Interactions of Nonionic Polyoxyethylene Alkyl and Aryl Ethers with Membranes and Other Biological Systems
- ALEXANDER T. FLORENCEALEXANDER T. FLORENCEDepartment of Pharmacy, University of Strathclyde, Glasgow G1 1XW, ScotlandCurrent address: C.S.I.R.O. Division of Animal Production, Box 239, Blacktown 2148, AustraliaCurrent address: Fisons Pharmaceuticals plc, Loughborough, EnglandMore by ALEXANDER T. FLORENCE
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- IAN G. TUCKERIAN G. TUCKERCurrent address: C.S.I.R.O. Division of Animal Production, Box 239, Blacktown 2148, AustraliaMore by IAN G. TUCKER
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- KENNETH A. WALTERSKENNETH A. WALTERSCurrent address: Fisons Pharmaceuticals plc, Loughborough, EnglandMore by KENNETH A. WALTERS
Abstract
Many nonionic surfactants of the poly(oxyethylene) alkyl and aryl ether class interact with biological membranes increasing their permeability and causing increased trans-membrane solute transport. The mechanisms of such effects are not fully understood. Studies of the interaction of homologous series of nonionic surfactants (varying either in hydrophobic or hydrophilic chain length) with a variety of biological substrates, reviewed here, indicate there to be an optimal lipophilicity for maximal membrane activity. Problems with the hydrophile-lipophile balance (HLB) as an index of lipophilicity result from the structural non-specificity of this value. The biological effects of surfactants are concentration dependent and structure dependent. In many cases C12 hydrocarbon chain compounds appear to exert maximal effects and in all series a parabolic relationship between membrane activity and lipophilicity is observed. The effects are complex resulting from penetration of the membrane, its fluidization and, at high surfactant concentrations, solubilization of structural components.