TY - JOUR
T1 - Biosynthesis of sterols and ecdysteroids in Ajuga hairy roots
AU - Fujimoto, Yoshinori
AU - Ohyama, Kiyoshi
AU - Nomura, Keiko
AU - Hyodo, Ryo
AU - Takahashi, Kyoko
AU - Yamada, Junko
AU - Morisaki, Masuo
N1 - Funding Information:
We wish to express our thanks to Professor Emeritus Nobuo Ikekawa of Tokyo Intitute of Technology for his continued encouragement. We are grateful to Mitsuhiro Nagakari, Takayoshi Naka-gawa, Akinori Tatara, Kinya Nakamura, Tomoko Yazaki-Yagi, and Dr. Tetsuo Kushiro for their partial contribution in the work. Part of this research was supported by a Grant-in-Aid for Scientific Research (No. 02640422) and a Grant-in-Aid for Scientific Research on Priority Areas (08276207) to Y.F. from the Ministry of Education, Science, Sports and Culture of Japan. Thanks are also due to Drs. Takeshi Matsumoto and Nobukazu Tanaka, Bioassay Laboratory, Research Center, Daicel Chemical Industries Ltd., for providing Ajuga hairy root cultures, and Dr. Akio Ozaki, Tokyo Research Laboratories, Kyowa Hakko Kogyo Co. Ltd., for providing the strain of Sphingomonas sp.
PY - 2000
Y1 - 2000
N2 - Hairy roots of Ajuga reptans var. atropurpurea produce clerosterol, 22- dehydroclerosterol, and cholesterol as sterol constituents, and 20- hydroxyecdysone, cyasterone, isocyasterone, and 29-norcyasterone as ecdysteroid constituents. To better understand the biosynthesis of these steroidal compounds, we carried out feeding studies of variously 2H- and 13C-labeled sterol substrates with Ajuga hairy roots. In this article, we review our studies in this field. Feeding of labeled desmosterols, 24- methylenecholesterol, and 13C2-acetate established the mechanism of the biosynthesis of the two C29-sterols and a newly accumulated codisterol, including the metabolic correlation of C-26 and C-27 methyl groups. In Ajuga hairy roots, 3α-, 4α-, and 4β-hydrogens of cholesterol were all retained at their original positions after conversion into 20-hydroxyecdysone, in contrast to the observations in a fern and an insect. Furthermore, the origin of 5β-H of 20-hydroxyecdysone was found to be C-6 hydrogen of cholesterol exclusively, which is inconsistent with the results in the fern and the insect. These data strongly support the intermediacy of 7-dehydrocholesterol 5α,6α-epoxide. Moreover, 7-dehydrocholesterol, 3β-hydroxy-5β-cholest-7- en-6-one (5β-ketol), and 3β,14α-dihydroxy-5β-cholest-7-en-6-one (5β- ketodiol) were converted into 20-hydroxyecdysone. Thus, the pathway cholesterol → 7-dehydrocholesterol → 7-dehydrocholesterol 5α, 6α-epoxide → 5β-ketol → 5β-ketodiol is proposed for the early stages of 20- hydroxyecdysone biosynthesis. 3β-Hydroxy-5β-cholestan-6-one was also incorporated into 20-hydroxyecdysone, suggesting that the introduction of a 7-ene function is not necessarily next to cholesterol. C-25 Hydroxylation during 20-hydroxyecdysone biosynthesis was found to proceed with ca. 70% retention and 30% inversion. Finally, clerosterol was shown to be a precursor of cyasterone and isocyasterone.
AB - Hairy roots of Ajuga reptans var. atropurpurea produce clerosterol, 22- dehydroclerosterol, and cholesterol as sterol constituents, and 20- hydroxyecdysone, cyasterone, isocyasterone, and 29-norcyasterone as ecdysteroid constituents. To better understand the biosynthesis of these steroidal compounds, we carried out feeding studies of variously 2H- and 13C-labeled sterol substrates with Ajuga hairy roots. In this article, we review our studies in this field. Feeding of labeled desmosterols, 24- methylenecholesterol, and 13C2-acetate established the mechanism of the biosynthesis of the two C29-sterols and a newly accumulated codisterol, including the metabolic correlation of C-26 and C-27 methyl groups. In Ajuga hairy roots, 3α-, 4α-, and 4β-hydrogens of cholesterol were all retained at their original positions after conversion into 20-hydroxyecdysone, in contrast to the observations in a fern and an insect. Furthermore, the origin of 5β-H of 20-hydroxyecdysone was found to be C-6 hydrogen of cholesterol exclusively, which is inconsistent with the results in the fern and the insect. These data strongly support the intermediacy of 7-dehydrocholesterol 5α,6α-epoxide. Moreover, 7-dehydrocholesterol, 3β-hydroxy-5β-cholest-7- en-6-one (5β-ketol), and 3β,14α-dihydroxy-5β-cholest-7-en-6-one (5β- ketodiol) were converted into 20-hydroxyecdysone. Thus, the pathway cholesterol → 7-dehydrocholesterol → 7-dehydrocholesterol 5α, 6α-epoxide → 5β-ketol → 5β-ketodiol is proposed for the early stages of 20- hydroxyecdysone biosynthesis. 3β-Hydroxy-5β-cholestan-6-one was also incorporated into 20-hydroxyecdysone, suggesting that the introduction of a 7-ene function is not necessarily next to cholesterol. C-25 Hydroxylation during 20-hydroxyecdysone biosynthesis was found to proceed with ca. 70% retention and 30% inversion. Finally, clerosterol was shown to be a precursor of cyasterone and isocyasterone.
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U2 - 10.1007/s11745-000-0524-z
DO - 10.1007/s11745-000-0524-z
M3 - Article
C2 - 10783005
AN - SCOPUS:0034075686
VL - 35
SP - 279
EP - 288
JO - Lipids
JF - Lipids
SN - 0024-4201
IS - 3
ER -