Dammarane group

Several studies have dealt with the problem of discriminating between mastic and dammar, and three marker compounds of mastic have been identified moronic, masticadienonic and acetyl masticadienolic acids [42], The chemical structure of (iso)masticadienonic acid and 3-0-acetyl-3-epi(iso)masticadienonic acid is characterized by a side chain, as for dammarane molecules, but with a carboxylic acid end group (Table 12.1). Under pyrolysis conditions this side chain is susceptible to cleavage as demonstrated by the presence, among the pyrolysis products of mastic, of 2-methyl-pent-2,4-dienoic acid, that perfectly matches with the chemical structure of the side chain end. In addition 3-(9-acetyl-3-epi-(iso)masticadienolic acid also loses the acetyl group and, in contrast to masticadienonic acid, is not detected at all. 

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. 

Yoshikawa, M., Sugimoto, S., Nakamura, S., and Matsuda, H. (2007a). Medicinal flowers. XL Structures of new dammarane-type triterpene diglycosides with hydroperoxide group from flower buds of Panax ginseng. Chem. Pharm. Bull. 55,571-576. 

Triterpenoids are a major group of natural products in higher plants. The tetracyclic triterpenoids, based on the lanostane, euphane, onocer-ane, and dammarane skeletons, are found mostly in vascular plants and... 

Irradiation of nitro aromatics produces excited states in which the nitro group oxygen can remove an accessible hydrogen. The resulting diradical can then undergo hydroxyl transfer to the substrate carbon. This process has been used to hydroxylate dammarane terpenes related to steroids, by preparing appropriate nitrophenyl esters of the substrates and then photolyzing (Scheme In Ae steroid series a... 

Alfhough bearing a sterane nucleus, fhe biosyntheses of cucurbitacins and dammaran-type saponins will not be reviewed here. Both groups belong to the triterpenoids, the chemistry, biosynthesis and biological activities of which have been described elsewhere (Charlwood and Banthorpe, 1991 ... 

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... 

Compound (44) showed -as principal differences with compounds previously described-and additional double bond and a carboxyl carbon. One secondary hydroxyl group was also found. With the aid of a HMBC experiment, the structure of (44) was confirming as a homo-dammarane, Fig. (25). 

Although rhombenone inhibited partially purified rat brain FPTase (IC50 = 2.3 pM), other dammaranes, for example, protopannaxydiol and protopannaxytriol, that possess a C-27 methyl group and lack other structural features of rhombenone, were weakly active as inhibitors of... 

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