title: Synthesis of Enantiopure Alicyclic Ethers and Their Activity on the Chemosensory Organ of the Ectoparasite of Honey Bees, Varroa destructor.
abstract: The preparation of enantiopure conformationally restricted alicyclic ethers and their inhibitory activities on the chemosensory organ of the Varroa destructor, a parasite of honey bees, are reported in this article. We tested the effect of enantiopure ethers of cis-5-(2'-hydroxyethyl)cyclopent-2-en-1-ol on the Varroa chemosensory organ by electrophysiology, for their ability to inhibit the responses to two honey bee-produced odors that are important for the mite to locate its host: nurse bee head space odor and (E)-β-ocimene, a honey bee brood pheromone. Previous work with the racemic compounds showed that they suppress the mite's olfactory response to its bee host, which led to incorrect host choice. Based on a structure-activity relationship, we predicted that the two most active compounds-cis-1-butoxy-5-(2'-methoxyethyl)cyclopent-2-ene, cy{4,1}, and (cis-1-ethoxy-5-(2'ethoxyethyl)cyclopent-2-ene, cy{2,2}-could have opposite active enantiomers. Here we studied the enantiomers of both ethers, whose preparation involved enzymatic resolution of racemic diol cis-5-(2'-hydroxyethyl)cyclopent-2-en-1-ol using Lipase AK with vinyl acetate. The racemic diol was prepared from commercially available 2,5-norbornadiene. We observed that the responses of the chemosensory organ to honey bee head space volatiles were significantly decreased by both enantiomers of cy{4,1} and cy{2,2}, but that responses to (E)-β-ocimene were decreased significantly only by (+)-cy{4,1} (1R,5S) and (-)-cy{2,2} (1S,5R) and not by their respective enantiomers. The importance of this result is that the racemates could be used to inhibit olfactory detection of bee odors by mites, without a loss in activity relative to the more expensive enantiopure compounds.
authors: Department of Chemistry, Simon Fraser University , Burnaby, British Columbia V5A 1S6, Canada.
authors: Govardhana R
authors: GR
authors: Pinnelli
authors: Agricultural Research Organization, Volcani Center , Bet Dagan 75359, Israel.
authors: Nitin K
authors: NK
authors: Singh
authors: Agricultural Research Organization, Volcani Center , Bet Dagan 75359, Israel.
authors: Victoria
authors: V
authors: Soroker
authors: Department of Chemistry, Simon Fraser University , Burnaby, British Columbia V5A 1S6, Canada.
authors: Erika
authors: E
authors: Plettner
mesh_terms: D056810:Acaricides / Q000138:chemical synthesis / Q000737:chemistry / Q000494:pharmacology*; D000825:Animal Structures / Q000187:drug effects / Q000502:physiology; D000818:Animals; D001516:Bees / Q000469:parasitology*; D004987:Ethers / Q000737:chemistry / Q000494:pharmacology; D012903:Smell; D013237:Stereoisomerism; D013329:Structure-Activity Relationship; D057077:Varroidae / Q000187:drug effects* / Q000502:physiology
chemical_list: D056810:Acaricides; D004987:Ethers
keywords: Varroa foreleg; Varroa mite; electrophysiology; enantiopure synthetic odors; honey bees