Glycosides fractionation

The alkaline hydrolysis of the ether-insoluble resin glycoside fraction from seeds of Ipomoea nil (L.) Roth (syn. Pharbitis nil Choisy) yielded a pentasaccharide of ipurolic acid, which was named pharbitic acid C (tetradecanoic acid, ll-[(0-6-deoxy- S-D-glucopyranosyl-(1 4)-0-6-deoxy-a-L-mannopyranosyl-(l—>6)-0-[6-deoxy-a-L-mannopyranosyl-(l—>2)-0-jS-D-glucopyranosyl-(l—>2)]- S-D-glucopyra-nosyl)oxy]-3-hydroxy). On complete hydrolysis, it produced two o-glucoses, two L-rhamnoses, one o-quinovose, and the aglycone moiety (77). 

Du X-M, Sun N-Y, Nishi M, Kawasaki T, Guo Y-T, Miyahara K (1999) Components of the Ether-Insoluble Resin Glycoside Fraction from the Seed of Cuscuta australis. J Nat Prod 62 722... 

A feeding experiment was conducted using field concentrations of the aikaloidal fraction and the total triterpenoid glycoside fraction of thirty related species of columnar cacti (most in the Pachycereeae). Survivorship was measured as + or - and indicates successful development, pupation and emergence after eggs were laid by several d, melanogaster or d. mojavensis females. The latter species is a desert fly known to specialize on several species of Pachycereeae the former is a nonspecialized, nondesert species. Heliothis zea larvae were also used in a separate bioassay of toxicity where compounds were added to commercial diet. 

Specific differences in toxicity toward each test species were discovered between the various plant chemical arrays. Table HI lists survivorship for these species for alkaloid-producing cacti. Additionally, data was obtained for 20 species in which alkaloids were not detected. The three insect species showed consistent differences in tolerance toward given plant species, with no clear phylogenetic pattern accounting for this. Insects also responded differently to aikaloidal fractions versus triterpenoid glycoside fractions. Alkaloids were found to be generally not toxic to D. 

Me Mahon, H. M., Zoecklein, B. W., Jasinski, (1999). The effects of prefermentation maceration temperature and percent alcohol (v/v) at press on the concentration of Cabernet Sauvignon grape glycosides and glycoside fractions. Am. J. Enol. Vitic., 50, 385-390. 

To avoid the above mentioned problems which are due to side activities of commercial glycosidase preparations and the specificity of glycosidases for both, the glycon as well as the aglycon moiety, an isolation and structural determination of individual constituents in a precursor fraction should be attempted. This requires the availability of preparative separation techniques that enable a gentle isolation of reactive aroma precursors from the complex glycosidic fraction of wine. 

Figure 3. Concentrations of five categories of volatile compounds, observed as a result of acid hydrolysis of the glycoside fractions isolated from juice and skin extracts of Napa Merlot (NMJ, NMS) and Cabernet Sauvignon (NCJ, NCS) fruit.

These observations are in accord with the results of a previous study which demonstrated that the aglycons from a Chardonnay glycosidic fraction wre not a significant source of added arona to the wine fran vrfiich it had been obtained ( ). The present work emphasises the inportance of mild acid hydrolysis and the associated chemical pathways to yield flavor significant volatiles in these non-floral varieties. 

Holotoxin Ai inhibits the RNA biosynthesis in Candida albicans and Saccharomyces carlsbergensis, as indicated by the decrease in incorporation of C-uridine to the acid-insoluble fraction of the cells. Similar results were obtained for glycoside fractions of 14 species of Pacific sea cucumbers [132]. Apparently the inhibition of RNA biosynthesis in Saccharomyces carlsbergensis is related to nucleotide loss from yeast cells after treatment with glycosides. Holotoxin Ai also inhibits biosyntheses of squalene, lanosterol and ergosterol in S. carlsbergensis [133]. Mitosis is arrested and DNA synthesis inhibited in onion root bulbs by crude holothurin [134]. 

The sea cucumber Cucumaria frondosa contains a complex mixture of A - and A -holothurins. Frondoside A2-6 (57c) [61] as well as the minoritary monosulfated pentaglycosides frondosides A2-I (50e), A2-2 (49a), A2-3 (49b) and A2-4 (49c) [61, 62] have a glucose residue as the third monosaccharide unit in the carbohydrate chain in contrast to frondoside A, the major component of the glycosidic fraction [85]. 

That was the beginning of the scientific discovery of the olive tree. In fact, in die pioneering researches of Panizzi, the polar and phenolic fraction of olive was forgotten. In 1993, we began to face up die isolation of olive glycosidic fraction from a systematic point of view, using a specific protocol for polar compounds, and succeeded in the isolation of many glycosidic components present in olive. 

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