Quinolizidine alkaloids sites

Wink M, Hartmaim T (1981) Sites of enzyme synthesis of quinolizidine alkaloids and their accumulation in Lupinus polyphyllus. J Plant Physiol 102 337-344... 

Figure 1.13. Degradation of quinolizidine alkaloids A—general structure. B—end product alkaloids, and C— products derived from alkaloids. The structure of lupine alkaloids four ring— sparteine type three ring—cytisine type two ring— lupinine type laige hollow arrow— most common oxidation and hydroxylation arrows from parallel lines— most common dehydrogenation site.

As a rule of thumb, we can assume that all parts of an alkaloidal plant contain alkaloids, although the site of synthesis is often restricted to a particular organ, such as the roots or leaves. Translocation via the phloem, xylem, or apoplastically must have therefore occurred. Phloem transport has been demonstrated for quinolizidine, pyrrolizidine, and indolizidine alkaloids, and xylem transport for nicotine and tropane alkaloids 36,39,511). 

Sites of biosynthesis are compartmentalized in the plant cell. While most biosynthetic pathways proceed (as least partially) in the cytoplasm, there is evidence that some alkaloids (such as coniine, quinolizidines and caffeine), furanocoumarins and some terpenes (such as monoterpenes, diterpenes. 

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