Chemical constituents of Millettia taiwaniana: structure elucidation of five new isoflavonoids and their cancer chemopreventive activity

We describe the isolation and identification of five new isoflavonoids, millewanins A (1), B (2), C (3), D (4), and E (5), together with six known isoflavonoids and three rotenoids, from the stems of Millettia taiwaniana collected in Japan. The major component, auriculasin (6), exhibited significant inhibitory effect on mouse skin tumor promotion in an in vivo two-stage carcinogenesis test. The results of the present investigation indicate that 6 might be a valuable antitumor promoter.     

The Ginkgo biloba extract (EGb 761) provides a neuroprotective effect on retinal ganglion cells in a rat model of chronic glaucoma

PURPOSE: To investigate the effect of Ginkgo biloba extract (EGb 761) against neurotoxicity of retinal ganglion cells of rats with chronic moderately elevated intraocular pressure (IOP). METHODS: Unilateral chronic moderately elevated IOP was produced in rats by cautery of three episcleral vessels. Secondary degeneration was measured with and without EGb 761 for 5 months. At 5 months, retinal ganglion cells were labeled with a fast blue tracer applied to both superior colliculi. Densities of surviving retinal ganglion cells were estimated by counting fast blue labeled cells in whole mounted retinas. RESULTS: When compared with their contralateral control eyes with normal IOP, in the peripheral retina, retinal ganglion cell loss in eyes with chronic, moderately elevated IOP was 29.8 +/- 1.5% (n=5) at 5 months in untreated animals and 4.6 +/- 4.5% (n=5) at 5 months in treated animals with EGb 761. CONCLUSIONS: Pretreatment and early posttreatment with EGb 761 is an effective neuroprotectant in a rat model of chronic glaucoma.     

Potential anti-tumor promoting activity of lupane-type triterpenoids from the stem bark of Glochidion zeylanicum and Phyllanthus flexuosus

Four known lupane-type triterpenoids, glochidonol (1), glochidiol (2), lup-20(29)-ene-1beta,3beta-diol (3) and glochidone (3) were isolated from the stem bark of Glochidion zeylanicum. Previously, lupeol (5), lup-20(29)-ene-3beta,24-diol (6) and betulin (7) were isolated from the stem bark of Phyllanthus flexuosus. This study reports the assays of these lupane-type triterpenoids: all isolates 1-7 and synthetic analogues, glochidonyl acetate (1a), lup-20(29)-ene-1,3-dione (1b) and lup-20(29)-ene 3beta,24-diacetate (6a) were tested for their inhibitory effects on Epstein-Barr virus early antigen (EBV-EA) activation induced by 12-O-tetradecanoylphorbol 13-acetate (TPA). Among them, the effects of compounds 2 (IC50 = 290 mol ratio/32 pmol TPA) and 3 (IC50 = 300) were stronger than the others. In addition, compound 2 exhibited a strong inhibitory effect on mouse skin tumor promotion in an in vivo mouse two-stage carcinogenesis test.     

Cancer chemopreventive activity of rotenoids from Derris trifoliata

A study of the chemical constituents of the stems of Derris trifoliata Lour. (Leguminosae) led to the isolation and identification of one new rotenoid, 6aalpha,12aalpha-12a-hydroxyelliptone ( 3), together with five other known rotenoids. In a search for novel cancer chemopreventive agents (anti-tumor promoters), we carried out a primary screening of five of the rotenoids isolated from the plant for their inhibitory effects on Epstein-Barr virus early antigen (EBV-EA) activation induced by 12- O-tetradecanoylphorbol 13-acetate (TPA) in Raji cells. The inhibitory activity of 3 was found to be equivalent to that of beta-carotene without any cytotoxicity. Deguelin ( 4) and alpha-toxicarol ( 5) exhibited a marked inhibitory effect on mouse skin tumor promotion in an in vivo two-stage carcinogenesis test. This investigation indicated that rotenoids might be valuable anti-tumor promoters.     

Cancer chemopreventive activity of rotenoids from Derris trifoliata

A study of the chemical constituents of the stems of Derris trifoliata Lour. (Leguminosae) led to the isolation and identification of one new rotenoid, 6aalpha,12aalpha-12a-hydroxyelliptone ( 3), together with five other known rotenoids. In a search for novel cancer chemopreventive agents (anti-tumor promoters), we carried out a primary screening of five of the rotenoids isolated from the plant for their inhibitory effects on Epstein-Barr virus early antigen (EBV-EA) activation induced by 12- O-tetradecanoylphorbol 13-acetate (TPA) in Raji cells. The inhibitory activity of 3 was found to be equivalent to that of beta-carotene without any cytotoxicity. Deguelin ( 4) and alpha-toxicarol ( 5) exhibited a marked inhibitory effect on mouse skin tumor promotion in an in vivo two-stage carcinogenesis test. This investigation indicated that rotenoids might be valuable anti-tumor promoters.     

Rho-kinase inhibition reduces neointima formation after vascular injury by enhancing Bax expression and apoptosis

Recently, we have shown that a specific Rho-kinase inhibitor, Y27632 (R-(+)-trans-N-(4-pyridyl)-4-(1-aminoethyl)-cyclohexanecarboxamide), prevents neointima formation after vascular injury associated with increased terminal deoxynucleotidyl transferase-mediated dUTP nickend labeling (TUNEL)+ smooth muscle cells. Because the mechanism of the action of Y27632 remains unclear, we investigated the expression changes in Bcl family proteins, apoptosis regulators of smooth muscle cells, in the rat carotid artery after balloon injury (BI). Y27632 (BI + Y group) or saline (BI group) was administered peritoneally from Day 1 to Day 14 after BI. Y27632 markedly prevented neointima formation at Day 14. In the BI group, TUNEL+ smooth muscle cells were transiently increased in the neointima, but not in the media, with a peak at Day 7, returning to a lower level by Day 14. Y27632 significantly increased TUNEL+ smooth muscle cells at Days 7 and 14. Smooth muscle cell apoptosis was confirmed by electron microscopic examination. At Day 14, although proapoptotic Bax was slightly, but not significantly, increased in the BI group, it was significantly upregulated in the BI + Y group. Antiapoptotic Bcl-xL was upregulated in the BI group, and the upregulated Bcl-xL was not affected by Y27632. These findings indicate that Rho-kinase inhibition induces neointimal smooth muscle cell apoptosis through Bax upregulation, resulting in reduced neointima formation.     

Tumor initiating activity of Helicobacter pylori water extract on mouse skin carcinogenesis

Helicobacter pylori (H. pylori) infection has been associated with gastric carcinogenesis, but responsible and detail mechanisms are insufficient by the absence of adequate data. To obtain direct evidence regarding the carcinogenicity of H. pylori, we investigated the initiating and promoting activity of H. pylori water extract (HPE) in two-stage mouse skin carcinogenesis model. HPE treatment, as an initiation, significantly enhanced tumor formation compared with control group. Moreover, HPE treatment increased production of 8-hydroxydeoxyguanosine in epidermal cells and HPE-initiated/TPA-promoted papillomas demonstrated a point mutation of the Ha-ras gene. These results suggest an initiating activity of HPE on two-stage mouse skin carcinogenesis.     

Heterogeneous gene alterations in primary breast cancer contribute to discordance between primary and asynchronous metastatic/recurrent sites: HER2 gene amplification and p53 mutation

The aim of the present study was to clarify differences in genetic events between primary breast cancers and asynchronous metastatic/recurrent lesions, by examining HER2 gene amplification and p53 mutation. The subjects were 44 breast cancer patients with asynchronous metastasis or recurrence. Synchronous metastases were excluded. HER2 overexpression and gene amplification were examined using immunohistochemistry and fluorescent in situ hybridization (FISH). P53 point mutation was examined by immunohistochemistry, laser-captured microdissection, PCR-single-strand conformation polymorphism, and a direct sequencing method. Immunohistochemistry showed that, for HER2, p53, ER and PgR, discordance rates between primary and recurrent tumor were 2 (4.5%), 1 (2.3%), 7 (15.9%) and 10 (22.7%), respectively. Two primary tumors with discordant HER2 overexpression were composed of at least two populations of carcinoma cells, with and without HER2 gene amplification. Distribution of HER2 gene amplification was consistent with protein overexpression. Corresponding recurrent tumors consisted of carcinoma cells without HER2 gene amplification. Of 6 recurrent tumors in which the primary carcinoma had a p53 point mutation, 3 tumors had identical mutations, 1 tumor had a different point mutation, and 2 tumors had no mutation. It was suspected that the latter 3 recurrent tumors comprised a minor component of the primary tumor. In the present study, we examined a large series of asynchronous recurrent tumors. A limited number of these tumors showed discordance between primary and recurrent tumors. Detailed observations revealed that cell populations present in recurrent tumors were also present in the primary tumors, although they comprised a minor component of the primary tumor. Heterogeneity of the primary tumor apparently contributed to discordance.