Aglycon glycosylation

The obtained spectra can also give information on the nature of the aglycone, glycosylation, and possibility of acylation (Hong et al., 1990). 

In active-latent glycosylations, the glycosyl donor capability of an acceptor is turned on by a slight chemical modification in its aglycone. Glycosylation of the latent compound (106) by the active... 

Aglycon Glycosyl moiety Starting material Method References ... 

Substitution Patterns of Flavonoids Flavone and Flavonol Aglycones Glycosylation and Methylation of Flavones and Flavonols... 

For the purposes of this chapter, an arbitrary distinction is made between protonic and thermal activation, wherein protonic activation is caused by the action of acid at room temperature or lower, and thermal activation refers to the use of elevated temperatures with or without the addition of acid. In fact, in both cases, the initial steps in the postulated mechanisms are protonation of the C-2 oxygen atom followed by elimination of the aglycone to yield a ketohexofuranosyl or pyranosyl cation, which is the reactive intermediate in certain circumstances, this might be in equilibrium with the derived glycosyl fluoride. 

Betalains are N-heterocyclic water-soluble pigments deposited in vacuoles. Their common precursor is betalamic acid consisting of a 1,7-diazaheptamethin system, an extended Jt-electron system exhibiting a canary yellow color. Betalamic acid may condense with cyc/o-dopa to yield betanidin, the common precursor aglycon of the red betacyanins. Betanidin in turn may be glycosylated and/or acylated, yielding 29... 

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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