Do biologically relevant compounds have more chance to be drugs?

To prove the innate advantages of endogenous compounds/fragments for drug discovery and development, a novel index termed biological relevance (BR) is proposed. The results clearly indicate its ability to distinguish between synthetic chemicals, bioactive compounds, drug candidates, and launched drugs. Primarily, the average BR of the databases investigated decreases in the order DNP > CMC > ACD-3D > MDDR. Second, for compounds with the same bioactivity, drugs (CMC) possess higher average BR than their candidates (MDDR). These results suggest that compounds with higher BR have more chance to survive the drug development pipeline. Third, the above conclusion is supported by the fact that compounds in the later development phases possess higher BR than those in the earlier phases. Comparisons were made between BR and other indices, including toxicity, druglikeness, and natural productlikeness.