Ionic derivatives of betulinic acid exhibit antiviral activity against herpes simplex virus type-2 (HSV-2), but not HIV-1 reverse transcriptase - Visalli, R J; Ziobrowski, H; Badri, K R; He, J J; Zhang, X; Arumugam, S R; Zhao, H (Bioorg Med Chem Lett, 2015)