Soybean (Glycine max) root lignification induced by ferulic acid. The possible mode of action.

Ferulic acid, in the form of feruloyl CoA, occupies a central position as an intermediate in the phenylpropanoid pathway. Due to the allelopathic function, its effects were tested on root growth, H(2)O(2) and lignin contents, and activities of cinnamyl alcohol dehydrogenase (CAD, EC 1.1.1.195) and peroxidase (POD, EC 1.11.1.7) from soybean (Glycine max (L.) Merr.) root seedlings. Three-day-old seedlings were cultivated in half-strength Hoagland's solution (pH 6.0), with or without 1.0 mM ferulic acid in a growth chamber (25 degrees C, 12/12 hr light/dark photoperiod, irradiance of 280 micromol m(-2) s(-1)) for 24 or 48 hr. Exogenously supplied ferulic acid induced premature cessation of root growth, with disintegration of the root cap, compression of cells in the quiescent center, increase of the vascular cylinder diameter, and earlier lignification of the metaxylem. Moreover, the allelochemical decreased CAD activity and H(2)O(2) level and increased the anionic isoform PODa5 activity and lignin content. The lignin monomer composition of ferulic acid-exposed roots revealed a significant increase of guaiacyl (G) units. When applied jointly with piperonylic acid (an inhibitor of the cinnamate 4-hydroxylase, C4H), ferulic acid increased lignin content. By contrast, the application of 3,4-(methylenedioxy) cinnamic acid (an inhibitor of the 4-coumarate:CoA ligase, 4CL) with ferulic acid did not. Taken together, these results suggest that ferulic acid may be channeled into the phenylpropanoid pathway (by the 4CL reaction) and, further, may increase the lignin monomer amount solidifying the cell wall and restricting the root growth.

Effects of norepinephrine on the metabolism of fatty acids with different chain lengths in the perfused rat liver.

The effects of norepinephrine on ketogenesis in isolated hepatocytes have been reported as ranging from stimulation to inhibition. The present work was planned with the aim of clarifying these discrepancies. The experimental system was the once-through perfused liver from fasted and fed rats. Fatty acids with chain lengths varying from 8-18 were infused. The effects of norepinephrine depended on the metabolic state of the rat and on the nature of the fatty acid. Norepinephrine clearly inhibited ketogenesis from long-chain fatty acids (stearate > palmitate > oleate), but had little effect on ketogenesis from medium-chain fatty acids (octanoate and laureate). With palmitate the decrease in oxygen uptake was restricted to the substrate stimulated portion; with stearate, the decrease exceeded the substrate stimulated portion; with oleate, oxygen uptake was transiently inhibited. Withdrawal of Ca2+ attenuated the inhibitory effects. 14CO2 production from [1-14C]oleate was inhibited. Net uptake of the fatty acids was not affected by norepinephrine. In livers from fed rats, oxygen uptake and ketogenesis from stearate were only transiently inhibited. The conclusions are: (a) in the fasted state norepinephrine reduces ketogenesis and respiration by means of a Ca2+-dependent mechanism; (b) the degree of inhibition varies with the chain length and the degree of saturation of the fatty acids; (c) norepinephrine favours esterification of the activated long-chain fatty acids in detriment to oxidation; (d) in the fed state the stimulatory action of norepinephrine on glycogen catabolism induces conditions which are able to reverse inhibition of ketogenesis and oxygen uptake.

Effects of fatty acids on carbohydrates and lipids of canola seeds during germination

The present work was carried out to investigate the effects of caprylic acid (C8) and oleic acid (C18) on carbohydrates and lipids during canola seed germination. The results showed that oleic acid influence carbohydrate concentration but did not influence lipid concentration. Significant results were found with caprylic acid that affected carbohydrates and lipids in cotyledons after three-day germination.

O presente trabalho foi realizado com o objetivo de investigar os efeitos dos ácidos caprílico (C8) oleico (C18) sobre carboidratos e lipídeos durante a germinação de sementes de canola. Os resultados mostraram que ácido oleico influencia a concentração de carboidratos mas não altera a concentração de lipídeos. Resultados significativos foram encontrados com ácido caprílico que afetou tanto carboidratos como lipídeos, nos cotilédones, após três dias de germinação.

Efeitos de compostos fenólicos sobre a atividade da urease de soja / Effects of phenolics compounds on soybean urease activity

Allelopathy is defined as any direct or indirect harmful effect of one plant (including microorganisms) on another through the production of chemical compounds that escape into the environment. The allelochemicals produced by microorganisms or higher plants include p-coumaric and ferulic acids: these phenolic compounds were found in soils at concentration between 0,01 mM and 0,1mM. Soybean urease (E.C.3.5.1.5) catalyzes the hydrolysis of urea, thus producing carbon dioxide and ammonia which are important for plant growth. This article analyzes a probable relation between allelopathic agents and enzymatic activity of urease. The results show that p-coumaric acids is an inhibitor of urease at high concentrations (10mM), while ferulic acid inhibits the enzyme at extremely low concentrations (10-7mM)