Sesquiterpene quinines

More than half of the reported secondary metabolites from macroalgae are isoprenoids. Terpenes, steroids, carotenoids, prenylated quinines, and hydroqui-nones make up the isoprenoid class, which is understood to derive from either the classical mevalonate pathway, or the mevalonate-independent pathway (Stratmann et al. 1992). Melavonic acid (MVA) (Fig. 1.2) is the first committed metabolite of the terpene pathway. Dimethylallyl (dl meth al lal) pyrophosphate (DMAPP) (Fig. 1.3) and its isomer isopentenyl pyrophosphate (IPP, Fig. 1.3) are intermediates of the MVA pathway and exist in nearly all life forms (Humphrey and Beale 2006). Geranyl (ja ran al) (C10) and famesyl (C15) units are generated by head-to-tail (Fig. 1.3) condensation of two (for C10) or three (for C15) 5-carbon DMA-like isoprene units, identifiable in final products by the characteristic fish-tail repeating units, as traced over the structure of a sesquiterpene in Fig. 1.3 (Humphrey and Beale 2006). Additional IPP condensation with famesyl pyrophosphate (FPP)... 

There are abundant and diverse flavonoids with carbohydrates and lipids, alkaloids (betalain alkaloids and other alkaloids), phenols (chromones, cou-marins, lignans, quinines, and other phenolics), terpenoids (monoterpenoids, sesquiterpene lactones, triperpenoid saponins, carotenoids, and other terpenoids), and minerals as micronutritional phytochemicals in fruits and vegetables of our daily diets. Among these phytochemicals, the flavonoids have specific functionality in relation to age-related diseases such as hypertension, diabetes, cardiac infarction, cataracts, and cancer. The authors of each chapter in the first section have presented their evidence in relation to the mechanism of the preventative and therapeutic ability of the compounds. 

With respect to the use of Cinchona alkaloid-derived organocatalysts, the first example of asymmetric Michel addition of ketones to enones appeared in 1979 when Trost illustrated, during the total synthesis of the sesquiterpene ( )-hirsutic acid C [101], a stereoselective (30% ee) quinine (59)-catalyzed intramolecular conjugate addition of an intermediate functionalized cyclohexanone (Scheme 2.32). 

---