Saponins basic structures

Fig. 105.1 Basic structures of spirostanol and furostanol saponins (left and middle, respectively) (R = sugar) and the structure of cholesterol (right)...

Figure 12.1 Basic structures of saponins (a) triterpene saponin QS-21 from Quillaya saponaria (b) steroidal saponin from Yucca schidigera (c) hederagenin glycoside from Sapindus mukurossi (d) soyasaponin I from soybean (Glycine max).

All prokaryote and eukaryote organisms are bounded by cell membranes that are basically phospholipid bilayers decorated with peripheral (loosely bound) and integral (tightly embedded) proteins. A variety of plant triterpenoid saponins (Table 12.3) and defensive antifungal proteins (Table 12.4) can directly interact with phospholipids and are accordingly likely to act by interfering with cell membrane structure, integrity and permeability. 

As regards the chemical constituents of Panax spp., the presence of saponins in American Ginseng was reported as early as 1854 (7). Since the beginning of this century, a number of Japanese, European and Korean chemists have concerned themselves with isolation and structure elucidation of Ginseng saponins these include Asahina (2), Kondo (i), Kotake (4 Wagner-Jauregg (5), Horhammer (6) and their coworkers. However, even the basic skeleton of the major sapogenin was not characterized until 1960. 

In the same year that he identified carbon suboxide, Diels began to investigate cholesterol with E. Abderhalden. The structure of this Hpid had not yet been determined. He was the first to study the products of the selenium dehydrogenation of cholesterol and isolated a hydrocarbon (CigHig), which became known as "Diels hydrocarbon." This substance proved to possess the basic steroidal ring structure its subsequent synthesis by Diels in 1935 (almost 30 years after he started this work) led to the rapid elucidation of the structures of a vast array of steroidal sex hormones, saponins, cardiac glycosides, bile pigments, and adrenal cortical hormones, such as cortisone. 

Fig. 11.4 The common basic saponin structure of Quillaja saponaria (Bankefors 2006)...

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