Oleanane Group

Arjunglucosides I (163) and II (164) from Terminalia arjuna are the glucose esters of arjungenin and arjunolic acid respectively. The full details of the structure elucidation of arjungenin are included in this paper. Three lyxosides (165)—(167) have been obtained, together with 16a,21/8,22a,28-tetrahydroxyolean-12-en-3- 

Full papers on the crystal structures of echinocystic acid diacetate bromo-lactone and papyrogenin have appeared. The structure of 3/3,16)3- 

Forced Wollf-Kishner reduction of the ketone (185) from arjunic acid and-subsequent methylation and acetylation afforded the 13o H derivative (186). Conversion of acacic acid lactone (187) into dihydrosapogenin B (188) establishes the 18 H configuration of (187). Phosphorus oxychloride converts (187) into 

Amagaya, M. Takai, Y. Ogihara, and Y. litaka, Acta Cryst., 1977, B33, 261. 

The friedelanes (146)—(148) have been isolated from Catha cassinoides (Celas-traceae). The structure and stereochemistry of (147) were proved unambiguously by X-ray analysis of the corresponding acetate.102 Structure (147) had previously been assigned to octandronal (see Vol. 4, p. 214), a compound with different 

Zeylasterone (154) is a novel phenolic 24-norfriedelane from K. zeylanica.108 Isoiquesterin (155) from Salaciamadagascariensis109 and (156) from S. macrosperma are new quinone methides.110 The biogenesis of triterpenoid quinone methides has been discussed.111 

Isomultiflorenol (157) co-occurs with cucurbitacins in seedlings of Bryonia dioica.41 The derivatives (158) and (159), both of which show diuretic activity in rats, occur in Antidesma menasu (Euphorbiaceae).112 3a-Hydroxymultiflora-7,9(ll)-dien-29-oic acid occurs in the roots of B. dioica as the p-hydroxycinnamate ester.113 

The compounds (160),114 (161),115 and (162)116 have been prepared as possible intermediates for pentacyclic triterpenoid synthesis. Treatment of oleana-12,15-diene-3p,28-diol 3-acetate with toluene-p-sulphonyl chloride in pyridine affords the D(16a)-homo compound (163). The mechanisms of this and related reactions are discussed.117 2a,3[3-Diacetoxy-28-noroleana-12,17-diene has been synthesized.118 

The selective oxidation of oleanane triterpenoids by a Cr03-py-BunOH-HaO-derived reagent has been studied.119 Some reactions of glycyrrhetic acid have been 

Vystrcil and M. Budesinsky, Coll. Czech. Chem. Comm., 1970, 35, 295. 

Klinot, N. Hovorkova, and A. Vystrcil, Coll. Czech. Chem. Comm., 1970, 35, 1105. T. Kubota, H. Kitatani, and H. Hinoh, Chem. Comm., 1969, 1313. 

Castanogenol (184), from the bark of Castanospermum australe, has been prepared by lithium aluminium hydride reduction of bayogenin methyl ester (18 5). The structure of entagenic acid (186) has been revised. The vicinal glycol 

(Japan), 1969,17, 1438. 

Aleuritolic acid (191) from Aleuritus montma, was readily transformed by acid into acetyloleanolic acid. The corresponding ester yielded myricadiol (192) on reduction with lithium aluminium hydride. 

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Ginsenosides with a few exceptions share a similar basic structure, consisting of a saturated 1,2-cyclopentanoperhydrophenanthrene (sterane or gonane) steroid nucleus. They are classified into two groups by the skeleton of aglycones, namely dammarane-type and oleanane-type. Ginsenosides... 

FIGURE 1.4 Proposed biosynthetic route for the biosynthesis of (A) squalene oxide (squalene-2,3-oxide) via the isoprenoid pathway and (B) triterpene saponins of the dammarane-type and oleanane-type from squalene oxide. PP, diphosphate group GPS, geranyl phosphate synthase FPS, farnesyl phosphate synthase NADPH, nicotinamide adenine dinucleotide phosphate. 

The distribution and structural elucidation of saponins have been reviewed. Glucuronides with a free carboxy-group and carbohydrate residues at C-2 and C-4 are readily cleaved with acetic anhydride in refluxing pyridine to give the genuine aglycone (see Vol. 7, p. 145). Details of the mass spectra of a series of permethylated oleanane saponins have been discussed. 

Papers have appeared on the effect of different reagents on the course of the dehydration of the 3/3-hydroxy-group of acacic acid lactone and related pentacyclic triterpenoids,the ring A conformation of 2-methyl-3-hydroxy- and 2-methyl-3-oxo-derivatives of 19/3,28-epoxy-18a-oleananes, the use of lead... 

Sejbal, J., Klinot, J., Vystrcil, A. Triterpenes. LXXXV. Photolysis of 19p,28-epoxy-18a-oleanan-2 3-ol nitrites functionalization of lOP- and 8P-methyl groups. Collect. Czech. Chem. Common. 1988, 53,118-131. 

The interesting biological properties shown by many saponins, coupled with improvements in spectroscopic methods of structure determination have led to the increased study of this class of compound. The following papers deal with saponins and prosapogenins which are based on known triterpenoids of the following groups dammarane-euphane,158 lupane,159 oleanane,160 and ursane.161... 

Triptohypol F (18) showed the presence of one double bond, two methine carbons attached to an oxygen function and one methoxy group, according to the 13C NMR spectrum. From these data and its H NMR and MS spectra, it was assumed to be an oleanane-type triterpene. The location of the double bond and the hydroxyl and methoxy groups were determined by a HMBC experiment. The stereochemistry of the hydroxyl and methoxy groups were determined by a NOESY spectrum. According to these data the structure of (18) was established as showed above. 

The main kind of anti-inflammatory triterpenes isolated have oleanane, ursane, taraxastane, lupane and lanostane skeletons (Table 1). Some minor compounds such as hopane are included in other structural groups. Other anti-inflammatory triterpenes like the different cucurbitacins are not included in this review because of their high toxicity. 

Oleanane triterpenoids are the largest group within the triterpenes and encompass a huge number of active compounds. They are structurally classified as olean-12-ene (Table 2) and ll-keto-olean-12-ene (Table 3), directly derived from the oleanane skeleton. Other modifications give rise to the D C-friedooleananes (Table 4), friedelanes (D A-friedooleananes), 24-nor-D A-friedooleananes (Table 5) and 24,30-dinor-D A-friedooleananes (Table 6). The oleananes include glycyrrhetinic acid, probably the most widely studied triterpene. 

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