Distribution in plant kingdom

The GC/MS(SIM) microanalytical method for BRs has most frequently been employed in the analytical studies of trace levels of BRs in plants and it has greatly contributed to the studies on identification of many natural BRs and also to their distribution in plant kingdom. 

Triterpenoids (including triterpenoid glycosides) are also widely distributed in plants kingdom as well as flavonoids. For searching new anti-tumor-promoters from natural resources, we have also been researching on triterpenoids rich plants which have been used for medicinal purpose in several countries. For a start, from Leguminous plants, many kinds of oleanene type triterpenoid saponins had been isolated and their anti-tumor-promoting activities were examined. 

Phenolic compounds are widely distributed in plant kingdom and are considered to be secondary metabolites. They do not seem to be essential for plant life, at least at the cellular level. Plants provide nearly all the phenols found in higher animals, since the latter can not synthesize compounds with benzenoid rings from aliphatic precursors. The present discussion is mainly confined to polymeric phenols commonly found in cereals and legumes. 

In this review, I summarize the BRs research from the following points (i) distribution of BRs in plant kingdom, (ii) bioassays for BRs, (iii) microanalytical methods of BRs. 

Monoterpenoids are widely distributed in plant and animal kingdoms, both terrestrial and marine (379). Lists of their occurrence in higher plants have been compiled (19, 155, 175, 275, 395, 396). Thble 8.1.2 lists plant families that are, by far, the most prolific in accumulating monoterpenoids. a-Pinene, cineol and limonene are the most widely distributed monoterpenoids. 

L-Ascorbic acid, better known as vitamin C, has the simplest chemical structure of all the vitamins (Figure 18.30). It is widely distributed in the animal and plant kingdoms, and only a few vertebrates—humans and other primates, guinea pigs, fruit-eating bats, certain birds, and some fish (rainbow trout, carp, and Coho salmon, for example)—are unable to synthesize it. In all these organisms, the inability to synthesize ascorbic acid stems from a lack of a liver enzyme, L-gulono-y-lactone oxidase. 

The wide distribution of chlorophylls throughout the plant kingdom facilitates the scrutiny of chlorophyll-rich vegetables for human nutrition with a view to their direct consumption. However, until now, little standardized information was available in the literature regarding the absolute total chlorophyll contents and the ratios of chlorophylls a and b in raw materials. The different analytical methods of extraction and quantification and the lack of data about moisture contents (that may vary considerably among varieties and preparations) can also influence the final contents of pigments. These factors have largely contributed to the discrepancies found in similar food samples. 

In marked contrasts to the flavonoids, the isoflavonoids have a very limited distribution in the plant kingdom and are almost entirely restricted to the subfamily Papilionoidae. Their estrogenic effect was discovered following the observation of a decline in birth rate for sheep fed on Trifolium sublerraneum. Changes in... 

The above outline of the evolution of the plant kingdom during coal-forming eras has been presented largely in the language of botanical anatomy. However, the alert chemist will note that the anatomical differences imply considerable quantitative and spatial differences in the distribution of the principal plant constituents [cellulose, lignin, cutin, suberin and other waxes, contents of protoplasmic cells, pigments, resins, sporopollenin. 

Saponins are glycosylated secondary metabolites that are widely distributed in the Plant Kingdom.3,4 They are a diverse and chemically complex family of compounds that can be divided into three major groups depending on the structure of the aglycone, which may be a steroid, a steroidal alkaloid, or a triterpenoid. These molecules have been proposed to contribute to plant defense.3 6 Saponins are also exploited as drugs and medicines and for a variety of other purposes.4 Despite the considerable commercial interest in this important group of natural products, little is known about their biosynthesis. This is due in part to the complexity of the molecules, and also to the lack of pathway intermediates for biochemical studies. 

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