Dammarane sapogenins

II. Structure and Chemistry of Dammarane Sapogenins 1. Panaxadiol, an Artifact... 

Sapogeniiis of the dammaran type were isolated from the leaves and roots of the plant Panax no-toginseng, native to China One of these sapogeniiis has the elemental eomposition C30//52O4 and produees the set of NMR results 51. What is the strueture of the sapogenin ... 

Since 1958, Shibata and his successors have conducted chemical studies on the saponins of the crude drug. After many twists and turns, it was determined that the major saponins of Ginseng were not oleanane oligoglycosides which are very common in nature, but that the genuine sapogenins were represented by triterpenes of the dammarane type. This was the first example of the occurrence of dammarane saponins in nature. The complications encountered in the isolation and structure determination were mainly due to an unexpected acid catalyzed epimerization of the tertiary hydroxyl group on c-20 of the carbon skeleton which was followed by cyclization of the side chain. This undesirable reaction accompanied acid hydrolysis of the saponins to the sapogenins. 

Acid Catalyzed Reactions of Dammarane Type Triterpenes and the Genuine Sapogenin of Ginseng... 

Treatment of (11) with cone. HCl at room temperature yielded (10). Furthermore, catalytic hydrogenation of the saponin mixture in ethanol-acetic acid followed by hydrolysis with dilute mineral acid did not yield (1) but afforded the dihydro derivative (12). This evidence indicated that (1) and (10) must be artifacts formed during the process of acid hydrolysis thus, at that stage, the genuine sapogenin seemed to be substance (11) which was named protopanaxadiol (9,10,11). However, as will be described later, investigation of the acid-catalyzed isomerization of dammarane type triterpenes and subsequent study of the mild hydrolysis of the purified... 

In an attempt toward syntheses of betulafolienetriol (13) and 20(5)-protopanaxadiol (26), the genuine sapogenin, introduction of an oxygen function at the unactivated methylene at c-12 of the dammarane skeleton was achieved 128, 129) by means of remote oxidation (130) using a photoexcited aromatic nitro group (131, 132, 133) (see Chart 18). Irradiation of the p-nitrophenyl-acetate (83) of 3-epidammaranediol-II (84)... 

Ohsawa, T., N. Tanaka, O. Tanaka, and S. Shibata Chemical Studies on the Oriental Plant Drugs XXIX. Saponins and Sapogenins of Ginseng Further Study on the Chemical Properties of the Side Chain of Dammarane Type Triterpenes. Chem. Pharm. Bull. (Japan) 20, 1890 (1972). 

Asakawa, j., R. Kasai, K. Yamasaki, and O. Tanaka C-NMR Study of Ginseng Sapogenins and Their Related Dammarane Type Triterpenes. Tetrahedron 33, 1935 (1977). 

Kasai, R., K. Matsuura, O. Tanaka, S. Sanada, and J. Shoji Mass Spectra of Trimethylsilyl Ethers of Dammarane-type Ginseng-sapogenins and Their Related Compounds.Chem. Pharm. Bull. (Japan) 25, 3277 (1977). 

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