... Bioorganic & Medicinal Chemistry Letters. ... As shown in Figure 2a, 8g and 10d inhibited CD3-induced IL2 release in male Lewis rats with ED 50 s of 5 mg/kg and 20 mg/kg, respectively, compared with an ED 50 of 25 mg/kg for compound 1. When efficacy in vivo is represented using free compound exposure in plasma (EC 50 free) for this series, a good correlation is seen to the in vitro potency (Fig. ...