Arilpropanóides em Embryobionta

Abstract

Lignins are among the most abundant organic products on earth. Their polyarylpropanoid molecules were, for this reason, subject of many investigations. In opposition, relatively little is known about bisarylpropanoids (lignans, neolignans) and arylpropanoids (propenylphenols, allylphenols). These metabolites function in Embryobionta as social hormones. Their evolutive potentiation led to the derivatives of the biogenetic group of benzyltetrahydroisoquinoline. Mapping of the biosynthetic routes which lead to these alcaloids (in previous work), as well as to mono- and bisarylpropanoids, starts from phenylalanine and makes possible not only the classification, but also the rational codification of all skeleta involved. The analysis of the aromatic oxygenation pattern of each of the classes of lignans and neolignans suggests details of the oxidative coupling mechanisms. In the case of propenylphenols and allylphenols, such an analysis, associated with consideration of the natural distribution of the derivatives, does not corroborate in vivo evidence on the biosynthesis of allylphenols, recently obtained in Italy. The structural variation, of lignins, lignans, and neolignans through 350 x 106 years of plant evolution can be accompanied, paying attention to one of the basic principles of Biochemical Systematics: evolution of a biogenetic group of metabolites operates through gradual diversification of skeleta and their derivatives up to a maximum, initiating, in sequence, gradual retraction of the number of skeleta and number of corresponding derivatives. The different classes of arylpropanoids, can, for this reason, in combination with the benzyltetrahydroisoquinoline group, be used as chemosystematic markers, a fact which, in the present case, served to suggest the singular taxonomic position of the subclass Magnoliidae and the phylogenetic relation of its families.