Saponin fraction

Saponins are a family of glycosides (sugar derivatives) widely distributed in plants. Each saponin consists of a sugar moiety bound to a sapogenin (either a steroid or a triterpene). The immunostimulatory properties of the saponin fraction isolated from the bark of Quillaja (a tree) has been long recognized. Quil A (which consists of a mixture of related saponins) is used as an adjuvant in selected veterinary vaccines. However, its haemolytic potential precludes its use in human vaccines. Research efforts continue in an attempt to identify individual saponins (or derivatives thereof) that would make safe and effective adjuvants for use in human medicine. 

On the other hand, Abri Herba, the whole plant of Abrus cantoniensis, is used as a folk medicine for infectious hepatitis in China. Its efficacy has been substantiated clinically [23]. Chiang et d. confirmed the efficacy of the total saponin fraction in a pharmacological experimental model [24]. We also reported that the total saponin fractions of this plant were effective for experimental liver injuries in an in vivo model induced by CC14, Fig. (1)... 

In our laboratory, an on-flow LC-NMR-MS screening (Figure 5.1.1) was applied to both saponin fractions which were not separated into pure compounds by classical column chromatography and further to total asterosaponin fractions obtained by the micropreparative technique, matrix solid-phase dispersion (MSPD) extraction [45] (see Figure 5.1.2). The LC-NMR-MS hyphenation is set up in the widely used parallel configuration of NMR and mass spectrometer (Figure 5.1.3). Typically, absolute amounts of asterosaponin mixtures of about 500 xg - 1 mg are injected onto the column. 

The only vaccine adjuvants currently licensed by the FDA are aluminium salts. All other adjuvants are considered experimental and must undergo special preclinical testing. In the search for well-characterized adjuvants, the saponins from Quillaja saponaria, having quillaic acid as aglycone were shown to be potent immune adjuvants, such as Quil A (a purified mixture of 23 saponins), Iscoprep 7 0 3 which is a mixture of well characterized saponin fraction QH-A, QH-B, QH-C in a ratio 7 0 3 and the pure saponins QS-7, QS-17, QS-18, QS-21 (31) [41] (see Fig. (2)) and QS-L1 (32) [42]. 

It was demonstrated that the anti-obesity effects of oolong tea in high-fat diet-treated mice might be partly due to the inhibitory actions of the saponin fraction in oolong tea on pancreatic lipase activity. In this study, tea saponin prevented the high-fat diet-induced increases in body and parametrial adipose tissue weights by inhibiting the intestinal absorption of dietary fat via inhibition of pancreatic lipase activity, Fig. (5). 

Fig. (10) Effect of erode saponin fraction isolated from the aqueous extract of Platycodi radix on pancreatic lipase activity in vitro Results are expressed as mean s.e.m. of four experiments.

It has been reported that various saponins isolated from foodstuffs have anti-obesity or hypolipidaemic actions [12-16], We found that the crude saponin fractions isolated from Platycodi radix strongly inhibited the pancreatic lipase activity, Fig. (10). 

Therefore, it seems likely that the anti-obesity, anti-hypolipidaemic, anti-fatty liver actions of the aqueous extract of Platycodi radix may be attributed in part to its crude saponin fractions. 

The saponin fraction of S. officinalis has shown antiinflammatory activity in vitro against carrageenan-induced rat-paw oedema and inhibited prostaglandin synthetase [49]. Purified saponins have been recently shown to possess hypocholesterolaemic effects in vivo, which is believed to be due to the ability of the saponin to form an insoluble complex with cholesterol, preventing its absorption from the small intestine [50]. The saponins also demonstrated spermicidal activity, which may come from their hemolytic property [51]. 

Elbary et al. [114] have correlated the spermicidal efficacy and the hemolytic index of the saponin fraction of Gypsophila paniculata and saponins derived from other plants. Gypsophila saponins were relatively superior when used either as aqueous solution or as formulation in polyethylene glycol ointment base. 

The co-occurrence of acids(17), (18) and (19) strongly indicated that both acids (18) and (19) could be artefacts formed from bassic acid (17) during acid hydrolysis of the saponin fraction. In fact, when a solution of bassic acid (17) in MeOH-HCl (aq.) was boiled under reflux for 4h and worked up as usual for the isolation of the products, acid (18) (40%), (19)... 

As an extension of chemical investigation on the pharmaceutically important naturally occurring saponins [48-57], Mahato and his coworkers isolated three acylated triterpenoid bisglycosides, acaciasides A (25), B (26) and C (27) from the water soluble saponin fraction obtained... 

Iscomatrix Immunostimulatory complex of a purified saponin fraction, cholesterol and phospholipid, which under defined conditions form cage-like structures typically 40 nm in diameter. The principal advantage of this combination is the reduction of toxicity of saponin component. Iscomatrix particulate vaccines are likely to be phagocytosed by macophages and induce cytokines such as IL-12 and IFN-y. They have a significant potential in cancer vaccine development [79]. 

In the course of our screening studies on the bioactive constituents of medicinal foodstuffs, the saponin fraction obtained from the roots of Japanese sugar beet was found to show an inhibitory effect on the increase of serum glucose levels in oral glucose-loaded rats. 

Table 2. Inhibitory Effects of saponin Fractions from Medicinal Foodstuffs and Natural Medicines on Increase of Serum Glucose levels in Glucose -loaded Rats...

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