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A large single crystal of a compound from the family of coordination polymer [Co(NCS)2(L)2]n chains was synthesized and its magnetic properties are reported. [Co(NCS)2(4-(3-phenylpropyl)pyridine)2]n is ferromagnetic with Tc = 3.39 K. Single-ion ab initio calculations predict an almost Ising-type magnetic anisotropy and the direction of the magnetic easy-axis nearly along the Co–Npy bond of the apical pyridine-based co-ligand. Both predictions are confirmed by single-crystal magnetic measurements. The magnetic relaxation of the single crystal sample significantly differs from the powder sample data, and clearly shows the presence of two separate relaxation processes. The process dominant below 3.2 K demonstrates a single chain magnet (SCM) behaviour, with a crossover between single-wall and two-wall processes, in spite of the fact that the system is ferromagnetically ordered. The faster process that dominates just below Tc is attributed to spin waves. Micromagnetic Monte Carlo simulations of the investigated compound show that the dipolar field cancels for some chains located at the border between 3-dimensional domains. Such chains are responsible for the measured ac signal, and demonstrate the SCM behaviour. The quantitative analysis of the SCM relaxation time is supported by preparing and examining a corresponding diamagnetically diluted compound, [CoxCd1−x(NCS)2(4-(3-phenylpropyl)pyridine)2]n (x = 0.013), which behaves as a field-induced single-ion magnet. The relaxation pathways for single Co(II) spins are determined to be Raman, direct, and quantum tunneling processes, which were included in an improved approach to describe the magnetic relaxation in the Co(II)-based SCM compound.

No previous study assessed the combined effect of olive pruning residues (OLPR) and spent coffee grounds (SCG) on P. ostreatus production and nutritional value. The aim of this study was to determine the capacity of P. ostreatus to degrade lignocellulosic nature of combined OLPR and SCG as well as their resultant nutrient composition. A complete randomized design was adopted with five treatments: S1:100%wheat straw (WS) (control), S2:33%WS+33%SCG+33%OLPR,S3:66%WS+17%SCG+17%OLPR,S4:17%WS+66%SCG+17%OLPR, and S5:17%WS+17%SCG+66%OLPR, and ten replicates per treatment. Substrate’s and mushroom’s composition were analyzed on chemical scale, including fatty acids and heavy metals profiles, following international standards. Only S1, S2, and S3 were productive, with comparable biological yield, economical yield, and biological efficiency. Organic matter loss decreased with increasing proportions of OLPR and SCG. Percentage lignin loss was higher in S1 than in S2 and S3 (53.51, 26.25, and 46.15% respectively). Mushrooms of S3 had some enhanced nutritional attributes compared to control: decrease in fat, increase in protein, increase in monounsaturated fatty acids, and lower zinc accumulation. Lead was less accumulated in S2 than S1 mushrooms. Sodium content of mushroom decreased in S2 and S3. The latter substrates yielded mushrooms with lower polyunsaturated fatty acids (PUFA) and higher saturated fatty acids (SFA) contents. All mushrooms had a valuable PUFA/SFA. This study suggests using OLPR and SCG in low proportions as nutritional supplements to the commercial wheat straw.

Three new nickel phosphonate complexes {[Na2Ni8(L)6]·nSolv}m (L = SAA3− (1), BSAA3− (2), NAA3− (3); Solv = H2O, MeOH; m = ∞ (1, 2), 1 (3)) were synthesized. All three complexes possess a novel octanuclear {Ni8} phosphonate core, which consists of four dinuclear doubly oxygen-bridged units, further interconnected to each other by phosphonate oxygen bridges. The steric features of the ligands influence the aggregation degree. Molecules of 1 and 2 are interconnected by sodium cations into 2D layered and 1D chain extended structures, respectively, while the molecules of 3 with the bulkiest ligand are not bonded with each other. Magnetic properties of the obtained {Ni8} core unit were studied for complex 1 as a representative of this family of compounds and are reported in detail. Magnetic susceptibility at low temperature is indicative of a singlet ground state. The absence of saturation and the magnetization behavior points to zero-field splitting (ZFS). Simulation of the magnetization data revealed an easy-plane magnetic anisotropy with an axial ZFS parameter D = 7.4 cm−1. The magnetic properties of 1 were also studied by broken-symmetry DFT calculations (BS-DFT), which revealed the presence of ferromagnetic exchange interactions within the dinuclear units of the {Ni8} core with a dominant antiferromagnetic interaction between these dinuclear entities. These results are in good agreement with coupling constants derived from the experimental susceptibility and magnetization data.

Five new lanthanide(III) sandwich and half-sandwich complexes with bulky cyclooctatetraenyl ligands have been prepared and fully characterized, including single-crystal X-ray structure determination. Treatment of anhydrous lanthanide(III) chlorides, LnCl3 (Ln = Pr, Tb, Yb), with 2 equiv. of Li2COT'' (COT'' = 1,4-bis(trimethylsilyl)-cyclooctatetraene dianion) followed by crystallization in the presence of coordinating solvent afforded the anionic sandwich complexes [Li(THF)4][Pr(COT″)2] (1), [Li(DME)3][Tb(COT″)2] (2), and [Li(TMEDA)2][Yb(COT″)2] (3). Attempted oxidation of 2 with silver iodide did not afford the neutral terbium(IV) sandwich complex Tb(COT″)2. Instead, the tri(µ-iodido)-bridged dinuclear half-sandwich complex Li(DME)2Tb2(µ-I)3(COT'')2 was isolated in 72% yield. In this complex, a Li(DME)2 fragment is attached to one of the µ-iodido ligands. A closely related binuclear lutetium complex, [Li(DME)3][Lu2(µ-Cl)3(COTbig)2]∙DME (5), was obtained using the "superbulky" COTbig ligand (COTbig = 1,4-bis(triphenylsilyl)cyclooctatetraenyl dianion). In addition to the spectroscopic and structural characterization, the magnetic properties of the paramagnetic terbium(III) derivative 2 have been investigated and further complemented by ab initio computational methods. These results are used to discuss the structural requirement for potential terbium(III) single-ion magnets.

Reaction of Co(NCS)2 with different coligands leads to the formation of three compounds with the general composition [Co(NCS)2(L)2]n (L = aniline (1), morpholine (2), and ethylenethiourea (3)). In ...

Reaction of Co(NCS)2 with 4-bromopyridine leads to the formation of discrete complexes with the composition Co(NCS)2(4-bromopyridine)4·(CH3CN)0.67 (1), Co(NCS)2(4-bromopyridine)2(H2O)2 (2), Co(NCS)2(4-bromopyridine)2(CH3OH)2 (3) and Co(NCS)2(4-bromopyridine)2(CH3CN)2 (4). Upon heating compounds 2 and 4 transform into a crystalline product with the composition Co(NCS)2(4-bromopyridine)2 (5-I) that also can easily be obtained from solution. In this compound, the Co cations are linked by single μ-1,3-bridging thiocyanate anions into layers. Thermal decomposition of 3 leads to a second isomer (5-II), which is thermodynamically metastable and can also be synthesized from solution under kinetic control. In contrast to 5-I, the Co cations are linked by pairs of anionic ligands into linear chains. The magnetic exchange is very weak in 5-I, but much stronger and ferromagnetic along the linear chains in 5-II. AF ordering in 5-II is reached at 3.05 K, and magnetic relaxation is observed at the metamagnetic transition with an Arrhenius barrier of 17.1(3) cm-1. Ab initio computational studies reveal a different type of magnetic anisotropy to be present in the two crystallographically - independent Co centers in 5-II.

The cobalt(II) in [Co(NCS)2(4‐methoxypyridine)2]n are linked by pairs of thiocyanate anions into linear chains. In contrast to a previous structure determination, two crystallographically independent cobalt(II) centers have been found to be present. In the antiferromagnetic state, below the critical temperature (T c=3.94 K) and critical field (H c=290 Oe), slow relaxations of the ferromagnetic chains are observed. They originate mainly from defects in the magnetic structure, which has been elucidated by micromagnetic Monte Carlo simulations and ac measurements using pristine and defect samples. The energy barriers of the relaxations are Δτ1=44.9(5) K and Δτ2=26.0(7) K for long and short spin chains, respectively. The spin excitation energy, measured by using frequency‐domain EPR spectroscopy, is 19.1 cm−1 and shifts 0.1 cm−1 due to the magnetic ordering. Ab initio calculations revealed easy‐axis anisotropy for both CoII centers, and also an exchange anisotropy Jxx/Jzz of 0.21. The XXZ anisotropic Heisenberg model (solved by using the density renormalization matrix group technique) was used to reconcile the specific heat, susceptibility, and EPR data., Slowly relax… The magnetic properties of the linear chain compound [Co(NCS)2(4‐methoxypyridine)2]n have been investigated both experimentally and theoretically. Slow relaxations of the ferromagnetic chains were observed in the antiferromagnetic state and the specific heat, susceptibility, and EPR data obtained have been reconciled by using the XXZ anisotropic Heisenberg model (see figure).

Two new transition metal thiocyanate coordination polymers with the composition [Co(NCS)2(4-vinylpyridine)2]n (1) and [Co(NCS)2(4-benzoylpyridine)2]n (2) were synthesized and their crystal structures were determined. In both compounds the Co cations are octahedrally coordinated by two trans-coordinating 4-vinyl- or 4-benzoylpyridine co-ligands and four μ-1,3-bridging thiocyanato anions and linked into chains by the anionic ligands. While in 1 the N and the S atoms of the thiocyanate anions are also in trans-configuration, in 2 they are in cis-configuration. A detailed magnetic study showed that the intra-chain ferromagnetic coupling is slightly stronger for 2 than for 1, and that the chains in both compounds are weekly antiferromagnetically coupled. Both compounds show a long range magnetic ordering transition at Tc = 3.9 K for 1 and Tc = 3.7 K for 2, which is confirmed by specific heat measurements. They also show a metamagnetic transition at a critical field of 450 Oe (1) and 350 Oe (2), respectively. Below Tc1 and 2 exhibit magnetic relaxations resembling relaxations of single chains. The exchange constants obtained from magnetic and specific heat data are in good accordance with those obtained from constrained DFT calculations carried out on isolated model systems. The ab initio calculations allowed us to find the principal directions of anisotropy.

[Co(NCS)2(py)2]n (py = pyridine) is composed of ferromagnetic chains of Co(ii) cations connected by double NCS bridges. The chains are irregular because of two crystallographically inequivalent Co(ii) cations. The coordination polyhedron of the Co(ii) cations is a distorted octahedron built from two N and two S atoms of four equatorial NCS anions and two apical N atoms of the pyridine ligands. Magnetic and specific heat studies show that the compound undergoes a phase transition at 3.7 K to a ferromagnetic state. The determined magnetic interactions, intrachain (J/kB = 28 K) and interchain (zJ'/kB = 0.5 K), confirm the quasi 1D Ising magnetic character of [Co(NCS)2(py)2]n. Using AC magnetic susceptibility measurements the energy barriers for magnetization reversal of different relaxation processes were determined including those of the individual chains. By means of high field-high frequency ESR study the magnetic excitations were observed and explained in the frame of the Ising model in agreement with the results of the magnetic study. Ab initio calculations confirm the high magnetic anisotropy of the system and allow determination of the direction of the easy-axis. The broken symmetry DFT calculations support the ferromagnetic intrachain interactions. The energetic relations relevant for relaxations are discussed. It is concluded that the magnetic model of [Co(NCS)2(py)2]n is not a pure Ising but the transversal exchange plays a role.

Effects of two coloured plastic films (‘Half Minus Green 248’ and ‘Pale Lavender 136’) 1 with different values of photosynthetically active radiation (‘Half Minus Green 248’: 120 ± 49 μmol m −2 s −1 , ‘Pale Lavender 136’: 83 ± 38 μmol m −2 s −1 ) and light spectra on growth, fresh and dry matter, nutrient solution uptake and secondary metabolites of Perilla frutescens grown in greenhouse were compared to natural light (154 ± 57 μmol m −2 s −1 photosynthetically active radiation). Both films differed in transmission of blue, green and red light, where ‘Pale Lavender 136’ had much lower transmission (62.00% blue, 39.00% green, 71.00% red light) than ‘Half Minus Green 248’ (75.40% blue, 65.25% green, 88.00% red light). ‘Half Minus Green 248’ film had higher red: far-red (660 nm: 730 nm) ratio (0.98) than ‘Pale Lavender 136’ film (0.82), but lower blue: red (400–500 nm: 600–700 nm) ratio (0.83) than ‘Pale Lavender 136’ film (0.92). Fresh matter under the plastic films was not lower than in the control after 3 weeks of cultivation. Compared to control dry matter (15.51%), ‘Pale Lavender 136’ treatment showed no significant difference, while under ‘Half Minus Green 248’ film significantly lower dry matter (13.77%) was recorded. Use of ‘Half Minus Green 248’ film did not have significant influence on nutrient solution uptake, while ‘Pale Lavender 136’ film reduced it by 11.91% comparing to control. Plant height increased significantly by 18.60% under ‘Half Minus Green 248’ film and by 15.61% in ‘Pale Lavender 136’ treatment compared to control which average height was 34 cm. Regarding concentration of secondary metabolites, use of ‘Pale Lavender 136’ film reduced it but not significantly compared to control. Use of ‘Half Minus Green 248’ film resulted in significantly lower concentration of anthocyanins (−81.36%) and polyphenols (−55.74%), as well as in reduced antioxidant activities (−53.63%). The flavonoid concentration did not differ between the treatments. The plant yield and the concentration of secondary metabolites could not be affected positively by the use of these plastic films, but with ‘Pale Lavender 136’ the same yield could be obtained with less nutrient uptake.

Two novel dioxidomolybdenum(VI) complexes [MoO2L′1] (1) and [MoO2L′2] (2) containing the MoO22+ motif with unexpected coordination motifs due to ligand rearrangement through Mo-mediated interligand C–C bond formation are reported. The ligands (H2L′1–2) are tetradentate C–C-coupled O2N2-donor systems formed in situ during synthesis of the complexes by reaction of [MoVIO2(acac)2] with Schiff base ligands of 2-aminophenol with 2-pyridinecarbaldehyde (HL1) and 2-quinolinecarbaldehyde (HL2). To confirm that the ligand rearrangement is assisted by molybdenum, the corresponding vanadium complexes [VO2L1] (3) and [VO2L2] (4) containing original Schiff base ligand (HL1,2) are also reported here. All complexes 1–4 are characterized by several physicochemical techniques and the structural features of 1 and 2 have been solved by X-ray crystallography. The proposed mechanism of molybdenum-mediated interligand C–C bond formation is supported by DFT calculations including the comparisons with the synthesized vanadium analogues. The catalytic potentials of 1–4 for the epoxidation of styrene and cyclohexene have also been explored.

The new tritopic triaminoguanidine-based ligand 1,2,3-tris[(pyridine-2-ylmethylidene)amino]guanidine (H2pytag) was synthesized. The reaction of a mixture of cobalt(II) chloride and cobalt(II) perchlorate with the ligand H2pytag in pyridine solution leads to the formation of the trinuclear cobalt(II) complex [Co3(pytag)(py)6Cl3]ClO4. Three octahedrally coordinated high-spin cobalt(II) ions are linked through the bridging triaminoguanidine backbone of the ligand leading to an almost equilateral triangular arrangement. The magnetic properties of the complex were investigated by magnetic measurements, variable-temperature, variable-field magnetic circular dichroism (MCD) spectroscopy, and density functional theory as well as ab initio calculations. A rather strong antiferromagnetic exchange interaction between the cobalt(II) centers of ca. −12 cm–1 is determined together with a strong local anisotropy. The single-ion anisotropy of all three cobalt(II) centers is found to be easy-plane, which coincides with th...

Reaction of cobalt(II) and nickel(II) thiocyanate with ethylisonicotinate leads to the formation of [M(NCS)2(ethylisonicotinate)2]n with M = Co (2-Co) and M = Ni (2-Ni), which can also be obtained by thermal decomposition of M(NCS)2(ethylisonicotinate)4 (M = Co (1-Co), Ni (1-Ni)). The crystal structure of 2-Ni was determined by single crystal X-ray diffraction. The Ni(II) cations are octahedrally coordinated by two N and two S bonding thiocyanate anions and two ethylisonicotinate ligands and are linked by pairs of anionic ligands into dimers, that are connected into layers by single thiocyanate bridges. The crystal structure of 2-Co was refined by Rietveld analysis and is isostructural to 2-Ni. For both compounds ferromagnetic ordering is observed at 8.7 K (2-Ni) and at 1.72 K (2-Co), which was also confirmed by specific heat measurements. Similar measurements on [Co(NCS)2(4-acetylpyridine)2]n that exhibits the same layer topology also prove magnetic ordering at 1.33 K. Constrained DFT calculations (CDFT) support the ferromagnetic interactions within the layers. The calculated exchange constants in 2-Ni were used to simulate the susceptibility by quantum Monte Carlo method. The single-ion magnetic anisotropy of the metal ions has been investigated by CASSCF/CASPT2 calculations indicating significant differences between 2-Ni and 2-Co.

Four new triphenylamine ligands with different substituents in the para position and their corresponding copper(II) complexes are reported. This study includes their structural, spectroscopic, magnetic, and electrochemical properties. The complexes possess a dinuclear copper(II) paddle‐wheel core, a building unit that is also common in metal‐organic frameworks. Electrochemical measurements demonstrate that the triphenylamine ligands and the corresponding complexes are susceptible to oxidation, resulting in the formation of stable radical cations. The square‐wave voltammograms observed for the complexes are similar to those of the ligands, except for a slight shift in potential. Square‐wave voltammetry data show that, in the complexes, these oxidations can be described as individual one‐electron processes centered on the coordinated ligands. Spectroelectrochemistry reveals that, during the oxidation of the complexes, no difference can be detected for the spectra of successively oxidized species. For the absorption bands of the oxidized species of the ligands and complexes, only a slight shift is observed. ESR spectra for the chemically oxidized complexes indicate ligand‐centered radicals. The copper ions of the paddle‐wheel core are strongly antiferromagnetic coupled. DFT calculations for the fully oxidized complexes indicate a very weak ferromagnetic coupling between the copper ions and the ligand radicals, whereas a very weak antiferromagnetic coupling is found among the ligand radicals.

In the last decade, investigations were carried out to analyze the effects of biostimulators (e.g., humate, lactate, Bacillus amyloliquefaciens ssp. plantarum, formerly Bacillus subtilis) in hydroponic systems especially under stress conditions (nutrient deficiency, temperature, salt, and pH stress) on the growth of different vegetables (tomatoes, cucumbers, water spinach, sweet potatoes) in different substrates. Applications of biostimulators are reported to reduce abiotic stress in plants. The physiological effects of these substances, however, are little investigated so far. For biostimulators as K-humate, LACTOFOL, and FZB24®, there were reports about their beneficial effects. Application of different biostimulating substances in diverse combinations, however, could be even more beneficial to plants’ growth and development than their separate utilization. Effects of humate, lactate, and Bacillus amyloliquefaciens ssp. plantarum FZB24® as single treatment and as mixture on pH and EC values in substrate culture confirmed this assumption. After application of each biostimulator to the roots, the number of marketable cucumbers was enhanced in total and in relation to the nonmarketable fruits. The application in the root zone had a stronger effect than the application on the leaves and should be preferred. This was also visible under stress condition, e.g., under growing conditions with suboptimal pH value and temperature. In previous experiments, we used therefore a bioactive complex containing K-humate, LACTOFOL, and FZB24® and recorded positive effects on plant growth and yield. If biostimulator mixture (humate, lactate, and Bacillus amyloliquefaciens ssp. plantarum) was applied, no plant growth reduction under pH and temperature stress was determined, in comparison to plants without biostimulator treatments. Results show that there is strong correlation between green biomass of treated plants and their root mass. It can be assumed that the effect of stress reduction by use of this biostimulator mixture is based mainly due to enhancing the root growth.

Vascular oxidative stress brought about by superoxide radicals and oxidized low-density lipoproteins (oxLDL) is a major factor contributing to decreased NO-dependent vasodilator function in hypercholesterolemia and atherosclerosis. We investigated whether chronic administration of L-arginine (2% in drinking water) or of alpha-tocopherol (300 mg/day) improves endothelium-dependent vasodilator function and systemic NO production, reduces vascular oxidative stress, and reduces the progression of atherosclerosis in cholesterol-fed rabbits with pre-existing hypercholesterolemia. Systemic NO production was assessed as urinary nitrate excretion; oxidative stress was measured by urinary 8-iso-PGF2alpha excretion in vivo, by lucigenin-enhanced chemiluminescence of isolated aortic rings ex vivo, and by copper-mediated LDL oxidation in vitro. Endothelium-dependent relaxation was almost completely abrogated in cholesterol-fed rabbits. Urinary nitrate excretion was reduced by 46+/-10%, and 8-iso-PGF2alpha excretion was increased by 61+/-18% as compared to controls (each P0.05). Vascular superoxide radical release stimulated by PMA ex vivo was increased by 273+/-93% in this group, and the lag time of LDL oxidation was reduced by 35+/-6% (each P0.05). Treatment with L-arginine and alpha-tocopherol reduced intimal lesion formation (by 68+/-6 and 4+/-11%, respectively; P0.05) and improved endothelium-dependent relaxation. Both treatments also normalized urinary 8-iso-PGF2alpha excretion. L-Arginine increased urinary nitrate excretion by 43+/-13% (P0.05) and reduced superoxide radical release by isolated aortic rings to control levels, which was unaffected by vitamin E treatment. By contrast, vitamin E dramatically increased the resistance of isolated LDL to copper-mediated oxidation in vitro by 178+/-7% (P0.05), which was only marginally prolonged by L-arginine. Intimal thickening was reduced by both treatments. We conclude that both L-arginine and alpha-tocopherol reduce the progression of atherosclerotic plaques in cholesterol-fed rabbits. However, while L-arginine increases NO formation and reduces superoxide release, alpha-tocopherol antagonizes mainly oxLDL-related events in atherogenesis. Thus, both treatments reduce urinary isoprostane excretion and improve endothelium-dependent vasodilation via different mechanisms.

The endothelium regulates vascular function by releasing the vasodilator autacoid nitric oxide (NO) and the vasoconstrictor peptide endothelin-1 (ET-1). Impaired activity of NO as well as excessive activity of ET-1 have been demonstrated in hypercholesterolemia and atherosclerosis. Because dietary L-arginine can restore NO function and improve abnormal endothelium-dependent relaxation in hypercholesterolemic rabbits, we examined the effects of dietary supplementation with L-arginine in cholesterol-fed rabbits on endothelium-dependent vascular relaxation and ET-1-induced vascular contraction, as well as the systemic synthesis of ET-1. Rabbits were initially fed a diet enriched with 1% cholesterol for 4 weeks, followed by 0.5% cholesterol alone or supplemented with 2% L-arginine in drinking water during the next 12 weeks. Cholesterol feeding impaired endothelium-dependent relaxation of rabbit aortic rings ex vivo and increased urinary immunoreactive ET-1 excretion, along with decreased urinary nitrate excretion, an index of NO production. L-Arginine partially restored endothelium-dependent relaxation in parallel to increased urinary nitrate excretion and decreased urinary immunoreactive ET-1 excretion. Selective inhibition of ET-A receptors with BQ123 partially restored endothelium-dependent relaxation in hypercholesterolemic rabbits but had no effect on arterial rings from rabbits supplemented with L-arginine or from control animals. The contractile vascular response of aortic rings to exogenous ET-1 was increased in rabbits fed a high-cholesterol diet; this enhanced contractility to ET-1 was completely reversed by L-arginine. These data suggest that L-arginine restores endothelial function and normalizes the synthesis and vasoconstrictor response to ET-1 in hypercholesterolemia.

Objectives : l-arginine exerts anti-atherosclerotic effects in hypercholesterolaemic rabbits via modulating endogenous NO production. We investigated whether l-arginine inhibits thromboxane formation in vivo and platelet aggregation ex vivo in this animal model. Methods : The urinary excretion rates of 2,3-dinor-6-keto-PGF1α (major urinary metabolite of PGI2) and 2,3-dinor-TXB2 (major urinary metabolite of thromboxane A2) were used as indicators of platelet–endothelial cell interactions in vivo. Rabbits were fed 1% cholesterol (Cholesterol group, N =8), 1% cholesterol plus 2,25% l-arginine (Cholesterol+l-arginine, N =8), or normal rabbit chow (Control, N =4) for 12 weeks. Urine samples were collected in weekly intervals. At the end of the study period platelet aggregation ex vivo and endothelium-dependent and -independent vascular function of isolated aortic rings in vitro was assessed. Results : Urinary 2,3-dinor-TXB2 excretion significantly increased in the cholesterol group ( p

Background We investigated whether l -arginine induces regression of preexisting atheromatous lesions and reversal of endothelial dysfunction in hypercholesterolemic rabbits, whether similar effects can be obtained by cholesterol-lowering therapy with lovastatin, and which mechanism leads to these effects. Methods and Results Rabbits were fed 1% cholesterol for 4 weeks and 0.5% cholesterol for an additional 12 weeks. Two groups of cholesterol-fed rabbits were treated with l -arginine (2.0% in drinking water) or lovastatin (10 mg/d) during weeks 5 through 16. Systemic nitric oxide (NO) formation was assessed as the urinary excretion rates of nitrate and cGMP in weekly intervals. Cholesterol feeding progressively reduced urinary nitrate excretion to ≈40% of baseline ( P l -arginine reversed the reduction in plasma l -arginine/ADMA ratio and partly restored urinary excretion of nitrate and cGMP (each P l -Arginine completely blocked the progression of carotid intimal plaques, reduced aortic intimal thickening, and preserved endothelium-dependent vasodilator function. Lovastatin treatment reduced plasma cholesterol by 32% but did not improve urinary nitrate or cGMP excretion or endothelium-dependent vasodilation. Lovastatin had a weaker inhibitory effect on carotid plaque formation and aortic intimal thickening than l -arginine. l -Arginine inhibited but lovastatin potentiated superoxide radical generation in the atherosclerotic vascular wall. Conclusions Dietary l -arginine improves NO-dependent vasodilator function in cholesterol-fed rabbits and completely blocks the progression of plaques via restoration of NO synthase substrate availability and reduction of vascular oxidative stress. Lovastatin treatment has a weaker inhibitory effect on the progression of atherosclerosis and no effect on vascular NO elaboration, which may be due to its stimulatory effect on vascular superoxide radical generation.

The sugar-modified Schiff-base ligands derived from benzyl 2-deoxy-2-salicylideneamino-α-D-glucopyranoside (H2L(5-Br) and H2L(3-OMe)) were used to prepare the chiral oxidovanadium(V) complexes [VO(L(5-Br))(OMe)] (1) and [VO(L(3-OMe))(OMe)] (2) which can be isolated from a methanol solution as the six-coordinate complexes with an additional methanol ligand [VO(L(5-Br))(OMe)(MeOH)] (1-MeOH) and [VO(L(3-OMe))(OMe) (MeOH)] (2-MeOH). Both complexes crystallize in the orthorhombic space group P2(1)2(1)2(1) together with two solvent molecules of methanol as 1-MeOH·2MeOH and 1-MeOH·2MeOH. In both crystal structures, only diastereomers with A configuration at the chiral vanadium centre (OC-6-24-A) are observed which corresponds to an cis configuration of the oxido group at the vanadium centre and the benzyl group at the anomeric carbon of the sugar backbone. Upon recrystallization of 2-MeOH from chloroform, the five-coordinate complex 2 was obtained which crystallizes in the monoclinic space group P2(1) with one co-crystallized chloroform molecule (2·CHCl3). For the chiral vanadium centre in 2·CHCl3, a C configuration (SPY-5-43-C) is observed which corresponds to an trans structure as far as the orientations of the oxido and benzyl groups are concerned. (1)H and (51)V NMR spectra of 1 and 2 indicate the presence of two diastereomers in solution. Their absolute configurations can be assigned based on the magnetic anisotropy effect of the oxidovanadium group. This effect leads to significant differences for the (1)H NMR chemical shifts of the H-2 (1.1 ppm) and H-3 protons (0.3 ppm) of the glucose backbone of the two diastereomers, with the downfield shift observed for the H-2 proton of the C-configured and the H-3 proton of the A-configured diastereomer at the vanadium centre. For 1 and 2 the difference between the (51)V NMR chemical shifts of the two diastereomers is 30 and 28 ppm, respectively. Also in the (13)C NMR significant chemical shift differences between the two diastereomers are observed for the carbon atoms C2 (2 ppm) and C3 (4 ppm). DFT calculations of the NMR chemical shift parameters have been performed which are in good agreement with the experimental data. Moreover, the isomerization mechanism between the diastereomers is analysed on the basis of DFT calculations which indicate the required presence of methanol molecules as protic donors.