1. Wolfson Laboratory of Medicinal Chemistry, Department of Pharmacy and Pharmacology, University of Bath, Bath BA2 7AY, U.K., National Medical Laser Centre, Division of Surgical and Interventional Sciences, UCL Medical School, University College London, London W1W 7EJ, U.K., Division of Microbial Diseases, UCL Eastman Dental Institute, University College London, London WC1X 8LD, U.K.