Die Pregnanderivate der Samen von Dregea abyssinica (HOCHST.) K. Schum. (Asclepiadaceae). II. Strukturbestimmungen Glykoside und Aglykone, 305. Mitteilung

Abstract

Die Pregnanderivate der Samen von Dregea abyssinica (HOCHST.) K. SCHUM. (Asclepiadaceae) I ) . 11. StrukturbestimmungenGlykoside und hglykone, 305. Mitteilung2) Summavy. The total or partial structure determinations of some new components from Dregea abyssinica are reported. The four drebyssogcnins (17, G, J and H) are esters of the drevogenins P (7) and D (9) and have the iollowing structures : Drebyssogenin F ( 5 ) = ll-O-acetyl-12-O-(cc-hydroxy-isovalcry1)-drevogenin P, drebyssogenin G (14) = 11 -0-acety1-12-0-isovalery1-drevogenin D, drebyssogenin J (15) = 11,12-di-0-acetyl-drevogenin D. Drebyssogenin K is a mixture of K 1 (16) and I i 2 (17), the mono-0-tiglyl and mono-0-isovaleryl derivatives of drevogenin D respectivcly, with as yet undetermined position of the acyl residues. The drebyssosides 1, 2 and 3 are glycosides of trisaccharides. Drebyssoside 1 (2) is pachybiosyl-cymarosyl-drevogenin A, drebyssoside 2 (3)asclepobiosyl-cymarosyl-drevogenin 4 and drebyssoside 3 (6) pachybiosyl-cymarosyl-drebyssogenin F. Drebyssoside 4 is a mixturc of a t least two components and contains the same aglycones and the same sugar units as the drebyssosides 1 and 3, but is different from them. The full structure of the two sugars (drebyssobiose (25) and sugar T (24)) has not been determined; i t is only shown that both are disaccharides which contain 3-0-methyl-6-deoxy-allose linked to a 2-deoxyhexose. In vorstehender Mitteilung [l] wurde die Isolierung von vier Esterglykosiden (den Drebyssosiden 1, 2, 3 und 4) aus den Samen von Dregea abyssinica beschrieben, von denen zwei in Kristallen erhalten worden waren. -Ferner wurde gezeigt, dass die l) Auszug aus Dissertation AJAY S. BHATNAGAR, Basel 1967. 2, 304. Mitt. s. vorstehende Mitteilung [l].