An entry from the Cambridge Structural Database, the world’s repository for small molecule crystal structures. The entry contains experimental data from a crystal diffraction study. The deposited dataset for this entry is freely available from the CCDC and typically includes 3D coordinates, cell parameters, space group, experimental conditions and quality measures.
Hemlock woolly adelgid (Adelges tsugae [Annand]), an invasive insect in the eastern United States, has caused widespread decline of eastern hemlock, Tsuga canadensis (L.) Carriére. Imidacloprid basal drench treatments were assessed 4-7 yr after a single treatment to determine hemlock woolly adelgid population suppression and effects on hemlock canopy health. The effects of sampling site, years post-treatment, and hemlock diameter at breast height (DBH) size classes were evaluated relative to imidacloprid treatment on hemlock woolly adelgid populations and hemlock canopy health characteristics. The influence of hemlock woolly adelgid populations on canopy health characteristics was also assessed. Imidacloprid treatments resulted in low-level hemlock woolly adelgid populations 7 yr post-treatment. Hemlock woolly adelgid was present on more hemlocks 7 yr compared with 4-6 yr post-treatment. Smaller hemlocks, dosed with 0.7 g active ingredient (AI)/2.5 cm DBH, had higher populations of hemlock woolly adelgid than the largest size class, which were treated at twice that dosage. Concentrations of imidacloprid and its olefin metabolite below the LC50 were sufficient for suppression of hemlock woolly adelgid populations, which suggests an additive effect of imidacloprid and olefin that compounds hemlock woolly adelgid mortality over many generations. Hemlock woolly adelgid populations observed in this study were too low to have an observable effect on hemlock canopy health, indicating that application intervals of up to 7 yr may be adequate to protect hemlocks.
The <sup>13</sup>C substituent chemical shifts C-2, C-4 and C-5 (with a particular focus at C-2) for disubstituted 2,3-diphenylthiazolidin-4-ones with one substituent in each phenyl ring are systematically being investigated. The substituents in question are <em>p</em>-NO<sub>2</sub>, <em>m</em>-NO<sub>2</sub>, <em>p</em>-F, <em>m</em>-F, <em>p</em>-Cl, <em>m</em>-Cl, <em>p</em>-Br, <em>m</em>-Br, H, <em>p</em>-CH<sub>3</sub>, <em>m</em>-CH<sub>3</sub>, <em>p</em>-OCH<sub>3</sub> and <em>m</em>-OCH<sub>3</sub>. This combination of substituents leads to a 13 x 13 matrix array of compounds with the fixed substituents in the 2-phenyl ring constituting the columns and the fixed substituents in the 3-phenyl rings constituting the rows. Including this present study, 81 of the total 169 compounds in the matrix have been analyzed. A single <em>para</em>-methoxy group interacting with another fixed substituent, as measured by <sup>13</sup>C substituent chemical shift values at C-2 in either the C-2 phenyl or N-3 phenyl rings, shows little deviation. This changes however when the moiety is either an alkyl group at N-3 or when a <em>para</em>-methoxy group is the fixed substituent on the N-3 phenyl ring. This present study shows that a <em>para</em>-methoxy group on a C-2 phenyl ring shows a similar deviation in the efficacy in the transmission of electronic effects witnessed in this set of matrix compounds and mimics the issues seen with a previously studied <em>para</em>-methoxy substituted system with the <em>para</em>-methoxy group on the N-3 phenyl ring. Reasons for these aberrations are discussed.
Plant tissue bioassays are a standard approach for bioassaying insects such as the sweetpotato whitefly, Bemisia tabaci (Gennadius) (Hemiptera: Aleyrodidae), an insect that specializes in systemic feeding on the phloem in leaves by using a piercing-sucking mouthpart apparatus. Systemic insecticides remain the most effective approach to whitefly management; however, little work has been done to quantify the amount of insecticide active ingredient that a species is exposed to when feeding. This study was conducted to estimate the imidacloprid and cyantraniliprole concentrations present in cotton (Gossypium hirsutum L.) leaves 24 h after a root drench for systemic toxicological bioassays. Insecticide active-ingredient quantification involved liquid chromatography–tandem mass spectrometry. Comparable concentration responses also were conducted to indicate the mortality of the sweetpotato whitefly at the tested concentrations. The results indicated significant active-ingredient retention with higher concentrations of insecticide treatments, which corresponded with higher sweetpotato whitefly mortality. Specifically, for imidacloprid and cyantraniliprole, the average slopes and intercepts of the log parts per billion of leaf tissue concentration to milligrams of active ingredient per liter of treatment solution were y = 4.08 x + 0.83 and y = 6.22 x + 0.47, respectively. These formulae estimate leaf tissue concentrations that can be linked to insect insecticide exposure in the leaves, with 50–73% of the overall variability explained. Significant correlations also were observed between the root drench concentrations, leaf tissue concentrations, and sweetpotato whitefly mortality.
Atomic emission spectroscopy is an important instrumental technique for both quantitative and qualitative analysis of metallic and non-metallic elements in inorganic and organic materials. In this ...
Quantifying sulforaphane (SFN) and its thiol metabolites in biological samples using liquid chromatography–tandem mass spectrometry is complicated by SFN's electrophilic nature and the facile dissociation of SFN-thiol conjugates. SFN can be lost during sample preparation due to conjugation with protein thiols, which are precipitated and discarded. We observe that only 32 ± 3% of SFN is recovered 2 h after spiking into fetal bovine serum. The SFN-glutathione conjugate prepared at 10 mM in 0.1% formic acid in water (pH 3) dissociated by approximately 95% to free SFN, highlighting the difficulty in preparing thiol metabolite standards. We used the alkylating agent iodoacetamide (IAA) to both release SFN from protein thiols and force the dissociation of SFN metabolites. This thiol-blocking method increased SFN percent recovery from serum from 32 to 94 ± 5%, with a 4.7 nM method limit of quantitation. Applying the method to clinical samples, SFN concentrations were on average 6 times greater than when IAA was omitted. The IAA thiol-blocking method streamlines the analysis of bioavailable SFN in plasma samples.
