The use of quantitative structure–activity relationships, since its advent, has become increasingly helpful in understanding many aspects of biochemical interactions in drug research. This approach was utilized to explain the relationship of structure with biological activity of antibacterial. For the development of new fungicides against, the quantitative structural–activity relationship (QSAR) analyses for fungicidal activities of Pyrroledione Derivatives were carried out using multiple linear regression (MLR) Quantitative structure–activity relationship (QSAR) analysis was performed on a series of 3-Bromo-4-(1-H-3-Indolyl)-2, 5-Dihydro-1H-2, 5- Pyrroledione Derivatives.QSAR investigations were based on Hansch's extra thermodynamic multi-parameter approach. QSAR investigations reveal that steric and electrostatic interactions are primarily responsible for enzyme–ligand interaction. These studies produced good predictive models and give statistically significant correlations of selective COX-2 inhibitory with physical property, connectivity and conformation of molecule. Also when available COX-1 inhibitory data was analyzed with descriptors obtained from chem. Office 2007, partial charge descriptor, van der Waal’s surface area and solvation energy gave statistically significant results. The results obtained by combining these methodologies give insights into the key features for designing more potent analogs antibacterial.