Monodesmosidic saponins

The information that the hydroxy group at C-29 reduced activity was similar to that on the structure-hepatoprotective relationship. In contrast, the sugar moiety in the E-ring enhanced anti-complementary activity. Further, we tested some oleanolic acid-type glucuronic acids. Although bisdesmosidic saponins showed moderate anti-complementary activity, a monodesmosidic saponin (9 4) showed cyototoxicity. 

Saponins have been considered toxic for different organisms. Meyer et ah (1990) found toxicity to brine shrimp. Woldemichael and Wink (2001) found monodesmoside saponins hemolytically active. The hemolysis may be produced by the interaction of the saponins with membranes, producing pores that lead to rupture of the (Seeman et ah, 1973). Kuljanabhagavad et ah (2008) described mainly saponins with an aldehyde group as cytotoxic in HeLa (cervix adenocarcinoma) cell line. 

Twenty nine steroidal saponins have been evaluated for their inhibitory effects on human spermatozoa motility in vitro according to a modified Sander-Cramer method [233]. Spirostane-type saponins have stronger inhibitory activities than those of furostane-type. The carbonyl group at C-12 and the double bond A (5,6) of the aglycone were important for the activity. The monodesmosidic saponin, diuranthoside B from Diuranthera major appeared the most active (motility of 45% at 0.1 mg/ml), almost equivalent to the commonly used spermicidal agent N-9. These results indicated the possibility of discovering natural spermicidal agents from steroidal saponins. Further work on the cytotoxic activity of these compounds are underway. 

Extraction of the dry plant material is most efficiently achieved using methanol or aqueous methanol. Depending on the proportion of water used for extraction, mixtures of either monodesmosidic or bidesmosidic saponins may be obtained [20]. 

The isolated triterpenoid saponins were found to be either of the saikosaponin type or the oleanolic acid type. Ten triterpenoid saponins were monodesmosidic, with a sugar chain at the C-3 position of the aglycone. A bidesmosidic saponin (sandrosaponin IX) showed sugar chains at C-3 (ether linkage) and also at C-28 (ester linkage). 

In vitro antileishmanial activity has been reported for saponins of Hedera helix on promastigote and amastigote forms from Leishmania infantum and L. tropica. Monodesmosides were found to be as effective on promastigote forms as the reference compound (pentamidine) whereas the bidesmosides have shown no effect [222]. Spiroconazole A (77), a spirostane saponin produced a dose-dependent inhibition of lesion caused by Leishmania panamensis in hamster [109]. Mimengoside A and budlejasaponin (62, 62a), two saikosaponins showed antileishmanial activity with a LCioo at 25 p.g/ml and 40 p.g/ml respectively (LC o of positive control = 5p.g/ml) [107, 108]. 

With the exception of Avenae sativae herba, Rusci aciileati radix, Sarsaparillae radix (steroid saponins) most saponin drugs contain a complex mixture of monodesmosidic or bidesmosidic triterpene glycosides. 

In 1995, Liu et al. reported the isolation of three new saponins from the roots of G. oldhamiana [78], which has been used as a substitute for the well-known traditional Chinese medicinal herb Sterllaria dichotoma var. lanceo-lata in the treatment of fever, consumptive disease, and infantile malnutrition. The most polar saponin was a bisdesmoside and its structure was established as shown in Fig. (26). The other two saponins were monodesmosides derived from C-28 methyl esters of quillaic acid and gypsogenin and having identical sugar moieties at C-3. 

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