1999 Fiscal Year Final Research Report Summary
Biosynthesis of iridoid glucosides and relationships between missing biosynthetic enzymes and dedifferentiation in plant cultured cells
| Project/Area Number |
10680572
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Bioorganic chemistry
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| Research Institution | Gifu Pharmaceutical University |
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Principal Investigator |
INOUE Kenichiro Gifu Pharmaceutical University. Faculty of Pharmaceutical Sciences, Professor, 薬学部, 教授 (40025713)
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| Co-Investigator(Kenkyū-buntansha) |
HAYASHI Hiroaki Gifu Pharmaceutical University. Faculty of Pharmaceutical Sciences, Professor, 薬学部, 助手 (50260998)
YAMAMOTO Hirobumi Gifu Pharmaceutical University. Faculty of Pharmaceutical Sciences, Assistant, 薬学部, 助手 (40210554)
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| Project Period (FY) |
1998 – 1999
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| Keywords | iridoid glucoside / secologanin / biosynthesis / Lonicera japonica / dedifferentiation / cultured cell / enzyme / cytochrome P450 |
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| Research Abstract |
The aim of this research is to show which enzymes responsible for the biosynthesis of iridoid glucosides lack in the dedifferentiated plant cells cultured in the medium and to reveal the relationships between missing enzymes and dedifferentiation as well as the properties of the biosynthetic enzymes present in the cultured cells. Cell suspension cultures of Lonicera japonica established in this study did not produce any iridoid and secoiridoid glucosides. The cells however, had the ability to convert loganin and 7-deoxyloganin into secologanin. furthermore, three biosynthetic precursors after iridodial glucoside were also converted into some biosynthetically succeeding iridoid glucosides such as loganin and secologanin, respectively, though to a lesser extent, but geraniol was not incorporated into either iridoid glucosides and secologanin. These results suggested that the cells lacked any enzymes associated with the early steps of monoterpenoid biosynthesis or with the formation of iridane skeleton.
The enzymatic experiments with the cultured cells revealed that 7-deoxy-loganin hydroxylase and secologanin synthase which catalyzes the oxidative cleavage of loganin into secologanin were both cytochrome P450 monoxygenases. The characterization of the latter enzyme, which remained unsettled for 30 years, would greatly contribute to the future biosynthetic research of plant constituents.
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