Figure shows the chemical structures of the ten most frequent and unique fragments in all databases, and the frequency and percentage of each fragment in the corresponding dataset. For NPDBEjeCol, the fragment with the largest abundance (1,01%) is for a hydroxylated linear chain and a double bond (Figure ). Three fragments have linear chains with at least one double bond with more than seven carbons. In these fragments are two structures with a tetrahydropyran ring, two with a phenol ring, and one with benzene. Also, carbonyl groups are evident, forming aldehydes and ketones. For BIOFACQUIM (Figure ), the ten most frequent fragments show 0.3% abundance; most of the structures have at least one oxygen atom, except one that is only a linear chain of six carbons, also eight of ten fragments present cycles, three have only heterocycles, one only carbocycle, and four a mix carbocycles and a heterocycle, of which there are benzene, dihydropyran, tetrahydrofuran rings and being predominant delta lactone. The most frequent fragments from NUBBEDB (Figure ) are diverse with fragment structures that include benzene, delta lactone, and pyrrolidone rings. The other frequent fragments are linear chains, all of them with the presence of carbonyls (aldehydes). The fragments from the PeruNPDB (Figure ) reveal the presence of one or more rings, the most abundant fragment featuring two fused rings (1,4-hidroxybenzene and dihydrofuran).