Isolation and NMR assignment of a pennogenin glycoside from Dioscorea bulbifera L. var sativa. - Teponno,R.B.; Tapondjou,A.L.; Djoukeng,J.D.; Abou-Mansour,E.; Tabacchi,R.; Tane,P.; Lontsi,D.; Park,H.J. (Nat Prod Sci, 2006)