相模湾のクダウミヒドラ Tubularia sp. から単離した免疫抑制活性ステロールの構造と活性

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Two immunosuppressive sterols, cholesta-5,23E-diene-3β, 25-diol (trans-liagosterol) (A) and cholesta-5,25 (26)-diene-3β, 24ζ-diol (B) were isolated respectively from the Sagami Gulf Hydrozoa Tubularia sp. by the guide of Mitogen bioassey. Structural determination was accomplished mainly by utilizing high-field (400MHz) 2D-NMR experiments, comparing to the spectra of cholesterol. Although these sterols, A and B, were known as the minor components of marine red alga, the presence in marine animal Hydrozoa such as Tubularia sp. was a new discovery. Sterol A inhibited T lymphocyte proliferation which was induced by plant lectins, concanavalin A (Con-A) and phytochemagglutinin (PHA), more than B lymphocyte proliferation which was induced by lipopolysaccharide (LPS). The activity of sterol B was more week than that of sterol A. On the other hand, by the Mitogen bioassay with hydrocortisone (HC) as a standard inhibitor and related five steroids, β-sitosterol (C), stigmesterol acetate (D), resibufogenin (E), 14,21-epoxy-3 β-hydroxy-5 β-chola-20 (21), 22-dienoic acid (F) and ergosterol (G), the inhibition of sterol A for PHA response was found to be most strong in them. However, for LPS response, the inhibition of hydrocortisone (HC) was more powerful than that of sterol A. Also, the immunosuppresive activity of related steroids, C, D, E and G was little found.