The diosgenin, (25R)-spirost-5-en-3 β -ol, was isolated from rhizomes of dioscorea meridensis and characterized by X-ray powder diffraction, IR and MS. The diosgenin was found to be monoclinic, with refined unit cell parameters a =16.774(3), b =7.259(2), c =10.383(2) Å, β =92.74(2)°, V =1262.9(3) (Å 3 ), Z =2, D x ( g ∕cm− 3 )1.089, with space group P 2 1 (No. 4).
