Atom level electrotopological state indexes in QSAR: designing and testing antithyroid agents

To design antithyroid agents with less side effects, the electrotopological-state (E-state) indexes of thiourylene moiety (SN&S) was utilized as a guideline to develop five acrylic thiourylene-type compounds with reduced antioxidant property.

These agents were synthesized and screened for antithyroid activity in rats using 125I-thiocyanate discharge technique. In addition, chemiluminescence studies on the activated polymorphonuclear leukocytes (PMNLs) were also conducted to reveal antioxidant properties of the tested compounds.

A linear relationship between the in vitro literature value of the formation constants of thiourylene-type compounds with iodine (Kc) and the SN&S was observed and utilized in designing those agents. At least one of the compounds (abouthiouzine) was found to have a potential value as an antithyroid agent. The relative efficacy of abouthiouzine [1-n-butyl-3(isonicotinamido)-2-thiourea], after equimolar dose, was 102% and 51.5% of that of propylthiouracil with respect to the rate of 125I-discharge and 125I-uptake, respectively. In addition, chemiluminescence studies on PMNLs revealed that abouthiouzine has slight oxidant property. Such properties may provide advantages in avoiding the iatrogenic hypothyroidism and antithyroid-induced immunological reactions.

The E-state approach provides guidelines to economize efforts and cost of designing new antithyroid drugs.