethane (15 mg/kg ip) once a week for two weeks. One week after the second injection, the rats were randomly divided into two groups. One group (n = 8) received daily prepared aqueous solutions of green tea extracts (GTE; 0.02%, wt/vol); the control group (n = 8) received tap water. After six weeks, rats receiving GTE showed a 60% reduction in the number of colonic preneoplastic lesions (aberrant crypts). The number of individual crypts per aberrant crypt focus (crypt multiplicity) was significantly reduced in the GTE group; the majority (80%) of the remaining aberrant foci contained only one or two preneoplastic crypts. A significant and selective decrease of cyclooxygenase (COX)-2 activity was observed in the colon of rats receiving GTE (23 ± 3 vs. 117 ± 30 mU/mg protein in controls), whereas COX-1 showed no alterations. Our data demonstrate that GTE reduces COX-2 and suppresses the formation of colonic preneoplastic lesions. They provide new insights into the mechanism of chemopreventive and anti-inflammatory properties of green tea.

Dimeric alkaloids fromPsychotria forsteriana

Abstract Three alkaloids, (−)-calycanthine, iso -calycanthine and meso -chimonanthine, a dimeric indole isomeric with the former compounds have been isolated from Psychotria forsteriana and identified on the basis of their spectral data and by comparison with those of previously described compounds.

Chemotaxonomical investigation in the genus Viburnum

A chemical examination of the leaves and branchlets of Viburnum sp. (Adoxaceae) has been carried out in order to find chemical clues of possible taxonomic value. Precise quantitative data of the amentoflavone content were obtained for about sixty representative taxa of the genus. A great heterogeneity of distribution of this biflavone was observed between the sections. The highest average concentration (more than 0.5%) was found in the section Lantana.

Kaempferol coumaroyl glucorhamnoside from Ginkgo biloba

Abstract A new flavonoid glycoside was isolated from the leaves of Ginkgo biloba and its structure elucidated as kaempferol 3-O-α-(6‴-p-coumaroylglucosyl-β-1,4-rhamnoside).

Triterpenoid glycosides from the bark of Mimosa tenuiflora.

Two new saponins were isolated from Mimosa tenuiflora and their structures established as 3-O-[alpha-L-rhamnopyranosyl(1----2)-beta-D-glucopyranosyl-(1----3]-(alp ha-L- arabinopyranosyl-(1----4]-beta-D-xylopyranosyl-(1----2)]-[beta-D- xylopyranosyl-(1----4)]-beta-D-glucopyranosyl)-28-O-alpha-L-rhamnopyrano syl oleanolic acid and 3-O-[alpha-L-rhamnopyranosyl-(1----2)-beta-D-glucopyranosyl-(1----3]-(al pha- L-arabinopyranosyl-(1----4]beta-D-xylopyranosyl-(1----2)]-[beta-D- xylopyranosyl-(1----4)]-beta-D-glucopyranosyl) oleanolic acid.

Quercetin coumaroyl glucorhamnoside from Ginkgo biloba

Abstract A new flavonoid glycoside was isolated from the leaves of Ginkgo biloba (Ginkgoaceae) and its structure elucidated as quercetin-3-O-α-(6‴-p-coumaroylglucosyl-β-1,4-rhamnoside).

Interactions of the monomeric and dimeric flavones apigenin and amentoflavone with the plasma membrane of L929 cells; a fluorescence study.

Flavonoids are ubiquitous polyphenolic compounds, found in vascular plants, which are endowed with a large variety of biological effects. Some of these effects have been assumed to result from interactions with the cell plasma membrane. In order to investigate the nature of these interactions a fluorescence study was performed with two flavonoids, currently used in one of the laboratories: apigenin and its homologous dimer amentoflavone. After preliminary assays with DPH in several types of phospholipid liposomes, the effects of these flavonoids on the membrane of mouse L929 fibroblasts were compared, using the non-permeant probe TMA-DPH. Amentoflavone, unlike apigenin, induced a static quenching effect, which denoted an important, but reversible, association of the molecule with the plasma membrane. In addition, amentoflavone treatment induced a dose-dependent increase in TMA-DPH fluorescence anisotropy, which could be interpreted as an increase in membrane lipidic order. For apigenin, the effect was much less important. Moreover, exploiting the capacity of TMA-DPH to label endocytic compartments, it was shown that, after association with the membrane, amentoflavone is not internalized into the cell. Possible correlations of these membrane effects with other biological properties are discussed.

La 5′-méthoxybilobétine, une biflavone extraite du Ginkgo biloba

Abstract A new biflavone, I-5′-methoxybilobetin has been isolated from Ginkgo biloba leaves. 1 H and 13 C NMR spectral data show that it is a II-4′, I-5, II-5, I-7, II-7-pentahydroxy-I-4′, I-5′-dimethoxy- [I-3′, II-8] biflavone.

Sulphated steroidal derivatives from Ruscus aculeatus

Abstract Two novel steroidal derivatives, (1β-hydroxyruscogenin 1-sulphate and 26-O-β- d -glucopyranosyl furost-5-en-1β,22ζ-triol 1-sulphate) were isolated from the rhizome of Ruscus aculeatus . The structures were established by spectroscopic methods.

Oxindole alkaloids from Neolaugeria resinosa

Abstract The new alkaloids neolaugerine, isoneolaugerine and 15-hydroxyneolaugerine, possessing an original oxindole skeleton, have been isolated from the root