Zhankuic acid A (ZAA) could suppress phosphorylation of JAK2 and JAK3 and signaling of downstream molecules. Moreover, ZAA could inhibit the IFN-γ/STAT1/IRF-1 pathway in vivo and in vitro. Furthermore, data show that pre-treatment with ZAA could significantly ameliorate Con A-induced hepatitis in mice. The above results strongly suggest that ZAA treatment could block JAK2 and JAK3 activation, and may be a valuable therapeutic approach for the treatment of immune cell induced inflammation.