P-Amyrin acetate

Glutinone, fernenone, lupenone, simiarenol, a-amyrin acetate, p-amyrin acetate, ethyl palmitate, ethyl oleate, ethyl linoleate, lupenyl acetate, 24-methylene-cycloartanone, trans-phenyllitaconic, gult-5-en-3p-yl acetate, dammara-20,24-dien-3p-yl acetate, cycloartenyl acetate, cycloart-23-en-3p,25-diol, cycloart-23-en-3p,25-diol monoacetate, arteminolides... 

The main constituents of the leaves responsible for sweetness are the ent-kaurene diter-pene glycosides stevioside (2.218.5%), rehaudiosides A and C, and dulcoside A rehaudiosides B, D, and E and steviolhioside are of much less importance. Lahdane diter-penes include jhanol, austroinuhn, 6-0-acet-ylaustroinuhn triterpenes include P-amyrin acetate andlupeol other constituents include P-sitosterol, stigmasterol, tannins, and a volatile oil (0.12-0.43%) from which at least 25 compounds have heen identified. ... 

P-Am5uin (24) is found in various plant resins in mixture with the a-isomer and especially in bee pollen oil of lotus Nelumbo nucifera Gaertn (Indian Lotus), 3g/kg [44], or the bark of Amphiptetygium adstringens, 2Aglkg [45]. p-Amyrin acetate (25) was deacetylated by Rhodobacter sphaeroides, a photosynthetic bacterium, and converted to olean-12-ene-3p,24-diol (26), and erythrodiol (olean-12-ene-3p,28-diol, 27) [46] (Figure 28.8). 

Bioconversion of p-amyrin acetate (25) to metabolites 26 and 27 by Rhodobacter sphaeroides [46]. 

The three fernene isomers (409, 413, and 414), all of which are natural triterpenes, and various functionalized variants thereof, suffer rearrangement in the retro-biogenetic direction to -neohopene (412) (501, 504—506). Evidently A -fernene (413) is relatively resistant to the acidic conditions since mixtures of (412) and (413) are often obtained. Both A -and A -fernene (414 and 409) are converted to the A -isomer under relatively mild conditions. The apparent ease of migration of the double bond into the A position in this series contrasts with the rapid rearrangement of multiflorenyl acetate (372-OAc) to P-amyrin acetate (352, R = OAc) mentioned in the preceding section. 

Reaction of shea triterpene alcohols with acetic anhydride and sulphuric acid to produce coloured products (Fitelson s reaction) was the basis of a sensitive early test for the presence of shea butter in cocoa butter (Fincke, 1975). Analysis of the triterpene fraction of a commercial cocoa butter by TLC fractionation followed by GC (Fincke, 1976), or argentation TLC followed by GC (Gegiou and Staphylakis, 1985), have been shown to have potential for detecting CBEs in chocolate based on the difference in levels of P-amyrin, butyrospermol and... 

P-Sitosterol and stigmasterol are the common steroids in the genus. So far only few common triterpenes such as friedelin (207), e/ /-fnedelinol (208), a-amyrin (204), P-amyrin (205), a-amyrin acetate (206), taraxasterol (213), lupeyl acetate (209), magnificol (210) were isolated from Tanacetum species. However, T. sinaicum afforded unusual new malabaricane type triterpenoids 3p-acetoxymalabarican-14(26),17E,21-triene (211) and 3-oxo-malabarica-14(26),17E,21-triene (212) (Table 1). 

The reported partial synthesis of oleanolic acid from jS-amyrin (see Vol. 1, p. 193) has been re-examined.It has been established by deuterium labelling studies that epoxidation of /3-amyrin acetate with m-chloroperbenzoic acid gives the 12a,13a-epoxide and not the 12)8,13/3-epoxide as previously suggested. It follows, therefore, that the compound synthesized in the original work was the lactone (124), erroneously identified as oleanolic lactone acetate. Unexpectedly,... 

From B. tricuneata collected in the surroundings of Santafe de Bogota (Colombia), several triterpenoids, e.g. p-sitosterol, a-amyrin acetate, friedelin, Fig. (25) and ursolic acid, Fig. (26) were also reported [59], while the species B. coridifolia yielded schottenol glucoside, Fig. (27), uvaol, Fig. (28) and ursolic acid, Fig. (26) [60],... 

The research leading to the major part of the increase involved identification of the following classes of esters (1) esters from long-chained aliphatic alcohols and saturated and unsaturated acids, (2) esters from solanesol and acetic acid and numerous saturated and unsaturated acids, (3) esters from several phytosterols and numerous saturated and unsaturated acids, and (4) P-amyrin and numerous saturated and unsaturated acids. 

The bark composition includes the triterpenes p-amyrin, a not yet designated triterpenic acetate [78, 79] and a number of dimeric and trimeric proanthocyanidines (44) containing (+)-epicatechin and (+)-epigallocatechin units, with the 2S configuration which are rarely found in nature [80]. 

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. 

Crude chicle contains 15-20% hydrocarbons that are polyisoprenes (mixture of low molecular weight cis-, A and trans-, A units in an approximately 2 7 ratio) up to 55% of a yellow resin, consisting primarily of lupeol acetate with minor amounts of P-amyrin and a-spi-nasterol acetates also, taraxasterol and other triterpene alcohol acetates a gum composed of a (1 —> 4)-linked xylan backbone highly substimtedwith oligosaccharidechains sugar ... 

The detection of triterpenoid compounds in extracts from Bidens pilosa may rationalize the use of this plant in traditional Egyptian medicine in the treatment of wounds and against bacterial infections of the gastrointestinal tract [211,212]. The chloroform extract gave 3-amyrin. Fig. (29), phytosterin B and P-sitosterol glucoside, while the petroleum ether extract afforded P-am5Tin, Fig. (29), phytosterin B, lupeol. Fig. (30), lupeol acetate, linolic acid and linolenic acid. The antimicrobial test was carried out to indicate an evident activity. 

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