Regioselective biotransformation of (+)- and (-)-citronellene by the larvae of common cutworm ( Spodoptera litura ).
Terpenoids, which have many biological activities and have occurred widely in nature, can be artificially synthesized. However, regioselective oxidation of terpenoids is difficult by chemical methods. In this study, (+)- and (-)-citronellene were biotransformed with Spodoptera litura to define the mechanism of metabolism of citronellene and gain a new natural terpenoid. (+)-Citronellene was converted to (2S,3S)-3,7-dimethyl-6-octene-1,2-diol and (2R,3S)-3,7-dimethyl-6-octene-1,2-diol (89.7%), (3S,6S)-(-)-3,7-dimethyl-1-octene-6,7-diol (3.8%), (3S)-(6E)-(+)-3,7-dimethyl-1,6-octadien-8-ol (4.2%), and (3S)-(6E)-(+)-3,7-dimethyl-1,6-octadien-8-oic acid (2.3%). In contrast, (-)-citronellene was converted to (2R,3R)-3,7-dimethyl-6-octene-1,2-diol and (2S,3R)-3,7-dimethyl-6-octene-1,2-diol (56.3%), (+)-iridan-7,8-diol (3.5%), and (3R)-(6E)-(-)-3,7-dimethyl-1,6-octadien-8-oic acid (40.2%). The main metabolic pathway of (+)- and (-)-citronellene by larvae of S. litura was oxidized at the terminal double bond and trans-allylic methyl position. Particularly on (+)-citronellene, the regioselective reaction was shown. On the oxidation of C-6, C-7, and C-8 positions, four new compounds (3S,6S)-(-)-3,7-dimethyl-1-octene-6,7-diol, (3S)-(6E)-(+)-3,7-dimethyl-1,6-octadien-8-oic acid, (+)-iridan-7,8-diol, and (3R)-(6E)-(-)-3,7-dimethyl-1,6-octadien-8-oic acid were produced in regioselective oxidation. It noted that stereoselective oxidation occurred between the enantiomers. The C-6 position was oxidized on the (+)-(3S) form, whereas cyclized and the C-7 position were oxidized on the (-)-(3R) form.
Miyazawa
Mitsuo
M
Department of Applied Chemistry, Faculty of Science and Engineering, Kinki University, Kowakae, Higashiosaka-shi, Osaka 577-8052, Japan. miyazawa@apch.kindai.ac.jp
Marumoto
Shinsuke
S
Masuda
Atsunori
A
Kano
Haruki
H
Takechi
Hiromune
H
D000818:Animals; D008401:Gas Chromatography-Mass Spectrometry; D007814:Larva / Q000378:metabolism; D009682:Magnetic Resonance Spectroscopy; D039821:Monoterpenes / Q000378:metabolism*; D010084:Oxidation-Reduction; D017550:Spectroscopy, Fourier Transform Infrared; D018411:Spodoptera / Q000378:metabolism*
D039821:Monoterpenes; C532173:beta-citronellene