Clioquinol
Clioquinol is a powerful anti-infective drug available for topical (Vioform) and internal (Enterovioform) use. It is neurotoxic in large doses and is associated with the SMON (Sub-Acute-Myelo-Optical-Neuropath) epidemic in Japan between 1957 and 1970 that affected over 10,000 people.
Recent research at UCSF indicates Clioquinol appears to block the genetic action of Huntington's disease in mice and in cell culture.