Pentacyclic triterpenoids hopane

Dammar resin was introduced into Europe in the nineteenth century, mainly as a paint varnish It is still used today since it has good optical properties and low acidity. It is derived from various species (the genus Hopea and Shorea of the Dipterocarpaceae family). It is characterised by tetracyclic triterpenoids of the dammarane series and contains minor amounts of pentacyclic triterpenoids of the series of olanane, ursane and hopane. It also contains a polymeric fraction named polycadinene or [S-resene. Dammar resin triterpenoids undergo oxidation with ageing, as described for the components of mastic resin. 

Although they are known to be synthesized by a wide variety of cultured aerobic bacteria there does not appear to be any obligate requirement for oxygen in their biosynthesis. The biosynthesis and cyclization of squalene to a pentacyclic triterpenoid with a hopane skeleton does not seem to require oxygen and, therefore, hopanoid synthesis might also be possible in anaerobes. For instance, analysis of microbial mats at methane seeps under anoxic Black Sea water revealed the presence of C-depleted (8 C = -lS%c) hopanoids with an unusual stereochemistry. This isotopic depletion indicates in situ production and, therefore, suggests that anaerobes are responsible (Thiel et ai, 2003). 

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. 

Serratenediol 207 is a member of a recently discovered class of pentacyclic triterpenes,which have a seven-membered C ring and an entirely different skeletal structure from the triterpenoids described above. The compounds may be classified as a modified hopane group with a close biogenetic relationship, serratenediol being chemically interrelated with a-onocerin by a simple transformation. 

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