We extracted information about biological targets for identified substances showing presence of warheads from multiple databases (CAS, CAS_PROJECTED, EVOLVUS_ADME, GOSTAR, GOSTAR_PROJECTED). Out of all the identified substances, a very small fraction of compounds had biological data associated with them. Figure shows the top 20 most targeted proteins and include protein tyrosine kinases such as BTK, Tec and protein kinases such as Akt, MAPK1, JAK3 among others. Protein tyrosine kinases can be sub-divided into two families: receptor and nonreceptor protein kinases with the latter being targeted by covalent inhibitors almost 7.5 times more than the former (Figure ). Covalent inhibitors containing the following warheads appear to target protein tyrosine kinases: α,β-unsaturated carbonyls, sulfonyls (SO2), nitriles (R-CN), halogen derivatives (Cl-CY, Br-CY and F-CY where Y = CO, SO(n) or NO2), alkyne carbonyls (R-CO), aldehydes (CHO) and epoxides. Perhaps unsurprisingly, α,β-unsaturated carbonyl containing substances have the largest number of targets associated with them (Supplementary Figure and Figure ). This is followed by nitriles (R-CN), fluoro derivatives (FCY) and aldehydes (CHO). Among the warheads, only for nitriles (R-CN), the number of indexed targets associated with patents are far greater than those for journals (Supplementary Figure ). On the other hand, aldehydes (CHO), boronic acid and esters, epoxides, bromo derivatives (BrCY), α-ketoamides, Se-based and disulfide containing substances have targets associated only with journals (Supplementary Figure ). Detailed breakdown of protein targets for each warhead is shown in Supplementary Figure .