Apiose structure

The glycosyl-residue compositions of the three purified fractions (Table 1) were very similar with a predominance of galacturonic acid, rhamnose and arabinose. The presence in the three purified fractions of the rare monosaccharides characteristic of RG-II (e.g. 2-( -methyl-L-fucose, 2-O-methyl-D-xylose, apiose, Kdo, Dha and aceric acid) was confirmed by GC-CIMS analysis. The molar ratios corresponded approximately to the known structure of the RG-II molecule (Figure 1) and to previously published data for RG-II from sycamore [26], rice [4], arabidospis leaves [8] and Pectinol [12]. 

The general chemistry of branched-chain sugars has not been the subject of systematic investigation, mainly because of the scarcity of these compounds. Nevertheless, the totality of reactions employed for elucidating the unique structures of these compounds constitutes a body of valuable information which is basic for future developments. Lucid articles on the chemistry of streptose, by Lemieux and Wolfrom,1 and of apiose, by Hudson, have appeared in earlier volumes of this Series the present article will therefore not include information on these two sugars, except as regards comparison with other sugars and in reference to new developments. 

In 1977, he published his last original paper on the structure of a quercetin triglycoside containing D-apiose, isolated from Solatium glaucophy-lum a plant toxic to cattle. In spite of this, his extraordinary capacity as a reader allowed him to remain up to date in a great variety of topics, not only in those of direct interest to him but in those that were studied by several graduate students working under different supervisors. 

Twenty-four years elapsed after the conclusion of Vongerichten s researches on apiose before the study of its structure and configuration was undertaken by Schmidt. He prepared 500 grams of purified... 

Chemists have long held intense interest in compounds whose structure appears to differ radically from the norm. Thus, the isolation and partial characterization, 73 years ago, of a branched-chain sugar, apiose, sparked enthusiasm to study this variation of the more common, straight-chain sugars.1 Subsequently, a second branched-... 

Fifty years after the discovery of apiose, a review of the literature1 showed that it was still a curiosity, and had been found only in the parsley plant. Apart from its structure, and those of the flavonoids from which it was isolated (primarily, apiin), little else was known about apiose. In the next two decades, this branched-chain sugar was shown to have very widespread occurrence in the plant kingdom, being identified, in most of the plants investigated,4-6 by paper chromatography. 

A free disaccharide containing apiose has been extracted from an Australian shrub, the native hop bush, Daviesia latifolia.40 The disaccharide was isolated as a dibenzoate. Methylation followed by de-benzoylation, as well as comparison with the disaccharide of D-apiose from apiin, suggested that they are similar in every aspect measured. Thus, the structure of the disaccharide without its two benzoyl groups is, tentatively, 2-O-D-apiofuranosyl-D-gIucose.40 The... 

The di-O-isopropylidene derivatives of D-apiose are prepared by treating the sugar with acetone containing 5% (v/v) of concentrated sulfuric acid.61-63,130 The structures of these derivatives were first... 

---