In the case of human proteins, most of the interactions (~75%) involve only five chemical classes: "Phenylpropanoids and polyketides", "Benzenoids", "Organoheterocyclic compounds", "Organic acids and derivatives", and "Fatty Acyls"; while in terms of target classes the distribution is more uniform, with "7TM1", "Oxidoreductase", "Lyase", "Other", and "Cytochrome P450" comprising only ~52% of the interactions. For the case of microbial targets, ~77% of the interactions are concentrated in the same previous five chemical classes, but now "Fatty Acyls" is replaced by "Organic nitrogen compounds". However, in terms of target classes the distribution is quite nonuniform in this case, with ~72% of the interactions that involve just "Transferase", "Hydrolase", and "Protease".