1. Department of Surfactant Technology, IIQAB-CSIC, J. Girona 18-26, 08034 Barcelona, Spain, Department of Peptide and Prot. Chem., IIQAB-CSIC, J. Girona 18-26, 08034 Barcelona, Spain, and Department of Fisiologia-División IV, Fac. Farmacy, UB, Barcelona, Spain