16. 高等植物における新規ラクトン型ブラシノステロイドとその生合成起源の探索

概要

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Three 7-oxalactone brassinosteroids (BRs), 7-oxateasterone (7-OXTE), 7-oxatyphasterol (7-OXTY) and brassinolide (BL), were identified from leaves of Distylium recemosum and pollens of Lilium longiflorum. 7-OXTE was a novel BR from plants. Biological activities of 7-oxalactone BRs were examined. The activity of 7-OXTE and 7-OXTY using rice lamina joint inclination test showed lower than that of castasterone and BL. In contrast, hypocotyl elongation activity of 7-OXTY using Chinese cabbage seedlings, which was treated with brassinosteroid biosynthetic inhibitor propiconazole, showed higher than that of castasterone. These results suggested that a novel BR biosynthetic pathway, early lactonization pathway, from 7-OXTE to BL via 7-OXTY may operate in higher plants. To elucidate the biosynthetic origin of 7-OXTE, it is important to identify a deduced precursor of 7-OYTE, 3β-hydroxy-7-oxa-campest-6-one. We succeeded a synthesis of a model compound 3β-hydroxy-7-oxa-stigmast-6-one from stigmasterol. We are synthesizing also a stable isotope-labeled 3β-hydroxy-7-oxa-campest-6-one and exploring intermediates of 7-oxalactone BRs.
植物化学調節学会の論文
2003-10-10