Effect of neocuproine and cuprizone on the development of amine oxidase and growth in pea seedlings

Effects of neocuproine (2,9-dimethyl-l,10-phenanthroline) andcuprizone (biscyclohexanone oxalyldihydrazone), as copper-chelatingagents on the development of amine oxidase and the growth ofpea plants were studied. Amine oxidase development in the apicalpart was inhibited by administration of neocuproine, and thiseffect was markedly reversed by the addition of copper disodiumethylenediaminetetraacetate(EDTA-Na₂-Cu). In this case, theamine oxidase activity was stimulated. Pea plant growth wasinhibited by this chelator but not in the presence of EDTA-Na₂-Cu.On the other hand, the development of enzyme activity and growthwere much less sensitive to cuprizone. (Received August 8, 1976; )     

Indole-3-acetaldehyde oxidase of pea seedlings

Indole-3-acetaldehyde oxidase was partially purified from the epicotyl of Pisum satiyum seedlings by column chromatography using CM-Sephadex and Sephadex G-150. The enzyme was only active in the presence of molecular oxygen. The activity was maximal at pH 8.0, and the Km value for indole-3-acetaldehyde was 1.4 × 10⁻³ M . The enzyme was inhibited strongly by p -hydroxymercuribenzoate, cyanide and hydroxylamine, suggesting that it contains sulfhydryl group(s) and a metal component such as iron.     

Changes in concentration of endogenous growth inhibitors during growth recovery of dwarf pea seedlings

In order to clarify the role of endogenous growth inhibitors A-2α and A-2β in a dwarf pea plant, red light (emission peak 657 nm) treated, 9-d-old seedlings of dwarf pea (Pisum sativum L. cv. Progress No. 9) were transferred to darkness, and the resulting changes in growth rate and concentrations of A-2α and A-2β were monitored. The growth rate of the epicotyls increased, and the concentration of the inhibitors in the epicotyls decreased, according to sigmoidal time courses. The relationship between the logarithms of the concentration of the inhibitors and the corresponding growth rate was linear. These results suggest that A-2α and A-2β, may play an important role in the growth recovery process of the dwarf pea cultivar after termination of red light irradiation. This revised version was published online in July 2006 with corrections to the Cover Date.     

Purification and characterization of amine oxidase from pea seedlings

A novel, simple, and rapid procedure for the purification of pea seedling amine oxidase is reported. The crude enzyme, obtained by ammonium sulfate fractionation, was purified in two steps: the first one by anion-exchange chromatography and the second one by affinity chromatography. The first chromatography step was carried out on a diethylaminoethyl-cellulose column. By lowering the amount of protein loaded on the column and the buffer concentration it was possible to obtain an enzyme pure at 95% (sp act 1.2 microkat/mg). To achieve a higher degree of purification various affinity resins were prepared and tested. The resins were obtained by covalent immobilization of polyamines on Sepharose according to three different procedures. The best results were obtained with 6-aminohexyl-Sepharose 2B, prepared using CNBr as coupling agent, and eluting the enzyme by a solution containing 1, 4-diaminocyclohexane. This last compound was found to be a relatively strong competitive inhibitor of the oxidative deamination of cadaverine catalyzed by pea seedling amine oxidase (Ki = 32 microM). According to this procedure an electrophoretically homogeneous enzyme, characterized by a specific activity of 1.63 microkat/mg, was obtained.     

Inhibitory effects of cis- and trans-resveratrol on noradrenaline and 5-hydroxytryptamine uptake and on monoamine oxidase activity

This study investigated for the first time the potential effects of cis- and trans-resveratrol (c-RESV and t-RESV) on noradrenaline (NA) and 5-hydroxytryptamine (5-HT) uptake by synaptosomes from rat brain, on 5-HT uptake by human platelets, and on monoamine oxidase (MAO) isoform activity. Both c-RESV and t-RESV (5-200 microM) concentration-dependently inhibited the uptake of [3H]NA and [3H]5-HT by synaptosomes from rat brain and the uptake of [3H]5-HT by human platelets. In both experimental models, t-RESV was slightly more efficient than c-RESV. Furthermore, in synaptosomes from rat brain, the RESV isomers were less selective against [3H]5-HT uptake than the reference drug fluoxetine (0.1-30 microM). On the other hand, both c-RESV and t-RESV (5-200 microM) concentration-dependently inhibited the enzymatic activity of commercial (human recombinant) MAO isoform (MAO-A and MAO-B) activity, c-RESV being slightly less effective than t-RESV. In addition, both RESV isomers were slight but significantly more selective against MAO-A than against MAO-B. Since the principal groups of drugs used in the treatment of depressive disorders are NA/5-HT uptake or MAO inhibitors, under the assumption that the RESV isomers exhibit a similar behaviour in humans in vivo, our results suggest that these natural polyphenols may be of value as structural templates for the design and development of new antidepressant drugs with two important biochemical activities combined in the same chemical structure: NA/5-HT uptake and MAO inhibitory activity.     

Selected furanochalcones as inhibitors of monoamine oxidase

The validity of the chalcone scaffold for the design of inhibitors of monoamine oxidase has previously been illustrated. In a systematic attempt to investigate the effect of heterocyclic substitution on the monoamine oxidase inhibitory properties of this versatile scaffold, a series of furanochalcones were synthesized. The results demonstrate that these furan substituted phenylpropenones exhibited moderate to good inhibitory activities towards MAO-B, but showed weak or no inhibition of the MAO-A enzyme. The most active compound, 2E-3-(5-chlorofuran-2-yl)-1-(3-chlorophenyl)prop-2-en-1-one, exhibited an IC₅₀ value of 0.174 μM for the inhibition of MAO-B and 28.6 μM for the inhibition of MAO-A. Interestingly, contrary to data previously reported for chalcones, these furan substituted derivatives acted as reversible inhibitors, while kinetic analysis revealed a competitive mode of binding.     

Pea leaf weevil herbivory on pea seedlings: effects on growth response and yield

Field experiments were conducted to determine growth and yield responses ofPisum sativum L. to defoliation by adultSitona lineatus (L.). Seedlings grown under conventional (moldboard plowed) and conservation (chisel plowed) tillage treatments were infested for a 1-week period with 0, 1 and 8 weevils per plant at two times: at 75% field emergence and 1 week later. After the early infestation, defoliation for the control, low and high weevil densities was about 0,15 and 50%, respectively, while defoliation after the late infestation was about 0, 10 and 35%. An undercompensatory growth response was observed in one experiment after seedlings were subjected to moderate levels of early defoliation. Exact compensation was observed in two experiments after early infestations of low and highSitona densities.Sitona defoliation reduced the number of pods per plant and pod length in two experiments. However, seed biomass was never significantly reduced. Averaged over all experiments, reduction in seed biomass due to highSitona densities was 10 and 5% for early and late infestations, respectively. Tillage treatments did not affectPisum compensatory growth response, although yield components were sometimes greater in conservation tillage than in conventional tillage, possibly due to slightly greater soil moisture in the conservation tillage plots.     

The therapeutic potential of monoamine oxidase inhibitors

Monoamine oxidase inhibitors were among the first antidepressants to be discovered and have long been used as such. It now seems that many of these agents might have therapeutic value in several common neurodegenerative conditions, independently of their inhibition of monoamine oxidase activity. However, many claims and some counter-claims have been made about the physiological importance of these enzymes and the potential of their inhibitors. We evaluate these arguments in the light of what we know, and still have to learn, of the structure, function and genetics of the monoamine oxidases and the disparate actions of their inhibitors.     

Naphthylisopropylamine and N-benzylamphetamine derivatives as monoamine oxidase inhibitors

A series of naphthylisopropylamine and N-benzyl-4-methylthioamphetamine derivatives were evaluated as monoamine oxidase inhibitors. Their potencies were compared with those of a series of amphetamine derivatives, to test if the increase of electron richness of the aromatic ring and overall size of the molecule might improve their potency as enzyme inhibitors. Molecular dockings were performed to gain insight regarding the binding mode of these inhibitors and rationalize their different potencies. In the case of naphthylisopropylamine derivatives, the increased electron-donating capacity and size of the aromatic moiety resulting from replacement of the phenyl ring of amphetamine derivatives by a naphthalene system resulted in more potent compounds. In the other case, extension of the arylisopropylamine molecule by N-benzylation of the amino group led to a decrease in potency as monoamine oxidase inhibitors.