Effect of diquat and several surfactants on membrane permeability in red beet root tissue

Combinations of 10-5or 10-3M diquat (6,7 dihydroxydipyrido [1,2-a:2',1'-c] = pyrazidiinium salt)- and 01% or 10% Tween 20 (nonionic surfactant containing polyoxyethylene sorbitan monolaurate) increased the efflux of betanin from root-tissue discs of red beet (Beta vulgaris L) Tween 20 alone, at concentrations of 0.1%, 1.0%, and 10% also increased membrane permeability slightly, after an incubation period Diquat alone was without effect and combinations of diquat and Tween 20 were fully additive, if not synergistic Two cationic surfactants, Hyamine 1622 (diisobutyl phenoxy ethoxy dimethyl benzyl ammonium chloride monohydrate) and Aerosol C-61 (ethanolated alkyl quanidineamine complex), and the anionic surfactant Vatsol OT (sodium dioctylsulfosuccinate), at concentrations from 0 001% to 10%, caused a rapid release of betanin Apparently, alteration of electrostatic stability of the membrane by the ionic surfactants resulted in rapid deterioration of membrane integrity The nonionic surfactant effect may be due to its combined hydrophilic properties and specific structure, with consequent alteration of energy relations at membrane surfaces