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2-Aza-3,7,8,12,13,17,18-heptaalkylporphyrins were synthesized by use of improved ‘3+1’ condensation under non-acidic conditions.

Treatment of bromovinylheptaethylporphyrin 1 with tetracyanoethylene leads to the formation of spirochlorin 2 and allylidenechlorin 3via the initially formed Diels-Alder adduct. The former product 2 is a new class of chlorin and the latter 3 exhibits unusual long-wavelength absorption in the red region of the spectrum.

A new cationic monoazaporphyrin, zinc 2-aza-8,12,13,17-tetraethyl-2,3,7,18-tetramethylporphyrinium iodide 3 was synthesized. Photodynamic activity of 3 in degradation of 2′,3′-isopropylideneguanosine 4 was compared with 2-aza-8,12,13,17-tetraethyl-3,7,18-trimethylporphyrin 1 , zinc 2-aza-8,12,13,17-tetraethyl-3,7,18-trimethylporphyrin 2 , and hematoporphyrin 5 . The quarternary ammonium 3 showed a remarkable increase of photodynamic activity compared with 5 , although no appreciable difference in the activity was observed between 1 and 5 .

2-Aza-3,7,8,12,13,17,18-heptaalkylporphyrins were synthesized by use of improved ‘3+1’ condensation under non-acidic conditions.

近年, 癌の光力学療法(PDT)が注目され, 精力的な研究が広範に進められている。現在, PDTの臨床試験に用いられている光増感剤としては, ヘマトポルフィリン誘導体(Hpd)が挙げられる。しかしながら, このHpdは, 高い組織透過性を有する600nm以上の可視光に対して弱い吸収を示すにとどまり, さらにHpd中の活性成分が腫瘍組織に取り込まれる割合は, 正常組織に比べてけた外れに大きいわけではない。したがって, より効果的なPDTを実施するにあたり, 適用される光増感剤としては, 組織透過性の高い赤色光領域に強い吸収を持ち, 腫瘍組織に対して高い選択性および親和性を具備するものが望まれる。このような理由で, 最近, 多種多様な新しい光増感剤が登場してきた。なかでも, メソ置換ポルフィリン, クロリン誘導体, バクテリオクロリンおよびフタロシアニンが, PDTにおける第二世代光増感剤として注目を集めている。, There is currently worldwide activity in the development of a photodynamic therapy (PDT) for cancer. The sensitizer currently used in clinical trials of PDT for cancer consists of a mixture of hematoporphyrin derivatives (Hpd). Hpd, however, absorbs only weakly above 600nm where light exhibits the deepest penetration into tissues. Furthermore, the uptake by the tumour of the active component in Hpd is only marginally higher than that by most normal tissues. Thus it has been evident for some time that the effectiveness of PDT could be enhanced by the use of photosensitizers that absorb more strongly towards the red end of the light spectrum and are more selectively retained by neoplastic tissues. For these reasons, several new classes of photosensitizers for PDT have been suggested over the past few years. Among them, substituted porphyrins, chlorin analogs, bacteriochlorins, and phtalocyanines have received increasing attention as a second- gereration photosensitizer in PDT.

現在わが国において使用を許可されている食用色素について, 可視光照射下におけるグアノシンの光分解反応に基づき, その光増感作用を検討した。その結果, ハロゲン多置換キサンテン系色素が光増感作用を有することを明らかにした。さらに, その光増感作用の強さは, 食用赤色3号(エリスロシン), The photosensitizing capability of food dyes, which are currently allowed to use as food additives in Japan, was examined on the basis of photodegradation of guanosine under irradiation of visible light. The results clearly demonstrated that the poly-halogenated xanthene dyes showed the photosensitizing capability, and it increased in the following order : erythrosine