That appears to be typo while putting that definition into my own words The quinolones are based on two types of ring structures the quinolone nucleus and the naphthyridone nucleus For example we see the use of term basic pharmacore used here to make reference to the quinoline ring The fluoroquinolones can cause varying degrees of QTc prolongation with a decreasing rank order of sparfloxacin grepafloxacin moxifloxacin levofloxacin gatifloxacin and ciprofloxacin The presence of an amino group at the C 5 position on the basic pharmacore of the fluoroquinolones e g sparfloxacin prolongs QTc to a greater extent than a methyl group at this position e g grepafloxacin the least amount of QTc prolongation is associated with a hydrogen atom at this position present in all other fluoroquinolones As well as within this article that describes this basic pharmacore Anti Infective Agents in Medicinal Chemistry 2007 6 49 56 49 Activities of Quinolones Against Obligately Anaerobic Bacteria R Schaumann and A C Rodloff Institute for Medical Microbiology and Epidemiology of Infectious Diseases University of Leipzig Leipzig Germany I have made that change to the article as well as within any of the other quinolone articles where that term was used Thank you for your efforts on the quinolone articles and pointing out this error to me I have added the above reference as well to help others who stumble across this who are not too sure what I am referring to