Epigoitrin is a natural alkaloid from Isatis indigotica, with antiviral activities. Epigoitrin reduces susceptibility to influenza virus via mitochondrial antiviral signaling[1][2].
[1]. Luo Z, et al. Epigoitrin, an Alkaloid From Isatis indigotica, Reduces H1N1 Infection in Stress-Induced Susceptible Model in vivo and in vitro. Front Pharmacol. 2019 Feb 7;10:78. [2]. Xiao P, et al. Antiviral activities against influenza virus (FM1) of bioactive fractions and representative compounds extracted from Banlangen (Radix Isatidis). J Tradit Chin Med. 2016 Jun;36(3):369-76.