title: pH-Sensitive surfactants from lysine: assessment of their cytotoxicity and environmental behavior.
abstract: The toxicity and environmental behavior of new pH-sensitive surfactants from lysine are presented. Three different chemical structures are studied: surfactants with one amino acid and one alkyl chain, surfactants with two amino acids on the polar head and one alkyl chain, and gemini surfactants. The pH sensitivity of these compounds can be tuned by modifying their chemical structures. Cytotoxicity has been evaluated using erythrocytes and fibroblast cells. The toxic effects against these cells depend on the hydrophobicity of the molecules as well as their cationic charge density. The effect of hydrophobicity and cationic charge density on toxicity is different for each type of cells. For erythrocytes, the toxicity increases as hydrophobicity and charge density increases. Nevertheless, for fibroblasts cationic charge density affects cytotoxicity in the opposite way: the higher charge density, the lower the toxicity. The effect of the pH on hemolysis has been evaluated in detail. The aquatic toxicity was established using Daphnia magna . All surfactants yielded EC(50) values considerably higher than that reported for cationic surfactants based on quaternary ammonium groups. Finally, their biodegradability was evaluated using the CO(2) headspace test (ISO 14593). These lysine derivatives showed high levels of biodegradation under aerobic conditions and can be classified as "readily biodegradable compounds".
authors.affiliation: Departamento de Tecnología Química y de Tensioactivos, IQAC, CSIC, C/Jordi Girona 18-26, 08034, Barcelona, Spain.
authors.forename: Aurora
authors.initials: A
authors.lastname: Colomer
authors.forename: Aurora
authors.initials: A
authors.lastname: Pinazo
authors.forename: Maria Teresa
authors.initials: MT
authors.lastname: García
authors.forename: Montserrat
authors.initials: M
authors.lastname: Mitjans
authors.forename: M Pilar
authors.initials: MP
authors.lastname: Vinardell
authors.forename: Maria Rosa
authors.initials: MR
authors.lastname: Infante
authors.forename: Verónica
authors.initials: V
authors.lastname: Martínez
authors.forename: Lourdes
authors.initials: L
authors.lastname: Pérez
mesh_terms: D016475:3T3 Cells; D000818:Animals; D059001:Aquatic Organisms / Q000187:drug effects; D055598:Chemical Phenomena; D003603:Cytotoxins / Q000737:chemistry* / Q000378:metabolism / Q000633:toxicity*; D003621:Daphnia / Q000187:drug effects; D015195:Drug Design; D004777:Environment; D004912:Erythrocytes / Q000187:drug effects; D005347:Fibroblasts / Q000187:drug effects; D006461:Hemolysis / Q000187:drug effects; D006801:Humans; D006863:Hydrogen-Ion Concentration; D008239:Lysine / Q000737:chemistry*; D051379:Mice; D008823:Micelles; D013329:Structure-Activity Relationship; D013501:Surface-Active Agents / Q000737:chemistry* / Q000378:metabolism / Q000633:toxicity*
chemical_list: D003603:Cytotoxins; D008823:Micelles; D013501:Surface-Active Agents; D008239:Lysine