Complex sentence: Some analog substances have been created which mimic caffeine's properties with either function or structure or both, one of the latter is the drug DMPX and 8-chlorotheophylline (both xanthines) which is an ingredient in dramamine.
Split into simpler sentences: Some analog substances have been created which mimic caffeine's properties with either function or structure or both. Of the latter group are the xanthines DMPX and 8-chlorotheophylline which is an ingredient in dramamine.