Seiko Oka

Bioactive Triterpene Saponins from the Roots of Phytolacca americana

Five new triterpene saponins named phytolaccasaponins N-1 (1), N-2 (2), N-3 (3) N-4 (4), and N-5 (5) were isolated from the roots of Phytolacca americana together with seven known triterpene saponins (6-12). The structures of the five new saponins were established as shown in structures 1-5 on the basis of their spectroscopic data. The MDR-reversal activity of 1-12 was evaluated on the basis of the amount of calcein accumulated in MDR human ovarian cancer 2780 AD cells in the presence of each compound. The most effective compound was 8 (155% of control at 25 microg/mL).

Proteomics analysis of heterogeneous flagella in brown algae (stramenopiles).

Flagella are conserved organelles among eukaryotes and they are composed of many proteins, which are necessary for flagellar assembly, maintenance and function. Stramenopiles, which include brown algae, diatoms and oomycetes, possess two laterally inserted flagella. The anterior flagellum (AF) extends forward and bears tripartite mastigonemes, whilst the smooth posterior flagellum (PF) often has a paraflagellar body structure. These heterogeneous flagella have served as crucial structures in algal studies especially from a viewpoint of phylogeny. However, the protein compositions of the flagella are still largely unknown. Here we report a LC-MS/MS based proteomics analysis of brown algal flagella. In total, 495 flagellar proteins were identified. Functional annotation of the proteome data revealed that brown algal flagellar proteins were associated with cell motility, signal transduction and various metabolic activities. We separately isolated AF and PF and analyzed their protein compositions. This analysis led to the identification of several AF- and PF-specific proteins. Among the PF-specific proteins, we found a candidate novel blue light receptor protein involved in phototaxis, and named it HELMCHROME because of the steering function of PF. Immunological analysis revealed that this protein was localized along the whole length of the PF and concentrated in the paraflagellar body.

Triglyceride accumulation and altered composition of triglyceride-associated fatty acids in the skin of tenascin-X-deficient mice.

Tenascin‐X (TNX) is a member of the tenascin family of glycoproteins of the extracellular matrix. Here, we observed abnormalities in the skin of TNX‐deficient mice in comparison with that of wild‐type mice. Histological analysis with Oil Red O staining demonstrated that there was considerable accumulation of lipid in the skin of TNX‐deficient (TNX−/−) mice. By thin‐layer chromatography of total lipids, it was found that the level of triglyceride was significantly increased in TNX−/− mice. The mRNA levels of most of the lipogenic enzyme genes examined were remarkably increased in TNX−/− mice. By gas chromatography‐mass spectrometry analysis of triglyceride‐associated fatty acids in the skin, saturated fatty acid palmitoic acid was decreased, whereas unsaturated fatty acids palmitoleic acid and oleic acid were increased in TNX−/− mice compared with those in wild‐type mice. Conversely, fibroblast cell lines transfected with TNX showed a significant decrease in the amount of triglyceride. An increase in the saturated fatty acid stearic acid and decreases in the unsaturated fatty acids palmitoleic acid, oleic acid and linoleic acid, compared to those in mock‐transfected cells were also caused by over‐expression of TNX. These results indicate that TNX is involved in the regulation of triglyceride synthesis and the regulation of composition of triglyceride‐associated fatty acids.