COMPARISON OF TOXICITIES AND MECHANISM OF ACTION OF N-ALKANOLS IN THESUBMITOCHONDRIAL PARTICLE AND THE VIBRIO-FISCHERI BIOLUMINESCENCE (MICROTOX(R)) BIOASSAY
Ke. Gustavson et al., COMPARISON OF TOXICITIES AND MECHANISM OF ACTION OF N-ALKANOLS IN THESUBMITOCHONDRIAL PARTICLE AND THE VIBRIO-FISCHERI BIOLUMINESCENCE (MICROTOX(R)) BIOASSAY, Environmental toxicology and chemistry, 17(10), 1998, pp. 1917-1921
Many studies on the toxicity of n-alkanols have been conducted and qua
ntitative structure-activity relationships (QSARs) established compari
ng bioassay toxicity data to carbon number. The results typically indi
cate increasing toxicity with increasing n-alkanol chain length, but o
ften higher homologues are not assessed, where toxicity no longer incr
eases with carbon number-a phenomenon commonly called the cutoff effec
t. The mode of toxic action of these compounds has been designated nar
cosis I; however, the specific mechanism is unknown and widely debated
. This study compares results for two commonly used bioassays, the sub
mitochondrial particle (SMP) and the Microtox(R) bioassay, for the hom
ologous series of n-alkanols ranging from methanol (C-1-OH) to stearyl
alcohol (C-18-OH). Analysis of dose-response curve slopes indicates t
hat the SMP assay exhibits a general mechanism of toxicity, whereas th
e Microtox assay exhibits this general mechanism to short-chain alkano
ls, but subsequently switches to specific interaction with the higher
alkanols. This specific interaction is likely competitive inhibition o
f the bacterial luciferase. Comparison of the toxicities in these assa
ys with octanol/water partition coeffients (K-ow), the results of whol
e-organism tests, and a bacterial luciferase assay further substantiat
e this claim and indicate that the SMP is a better model of toxicity i
n whole organisms.