Preparation of a New Chiral Stationary Phase Based on Macrocyclic Amide Chiral Selector for the Liquid Chromatographic Chiral Separations

A new chiral stationary phase (CSP) based on macrocyclic amide receptor was prepared starting from (1R,2R)‐1,2‐diphenylethylenediamine. The new CSP was successfully applied to the resolution of various N‐(substituted benzoyl)‐α‐amino amides with reasonably good separation factors and resolutions (α = 1.75 ~ 2.97 and R_S = 2.89 ~ 6.82 for 16 analytes). The new CSP was also applied to the resolution of 3‐substituted 1,4‐benzodiazepin‐2‐ones and some diuretic chiral drugs including bendroflumethiazide and methylchlothiazide and metolazone. The resolution results for 3‐substituted 1,4‐benzodiazepin‐2‐ones and some diuretic chiral drugs were also reasonably good. Chirality 28:253–258, 2016. © 2016 Wiley Periodicals, Inc.     

A convenient and validated enantiomer separation of chiral aliphatic amines as nitrobenzoxadiazole derivatives on polysaccharide‐derived chiral stationary phases under simultaneous ultraviolet and fluorescence detection

A convenient method using a fluorogenic agent, 4‐chloro‐7‐nitro‐1,2,3‐benzoxadiazole (NBD‐Cl), was developed for enantiomer separation of chiral aliphatic amines including amino alcohols by normal high‐performance liquid chromatography. The enantiomer separation of chiral aliphatic amines as NBD derivatives was performed on six covalently bonded and four coated‐type polysaccharide‐derived chiral stationary phases (CSPs) under simultaneous ultraviolet (UV) and fluorescence detection (FLD). Among the covalently bonded CSPs, Chiralpak IE showed the best enantiomer separation for most analytes. The other CSPs also showed good enantioselectivity except for Chiralpak IB. On the other hand, Chiralpak AD‐H and Amylose‐1 generally exhibited better enantiomer separation of NBD derivatized chiral amines among the coated CSPs. The developed analytical technique was also applied to determine the optical purity of commercially available (R)‐ and (S)‐leucinol; the impurity was found to be 0.06%. The developed method was validated and proved to be an accurate, precise, sensitive, and selective method suitable for separation of chiral aliphatic amines as NBD derivatives under simultaneous UV and FLD.     

Lead Accumulation Ability of Selected Plants of Noccaea spp.

Several species of the Noccaea genus are known for their hyperaccumulation ability especially in the case of Cd, Ni, and Zn. However, ambiguous observations were previously published concerning their accumulation properties for Pb. The Pb accumulation properties of Noccaea rotundifolia, Noccaea montana, and Noccaea jankae hungarica plants were tested in field and pot experiments in soils differing in the mobile pool of Pb, as well as in soilless hydroponic culture. The Pb content in the dry biomass of plant shoots reached up to 54 mg/kg in field conditions and 84 mg/kg in pots regardless of the bioavailable pool of Pb in the pots. The hydroponic experiment showed a stepwise increase in Pb content in plant biomass with increasing Pb concentration in the solution, but the predominant proportion of plant Pb was retained in the roots. Although the hyperaccumulation ability of some of the Noccaea species is widely discussed in the literature, our results are in agreement with those suggesting no Pb hyperaccumulation potential in these plants.     

Effects of L-cysteine on lead acetate induced neurotoxicity in albino mice

Lead is a toxic heavy metal that adversely affects nervous tissues; it often occurs as an environmental pollutant. We investigated histological changes in the cerebral cortex, hippocampus and cerebellum of adult albino mice following exposure to lead acetate. We also studied the possible ameliorative effect of the chelating agent, L-cysteine, on lead-induced neurotoxicity. We divided albino mice into six groups: 1) vehicle-only control, 2) L-cysteine control, 3 and 4) treated for 7 days with 20 and 40 mg/kg lead acetate, respectively, and 5 and 6) treated for 7 days with 20 and 40 mg/kg lead acetate, respectively, followed by 50 mg/kg L-cysteine for 7 days. Lead acetate administration caused disorganization of cell layers, neuronal loss and degeneration, and neuropil vacuolization. Brain sections from lead-intoxicated mice treated with L-cysteine showed fewer pathological changes; the neuropil showed less vacuolization and the neurons appeared less damaged. L-cysteine at the dose we used only marginally alleviated lead-induced toxicity.     

Human health risks associated with heavy metals in soil in different areas of San Luis Potosí, México

The aim of this study was to develop a health risk assessment in different areas of San Luis Potosí, México. Four heavy metals (arsenic, mercury, cadmium, and lead) were analyzed in soil from communities assessed. The mean arsenic concentration was significantly higher (p < .05) in the city of San Luis Potosí (51.85 mg/kg) compared to the other assessed areas (5.52–8.43 mg/kg). For cadmium, the mean concentration was significantly higher (p < .05) in Santa Maria Picula (7.46 mg/kg) than in the other areas (3.72–4.15 mg/kg). Regarding mercury levels, a significantly higher (p < .05) mean concentration was found in Mezquitic (1.54 mg/kg) compared to other areas (0.56–0.81 mg/kg). Lastly, when comparing the mean lead concentration in the city of San Luis Potosí (108 mg/kg), it was found to be significantly lower (p < .05) than in other areas (219–227 mg/kg). Subsequently, a probabilistic health risk assessment was performed, ingestion was the major exposure pathway for all four metals. Maximum cumulative hazard index (HI) values showed higher risk in all sampled locations (HIs > 1.0), suggesting that these sites can pose a non-carcinogenic risk to the populations (children) living in those areas. This study highlights the necessity of establishing a biomonitoring program for the surveillance of the child populations living in the assessed locations.     

The influence of cadmium,copper, lead,and zinc on the distribution and evolution of metallophytes in the British Isles

Mine spoils and other soils contaminated with cadmium, copper, lead and zinc show natural colonization by species which have strategies of avoidance or tolerance of metal toxicities. The distribution of plants on such substrata in the British Isles is examined in the light of present knowledge of such strategies. Evolutionary processes mediating the selection of tolerant individuals and ecotypic differentiation of adapted populations on metalliferous soils are considered. Other factors determining which species can and which cannot evolve tolerance include constitutional differences in species sensitivity to toxic metals, and phenotypic (environmentally-induced) tolerances. The importance of constitutional properties and phenotypic responses in providing explanations for plant distribution on metalliferous soils is assessed.     

Comparative metal analyses in amphipod crustaceans

Concentrations of Cu, Zn, Fe and Pb have been measured in amphipods (Crustacea:Amphipoda) from marine, littoral, semi-terrestrial and freshwater habitats in S. W Scotland, including amphipods expected to have high body metal loads. Metal concentrations (y) were affected greatly by body size (x) and could be modelled by the power function (y = a x ^b ), with the smallest amphipods containing the highest concentrations. This finding cautions against the uncritical use of mean metal concentrations in assessments of heavy metal contamination using crustacean monitors. Data were transformed logarithmically for comparison by regression analysis, analysis of variance and analysis of covariance which compensated for the size effect. Essential metal concentrations are compared against theoretical estimates of metabolic requirements. The effects of seasonal changes and the presence of gut contents on metal concentrations have also been considered.     

Effect of Inorganic Lead on Rat Brain Mitochondrial Respiration and Energy Production

Abstract: Toxicologically significant amounts of inorganic lead were added to rat brain mitochondrial preparations that did not contain EDTA or P_i. The binding of the lead to the mitochondria was measured by anodic stripping voltometry. In the presence of lead, the respiratory control ratios decreased, implying a decrease in the degree of dependence of respiration on a phosphate acceptor. Nucleotide contents were also measured, and in the presence of inorganic lead the actual amounts of ATP formed from ADP were found to be significantly decreased as well.     

A comparison of lead and zinc sediment profiles from cores taken by diver and a gravity corer

The zinc and lead concentrations were compared in several pairs of sediment cores obtained with a modified K-B corer and by Scuba diver from Coon Lake, Canada. A slow approach to and penetration of the sediments (ca. 0.1 m s^-1) was employed for both coring devices. The modified K-B corer gave similar lead and zinc profiles to the diver cores. The divers observed that the K-B corer caused no disturbance of the surface sediment layers as it approached and entered the sediments. These results suggest that the K-B corer is suitable for use in lake studies requiring short, undisturbed cores from fine-grained sediments.