Cancer chemoprevention by ginseng in mouse liver and other organs.

Oral administration of red ginseng extracts (1% in diet for 40 weeks) resulted in the significant suppression of spontaneous liver tumor formation in C3H/He male mice. Average number of tumors per mouse in control group was 1.06, while that in red ginseng extracts-treated group was 0.33 (p<0.05). Incidence of liver tumor development was also lower in red ginseng extracts-treated group, although the difference from control group was not statistically significant. Anti-carcinogenic activity of white ginseng extracts, besides red ginseng extracts, was also investigated. In the present study, the administration of white ginseng extracts was proven to suppress tumor promoter-induced phenomena in vitro and in vivo. It is of interest that oral administration of the extracts of Ren-Shen-Yang- Rong-Tang, a white ginseng-containing Chinese medicinal prescription, resulted in the suppression of skin tumor promotion by 12-o-tetradecanoylphorbol-13-acetate in 7,12-dimethylbenz[a]anthracene-initiated CD-1 mice. These results suggest the usefulness of ginseng in the field of cancer prevention.

Transmembrane phosphoprotein Cbp regulates the activities of Src-family tyrosine kinases.

The Src family of protein tyrosine kinases (Src-PTKs) is important in the regulation of growth and differentiation of eukaryotic cells. The activity of Src-PTKs in cells of different types is negatively controlled by Csk, which specifically phosphorylates a conserved regulatory tyrosine residue at the carboxy-terminal tail of the Src-PTKs. Csk is mainly cytoplasmic and Src-PTKs are predominantly membrane-associated. This raises a question about the mechanism of interaction between these enzymes. Here we present Cbp--a transmembrane phosphoprotein that is ubiquitously expressed and binds specifically to the SH2 domain of Csk. Cbp is involved in the membrane localization of Csk and in the Csk-mediated inhibition of c-Src. In the plasma membrane Cbp is exclusively localized in the GM1 ganglioside-enriched detergent-insoluble membrane domain, which is important in receptor-mediated signalling. These findings reveal Cbp as a new component of the regulatory mechanism controlling the activity of membrane-associated Src-PTKs.

Suppression of lung and liver carcinogenesis in mice by oral administration of myo-inositol.

It has been reported that myo-inositol can inhibit carcinogenesis in various organs, such as the mammary gland, colon and lung. In the present study, at first, inhibitory effects of myo-inositol on lung carcinogenesis were confirmed. Then, the influence of myo-inositol on liver carcinogenesis in mice was investigated. In C3H/He male mice, the rate of spontaneous liver carcinogenesis is known to be high. Using this experimental model, the effects of oral administration of myo-inositol (added into the drinking water at the concentration of 1%) were assessed. Significant suppression of liver carcinogenesis was observed in mice treated with myo-inositol for 40 weeks. In the control group without myo-inositol administration, 88% of the animals developed liver tumors, whereas in the myo-inositol-supplemented group, the incidence of liver tumors was 38% (p < 0.05). The average number of liver tumors per mouse was also decreased significantly by myo-inositol treatment; from 7.8 in the control group to 0.8 in the myo-inositol-supplemented group (p < 0.01). Thus, myo-inositol may be useful for cancer chemoprevention in the liver, as well as the lung.

Steroidal saponins from the underground parts of Chlorophytum comosum and their inhibitory activity on tumour promoter-induced phospholipids metabolism of HeLa cells.

Three new spirostanol pentaglycosides embracing beta-D-apiofuranose were isolated from the fresh underground parts of Chlorophytum comosum together with four known saponins. The structures of new compounds were determined by spectroscopic data, including two-dimensional NMR, and partial acid-catalysed hydrolysis to be (25R)-5 alpha-spirostane-2 alpha,3 beta-diol 3-O-[O-beta-D-glucopyranosyl- (1-->2)-O-[O-beta-D-apiofuranosyl-(1-->4)-beta-D-glucopyranosyl-(1 -->3)]-O- beta-D-glucopyranosyl-(1-->4)-beta-D-galactopyranoside], (25R)-3 beta-hydroxy-5 alpha-spirostan-12-one (hecogenin) 3-O-[O-beta-D-glucopyranosyl-(1-->2)-O-[O-beta-D-apiofuranosyl-(1- ->4)- beta-D-xylopyranosyl-(1-->3)]-O-beta-D-glucopyranosyl-(1-->4)-beta-D- galactopyranoside] and hecogenin 3-O-[O-beta-D-glucopyranosyl-(1-->2)-O-[O-beta-D- apiofuranosyl-(1-->4)-beta-D-glucopyranosyl-(1-->3)]-O-beta-D-gluc opyranosyl- (1-->4)-beta-D-galactopyranoside], respectively. The isolated saponins were examined for inhibitory activity using 12-O-tetradecanoylphorbor-13-acetate-stimulated 32P-incorporation into phospholipids of HeLa cells as the primary screening test to identify new antitumour-promoter compounds.

Steroidal saponins from the underground parts of Hosta longipes and their inhibitory activity on tumor promoter-induced phospholipid metabolism.

Phytochemical study on the underground parts of Hosta longipes gave six new steroidal saponins together with a known one. The structures of the new compounds were determined by detailed analysis of their 1H- and 13C-NMR spectra including two-dimensional NMR spectroscopy, acid-catalyzed hydrolysis followed by chemical correlation, and by comparison with spectral data of known compounds. The isolated saponins and their aglycones were examined for inhibitory activity on 12-O-tetradecanoylphorbol-13-acetate (TPA)-stimulated 32P-incorporation into phospholipids of HeLa cells to identify new antitumor-promoter compounds.

Structures of steroidal saponins from the tubers of Brodiaea californica and their inhibitory activity on tumor promoter-induced phospholipid metabolism.

Phytochemical examination of the fresh tubers of Brodiaea californica resulted in the isolation of four new steroidal saponins. Their structures were determined, by extensive spectral analysis including two-dimensional (2D) NMR spectroscopy and acid-catalyzed hydrolysis, to be (25S)-spirost-5-ene-1 beta,3 beta-diol [(25S)-ryscogenin] 1-O-[O-beta-D-glucopyranosyl-(1-->3)-O-alpha-L-rhamnopyranosyl-(1-->2)- beta-D-glucopyranoside] (1), (25S)-ruscogenin 1-O-[O-beta-D-glucopyranosyl-(1-->3)-O-alpha-L-rhamnopyranosyl-(1-->2)-O -[beta-D-xylopyranosyl-(1-->3)]-beta-D-glucopyranoside] (2), the C-20 and C-22 isomer of 2 (3) and the 6'-O-acetyl derivative of 2 (4), respectively. The conformations of the tetrasaccharide moiety of 2 and 4 were inspected through molecular mechanics and molecular dynamics calculation studies, showing that the acetyl group attached to C-6 of the inner glucose was near the C-21 methyl of the aglycon in the calculated preferred conformation of 4, which must cause the downfield shift of 21-Me by 0.07 ppm in comparing the 1H-NMR of 4 with that of 2. The inhibitory activity of the isolated saponins on 12-O-tetradecanoylphorbor-13-acetate (TPA)-stimulated 32P-incorporation into phospholipids of HeLa cells was evaluated to identify new antitumor-promoter compounds.

Inhibitory effects of steroidal saponins on 12-O-tetradecanoylphorbol-13-acetate (TPA)-enhanced 32P-incorporation into phospholipids of HeLa cells and proliferation of human malignant tumor cells.

Certain Lilium plants contain (25S)-spirost-5-ene-3 beta,27-diol glycosides embracing 3-hydroxy-3-methylglutaric acid at the C-27 hydroxy position. One of their derivatives, methyl ester of (25R)-27-O-[(S)-3-hydroxy-3-methylglutaryl]-spirost-5-ene-3 beta,27-diol 3-O-(O-alpha-L-rhamnopyranosyl-(1-->2)-O-[beta-D-glucopyranosyl-(1-->4)] - beta-D-glucopyranoside) was found to inhibit 12-O-tetradecanoylphorbol-13-acetate (TPA)-stimulated 32P-incorporation into the phospholipids of human cervical cancer (HeLa) cells and also to inhibit the proliferation of various kinds of human malignant tumor cells, pancreatic cancer (PANC-1), osteosarcoma (OST), human gastric cancer (HGC-27), pheochromocytoma (PC-12) and HeLa cells, in vitro.

Steroidal saponins from the bulbs of Lilium longiflorum and their antitumour-promoter activity.

Two new spirostanol saponins and two new furostanol saponins were isolated from the fresh bulbs of Lilium longiflorum together with several known saponins. The structures of new compounds were determined to be (25S)-spirost-5-ene-3 beta, 27-diol 3-O-(O-alpha-L-rhamnopyranosyl-(1-->2)-O- [alpha-L-arabinopyranosyl-(1-->3)]-beta-D-glucopyranoside), (25R)-27-O-[(S)-3-hydroxy-3-methylglutaryl]-spirost-5-ene-3 beta,27 diol 3-O-(O-alpha-L-rhamnopyranosyl-(1-->2)-O-[alpha-L-arabinopyranosyl -(1-->3)] - beta-D-glucopyranoside), 22-O-methyl-26-O-beta-D-glucopyranosyl-(25R)-furost-5-ene-3 beta,22 xi, 26-triol 3-O-(O-alpha-L-rhamnopyranosyl-(1-->2)-O-[alpha-L- arabinopyranosyl-(1-->3)]-beta-D-glucopyranoside) and 22-O-methyl-26-O-beta-D-glucopyranosyl-(25R)-furost-5-ene-3 beta, zeta, 26-triol 3-O-(O-alpha-L-rhamnopyranosyl-(1 --> 2)- O-[beta-D-xylopyranosyl-(1 --> 3)]-beta-D-glucopyranoside). The isolated saponins and their derivatives were examined for inhibitory activity on 12-O-tetradecanoylphorbol-13-acetate (TPA)-stimulated 32P-incorporation into phospholipids of HeLa cells as the primary screening test to find new antitumour-promoter compounds.

Antitumor-promoting activity of mallotojaponin, a major constituent of pericarps of Mallotus japonicus.

Mallotojaponin, a major constituent of the pericarps of Mallotus japonicus (Euphorbiaceae), inhibited the action of tumor promoter in vitro and in vivo; it inhibited tumor promoter-enhanced phospholipid metabolism in cultured cells, and also suppressed the promoting effect of 12-O-tetradecanoylphorbol-13-acetate on skin tumor formation in mice initiated with 7,12-dimethylbenz-[a]anthracene.

Antitumor-promoting activity of scopadulcic acid B, isolated from the medicinal plant Scoparia dulcis L.

Scopadulcic acid B (SDB), a tetracyclic diterpenoid isolated from a medicinal plant, Scoparia dulcis L., inhibited the effects of tumor promoter 12-O-tetradecanoylphorbol-13-acetate (TPA) in vitro and in vivo; SDB inhibited TPA-enhanced phospholipid synthesis in cultured cells, and also suppressed the promoting effect of TPA on skin tumor formation in mice initiated with 7,12-dimethylbenz[a]anthracene. The potency of SDB proved to be stronger than that of other natural antitumor-promoting terpenoids, such as glycyrrhetinic acid.

Potent preventive action of alpha-carotene against carcinogenesis: spontaneous liver carcinogenesis and promoting stage of lung and skin carcinogenesis in mice are suppressed more effectively by alpha-carotene than by beta-carotene.

Although beta-carotene has been considered to be a key cancer preventive agent in green and yellow vegetables, other types of carotenoids, such as alpha-carotene, may also contribute to anticarcinogenic action, since these carotenoids usually coexist with beta-carotene and are detectable in human blood and tissues. In this study, we compared the inhibitory effect of natural alpha-carotene, obtained from palm oil, with that of beta-carotene on spontaneous liver carcinogenesis in C3H/He male mice. The mean number of hepatomas per mouse was significantly decreased by alpha-carotene supplementation (per os administration in drinking water at a concentration of 0.05%, ad libitum) as compared with that in the control group (P < 0.001, Student's t test). On the other hand, beta-carotene, at the same dose as alpha-carotene, did not show any such significant difference from the control group. Furthermore, we also compared the antitumor-promoting activity of alpha-carotene with that of beta-carotene against two-stage mouse lung carcinogenesis (initiator, 4-nitroquinoline 1-oxide; promoter, glycerol). alpha-Carotene, but not beta-carotene, reduced the number of lung tumors per mouse to about 30% of that in the control group (P < 0.001, Student's t test). The higher potency of the antitumor-promoting action of alpha-carotene compared to beta-carotene was confirmed in other experimental systems; e.g., alpha-carotene was also found to have a stronger effect than beta-carotene in suppressing the promoting activity of 12-O-tetradecanoylphorbol-13-acetate on skin carcinogenesis in 7,12-dimethylbenz[a]anthracene-initiated mice. These results suggest that not only beta-carotene, but also other types of carotenoids, such as alpha-carotene, may play an important role in cancer prevention.