Gramine concentration

Effect of water stress on susceptibility of barley to aphids. Barley seedlings were subjected to water stress. These plants accumulated among other compounds proline and glycine-betaine (Table IV). Also, the more stressed plants were the most susceptible to aphids. The cultivar used in this experiment lacked gramine. However, when a gramine-containing cultivar was used gramine concentration was not affected by water stress. 

Indoleacetic acid In a 1-litre flask, fitted with a reflux condenser, place a solution of 35 2 g. of sodium cyanide in 70 ml. of water, then add 25 g. of gramine and 280 ml. of 95 per cent, ethanol. Reflux the mixture (steam bath) for 80 hours. Dilute the cooled reaction mixture with 35 ml. of water, shake with a little activated charcoal (e.g., Norit), filter and concentrate to about 350 ml. imder reduced pressure (water pump) in order to remove most of the alcohol. Cool to about 5°, filter off the solid and wash it with a little cold water keep the filtrate (A). Recrystallise the solid from alcohol-ether to give 5-0 g. of 3-indoleacetamide, m.p. 150-151°. 

Voles M.pennsylvanicus) suffer renal lesions (interstitial nephritis) when fed extracts of white clover, T. repens. Milder lesions were observed after feeding on reed phalaris Phalaris arundinacea) and timothy Phleum pratense). Many varieties of reed phalaris contain the toxic compoimds gramine and tryptamine (Fig.11.15). In summer and autumn, protein levels in the leaves decrease, fiber content goes up, and secondary compoimds increase in concentration. Therefore, second growth plants have more toxic effects on voles than the spring plants that grow fast and have lower levels of secondary compounds (Bergeron etal, 1987). 

Distribution of compounds in barley and wheat tissues. Tissues of barley and wheat leaves were mechanically separated under the microscope. It was observed that in barley gramine was more concentrated in the epidermis than in the entire leaf (Table II). Hydroxamic acids in wheat were absent in epidermic tissues and were more concentrated in the vascular tissues than in the entire leaf. Neither compound was detected in xylem exudates nor in guttation drops. 

The samples for gramine analyses were frozen and macerated with 20 ml of MeOH NHi,0H (100 1 v/v). The extract was filtered through glass wool. Solvent and endogenous water were evaporated to dryness. The chlorophyllous residue was dissolved in 5 ml 0.1 M HCl, and the solution filtered (Whatman N°1 paper). The aqueous filtrate was adjusted to pH 9 with concentrated NHi,0H and shaken twice with... 

Under neutral conditions and at low temperature indole reacts with a mixture of formaldehyde and dimethylamine by substitution at the indole nitrogen it seems likely that this reaction involves a low equilibrium concentration of the indolyl anion. In neutral solution at higher temperature or in acetic acid, conversion into the thermodynamically more stable, 3-substituted product, gramine, takes place. Gramine is formed directly, smoothly and in high yield, by reaction in acetic acid. The Mannich reaction is very useful in synthesis because not only can the electrophilic iminium ion be varied widely, but the product gramines are themselves intermediates for further manipulation (section 17.12). 

Silicon resembles aluminum in its high concentration in soils and atmospheric dust and its relatively low concentrations in animal tissues. It occurs, however, in comparatively large amounts in many plants, particularly gramineous species. Silicon is apparently essential in the nutrition of the higher plants and for the reproduction of marine plankton, but whether it is an essential component of the diet of animals has not yet been decided. 

Gramine (Donaxine). This base, readily accessible via a Mannich condensation between indole, formaldehyde and dimethylamine, is produced in the plant from tryptophan by a route not completely understood but which retains the original indole moiety and the first carbon of the side chain. The usefulness of gramine to the plant is obscure but is certainly functional since in sprouting barley its concentration builds up to a maximum in ten days after germination and has practically disappeared in a month. 

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