Biological and Organic Chemical Investigation on Blepharismins and Their Related Natural Products

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(a) Structural Study of Blepharismins and Their Related Natural Pigments : Computer-aided analysis of blepharismins, stentorins, and hypericin has been performed and their three-dimensional structures having the "propeller" butterfly-like conformation have been clarified.(b) Synthetic Study of Blepharismins and Their Related Natural Pigments :-1. New Method for Aromatic Alkylation : To introduce an alkyl side chain on an aromatic ring, we developed the following two methods : (a) Friedel-Crfats-type alkylation using secondary alcohol methanesulfonates as an electrophile in the presence of a catalytic amount of Sc(OTf)_3 or TfOH ; (b) Regioselective nucleophilic aromatic substitution using Grignard reagents upon o- or p-methoxy-substituted aromatic carboxylates.-2. Synthesis of Anthraquinone Key Skeletons : The anthraquinone key component of blepharismin-3 and stentorin-C was prepared by treatment of benzoic acid derivatives with (CF_3CO)_2O via intramolecular Friedel-Crafts acylation f … More ollowed by oxidation in the air.-3. High-Pressure Promoted Construction of Biphenol Key Skeleton : High-pressure promoted condensation between phenols and aromatic aldehydes was efficiently proceeded in the presence of a catalytic amount of TfOH to produce the desired biphenol key skeleton of blepharismins.-4. Synthesis of Perylene Quinone Structure : Intramolecular oxidative coupling of biphenol derivatives has been achieved by using the Koga' reagent (CuCl(OH)・TMEDA complex) in giving the perilene quinone structure of blepharismins.(c) Structure of Photosensory Complex : Spectroscopic analysis of free pigment(blepharismin) and pigment (blepharismin)/protein complex, analysis of pigment contents bound to the protein or observation of photosensory organelle suggested that a large number of free pigment molecules are regularly arranged in vivo. This crystal -like structure may function as light-harvesting antenna for activating reaction center blepharismin/200 kD proteincomplex.(d) Photosensory Transduction : Analyses of molecular structure of light-irradiated blepharismin suggested that light-induced dissociation of phenol group (side chain) is notinvolved in activation of photosensory transduction chain. Spectroscopic analysis of photoreceptor complex indicated that active oxygen produced by photosensitization of light-activated blepharismin or energy or electron transfer from first excited singlet of pigment would be involved in activation of photosensory transduction chain.(e) Singaling Mechanism between Photoreceptor Organelle and Cell Membrane : We revealed that photosignal is finally transduced into H+ signal ; H+ is released from outer membrane of photoreceptor organelle so that evoked depolarization of cell membrane. Less