{Pentacyclic triterpenes, inhibitors of glycogen phosphorylase, as potential drugs for type 2 diabetes: X-ray crystallographic studies} - Zographos, S E; Leonidas, D D; Alexacou, K M; Gimisis, T.; Hayes, J.M.; Oikonomakos, N G; Wen, X; Sun, H.; Liu, J.; Cheng, K; Zhang, P; Zhang, L; et al. (Planta Med., 2008)