QSAR with electrotopological state atom index. Part-3. Receptor binding affinity of estrogens and non-steroidal estrogen analogs

Quantitative Structure Activity Relationship(QSAR) analysis of estrogens an d non-steroidal analogs of estrogen with electrotopological state atom (ETS A) index has been performed in an attempt to explore the atoms or fragments of the molecules that are most important for the binding affinity to recep tor. The study reveals the importance of phenyl ring fragment (C1, C5 and C 10 atoms of steroidal estrogen, and C1, C3, C4, C9 and C10 atoms in case of non-steroidal analogs) for receptor binding affinity. The importance of th ese atoms or fragments is also supported from the literature survey. Thus, the phenyl ring constitutes the pharmacophore for receptor binding affinity of estrogen analogs, Hence, diagnostic potential of the ETSA scheme in ide ntifying the atoms or fragments important for activity is revealed from the study.