Mr. Moyaquiles et al., THE PYRETHROID INSECTICIDE DELTAMETHRIN MODIFIES THE THERMOTROPIC PROPERTIES AND LIPID PACKING ORDER OF MODEL MEMBRANES, Chemistry and physics of lipids, 83(1), 1996, pp. 61-69
The effects of deltamethrin on model membranes were investigated by DS
C and by DPH and TMA-DPH fluorescence anisotropy. At a 5:1 phospholipi
d/pyrethroid ratio the thermal transition temperature (T-m) of dimyris
toyl- (DMPC), dipalmitoyl- (DPPC) and distearoyl-phosphatidylcholine (
DSPC) decreased by 3.0, 0.5 and 0.7 degrees C, respectively. Deltameth
rin broadened the phase transition of DMPC, but not of DPPC or DSPC. D
PH and TMA-DPH fluorescence anisotropy experiments showed that, below
the T-m, deltamethrin reduced the lipid packing order, whereas above t
he T-m, it induced an ordering effect. In egg-phosphatidylcholine vesi
cles, deltamethrin increased the DPH, but not the TMA-DPH fluorescence
anisotropy. The low solubility of deltamethrin in water prevented us
for further investigating its effects on native membranes. The results
suggest that deltamethrin is preferentially located in the hydrophobi
c core of model membranes, where it reduces the lipid packing order in
the gel stale and enhances it in the liquid-crystalline state.