The constituents of Petasites japonicus subsp. giganteus KITAM. (Japanese name: Akita-buki), and the other genus Petasites are reviewed in this paper. Consequently, the structure of new bitter sesquiterpenoids in which the isolations of bakkenolides from the bud of Akita-buki, (local name Bakke), and the mechanism of biosynthesis from an eremophilane skeleton to the novel carbon skeleton (bakkane) as well as total synthesis of bakkenolide-A (B-A) were described. Furthermore, the distribution of bakkenolides from the plants and their bioactive properties are also reviewed.

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It is well-known that non-covalent interaction plays important roll in biological events, such as double-helix formation of nucleotides and molecular recognition of proteases. Since the non-covalent interaction is reversible in contrast to covalent bonds, the materials containing non-covalent interaction have a potential to show dynamic properties by external stimuli. This paper reviews our recent approach to prepare the complexes of terminal functions of dendrimers and linear polymers via multiple hydrogen bondings. Dendritic aromatic polyamides having carboxyl groups on the periphery were prepared as multiple-donor molecules. The dendritic polyamide/poly (4-vinylpyridine)(P4VP) complex showed a single glass transition temperature whose temperature was highly dependent on the donor/acceptor ratio. NMR study of the complexes clearly demonstrates that the multiple hydrogen bondings are essential to immobilize P4VP segments in solution. Novel dendritic polyamide-co-poly (4-vinylpyridine) block copolymer was prepared by atom transfer radical polymerization of 4-vinylpyridine initiated by the dendritic macroinitiator. The dynamic light scattering and ¹H NMR spectra suggest that the intra- or intermolecular interaction of the copolymer is highly dependent on the solvent used for the measurements.

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The effect of pH and counterion of solvent extraction for the metal cations was investigated with thiacalix[6]arene derivative as extracting reagents. In this study, a novel thiacalix[6]arene derivative was synthesized from modification of carboxylic acid at a lower rim of thiacalix[6]arene. The mixed metal solution, which was used at liquid-liquid extraction, was prepared from automotive catalyst residue including the rare metals(Rh, Pd, Pt, Zr, Ce, Ba, Al, La, Y). The derivative of thiacalix[6]arene shows high selectivity and extraction capability of Pd and Zr cations which extractability were over 80% at pH 0.8.

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We attempted to make irrigation water from seawater with a simple treatment of natural zeolite. Cations contents in artificial seawater can be adjusted by the treatment of natural zeolite, and Na⁺ can be reduced, but high contents of Cl^- and SO₄^2-remains in the solution after treatment. With a simple two-step process using calcined hydrotalcite and natural zeolite, Cl^- and SO₄^2- in artificial seawater can be reduced by calcined hydrotalcite, and Na⁺ can be reduced by ion exchange with natural zeolite. The obtained solution was neutral, and includes the nutrients, K⁺, Mg²⁺, and Ca²⁺, and low levels of Na⁺ and Cl^-. Although Radish sprouts did not grow in artificial seawater, the solution treated with natural zeolite and the solution treated with calcined hydrotalcite, they could be grown in the solution treated with two-step process. These results suggest that it is possible to make a solution for irrigation water from seawater.

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