The neutral red cytotoxicity assay was used in vitro to evaluate the potencies of phenylpropanolamine (PPA), nicotine, caffeine, some of their metabolites, and related chemicals. The human cell types used as targets included fibroblast (HFF), melanoma (SK-Mel/27), and hepatoma (HepG2) cell lines and early passage endothelial (ENDO) cells and keratinocytes (NHEK). For all of these […]