Magnesium and ammonium-potassium lithospermates B, the active principles having a uremia-preventive effect from Salvia miltiorrhiza - Tanaka,T.; Morimoto,S.; Nonaka,G.; Nishioka,I.; Yokozawa,T.; Chung,H.Y.; Oura,H. (Chem Pharm Bull, 1989)