Quantitative relationship between steady-state blood concentrations and structural features of aliphatic hydrocarbons

The objective of this study was to investigate the quantitative relationship between steady-state blood concentrations and structural features of aliphatic hydrocarbons. The literature data on steady-state blood concentrations (Cb(ss)) of 11 C6 to C10-aliphatic hydrocarbons (five n-alkanes, three alkenes, and three iso-alkanes) obtained in rats after exposure to 100 ppm of these chemicals were analyzed using a commercially available software (QSAR-PC). Based on a multiple linear regression analysis, the contribution values of (i) the basic structure [=C1H2-CH2-CH2-CH2C5H2-, + 6.8009], (ii) the substituents at carbon position 1 [(-H)2,=CH2, and (-CH3)2, associated with values of - 3.25, + 7.44 and - 2.02, respectively) and (iii) the substituents at carbon position 5 (CH3, C2H5, C3H7, C4H9 and C5H11 associated with values of - 1.20, - 1.69, +0.71, + 1.26 and + 2.82, respectively) were quantified. This analysis explained 98.8% of the variability in rat Cb(ss) among the hydrocarbons investigated. The present work represents the first attempt to characterize the quantitative contributions of specific molecular fragments to the toxicokinetic behavior of aliphatic hydrocarbons.