Saponins carboxylic acids

The saponin 3, at C-30 carboxylic acid, and compound 4, containing both, a hydroxyl at C-29 and a carboxylic group at C-30, were also found in the aerial parts. 

Sulphuric acid esters of tri- 8-hydroxyethyl-/J-propane tri-carboxylic acid ammonium (ThromboHolzinger), polyethylene sulphate sodium, polyanethol (liquoid), polyvinyl alcohol (elvanol), yeast nucleic acid, lignin, saponin, tannin, oromucoid, proteins... 

Fig. 30C Phenol carboxylic acids, flavonoids and saponines. (System A) Treatment with NP/PEG reagent reveals caffeoyl (CQA) and dicaffeojd quinic acids as blue and the flavonoid glyco.sides as orange-yellow or green fluorescent zones in UV-365nm. Coffeae. semen (1) and Mate folium (2) the blue 5-CQA, 3-CQA (R,- 0.45-0.5) and additional dicaffeoyl quinic acids in the upper R, range are characteristic. One additional orange-yellow zone of rutin at R, — 0.4 (Tl) is found in Mate folium (2) only.

The glucuronic acid residue at C-3 does not seem to play an essential role in adjuvanticity. Derivatization of the carboxylic acid function of the glucuronic acid of QS-21 with glycine produces a derivative with adjuvant activity similar to that of QS-21, albeit with less potency [92]. In strong contrast, reductive amination of the C-4 aldehyde of QS-21 eliminates adjuvant activity. These results again stress the pivotal role that the aldehyde group plays in the adjuvant properties of quillaja saponins, and presumably also in the saponins from gypsophila and saponaria. 

From the fruits of Gleditsia japonica, which have been used in Japanese and Chinese folk medicine as a diuretic and expectorant, seven saponins (gleditsiasaponins B, C, Dj, D2, E, G and I) had been isolated. The structural elucidation of these saponins have been carried out by the chemical degradations, enzymatic hydrolysis and C-NMR spectra, and characterized as 3, 28-0-bisglycosides of echinocystic acid acylated with monoterpene carboxylic acid [46-49]. 

I The saponins isolated in the plant possess aglycones of three skeletons cycloartane, ursane and oleanane, with some variation in each structure—type. It s very interesting to discover such cycloartane-type saponins, that its side-chain has been modified naturally to conjugated diene-carboxylic acid, which formed amide with 2 -amino-3, 4 -dimethyl-y-lactone moiety. 

Oleanolic acid a monounsaturated, pentacyclic THterpene (see), with a carboxylic acid group. M, 456.71, m.p. 310°C, [a], -tSO (methanol). It differs structurally from p-amyrin by the presence of a carboxyl group in place of the 28-methyl group (see Amyrin). O.a. occurs free, esterified with acetic acid, or as the aglycon of triterpene saponins (see Sapo-nins) in many plants, e.g. sugar beet, bilberry, mistletoe, cloves and cacti. 

Ursolic acid a simple unsaturated pentacylic tri-terpene carboxylic acid, M, 456.71, m.p. 292°C, [d o + T2° (CHCI3). U.a. is a structural derivative of a-Amyrin in which the 28-methyl group is replaced by a carboxyl group (see Amyrin). It occurs widely in plants as the free acid, esterified, or as the aglycon of triterpene saponins (see Saponins), e.g. in the wax layer of apples pears and cherries in the skin of bilberries and cranberries, and in the leaves of many members of the Rosaceae Oieoceae and Labiatae. 

Furthermore, since one of the saponins showed strong cytotoxicity in these experiments, we also examined the cytotoxicity toward hepatocytes without antiserum. Moreover, from the standpoint of the structure-hepatoprotective and -hepatotoxic relationships for the carboxyl group at C-28, oleanolic acid 3-Oglucuronide (96) and oleanolic acid 28-Oglucoside (97) were prepared and tested. 

The acidic nature of the triterpene saponins is due to a carboxyl group in the aglycones or in the sugar-part, if there is an uronic acid. 

Deacylated quillaja saponins were modified by incorporation of a Cn alkyl chain at the carboxyl group of the glucuronic acid residue to yield a family of saponin analogs referred to as GPI-OIOO. These stable derivatives, when compared by reverse phase HPLC to the acylated or deacylated forms of quillaja saponins, are more hydrophobic. The presence of the alkyl chain in GPI-OIOO is expected to increase the selfassociating properties of these derivatives in water, as well as their capacity to form complexes with proteins that are held by hydrophobic interactions. These analogs are similar to the deacylated quillaja saponins in that they appear to be devoid of toxicity in mice at a dose up to 1 mg. 

It was found that the 3-0-glucuronide moiety and the 28-carboxyl group in oleanolic acid glucuronide saponin were required to exert the inhibitory activity. Elatoside A and B were found to show potent inhibitory activity on ethanol absorption. 

Three novel triterpenoid saponins with hypoglucaemic activity, isolated from a Colombian climbing plant and named tuberosides A, B, and C, contain P-d-glucopyranose esterified at the anomeric centre with oleanic acid derivatives. Porphyrine-carboxylate esters of D-galactopyranose have been synthesized either by transesterification of a porphyrine methyl ester with l,2 3,4-di-0-iso-propylidene-a-D-galactopyranose, followed by acetal hydrolysis or by condensation of 6-0-(4-formylbenzoyl)-D-galactose (37) with pyrrole. ... 

Hydrolysis of the saponin has afforded [352] glucose, arabinose, and two acidic aglycones acerotin (LXXVIIa) and acerocin (LXXVIIb). Acer saponin P has a therapeutic index of greater than two against W 256 and so has been selected for clinical study [351], It has been suggested that its activity may be associated with the two a, -unsaturated carboxyl groups [352],... 

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