Applications of chemotaxonomy

Answer 1

APPLICATIONS OF CHEMOTAXONOMY:

1. Separation of higher systemic categories :

plant division:

· Chemical characters are always advantageous over morphological character.

Eg. Flavonoids are generally found in bryophyte except one or two reports where it has been reported the isolation of crystalline anthocyanin

From a red Bryum species was being reported.

Similarly, lignin that no plant lower than mosses contains a substance like lignin.

So lignin and flavonoids are common in almost all plant groups higher than the bryophytes.

· There are few chemical substances which confirms the relations between those two orders - Isoquinoline alkaloids, Salsoline in a salsola species and carnegine in a cactaceae; corypalline from a corydalis species having the similar isoquinoline nucleus intheir structures.

2. Related genera having similar enzyme system producing analogous metabolites:

· The pyrrolizidine alkaloids are analogous with quinolizidine, although their precursors are ornithine and lysine respectively but they have similar enzyme system.

· Both type alkaloids have been found to occur in botanically related genera.

Eg. "Pyrrolizidine "alkaloids reported to occur in crotalaria and "Quinolizidine" alkaloids have been isolated from lupines and cytisus.

Both belonging to genistae genera.

3. Complex metabolic products are good chemotaxonomic marker:

· The occurrence of complex secondary metabolites like biflavonoid and complex alkaloids are helpful in classification of medicinal plants.

· The biflavonoids are plant polyphenols, structurally they are divided into several subclasses, flavanol, anthocyains and chalcones.

· They are biosynthesized through a combination of the shikimic acid and the acylopolymalonate pathways.

· They are omni present in vascular plants but more rarely in bryophytes.

· Some biflavonoids classes have a restricted distribution ; eg. Isoflavonids occur predominantly in the Fabaceae family.

· The biflavonyls have mainly been reported in leaves of gymnosperms.

· It has been reported that biflavonyls are absent in genera of Pinaceae, hence the inability to synthesize bifllvonyls can be used as a characteristic of the order pinales.

Hence the complex structure compounds like Biflavonyls are very important for the chemical classification of the gymnosperms.