Pentacyclic triterpenoids lupane

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). 

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]. 

Betulin and lupeol, together with low amounts of lupenone, betulone and betulinic acid, are characteristic of birch bark [87,153 157]. All these compounds are pentacyclic triterpenoids with a lupane skeleton. In addition to triterpenoids, birch bark contains high amounts of a lipid material, called suberin [158]. 

Lupanes are another example of plant-derived pentacyclic triterpenoids that are represented by friedelin, lupeol and betulin. Several representative family members, for example, ochraceolide A, ochraceolide B, dihydroochraceolide A, betulin and lupeol, were isolated from the mixed... 

Allemand (9) used MS-MS for identification of triterpenes and steroids in Evernia prunastri while Shojima et al. (650) reported the MS of about 100 natural and unsaturated pentacyclic triterpenoids, including hopanes and lupanes. 

This review summarizes, up to mid 2014, the most representative microbial transformations and the derivatives of special interest obtained from the lupan-type (lupeol), olean-t) e (p-amyrin), and ursan-type (a-amyrin) pentacyclic triterpenoids (Figure 28.1) in the last 20years. 

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