Correlation between lipid partition coefficients and surface permeation in Schistosoma japonicum

Comparison of transintegumental membrane permeability and partition coefficients of selected nonelectrolytes was attempted to correlate the parameters of lipid solubility, hydrophilicity, and membrane permeation in male and female schistosomes (parasites of the portal venous tributaries of man). Surface permeation (measured by the triple isotope technique) and octanol/water partition coefficients were determined for 17 compounds (acetamide, aminopyrine, antipyrine, benzyl alcohol, butanol, caffeine, ethanol, ethylene glycol, glycerol, inosine, mannitol, methanol, polyethylene glycol, propylene glycol, sucrose, thiourea, and urea). Linear regression analyses comparing the logarithm of the partition coefficient to transintegumental uptakes indicate a positive correlation in both sexes: R = 0.76 (P less than 0.001) for males, and R = 0.77 (P less than 0.001) for females. Similarly, linear regression analyses comparing hydrogen bond number with the logarithm of tissue uptake index demonstrate a high (negative) correlation in both males (R = 0.85, P less than 0.001) for females (R = -0.90, P less than 0.001). The male and female schistosomes showed no statistically significant differences in correlation of these parameters. Surface permeation was the same in male and female schistosomes, suggesting that male-female variations in integumental uptake rates previously observed may be restricted to metabolites which enter by way of a selective carrier system.