Inhibition root metabolism

Protoanemonin, which has been isolated from Anemone pulsatilla and Ranunculus spp., was reported to inhibit root growth by slowing down metabolism and blocking mitosis 35). Erickson and Rosen 35) observed cytological effects in corn root tips at concentrations of 10M and lower. Cells undergoing division appeared to accumulate in the interphase or prophase stages. Metaphase, anaphase, and telophase stages were not observed. Cytoplasmic and vacuolar structures were disturbed and the presence of mitochondria could not be demonstrated in treated tissue. Thimann and Bonner 141) reported that protoanemonin was 10 to 30 times more inhibitory than coumarin in coleoptile and split pea stem tests, and that BAL prevented the inhibitory action. 

Cell Division Inhibition. If the mitotic index (% of cells in mitosis) decreases to zero during the first few hours of treatment (approximately 8 h), the compound is inhibiting some metabolic process in interphase (Gi, S, or G2) The location and possible cause of the inhibition, which can be determined by autoradiographic techniques, involves treating root meristems with radioactive thymidine after herbicide treatment. The details of this procedure have been published by Van t Hof (33). An alternative to the above procedure is to treat root tissue with herbicide plus radioactive thymidine or uridine and follow the increase of radioactivity precipitable by trichloroacetic acid (34). 

Abstract Cadmium is an important poiiutant in the environment, toxic to most organisms and a potential threat to human heaith Crops and other plants take up Cd from the soil or water and may enrich it in their roots and shoots. In this review, we suimnarize natural and anthropogenic reasons for the occurrence of Cd toxicity, and evaluate the observed phytotoxic effects of plants growing in Cd-supplemented sou or nutrient solution. Cd-induced effects include oxidative stress, genotoxicity, inhibition of the photosynthetic apparatus, and inhibition of root metabolism. We explain proposed and possible interactimis between these modes of toxicity. WhUe discussing recent and older studies, we further emphasize the environmental relevance of the experiments and the physiological response of the plant. 

The reported (14) mechanisms of action of allelochemlcals Include effects on root ultrastructure and subsequent Inhibition of Ion absorption and water uptake, effects on hormone-induced growth, alteration of membrane permeability, changes In lipid and organic acid metabolism, inhibition of protein synthesis and alteration of enzyme activity, and effects on stomatal opening and on photosynthesis. Reduced leaf water potential Is one result of treatment with ferulic and p-coumaric acids (15). Colton and Einhellig (16) found that aqueous extracts of velvetleaf (Abutllon theophrastl Medic.) Increased diffusive resistance In soybean fGlycine max. (L.) Merr.] leaves, probably as a result of stomatal closure. In addition, there was evidence of water stress and reduced quantities of chlorophyll In Inhibited plants. 

There may also be effects via the concentrations of competing cations at the root surface. In studies of short-term uptake of Zn by rice from nutrient solutions containing realistic Zn " " concentrations, Giordano and Mortvedt (1974) found uptake was inhibited by various metabolic inhibitors and by Fe +, Mn +, Ca and Mg + as Cl salts at typical concentrations in flooded soil solutions. Translo-... 

Boron also appears to be involved in redox metabolism in cell membranes. Boron deficiency was shown to inhibit membrane H -ATPase isolated from plant roots, and H -ATPase-associated proton secretion is decreased in boron-deficient cell cultures [71]. Other studies show an effect of boron on membrane electron transport reactions and the stimulation of plasma reduced nicotinamide adenine dinucleotide (NADH) oxidase upon addition of boron to cell cultures [72, 73]. NADH oxidase in plasma membrane is believed to play a role in the reduction of ascorbate free radical to ascorbate [74]. One theory proposes that, by stimulating NADH oxidase to keep ascorbate reduced at the cell wall-membrane interface, the presence of boron is important in... 

Belver, A. and J.P. Donaire. 1987. Phospholipid metabolism in roots and microsomes of sunflower seedlings inhibition of choline phosphotransferase activity by boron. Phytochem. 26 2923-2921. 

One final consideration of drug interactions involving intestinal CYP3A is the fact that differential modulation of intestinal and hepatic CYP3A is possible. Simultaneous inhibition of intestinal first-pass metabolism and stimulation or induction of hepatic first-pass metabolism has been reported for the interaction between the herbal supplement echinacea (Echinacea purpurea root) and... 

Prenylated flavonoids contain one or two isoprenyl, geranyl, dimethylallyl, and lavandulyl on the skeleton. They have limited distribution and are mostly isolated from the Moraceae family. Chi et al. isolated 19 prenylated flavonoids from six different genera of Chinese medicinal plants and evaluated inhibition activities on eicosanoid metabolisms with multiple cell line models [189]. Two 8-lavandulylated flavanones, kurarinone and sophoraflavanone G, were discovered to be dual inhibitors. They possessed the most potent COX-1 inhibitory activities with IC50 less than 1 pM comparable with that of indomethacin. Sophoraflavanone G isolated from the roots of Sophora flavescense Art (Fabaceae) also had potent 5-LOX inhibition activity with an IC50 below 0.25 pM. 

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