Potential hydrolysis of soyasaponin I and hepatoprotective effects of the hydrolytic products. Study of the structure-hepatoprotective relationship of soyasapogenol B analogs. - Ikeda,T.; Udayama,M.; Okawa,M.; Arao,T.; Kinjo,J.; Nohara,T. (Chem Pharm Bull, 1998)