Studies on the Steroidal Components of Domestic Plants. LI. Steroidal Compounds contained in the Rokko Population of Dioscorea tenuipes Complex

The steroidal components contained in the Rokko population of the D. tenuipes complex were inverstigated. From its aerial parts, one triterpene, one sterol and eight steroidal sapogenins were isolated. They were taraxerol, β-sitosterol, yamogenin, yonogenin, tokorogenin, diotigenin, recently isolated, three new sapogenins and an unknown steroidal compound. Two of the new sapogenins were 25L-epimers of yonogenin and tokorogenin, and named neoyonogenin and neotokorogenin, respectively. Another new sapogenin was a 25L-tetrahydroxysapogenin and named tenuipegenin. Besides these, diosgenin and stigmasterol were detected by infrared spectrum and gas chromatography, respectively. The steroidal sapogenins of this population were chiefly composed of 25L members. The coexistence of 25 D- and 25L-sapogenins in individual plants was also discussed.