Oleananes

More than 300 oleananes are reported to exist in plants The parent (+)-oleanane is isolated from petroleum, and its (+)-3p,lla,13p-triol derivative from Pistazia 

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Masazumi M, Yoshiteru I, Susumu I, Junzo S. 3a-Hydroxy-oleanane-type triterpene glycosyl esters from leaves of Acanthopanax spinosus. Phytochemistry 1993 34 1599-1602. 

The plant is known to produce norbisabolane diterpenes, including phyllanthusols A and B, which are both cytotoxic (36). From the bark, pentacyclic triterpenoids, phyl-lanthol, and olean-12en-3[3-ol (p-amyrin) have been isolated (37). Note lupane- and oleanane-type triterpenoids isolated from the bark of Phyllanthus flexuosus, such as olean-12-en-3 (3,15 a-diol, olean-12-en-3 [3,15 a,24-triol, lupeol, and betulin inhibited the enzymatic activity of topoisomerase II activity with IC50 values in the range of 10 to 39 p.M (38). 

Sakai K, Fukuda Y, Matsunaga S, Tanaka R, Yamori T. New cytotoxic oleanane-type triterpenoids from the cones of Liquidamber styraciflua. J Nat Prod 2004 67 1088-1093. 

Burseraceae Commiphora (myrrh) Boswellia (olibanum or frankincense) Canarium (elemi) a and (3 amyrin, euphanes, oleananes... 

Frankincense, also known as olibanum, is obtained from trees belonging to the genus Boswellia (Burseraceae family). It is one of the best-known ancient plant resins. The ancient Egyptians were the first to use it as incense in embalming practices and in the preparation of medicines, cosmetics and perfumes, and today it is still used therapeutically. It contains pentacyclic triterpenoids belonging to oleanane, ursane or lupane type molecules and in particular of a- and p-boswellic acids, and their O-acetates [104 111], 11 -Oxo-p-boswellic acid and its acetyl derivative, identified in several Boswellia species, are also diagnostic for frankincense [112]. 

Figure 5.5 Norrish reaction of a triterpenoid (e.g. dammarane, oleanane or ursane type) leading to ring opening and subsequent oxidation of the ketone to the corresponding acid...

Triterpenoid saponins are synthesized via the isoprenoid pathway.4 The first committed step in triterpenoid saponin biosynthesis involves the cyclization of 2,3-oxidosqualene to one of a number of different potential products (Fig. 5.1).4,8 Most plant triterpenoid saponins are derived from oleanane or dammarane skeletons although lupanes are also common 4 This cyclization event forms a branchpoint with the sterol biosynthetic pathway in which 2,3-oxidosqualene is cyclized to cycloartenol in plants, or to lanosterol in animals and fungi. 

Fig. 12 Structures of oleanane glycosides from chrysomelid beetles...

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. 

As described above, the cyclization of squalene oxide is a biosynthetic branching point not only for phytosterols and triterpenes but also for dammarane- and oleanane-type ginsenosides. In ginseng, the enzyme... 

In our study on the chemical constituents of Salvia frigida Boiss., we report here the isolation and identification of two oleanane type (componnd 1, 2) and two cycloartane type triterpenoids (compound 3,4) with the componnds a-amyrin 5 and P-sitoserol 6. The compounds have been characterized by UV/vix, IR, H NMR, NMR and MS spectroscopy. 

Smith GW, Fowell DT, Melsom BG, Grystal structure of 18a(H)-oleanane, Nature 228 355-356, 1970. 

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. 

Trraidel, J.M. Graff, R. Albrecht, P. Riva, A. (1991) 24,28-Dinor-18a-oleanane, a novel demethylated higher plant derived triterpene hydrocarbon in petroleum. Tetrahedron Lett., 32,2959-62. 

Some oleanane type triterpenoids with highly oxygenated were isolated form Barringtonia racemosa as shown in Fig 6. Six friedelane type triterpenoids were isolated from bark of Hibiscus tiliaceus collected from Flainan province as shown in Figure 7. 

Gowri, P. M, Radhakiishnan, S. V, Basha, S. J, Sarma, A. V, Rao, J. M. Oleanane-t)rpe isomeric triterpenoids from Barringtonia racemosa. Journal Natural Product. (2009). 

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