Saponins, structures

OLESZEK, W., Alfalfa saponins structure biological activity and chemotaxonomy. In Saponins Used in Food and Agriculture Advances in Experimental Medicine and Biology, (G. R. Waller and K. Yamasaki, eds.), Plenum Press, New York. 1996, pp. 155-170... 

Yoshikawa, M., Morikawa, T., Yashiro, K., Murakami, T., Yamahara, J., and Matsuda, H. (2001). Bioactive saponins and glycosides. XIX. Notoginseng (3) Immunological adjuvant activity of notoginsenosides and related saponins Structures of notoginsenosides-L, -M, and -N from the roots of Panax notoginseng (Burk.) F. H. Chen. Chem. Pharm. Bull. 49, 1452-1456. 

The function of these tomatinase in formae speciales that do not pathogenise tomato is unknown. One possible explanation could be the presence of tomatine or similar saponins in their host plant species. However, (i) tomatine has not yet been reported in these plants [2, 7, 9] and (ii) although some of these species contain small amount of tomatine and other saponins structurally related to tomatine (e.g. potato contains a- solanine and a-chaconine [2, 4, 9, 90]), these are inactive as inducers of tomatinase and, moreover, tomatinase cannot use any of these glycoalkaloids as substrate [89]. In addition, it is clear that tomatinase is not required for pathogenicity in these isolates, at least in the case of F. oxysporum f. sp. melonis, where some strains that are fully pathogens on muskmelon lack tomatinase activity [89]. 

The pentacyclic triterpenoid skeletons exemplified by lupeol, a-amyrin, and p-amyrin (Figure 5.60) are frequently encountered in the form of triterpenoid saponin structures. Saponins are... 

The saponin structure is either of the steroidal (commonly tetracyclic triterpenoids) or pentacyclic triterpenoid type. Triterpenoid saponins are found, for example in Quillaia bark and in liquorice root. Quillaia B.P. is defined as the dried inner part of the bark of Quillaja saponaria and other species of Quillaja and is used as an emulsifying agent. Liquorice, the root of which also contains tiiterpenoid saponins, has long been used in pharmacy as a flavoring agent, demulcent, and mild expectorant. 

Please, note that sometimes the stereodiemistiy of the sapogenins was not expiicitely defined in the original paper, thus problems of ambiguity have been meet in the saponin structure definition. 

Bisdesmosidic triterpene saponins were isolated from the aquatic plant Ranunculus fluitans L. (Ranunculaceae) in the Rhine river. The saponin structures were established by the identification of the aglycon and sugar moieties by HPLC and chiral capillary zone electrophoresis (CZE), ion-spray LC/MS, and extensive 1-D and 2-D homonu-clear and heteronuclear NMR spectroscopy. 

In order to illustrate some of the points raised above, the following pages display typical examples of some important NMR experiments presently in use to solve saponin structures. They all concern a saponin from Medicago sativa, isolation of which is reported in reference 55. 

Cholestane glycosides furostanol open-chain steroidal glycosides spirostanol stereochemistry steroidal saponins structure elucidation... 

Fig. 11.1 Some saponin structures in the fruit s pericarp of Sapindus rarak (Asao et al. 2009)...

Fig. 11.2 Some saponin structures in tea Camellia sinesis) seed (Yoshikawa et al. 2005)...

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

The different plant source and structure of saponins, structure of algycone, length and position of sugar moiety may contribute various activities toward bacteria, fungi, protozoa and further studies are warranted. 

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