Ureide


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The following article is from The Great Soviet Encyclopedia (1979). It might be outdated or ideologically biased.

Ureide

 

(also known as ureid), any of the derivatives of urea [CO(NH2)2] resulting from the substitution of acyl (RCO) radicals for hydrogen atoms in the NH2 groups. Ureides are crystalline, high-melting compounds; the melting point of acetylurea (CH3CONHCONH2) is 218°C, while that of diacetylurea (CH3CONH)2CO is 153°C. Cyclic ureides are obtained from the reaction of urea with dibasic acids; for example, barbituric acid is obtained by reacting urea with malonic acid or malonic ester. The ureides of brome-substituted acids (bromisoval, carbromal) and cyclic ureides of the barbiturate type are used as sedatives.

The Great Soviet Encyclopedia, 3rd Edition (1970-1979). © 2010 The Gale Group, Inc. All rights reserved.
References in periodicals archive ?
Ureide accumulation in response to Mn nutrition by eight soybean genotypes with [N.sub.2] fixation tolerance to soil drying.
Leaflets were separated from the petiole, oven-dried (40[degrees]C for 2 d), finely ground, and analyzed for ureide concentration.
The ureide concentration in pod walls from immature plants of Harosoy was about 100-fold greater than in pod walls of the nonnodulated plants (Table 1).
Evaluation of the relative ureide content of xylem sap as an indicator of [N.sub.2] fixation.
Because ureide concentration in xylem sap (Serraj and Sinclair, 1996) and stem extracts (de Silva et al., 1996; Serraj and Sinclair, 1996) increases greatly under drought conditions, it is important to establish the relationship between RAU and [N.sub.2] fixation under water-limited conditions.
The possibility of differing catabolic enzymes for allantoic acid leading to differences in [N.sub.2] fixation sensitivity to water deficits opens the possibility of genotypic segregation based on ureide degradation characteristics.
There are at least two possible hypotheses based on degradation of ureides in the leaves as water deficits develop to explain the low ureide concentrations in Jackson.
Response of leaf ureide concentration to main effects of cultivar and fraction transpirable soil water (FTW) in the nodule size experiments.
(1996) proposed an index based on ureide levels per unit petiole dry weight.
We hypothesized that the decrease in [N.sub.2] fixation during water deficit was associated with ureide accumulation in shoots.
Water deficit in soybean [Glycine max (L.) Merr.] results in the accumulation of the products of [N.sub.2] fixation (ureides) in shoots, and this may lead to feedback inhibition of [N.sub.2] fixation.
Tolstikov, Synthesis and antiviral activity of ureides and carbamates of betulinic acid and its derivatives, Bioorg.