Determination of Dicyclohexylamine in Beeswax by Aqueous Normal Phase Liquid Chromatography Coupled With Tandem Mass Spectrometry.
Dicyclohexylamine (DCH) is an excipient present in commercial formulations of fumagillin (Fumagilin-B® and Fumidil-B®), an antibiotic which is employed in apiculture for the control of nosema disease. DCH has been demonstrated to be stable in harvested honey; however, its fate in the beehive has not been investigated. In this study, DCH residues were determined in beeswax samples collected from brood chambers and honey supers from various apiaries throughout Alberta. The determination of DCH was performed using a simple extraction procedure followed by low-temperature cleanup and finally analysis with aqueous normal phase liquid chromatography-electrospray ionization tandem mass spectrometry. The method was found to yield high accuracy and precision (94.9 ± 1.7% to 110.8 ± 6.6%) for replicate beeswax samples spiked with 4, 80, 360 and 2,000 μg kg-1 of DCH. With a limit of quantification of 1 μg kg-1, 100% of the 61 beeswax samples analyzed were found to contain residues of DCH ranging from 15 to 6,410 μg kg-1. The results indicate that DCH can accumulate in beeswax when Fumagilin-B® or Fumidil-B® is applied in apiculture and that these concentrations can vary significantly among beekeeping operations.
Does fumagillin control the recently detected invasive parasite Nosema ceranae in western honey bees (Apis mellifera)?
Western honey bee (Apis mellifera) colonies in Nova Scotia, Canada were sampled in spring and late summer 2007 to evaluate efficacy of fumagillin dicyclohexylammonium (hereafter, fumagillin) against Nosema ceranae. Colonies treated with fumagillin in September 2006 (n=94) had significantly lower Nosema intensity in spring 2007 than did colonies that received no treatment (n=51), but by late summer 2007 no difference existed between groups. Molecular sequencing of 15 infected colonies identified N. ceranae in 93.3% of cases, suggesting that fumagillin is successful at temporarily reducing this recent invasive parasite in western honey bees.
Studies on the stability of fumagillin. III. Thermal degradation in the presence and absence of air.
Abstract The tetraenedioic chromophore of crystalline fumagillin is thermally destroyed in the presence and absence of air by different mechanisms. The degradation in air is characterized by rates that are second order with respect to fumagillin and can be explained by the reaction of one molecule of oxygen with two molecules of fumagillin. This reaction may completely transform all the fumagillin. The degradation under nitrogen is initially pseudo zero order at all temperatures to about 80 per cent of the absorptivity of pure fumagillin. Further chromophore degradation is not linear with time and the extent is a function of temperature. The rate constants have been evaluated for both types of chromophore degradation at 70, 60, 50, and 40° and the heats of activation have been calculated. The fumagillin chromophore in ethanol solution under nitrogen undergoes slight initial modification and is more stable than in the crystalline form.