Aroma isoprenoid compounds

Perhaps the most interesting arthropodan defensive compounds from the point of view of structural diversity are the alkaloids. While alkaloids had long been believed to arise only as a consequence of plant secondary metabolism, it has become apparent over the last few decades that arthropods are both prolific and innovative alkaloid chemists. The millipede Polyzonium rosalbum, once thought to secrete camphor (20), in fact gives off a camphoraceous/earthy aroma produced by the spirocyclic isoprenoid imine polyzonimine (21). 

The powerful potentialities of SBSE followed by thermal desorption and GC-qMS methodology to characterize Madeira wine was also explored by Perestrelo et al. (2009). This methodology provided higher ability for profiling traces and ultratraces of compounds in Madeira wines, including esters (80.7-89.7%), higher alcohols (3.5-8.2%), Ci3 nor-isoprenoids (1.7-6.5%), carboxylic acids (1.6H-.2%), aldehydes (0.9-3.7%) pyrans (0.2-1.7%), lactones (0.3-2.7%), and mono (0.1-1.4%), and sesqui-terpenoids (0.1-0.8%). The authors reported that the concentration of some of them is above their odor threshold, and therefore can probably play a remarkable impact on the aroma complexity of the corresponding wines. 

Although the number of aroma compounds derived from acyclic carotenoids is much inferior to that of the mono- and bicyclic compounds, some of them can also be considered as breakdown products from genuine mono-, sesqui- and diterpenoids. The importance of the aliphatic isoprenoids (282) to (291) in the formation of total flavors of certain foodstuffs is not less than that of the cyclic compounds, the three methyl ketones (282), (287) and (290) which are related to the main tomato pigment lycopene were observed in tomato flavor (75). The hexahydro derivative (291) from coffee (595), jasmine oil (722) and green tea 438) is perceived as flowery and warm and can be considered as an oxidative biodegradation product of phytol and phyta-diene. 6-Methyl-3,5-heptadien-2-one (283), with a grassy and cinnamonlike aroma 438) [detected in tomato 668), the essential oil of Hama-metis leaves 383), Ceylon tea (722) and passion fruit (777)], and pseudo-ionone (288) [also isolated from passion fruit (777)] are believed to be formed from two different dehydrolycopenes. Compounds other than carotenoids, such as solanesol or squalene, can also be considered... 

Flavor and aroma of fruit and scent of flowers is represented by a mixture of dozens of volatile components [160, 161]. Most of these volatiles are derived from three chemical groups, namely isoprenoids, phenylpropanoids and aliphatics. Several volatiles in the mixture will have a dominant effect on the overall fruit aroma or flower scent that is independent from their relative levels. Namely, trace levels of a certain component might have a substantial effect on the typical aroma and scent associated with a particular fruit or flower. Due to promiscuity of enzymes associated with volatile compounds metabolism, a relatively large number of volatile components could be altered by modifying a single gene. For instance, overexpression of the ( )-j3-caryophyllene synthase from rice in Arabidopsis results in emission of a bouquet of terpenoid volatiles, including (EyP-caryophyllene, j8-elemene and a-humulene... 

Abstract Isoprenoids are the largest class of natural compounds and have extremely diverse chemical and functional properties. They are involved in many different cellular processes, including hormonal regulation, signalling, pest/patho-gen defence and redox status. They also provide many of the colours, flavours and aromas found in biology. The diversity of isoprenoids lends them to a wide variety... 

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