**6.4 FEDAM plot**

All the coumestrol derivatives pointed out were good radical scavengers relative to coumestrol. From the **Figure 4**, it was clear that the derivatives like 16-F Coumestrol, 16-Cl Coumestrol, 16-Br Coumestrol, 16-CN Coumestrol, 16-NO2 Coumestrol, 16-SO3H Coumestrol, 16-CHO Coumestrol, 16-COR Coumestrol, 16-COCl Coumestrol, 16-COOR Coumestrol, 16-COOH Coumestrol, 16-OH Coumestrol, 16-OCOR Coumestrol and 16-NHCOR Coumestrolexhibit good accepting capacity and 16-NH2 Coumestrol, 16-CH3 Coumestrol, and 16-CHCR2 Coumestrol exhibit good donating capacity of electron. Therefore, all these derivatives were good radical scavengers while 16-PhCoumestrol and 16-OCH3 Coumestrolwere best radical scavengers with both electron donating and electron accepting capacity. The substitution of electron withdrawing groups on coumestrol imparts electron accepting and donating groups impart electron donating capacity on the derivatives. The size distribution says that good electron acceptors are large in size and good electron donors are small in size (**Figure 5**).
