20-Protopanaxadiol saponins

Wakabayashi, C., Hasegawa, H., Murata, J., and Saiki, 1. (1997). In vivo antimetastatic action of ginseng protopanaxadiol saponins is based on their intestinal bacterial metabolites after oral administration. Oncol. Res. 9, 411-417. 

Calculated from dry-weights of roots, Saponins of 20(5)-protopanaxadiol, Saponins of 20(5)-protopanaxatriol, — not determined. 

Shibata, S., Tanaka, O., Ando, T., Sado, M., Tsushima, S., and Ohsawa, T. (1966). Chemical studies on oriental plant drugs. XIV. Protopanaxadiol, a genuin sapogenin of ginseng saponins. Cheni. Pharm. Bull. 14, 595-600. 

Tohda, C., Matsumoto, N., Zou, K., Meselhy, M. R., and Komatsu, K. (2002). Axonal and dendritic extension by protopanaxadiol-type saponins from ginseng drugs in SK-N-SH cells. Jpn. J. Pharmacol. 90, 254-262. 

Ginsengoside Rbi (60) is a representative of the saponins derived from 20(5)-protopanaxadiol. It exhibits central nervous system-depressant and antipsychotic activity, protection against stress ulcer, increase of gastrointestinal motility and weak anti-inflammatory action. Rgi (61) -the major saponin of 20(5)-protopanaxatriol - shows weak CNS-stimulant action, antrfatigue activity and blood pressure activity [108,109] (O Scheme 25). 

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... 

It followed that the same epimerization probably occurred during acid hydrolysis of the Ginseng saponins. The chloro compound (10) was obtained from the ether insoluble fraction of the crude hydrolysate of the saponin mixture with cone. HCl. The ether soluble fraction of the hydrolysate was subjected to dehydrochlorination to give an 20-epimer of (11) named 20(S)-protopanaxadiol (26) (Chart 2), the structure of which was elucidated by correlating it with (13) as follows. The dihydro derivative (27) of (26) was oxidized to give a diketone (28) which was identical with the diketone derived from (13) via (16) 16, 17, 19). Crystalline substances (1) and (12) of the 20(R)-series were also readily obtained from the less soluble fractions of the hydrolysates of the saponin mixture and from the hydrogenated saponin mixture, respectively, while the corresponding 20 ( S)... 

On the aforementioned evidence, Rb, Rb2, Rc and Rd can be formulated as 20-o-glycosides of 3-o-P-sophorosyl-20(5)-protopanaxadiol. The isolation of Ginseng saponins on a preparative scale was accomplished... 

It has been reported that the pharmacological activities of saponins of 20( S)-protopanaxadiol (26) differ somewhat from those of 20 (S)-protopanaxatriol (36) for example, saponins of (26) such as Rbj exhibit a sedative action while those of (36) such as Rgj stimulate the central nervous system (see Chapter XIII). It is therefore pharmacologically significant that the common sapogenin of the aerial parts of these Chinese Panax... 

In contrast to leaves from Hiroshima which contain saponins of (36) only, the major saponins of leaves collected on the Japan Sea coast were all based on the 12-ketone (67) of 20( S)-protopanaxadiol. Leaves collected in Tottori and Kyoto gave the new saponins chikusetsusaponins-LT5 (C-LT5, 0.5 —2.0% yield) and -LT8 (C-LT8, 0.1%) and leaves collected in Niigata gave a new saponin named chikusetsusaponin-LN4 (C-LN4, 1.4%yield) (722). Structures were established as shown in Chart 15. The rhizomes of these collections exhibited no significant differences in saponin composition. 

Shibata, S., O. Tanaka, T. Ando, M. Sado, S. Tsushima, and T. Ohsawa Chemical Studies on the Oriental Plant Drugs XIV. Protopanaxadiol, a Genuine Sapogenin of Ginseng Saponins. Chem. Pharm. Bull. (Japan) 14, 595 (1966). 

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