Lovering et al. suggested that a higher fraction of saturation in molecules results in the coverage of more diverse structural space and improved potential to identify compounds with matching spacial complementarity to the pockets of target proteins. An increase in Fsp3 can result in higher architectural complexity of molecules without an increase in the number of heavy atoms by allowing access to a larger number of isomers and broader conformational diversity. It was proposed that a potential improvement in the three-dimensionality of molecules caused by an increase in saturation of the skeleton, could result in greater selectivity and a decrease in off-target interactions. Thus, Lovering et al. showed a clear trend where compounds with a higher Fsp3 are more likely to succeed in advancing from the discovery stage to clinical trials and ultimately to yield marketed drugs. Subsequently, Lovering demonstrated that the promiscuity of compounds in different assays decreased as a function of Fsp3. This finding was later confirmed, and a trend of improvement in protein binding selectivity and frequency for compounds with higher proportion of sp 3 carbons was recorded. As increasing specificity and selectivity typically reduces the likelihood of toxicity due to the minimisation of off-target effects, an increase in Fsp3 of synthesised compounds could also result in a general reduction of toxicity. FCstereo is a size independent score, defined as a number of stereogenic carbons divided by the total number of all carbons (eq. 2). In the context of the FCstereo indicator, the stereogenic carbons are assumed to be carbons which are connected to four different groups. FCstereo = (number of stereogenic carbons / total carbon count) (