title: Positions and stereochemistry of methyl branches in the novel sex pheromone components produced by a lichen moth, Lyclene dharma dharma.
abstract: Female moths of Lyclene dharma dharma (Arctiidae, Lithosiinae) produce three sex pheromone components (I-III), for which we assigned the following novel chemical structures; 6-methyl-2-octadecanone (1) for I, 14-methyl-2-octadecanone (2) for II, and 6,14-dimethyl-2-octadecanone (3) for III. In the Iriomote Islands where the insects were collected, a lure including racemic 1 and 2 attracted the male moths without mixing 3. In this study for further confirmation of the plane structures, the positional isomers with a methyl branch at the 4-, 5-, 7-, 13-, or 15-position (4-8, respectively) were synthesized. The GC-MS analyses revealed that natural components I and II were best fitted with those of 1 and 2, respectively, among the methyl-2-octadecanones examined, indicating the usefulness of this analytical instrument and authentic standards for the determination of the positions of methyl branches. In field trapping tests, 4-8 could not substitute for 1 or 2, nor did these compounds inhibit the active binary lure of 1 and 2, indicating that the males strictly recognized the 2-ketones with a methyl branch at the 6- or 14-positions. Next, the absolute configurations of I and II were determined by HPLC with a normal-phased chiral column (Chiralpak AD-H), which could separate the enantiomers of both 1 and 2. The chiral HPLC analysis of a crude pheromone extract indicated that the females exclusively produced (S)-1 and (S)-2. Furthermore, a field evaluation of each enantiomer revealed that (S)-1 and (S)-2 were bioactive but (R)-1 and (R)-2 were not.
authors.affiliation: Graduate School of Bio-Applications and Systems Engineering, Tokyo University of Agriculture and Technology, Koganei, Tokyo, 184-8588, Japan.
authors.forename: Yasushi
authors.initials: Y
authors.lastname: Adachi
authors.forename: Duc Do
authors.initials: DD
authors.lastname: Nguyen
authors.forename: Masakatsu
authors.initials: M
authors.lastname: Kinjo
authors.forename: Saori
authors.initials: S
authors.lastname: Makisako
authors.forename: Rei
authors.initials: R
authors.lastname: Yamakawa
authors.forename: Kenji
authors.initials: K
authors.lastname: Mori
authors.forename: Tetsu
authors.initials: T
authors.lastname: Ando
mesh_terms: D000818:Animals; D002851:Chromatography, High Pressure Liquid; D005260:Female; D008401:Gas Chromatography-Mass Spectrometry; D008297:Male; D009036:Moths / Q000187:drug effects / Q000378:metabolism*; D055620:Optical Phenomena; D012724:Sex Attractants / Q000096:biosynthesis* / Q000138:chemical synthesis / Q000737:chemistry* / Q000494:pharmacology; D013237:Stereoisomerism
chemical_list: D012724:Sex Attractants