Of oleanane triterpenoid

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... 

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...

Fig. 5. 19 Formation of oleanane from higher-plant triterpenoids (large arrows indicate biogenic inputs after ten Haven Rullkotter 1988 Ekweozor Telnaes 1990 Rullkotter et al. 1994).

Table l Effects of Oleanane-Type Triterpenoids on TPA-Induced Pi Incorporation into phospholipids of cultured cells... 

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. 

The triterpenoid constituents of resins analysed are usually seen as a group of peaks eluting at around 30 minutes retention time under the analytical conditions used. Of the triterpenoid resins in Table I, four of the five come from the Dipterocarpaceae family. Their complexity and triterpenoid composition varies to some degree, but common to all are a number of peaks identifiable as compounds from the tetracyclic dammarane series (Figures 3-6). In addition to these, pentacyclic triterpenoids from the ursane and oleanane series are present. Although some peaks have yet to be conclusively identified, they are included since they are detected in more than one of the Dipterocarp reference samples and have also been observed in some archaeological material. 

Fig. 1.6 Chemical stractures of sapogenins triterpenoid, for example, oleanane (a) steroids, for example, spirostanol (b) and furostanol (c)...

Ten new metabolites (507—516), isolated from Pseudocyphellaria species by Corbett, Wilkins and co-workers (57), provide the first examples of this new group of triterpenoids. The structures of these metabolites followed primarily from a detailed comparison of the H-n.m. r. spectra with those of other triterpenoid groups. Corbett and coworkers had previously synthesized a number of the parent triterpanes, 18a-oleanane (5 ), 17aH-hopane (55), 17aH-moretane (55) and 14a-taraxerane (55), by methods similar to those exemplified for stictane (Scheme 66). Thus oxidation of the alcohol (516) gave the diketone (517) which upon Wolff-Kishner reduction yielded the parent stictane (518). The physical and spectroscopic properties of this triterpane confirmed the novelty of this group of compounds. 

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. 

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]. 

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. 

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. 

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. 

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