Studies on Chemical Constituents of Antitumor Fraction from Periploca sepium Bge. I

When the CHC1₃ extract obtained by partitioning the methanolic extract of Periploca sepium between H₂0. and CHC1₃ was subjected to column chromatography on silica gel, the antitumor activity against Sarcoma 180 ascites in mice was concentrated in the fraction eluted with CHC1₃-MeOH (10:1). From the antitumor fraction, eight products, S-l—S-8, were isolated. S-l was identified as 12β-hydroxypregna-4,6,16-triene-3,20-dione (neridienone-A), obtained for the first time from Asclepiadaceous plants, by direct comparison with an authentic sample and the others were found to be steroidal glycosides. A new compound S-2A (named periplocogenin), and two known aglycones S-3A and S-5A, obtained by hydrolyzing the above glycosides with diluted acid, were respectively identified as 3β-0-(4’,6’-dideoxy-3’-O-methyl-/l³-D-2’-hexosulosyl)-d⁵-pregnene-17α,20(5)-diol, periplogenin, and △⁵-pregnene-3β,20(5)-diol from the proton and carbon-13 nuclear magnetic resonance spectral data. The structure of S-6A was identical with that of S-5A, and S-7A and S-8A were identical with S-2A.