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Marine natural products (MNPs) continue to be tested primarily in cellular toxicity assays, both mammalian and microbial, despite most being inactive at concentrations relevant to drug discovery. These MNPs become missed opportunities and represent a wasteful use of precious bioresources. The use of cheminformatics aligned with published bioactivity data can provide insights to direct the choice of bioassays for the evaluation of new MNPs. Cheminformatics analysis of MNPs found in MarinLit ( n = 39,730) up to the end of 2023 highlighted indol-3-yl-glyoxylamides (IGAs, n = 24) as a group of MNPs with no reported bioactivities. However, a recent review of synthetic IGAs highlighted these scaffolds as privileged structures with several compounds under clinical evaluation. Herein, we report the synthesis of a library of 32 MNP-inspired brominated IGAs ( 25 - 56 ) using a simple one-pot, multistep method affording access to these diverse chemical scaffolds. Directed by a meta-analysis of the biological activities reported for marine indole alkaloids (MIAs) and synthetic IGAs, the brominated IGAs 25 - 56 were examined for their potential bioactivities against the Parkinson's Disease amyloid protein alpha synuclein (α-syn), antiplasmodial activities against chloroquine-resistant (3D7) and sensitive (Dd2) parasite strains of Plasmodium falciparum , and inhibition of mammalian (chymotrypsin and elastase) and viral (SARS-CoV-2 3CL pro ) proteases. All of the synthetic IGAs tested exhibited binding affinity to the amyloid protein α-syn, while some showed inhibitory activities against P. falciparum , and the proteases, SARS-CoV-2 3CL pro , and chymotrypsin. The cellular safety of the IGAs was examined against cancerous and non-cancerous human cell lines, with all of the compounds tested inactive, thereby validating cheminformatics and meta-analyses results. The findings presented herein expand our knowledge of marine IGA bioactive chemical space and advocate expanding the scope of biological assays routinely used to investigate NP bioactivities, specifically those more suitable for non-toxic compounds. By integrating cheminformatics tools and functional assays into NP biological testing workflows, we can aim to enhance the potential of NPs and their scaffolds for future drug discovery and development.

Our ongoing exploration of Australian rainforest plants for the biodiscovery of anti-inflammatory agents led to the isolation and structural elucidation of eight new arylalkenyl α,β-unsaturated-δ-lactones, triplinones A-H ( 1-8 ), from the leaves of the Australian rainforest plant Cryptocarya triplinervis B. Hyland (Lauraceae). The chemical structures of these compounds were established by NMR spectroscopic data analysis, while their relative and absolute configurations were established using a combination of Mosher ester analysis utilizing both Riguera's and Kishi's methods, ECD experiments, and X-ray crystallography analysis. Compounds 1-8 exhibited good inhibitory activities toward nitric oxide (NO) production in lipopolysaccharide (LPS) and interferon (IFN)-γ induced RAW 264.7 macrophages, in particular compounds 1-3 and 5 , with IC 50 values of 7.3 ± 0.5, 6.0 ± 0.3, 5.6 ± 0.3, and 5.4 ± 2.5 μM, respectively.

Synthetic efforts toward complex natural product (NP) scaffolds are useful ones, particularly those aimed at expanding their bioactive chemical space. Here, we utilised an orthogonal cheminformatics-based approach to predict the potential biological activities for a series of synthetic bis-indole alkaloids inspired by elusive sponge-derived NPs, echinosulfone A ( 1 ) and echinosulfonic acids A-D ( 2 - 5 ). Our work includes the first synthesis of desulfato-echinosulfonic acid C, an α-hydroxy bis(3'-indolyl) alkaloid ( 17 ), and its full NMR characterisation. This synthesis provides corroborating evidence for the structure revision of echinosulfonic acids A-C. Additionally, we demonstrate a robust synthetic strategy toward a diverse range of α-methine bis(3'-indolyl) acids and acetates ( 11 - 16 ) without the need for silica-based purification in either one or two steps. By integrating our synthetic library of bis-indoles with bioactivity data for 2048 marine indole alkaloids (reported up to the end of 2021), we analyzed their overlap with marine natural product chemical diversity. Notably, the C-6 dibrominated α-hydroxy bis(3'-indolyl) and α-methine bis(3'-indolyl) analogues ( 11 , 14 , and 17 ) were found to contain significant overlap with antibacterial C-6 dibrominated marine bis-indoles, guiding our biological evaluation. Validating the results of our cheminformatics analyses, the dibrominated α-methine bis(3'-indolyl) alkaloids ( 11 , 12 , 14 , and 15 ) were found to exhibit antibacterial activities against methicillin-sensitive and -resistant Staphylococcus aureus . Further, while investigating other synthetic approaches toward bis-indole alkaloids, 16 incorrectly assigned synthetic α-hydroxy bis(3'-indolyl) alkaloids were identified. After careful analysis of their reported NMR data, and comparison with those obtained for the synthetic bis-indoles reported herein, all of the structures have been revised to α-methine bis(3'-indolyl) alkaloids.

Production of phytocannabinoids remains an area of active scientific interest due to the growing use of cannabis by the public and the underexplored therapeutic potential of the over 100 minor cannabinoids. While phytocannabinoids are biosynthesized by Cannabis sativa and other select plants and fungi, structural analogs and stereoisomers can only be accessed synthetically or through heterologous expression. To date, the bioproduction of cannabinoids has required eukaryotic hosts like yeast since key, native oxidative cyclization enzymes do not express well in bacterial hosts. Here, we report that two marine bacterial flavoenzymes, Clz9 and Tcz9, perform oxidative cyclization reactions on phytocannabinoid precursors to efficiently generate cannabichromene scaffolds. Furthermore, Clz9 and Tcz9 express robustly in bacteria and display significant tolerance to organic solvent and high substrate loading, thereby enabling fermentative production of cannabichromenic acid in Escherichia coli and indicating their potential for biocatalyst development.

NMR fingerprints are valuable tools for analyzing complex natural product mixtures and identifying incorrectly assigned structures in the literature. Our diagnostic NMR fingerprints for formyl phloroglucinol meroterpenoids revealed discrepancies in the structures reported for eucalyprobusal C ( 1a ) and eucalypcamal K ( 2a ). NMR fingerprinting PCA analyses identified 1a as an oxepine-diformyl phloroglucinol and 2a as an oxepine 3-acyl-1-formyl phloroglucinol, contrary to their initial assignments as pyrano-diformyl and pyrano 3-acyl-1-formyl phloroglucinols, respectively. Extensive reinterpretation of their reported one- and two-dimensional NMR data, coupled with GIAO DFT-calculated 1 H and 13 C NMR chemical shift and DP4+ analyses, supported the unequivocal reassignment of eucalyprobusal C to 1b and eucalypcamal K to 2b . The absolute configurations of the revised oxepine-containing phloroglucinol meroterpenoids were confirmed via the reinterpretation of their reported ROESY and NOESY NMR data, along with comparative TDDFT-calculated and experimental ECD spectra.

Catecholamines (CAs) are aromatic amines containing a 3,4-dihydroxyphenyl nucleus and an amine side chain. Representative CAs included the endogenous neurotransmitters epinephrine, norepinephrine, and dopamine. CAs and their derivatives are good resources for the development of sympathomimetic or central nervous system drugs, while they also provide ligands important for G-protein coupled receptor (GPCR) research. CAs are of broad interest in the fields of chemical, biological, medical, and material sciences due to their high adhesive capacities, chemical reactivities, metal-chelating abilities, redox activities, excellent biocompatibilities, and ease of degradability. Herein, we summarize CAs derivatives isolated and identified from microorganisms, plants, insects, and marine invertebrates in recent decades, alongside their wide range of reported biological activities. The aim of this review is to provide an overview of the structural and biological diversities of CAs, the regularity of their natural occurrences, and insights toward future research and development pertinent to this important class of naturally occurring compounds.

Covering: marine indole alkaloids ( n = 2048) and their reported bioactivities up to the end of 2021Despite increasing numbers of marine natural products (MNPs) reported each year, most have only been examined for cytotoxic, antibacterial, and/or antifungal biological activities with the majority found to be inactive in these assays. In this context, why are natural products continuing to be examined in assays they are unlikely to show significant activity in, and what targets might be more useful for expanding knowledge of their biologically relevant chemical space? We have undertaken a meta-analysis of the biological activities for 2048 marine indole alkaloids (MIAs), a diverse sub-class of MNPs reported up to the end of 2021, and this has highlighted that the bioactivity potentials for up to 86% of published MIAs remains underexplored and/or undefined. Although most published MIAs are not cytotoxic or antimicrobial, there is a continued focus on using these assays to evaluate new structurally related analogues. Using cheminformatics analyses, the chemical diversity of the 2048 MIAs were clustered using fragment based fingerprints and their reported bioactivity potency towards specific disease targets was assessed for structure activity trends. These analyses showed that there are groups of MIAs that possess potent and diverse activities and that many analogues, previously tested only in cellular toxicity assays, could be better exploited to generate structure activity relationships associated with leads to treat emerging diseases. A collection of indole drug and drug-lead structures from non-natural sources were also incorporated into the dataset providing complementary bioactivity profiles that were further used to predict underexplored areas of potential new activity and to better direct future testing of MIAs. Our findings clearly suggest the biological evaluation of MIAs continues to be conducted on a narrow range of bioassays and disease targets, and that shifting the focus to non-toxic disease targets should provide expanded knowledge of biologically relevant chemical space aimed at maximising the potential of MIAs for drug discovery.

Background: To examine counselors' perceptions of their formal preparation for engaging in telemental health (TMH) counseling with the intent of gaining an understanding of their lived experiences., Materials and Methods: Semistructured interviews were conducted with seven seasoned counselors who regularly engage in technology-mediated distance counseling., Results: The results highlighted themes within two emerging categories: the counselor and training/education. Themes related to motivation and specific counselor attributes emerged from the first category and themes of availability, inadequacy, and modality emerged from the second category., Discussion: The implications from this study suggest a lack of availability and standardization of effective training on TMH delivery., Conclusion: This study identifies areas of potential future research related to counselors' preparation experiences as well specific areas of need for TMH training in counseling graduate programs and other natural opportunities., Competing Interests: No competing financial or personal financial interests exists for any of the authors. A large portion of this article was previously submitted for the primary author's dissertation.20, (© Daniel C. Holland et al., 2023; Published by Mary Ann Liebert, Inc.)

Six new thiazole-containing cyclic peptides, the cyclotheonellazoles D-I ( 1 - 6 ), were isolated from the Australian marine sponge Theonella sp. (2131) with their structures assigned by comprehensive 1D and 2D NMR spectroscopic and MS spectrometric analyses, Marfey's derivatization studies, and comparison with time-dependent density functional theory (TDDFT) calculated ECD data. The Type 2 azole-homologated peptides herein comprise up to five nonproteinogenic amino acids, including the protease transition state mimic α-keto-β-amino acid residue 3-amino-4-methyl-2-oxohexanoic acid (Amoha), while 1 - 3 also contain a terminal hydantoin residue not previously found in cyclotheonellazoles. The keramamides A ( 7 ) and L ( 8 ) were reisolated affording expanded exploration of their biological activities. The peptides were examined for protease inhibitory activities against two mammalian serine proteases (elastase and chymotrypsin) and SARS-CoV-2 3-chymotrypsin-like protease (3CL pro ), a validated antiviral therapeutic target for COVID-19. Peptides 1 - 6 and keramamide A ( 7 ) displayed potent nanomolar inhibition of elastase (IC 50 16.0 to 61.8 nM), while 7 also contained modest inhibition of chymotrypsin and SARS-CoV-2 3CL pro (IC 50 0.73 and 1.1 μM, respectively). The cyclotheonellazoles D-E ( 1 - 3 ) do not affect the viability of human breast, ovarian, and colon cancer cells (>100 μM), with the cytotoxicity previously reported for keramamide L ( 8 ) not replicated (inactive >20 μM).

Amyloid protein aggregates are linked to the progression of neurodegenerative conditions and may play a role in life stages of Plasmodium falciparum , the parasite responsible for malaria. We hypothesize that amyloid protein aggregation inhibitors may show antiplasmodial activity and vice versa. To test this hypothesis, we screened antiplasmodial active extracts from 25 Australian eucalypt flowers using a binding affinity mass spectrometry assay to identify molecules that bind to the Parkinson's disease-implicated protein α-syn. Myrtucommulone P ( 1 ) from a flower extract of Eucalyptus cloeziana was shown to have α-syn affinity and antiplasmodial activity and to inhibit α-syn aggregation. 1 exists as a mixture of four interconverting rotamers. Assignment of the NMR resonances of all four rotamers allowed us to define the relative configuration, conformations, and ratios of rotamers in solution. Four additional new compounds, cloeziones A-C ( 2 - 4 ) and cloeperoxide ( 5 ), along with three known compounds were also isolated from E. cloeziana . The structures of all compounds were elucidated using HRMS and NMR analysis, and the absolute configurations for 2 - 4 were determined by comparison of TDDFT-calculated and experimental ECD data. Compounds 1 - 3 displayed antiplasmodial activities between IC 50 6.6 and 16 μM. The α-syn inhibitory and antiplasmodial activity of myrtucommulone P ( 1 ) supports the hypothesized link between antiamyloidogenic and antiplasmodial activity.

Three new bis-formyl phloroglucinol-meroterpenoids ( 1 - 3 ), three new euglobal type formyl phloroglucinol-meroterpenoids ( 4 - 6 ), and one new dimeric formyl phloroglucinol ( 7 ) were isolated from the leaves of Eucalyptus camaldulensis . Camaldulensal A ( 1 ) is the first bis-isovaleryl-formyl-phloroglucinol-sesquiterpenoid. It features a novel 6/6/10/3/6/6 fused ring system and contains six stereogenic centers. Camaldulensals B ( 2 ) and C ( 3 ) are the first bis-isovaleryl-formyl-phloroglucinols, each conjugated to a monoterpene. Formyl phloroglucinol compounds (FPCs) containing two spatially separated formyl phloroglucinols conjugated to a terpene core such as 1 - 3 have not been reported previously. The structures of these compounds were elucidated by spectroscopic methods and computational analysis. Camaldulensals B ( 2 ) and C ( 3 ) exhibited significant antibacterial activity against methicillin-susceptible and methicillin-resistant Staphylococcus aureus . Structure activity relationships are discussed in relation to previously reported antibacterial activities of other molecules from the FPC structure class.

NMR fingerprints provide powerful tools to identify natural products in complex mixtures. Principal component analysis and machine learning using 1 H and 13 C NMR data, alongside structural information from 180 published formyl phloroglucinols, have generated diagnostic NMR fingerprints to categorize subclasses within this group. This resulted in the reassignment of 167 NMR chemical shifts ascribed to 44 compounds. Three pyrano-diformyl phloroglucinols, euglobal In-1 and psiguadiols E and G, contained 1 H and 13 C NMR data inconsistent with their predicted phloroglucinol subclass. Subsequent reinterpretation of their 2D NMR data combined with DFT 13 C NMR chemical shift and ECD calculations led to their structure revisions. Direct covariance processing of HMBC data permitted 1 H resonances for individual compounds in mixtures to be associated, and analysis of their 1 H/ 13 C HMBC correlations using the fingerprint tool further classified components into phloroglucinol subclasses. NMR fingerprinting HMBC data obtained for six eucalypt flower extracts identified three subclasses of pyrano-acyl-formyl phloroglucinols from Eucalyptus gittinsii subsp. gittinsii . New, eucalteretial F and (+)-eucalteretial B, and known, (-)-euglobal VII and eucalrobusone C, compounds, each belonging to predicted subclasses, were isolated and characterized. Staphylococcus aureus and Plasmodium falciparum screening revealed eucalrobusone C as the most potent antiplasmodial formyl phloroglucinol to date.

The aggregation of the neuronal protein α-synuclein (α-syn) is intrinsically linked to the development and progression of Parkinson's disease (PD). Recently we screened the MeOH extracts from 283 marine invertebrates for α-syn binding activity using an affinity mass spectrometry (MS) binding assay and found that the extract of the ascidian Polycarpa procera displayed activity. A subsequent bioassay-guided purification led to the isolation of one new α-syn aggregation inhibitory butenolide procerolide E ( 3 ) and one new α-syn aggregation inhibitory diphenylbutyrate methyl procerolate A ( 5 ). Herein we report the structure elucidation of procerolide E ( 3 ) and methylprocerolate A ( 5 ) and α-syn aggregation inhibitory activity of procerolides C-E ( 1 - 3 ), methyl procerolate A ( 5 ) and procerone A ( 4 ). We also report the α-syn binding activity of 3-bromo-4-methoxyphenylacetamide ( 6 ) and a synthetic butenolide library, which has allowed us to determine α-syn aggregation inhibitory structure-activity relationships for this class of compounds.

A new aryl dihydronaphthalene lignan, echiumin E ( 1 ), and four known compounds, echiumin A, globoidnan A, (-)-rabdosiin, and rosmarinic acid ( 2 - 5 ), were isolated from the Australian invasive plant Echium plantagineum (Paterson's curse) for the first time. Echiumin E ( 1 ) was characterized by 1D/2D NMR spectroscopy and MS spectrometry, with its absolute configuration assigned through comparison of experimental and TDDFT-calculated ECD data. Echiumin E ( 1 ) along with compounds 3 - 5 were screened in vitro against three cancer cell lines (SH-SY5Y, HeLa, and PC-3) and a prostate stromal (normal) cell line (WPMY-1) using a resazurin reduction assay. Echiumin E ( 1 ) was found to be active toward HeLa cells (IC 50 0.21 μM).

Background: Pediatric brain tumor (PBT) survivors are at risk for developing sleep disturbances. While in other pediatric populations sleep disturbance has been associated with worse cognitive functioning, it is unclear to what extent this relationship generalizes to PBT survivors. The aim of the current study was to assess the relationship between sleep disturbance and aspects of cognition, including sluggish cognitive tempo (SCT) as well as attention and working memory., Materials and Methods: Eighty-three PBT survivors 6-18 years of age who were at least 3 months post-treatment were included in the present cross-sectional study. Level of sleep disturbance was measured as a composite score reflecting various sleep problems as rated by caregivers. Cognitive measures included caregiver-ratings of sluggish cognitive tempo and attention problems, as well as performance-based cognitive measures assessing attention and executive functioning. Hierarchical regression analysis was used to assess associations between sleep and cognition., Results: Of all caregivers, 32.5% reported one or more sleep disturbances as "very/often true" and over 68% of caregivers rated at least one sleep-related item as "somewhat true." Of all cognitive variables, scores were most frequently impaired for SCT (30%). A higher level of sleep disturbance was associated with worse SCT and parent-rated attention problems. Associations between sleep and performance-based cognitive measures assessing attention and working memory were not statistically significant., Conclusion: Findings of the current study highlight the importance of further investigation into the relationship between sleep and cognition in PBT survivors, which may assist efforts to maximize cognitive outcome and health-related quality of life in PBT survivors. The current study additionally suggests further investigation of SCT in this population is warranted, as it may be more sensitive to detecting possible associations with sleep disturbance relative to discrete measures that assess cognitive performance under ideal circumstances., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2022 Olsthoorn, Holland, Hawkins, Cornelius, Baig, Yang, Holland, Zaky and Stavinoha.)

Seven new polyaromatic bis-spiroketal-containing butenolides, the prunolides D-I ( 4 - 9 ) and cis -prunolide C ( 10 ), a new dibrominated β-carboline sulfamate named pityriacitrin C ( 11 ), alongside the known prunolides A-C ( 1 - 3 ) were isolated from the Australian colonial ascidian Synoicum prunum . The prunolides D-G ( 4 - 7 ) represent the first asymmetrically brominated prunolides, while cis -prunolide C ( 10 ) is the first reported with a cis -configuration about the prunolide's bis-spiroketal core. The prunolides displayed binding activities with the Parkinson's disease-implicated amyloid protein α-synuclein in a mass spectrometry binding assay, while the prunolides ( 1 - 5 and 10 ) were found to significantly inhibit the aggregation (>89.0%) of α-synuclein in a ThT amyloid dye assay. The prunolides A-C ( 1 - 3 ) were also tested for inhibition of pSyn aggregate formation in a primary embryonic mouse midbrain dopamine neuron model with prunolide B ( 2 ) displaying statistically significant inhibitory activity at 0.5 μM. The antiplasmodial and antibacterial activities of the isolates were also examined with prunolide C ( 3 ) displaying only weak activity against the 3D7 parasite strain of Plasmodium falciparum . Our findings reported herein suggest that the prunolides could provide a novel scaffold for the exploration of future therapeutics aimed at inhibiting amyloid protein aggregation and the treatment of numerous neurodegenerative diseases.

During a research program to identify new cholinesterase inhibitors of natural origin, two new 7,8-didehydroprotoberberine alkaloids ( 1 and 2 ) and nine known compounds ( 3 - 11 ) were isolated from the capsules of the common ornamental poppy, Papaver setiferum (previously P. pseudo-orientale ). Despite their reported instability, the 7,8-didehydroprotoberberines isolated herein appeared relatively stable, particularly as their trifluoroacetic acid salts. The spatial distributions of the isolated alkaloids were also analyzed using desorption electrospray ionization imaging mass spectrometry. The alkaloids were localized predominantly within the walls and vascular bundles of the capsules, with the highest relative abundances occurring in the lower half of the capsules toward the peduncle. The relative abundances of the alkaloids were also compared across plant development stages. Although most alkaloids did not show clear patterns in their concentration across development stages, the concentration of suspected oxidation products clearly spiked upon plant death. Finally, all isolated natural products were screened for inhibitory activities against a panel of cholinesterases, from both human and animal sources. These studies identified several competitive inhibitors of cholinesterases with potency in the low micromolar range ( 1 - 4 , 6 , 7 ), offering new lead compounds for the development of cholinesterase inhibitory drugs.

Diffusion-ordered NMR spectroscopy (DOSY) can be used to analyze mixtures of compounds since resonances deriving from different compounds are distinguished by their diffusion coefficients ( D ). Previously, DOSY has mostly been used for organometallic and polymer analysis, we have now applied DOSY to investigate diffusion coefficients of structurally diverse organic compounds such as natural products (NP). The experimental D s derived from 55 diverse NPs has allowed us to establish a power law relationship between D and molecular weight (MW) and therefore predict MW from experimental D . We have shown that D is also affected by factors such as hydrogen bonding, molar density and molecular shape of the compound and we have generated new models that incorporate experimentally derived variables for these factors so that more accurate predictions of MW can be calculated from experimental D . The recognition that multiple physicochemical properties affect D has allowed us to generate a polynomial equation based on multiple linear regression analysis of eight calculated physicochemical properties from 63 compounds to accurately correlate predicted D with experimental D for any known organic compound. This equation has been used to calculate predicted D for 217 043 compounds present in a publicly available natural product database (DEREP-NP) and to dereplicate known NPs in a mixture based on matching of experimental D and structural features derived from NMR analysis with predicted D and calculated structural features in the database. These models have been validated by the dereplication of a mixture of two known sesquiterpenes obtained from Tasmannia xerophila and the identification of new alkaloids from the bryozoan Amathia lamourouxi . These new methodologies allow the MW of compounds in mixtures to be predicted without the need for MS analysis, the dereplication of known compounds and identification of new compounds based solely on parameters derived by DOSY NMR., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)

Two new fluorescent pteridine alkaloids, tedaniophorbasins A ( 1 ) and B ( 2 ), together with the known alkaloid N -methyltryptamine, were isolated, through application of mass directed purification, from the sponge Tedaniophorbas ceratosis collected from northern New South Wales, Australia. The structures of tedaniophorbasins A and B were deduced from the analysis of 1D/2D NMR and MS data and through application of 13 C NMR DFT calculations. Tedaniophorbasin A possesses a novel 2-imino-1,3-dimethyl-2,3,7,8-tetrahydro-1H-[1,4]thiazino[3,2-g]pteridin-4(6 H )-one skeleton, while tedaniophorbasin B is its 2-oxo derivative. The compounds show significant Stokes shifts (~14,000 cm -1 ) between excitation and emission wavelengths in their fluorescence spectra. The new compounds were tested for bioactivity against chloroquine-sensitive and chloroquine-resistant strains of the malaria parasite Plasmodium falciparum , breast and pancreatic cancer cell lines, and the protozoan parasite Trypanosoma brucei brucei but were inactive against all targets at 40 µM.

Citronamine A ( 1 ), an isoquinoline alkaloid containing an unprecedented pentacyclic ring system, was isolated from the Australian marine sponge Citronia astra . Based on the combination of MS and NMR analyses and comparison of experimental and TDDFT calculated ECD spectra, the absolute structure of 1 was determined. Compound 1 displayed moderate activity against drug sensitive (3D7) and drug resistant (Dd2) strains of the parasite, Plasmodium falciparum , responsible for malaria.

An extract from the bryozoan Amathia lamourouxi with antiplasmodial activity was identified through high-throughput screening of an Australian marine invertebrate extract library against Plasmodium falciparum . Chemical investigation of A. lamourouxi resulted in the isolation of six new brominated alkaloids, convolutamines K and L ( 1 and 2 ), volutamides F-H ( 3 - 5 ), and 2,5-dibromo-1-methyl-1 H -indole-3-carbaldehyde ( 6 ). Three of the compounds ( 2 - 4 ) displayed moderate to potent antiplasmodial activity against both the chloroquine-sensitive (3D7) and chloroquine-resistant (Dd2) parasite strains of Plasmodium falciparum with an IC 50 range of 0.57-1.7 μM and a high selectivity index against a human cell line (HEK293).

The structure of 2,4-(4'-aminobenzenamine)pyrimidine ( 1 ), a pyrimidine alkaloid previously isolated from the bulbs of Scilla madeirensis (Asparagaceae, synonym Autonoë madeirensis ), has been revised. These conclusions were met via comparison of reported NMR and EIMS data with those obtained from synthetic standards. The corrected structure is the antibiotic sulfadiazine ( 2 ), which has likely been isolated as a contaminant from the site of collection. The reported bioactivity of 1 as an α 1 -adrenoceptor antagonist should instead be ascribed to sulfadiazine. Our findings appear to show another example of an anthropogenic contaminant being identified as a natural product and emphasize the importance of considering the biosynthetic origins of isolated compounds within a phylogenetic context.

The structures of the sponge-derived dibrominated bis-indole alkaloids, namely, echinosulfone A ( 2 ) and the echinosulfonic acids A to D ( 9 - 12 ), have been revised based upon reanalysis of their NMR spectroscopic and MS spectrometric data, comparison of this data with those reported for structurally related compounds, and based on their common biogenesis. The reinterpreted spectroscopic evidence has been corroborated by the total synthesis of the revised structure of echinosulfone A ( 2 ). This was achieved by bis-carbonylation at C-3 of the magnesium salt of 6-bromoindole with triphosgene to afford the new dibrominated bis-indole ketone, bis(6-bromo-1 H -indol-3-yl)methanone ( 3 ), followed by N-sulfonation of one indole moiety to furnish 6-bromo-3-(6-bromo-1 H -indole-3-carbonyl)-1 H -indole-1-sulfonate ( 2 ). The five marine alkaloids corrected herein each contain an indole sulfamate and are all carbon-bridged dibrominated bis-indoles: echinosulfone A ( 2 ) is a di(1 H -indol-3-yl)methanone, while the echinosulfonic acids A to D ( 9 - 12 ) are methyl 2,2-bis(1 H -indol-3-yl) acetates.

Background: Diagnosis, prognostication and treatment in chronic kidney disease is often informed by an estimate of the glomerular filtration rate (GFR). Commonly used GFR estimation (eGFR) equations are based on serum creatinine (Cr) concentrations and display suboptimal precision and accuracy. Newer equations incorporating additional endogenous markers such as β-Trace Protein (BTP), β 2 -Microglobulin (B2M) and cystatin C (cysC) have been developed but require validation., Methods: This prospective cohort study evaluated the performance of 6 eGFR equations developed by the chronic kidney disease - epidemiology collaboration group (CKD-EPI) against urinary inulin clearance GFR in patients recruited from outpatient nephrology clinics., Results: Mean biases were negligible and similar between equations. The eGFR-EPI Cr/cysC had the best precision and accuracy of all the equations and the best agreement with inulin mGFR when classifying participants into GFR categories. The BTP and B2M equations displayed the worst precisions and accuracies and showed the least consistent performance across levels of GFR. Thus, the eGFR-EPI Cr/cysC is the least biased, most precise and has the highest accuracy as compared to other eGFR-EPI equations., Conclusions: The BTP and B2M equations are the worst performing of the eGFR-EPI equations, and no benefit is observed with the addition of BTP or B2M to Cr/cysC., (Copyright © 2018 Elsevier B.V. All rights reserved.)

Objective: We sought to measure the prevalence of inadequate glycemic control in prevalent hemodialysis patients with diabetes and to examine independent predictors of inadequate glycemic control in these patients., Research Design and Methods: This is a cross-sectional study of prevalent hemodialysis patients with diabetes in southeastern Ontario (n = 100). Data were collected by chart review and interview. The outcome variable was inadequate glycemic control defined as HbA1c (A1C) >0.07. Other measured variables were diabetes type, diabetes duration, diabetes physician, blood glucose monitoring, diabetes medications, BMI, time on dialysis, and other demographic, clinical, and laboratory variables., Results: Fifty-four patients had A1C >0.07. In bivariate analysis, these patients had a longer diabetes duration (23.6 vs. 14.7 years, P < 0.001), higher proportion with insulin use (81.5 vs. 58.7%, P = 0.012), higher proportion with microvascular complications (66.7 vs. 43.5%, P = 0.017), and lower erythropoietin (EPO) dose (7.0 vs. 11.9 x 10(3) units/week, P < 0.01) than patients with adequate glycemic control. There was no difference between the two groups in terms of macrovascular complications (59.3 vs. 65.2%, P = 0.54). In multiple logistic regression controlling for age and diabetes type, the diabetes duration (odds ratio 1.09 [95% CI 1.04-1.15], P < 0.001), EPO dose (0.90 [0.85-0.97], P < 0.01), and blood glucose monitoring (10.06 [1.03-98.74], P = 0.05) were the only significant independent predictors of A1C >0.07., Conclusions: A high proportion of hemodialysis patients with diabetes had inadequate glycemic control, particularly those with longstanding disease. Patients with inadequate glycemic control had a significantly higher burden of microvascular complications.

Background: Sleep disorders are common in patients with renal failure on dialysis; however, the prevalence of "poor sleep" in patients with chronic kidney disease (CKD) not yet on dialysis is not known. This study aimed to measure the prevalence of "poor sleep" in CKD patients and to examine the association between quality of sleep and the degree of renal impairment in this population., Methods: Quality of sleep was measured using the Pittsburgh Sleep Quality Index (PSQI) in 120 prevalent CKD patients., Results: Sixty-three subjects (53%) had "poor sleep" defined as a global PSQI score >5. There was no statistically significant relationship between the global PSQI score and the blood urea nitrogen level (BUN), serum creatinine level or calculated creatinine clearance, but the sleep efficiency component score correlated with BUN (r = 0.19, P = 0.04) and serum creatinine (r = 0.20, P = 0.03). A history of depression was the only independent predictor of "poor sleep" (global PSQI >5)., Conclusions: "Poor sleep" is common in CKD patients. Quality of sleep decreases in the early stages of CKD and does not appear to be associated with the subsequent degree of renal failure. Large prospective longitudinal studies of quality of sleep in CKD patients are needed to confirm the high prevalence of impaired quality of sleep in this population and examine the association between renal function and quality of sleep while controlling for potential confounding variables.

Background: Although previous research has demonstrated that referral to pre-dialysis clinics is associated with favourable objective outcomes, the benefit of a pre-dialysis clinic from the perspective of patient-perceived subjective outcomes, such as quality of life (QOL), is less well defined., Methods: A retrospective incident cohort study was conducted to determine if pre-dialysis clinic attendance was a predictor of better QOL scores measured within the first six months of hemodialysis (HD) initiation. Inclusion criteria were HD initiation from January 1 1998 to January 1 2000, diagnosis of chronic renal failure, and completion of the QOL questionnaire within six months of HD initiation. Patients receiving HD for less than four weeks were excluded. An incident cohort of 120 dialysis patients was identified, including 74 patients who attended at least one pre-dialysis clinic and 46 patients who did not. QOL was measured using the SF 36-Item Health Survey. Independent variables included age, sex, diabetes, pre-dialysis clinic attendance and length of attendance, history of ischemic heart disease, stroke, peripheral vascular disease, heart failure, malignancy, and chronic lung disease, residual creatinine clearance at dialysis initiation, and kt/v, albumin and hemoglobin at the time of QOL assessment. Bivariate and multivariate linear regression analyses were used to identify predictors of QOL scores., Results: Multivariate analysis suggested that pre-dialysis clinic attendance was an independent predictor of higher QOL scores in four of eight health domains (physical function, p < 0.01; emotional role limitation, p = 0.01; social function, p = 0.01; and general health, p = 0.03), even after statistical adjustment for age, sex, residual renal function, kt/v, albumin, and co-morbid disease. Pre-dialysis clinic attendance was also an independent predictor of the physical component summary score (p = 0.03)., Conclusions: We conclude that pre-dialysis clinic attendance favourably influences patient-perceived quality of life within six months of dialysis initiation.

Objective: Although earlier research has suggested that baseline prealbumin level is an independent predictor of outcome among dialysis patients, the prognostic importance of serial prealbumin levels is less clear. The present study had 3 objectives: first, to determine if prealbumin (a marker of visceral protein stores with a relatively short half-life) predicts subsequent albumin levels taken at least 1 month later; second, to examine the association between serial prealbumin levels and clinical outcome; and third, to examine the association between changes in prealbumin level and outcome., Design: The prognostic value of serial prealbumin levels was examined by linear regression analysis and Cox hazard models in an observational cohort study using a repeated measures design and time-dependent covariates., Setting: Patients were followed by a tertiary care center, receiving hemodialysis (HD; at either an in-center dialysis unit or one of several satellite units operated by the hospital) or home peritoneal dialysis (PD)., Patients: A retrospective cohort was identified consisting of 268 incident and prevalent chronic HD and PD patients receiving dialysis from June 1998 to September 1999., Main Outcome: The study examined the association between serial prealbumin measurements and future laboratory and clinical outcomes (albumin, hospitalization, and death)., Results: Serial prealbumin values were independent predictors of future albumin levels among HD patients (P =.04), but not PD patients. Independent predictors of hospitalization included diabetes for PD patients (P =.0012) and advanced age for HD patients (P =.0008). Advanced age and diabetes were independent predictors of death for both HD (P =.0001 and P =.0368) and PD patients (P =.0014 and P =.0164). Serial prealbumin values, measured as time-dependent covariates, did not predict hospitalization or death. Further analyses examined the prognostic value of changes in prealbumin and albumin values as time-dependent covariates. The final multivariate analysis identified low baseline albumin level as an independent predictor of hospitalization among HD patients (P =.0282), whereas low baseline prealbumin was an independent predictor of death for HD patients (P =.0001). Interestingly, negative changes in serial prealbumin measurements were also independent predictors of death among HD patients (P =.0025)., Conclusion: Serial prealbumin measurements predict subsequent albumin values among HD patients. As well, low baseline prealbumin level is an independent predictor of adverse outcome among HD patients. Although repeated prealbumin measurements in and of themselves were of no added prognostic value, falling prealbumin values identified by repeated measurements were additional independent predictors of death. These results support the clinical utility of regular prealbumin monitoring among HD patients., (Copyright 2001 by the National Kidney Foundation, Inc.)

Objective: Previous investigations using univariate study designs have reported that delayed referral to predialysis clinics is associated with adverse outcomes at the time of dialysis initiation. However, the independent effect of delayed referral is poorly defined. Moreover, the optimal time at which to refer patients to predialysis programs remains unclear. The aim of this study was to identify independent predictors of dialysis initiation requiring hospitalization., Materials and Methods: A retrospective cohort of 201 predialysis patients was investigated using multivariate logistic regression analysis., Results: Multivariate analysis selected advanced age (odds ratio (OR) 1.038,95% confidence interval (CI) 1.011-1.065), history of congestive heart failure (OR 2.877, 95% CI 1.205-6.871), and shorter predialysis follow-up time (OR 0.945, 95% CI 0.920-0.971) as independent predictors of in-hospital dialysis initiation. The risk of in-hospital dialysis initiation increased by 5.5% for every month lost due to late referral., Conclusion: Patients should be referred to predialysis programs as early as 24 months before anticipated dialysis initiation in order to minimize the risk of future adverse outcomes.

Background: Although there is abundant research describing predictors of patient morbidity and mortality among dialysis patients, predictors of adverse clinical outcomes among pre-dialysis patients are less well defined. The purpose of this study was to identify baseline predictors of first non-elective hospitalization among a retrospective cohort of 362 pre-dialysis patients., Methods: Univariate and multivariate Cox proportional hazard models were used to identify predictors of hospitalization prior to dialysis initiation, adjusted for baseline creatinine level. Dialysis initiation, loss to follow-up, and study conclusion were censored events. Secondary outcomes included cause-specific hospitalization and death., Results: Univariate analysis indicated that advanced age (RR 1.026, CI 1.016-1.037), number of prescribed anti-hypertensive medications (RR 1.149, CI 1.019-1.296), history of myocardial infarction (RR 1.979, CI 1.339-2.926), congestive heart failure (RR 2.299, CI 1.616-3.270), angina (RR 2.289, CI 1.695-3.091), peripheral vascular disease (RR 1.841, CI 1.282-2.644), renal failure secondary to nephrosclerosis (RR 1.413, CI 1.033-1.933) or renal artery stenosis (RR 1.587, CI 1.036-2.430), lower baseline haemoglobin level (RR 0.986, CI 0.979-0.992), and baseline creatinine greater than 300 micromol/l (RR 1.636, CI 1.233-2.171) were predictors of hospitalization. Gender, diabetes, diastolic blood pressure, mean arterial pressure, history of stroke, and hypoalbuminaemia did not predict outcome. Multivariate analysis, adjusted for baseline creatinine level, selected advanced age (RR 1. 017, CI 1.006-1.027), angina (RR 1.893, CI 1.371-2.613), peripheral vascular disease (RR 1.545, CI 1.054-2.266), and haemoglobin level (RR 0.987, CI 0.944-0.979) as independent predictors of hospitalization., Conclusion: Advanced age, co-morbid cardiovascular illness and anaemia are independent predictors of non-elective hospitalization prior to dialysis initiation. Further study is needed to determine the extent to which aggressive pre-dialysis management of anaemia and cardiovascular disease can improve patient outcomes.

A peer-verified, liquid chromatographic (LC) method for simultaneous determination of residues of flumequine (FLU), nalidixic acid (NAL), oxolinic acid (OXO), and piromidic acid (PIR) in catfish muscle is presented. Sample workup involves homogenizing tissue with acetone, defatting with hexane, and extracting quinolones into chloroform. Sample is purified further by partitioning into base and then subsequently back-extracting into chloroform after acidifying the aqueous phase. After solvent is evaporated, the residue is diluted with mobile phase, and analytes are introduced into an LC system where separations are made with a 5 microns, reversed-phase polymer column and an isocratic, buffered acetonitrile-tetrahydrofuran mobile phase. Determinations are made by UV detection at 280 nm for PIR and by fluorescence detection (excitation at 325 excitation and emission at 365 nm) for the other 3 analytes. Each quinolone was used to fortify catfish muscle at 5, 10, 20, 40, and 80 ng/g. The following recoveries and relative standard deviation (RSD) values represent an average of the 5 levels for each analyte: FLU, 79.7% (RSD = 5.7%); OXO, 80.8% (RSD = 6.3%); PIR, 75.0% (RSD = 5.9%); and NAL, 87.1% (RSD = 10%). Assay of 5 levels (base incurred catfish, plus 4 dilutions with control catfish) of catfish muscle incurred with the 4 quinolones gave the following averages: FLU: base, 198 ng/g (RSD = 2.3%); dilutions, 98.0 ng/g (RSD = 4.2%), 61.6 ng/g (RSD = 4.4%), 21.6 ng/g (RSD = 2.8%), 9.24 ng/g (RSD = 8.7%); OXO, base, 257 ng/g (RSD = 6.9%); dilutions, 146 ng/g (RSD = 5.5%), 95.0 ng/g (RSD = 4.1%), 30.7 ng/g (RSD = 3.8%), 13.7 ng/g (RSD = 4.6%); PIR, base, 22.1 ng/g (RSD = 4.2%); dilutions, 13.7% ng/g (RSD = 6.7%), 6.49 ng/g (RSD = 15%), 2.65 ng/g (RSD = 15%); and NAL, base, 75.1 ng/g (RSD = 3.8%); dilutions, 42.3 ng/g (RSD = 5.1%), 24.1 ng/g (RSD = 6.3%), 8.59 ng/g (RSD = 4.8%). A second multiresidue analysis of the 4 quinolones was performed by an outside analyst. Average recoveries from catfish fortified at 5, 10, 20, and 40 ng/g were FLU, 75.9% (RSD = 4.0%); OXO, 84.0% (RSD = 5.5%); NAL, 85.6% (RSD = 8.9%); and PIR, 66.2% (RSD = 8.7%).

A previously published liquid chromatographic (LC) method for determining residues of flumequine (FLU) and nalidixic (NAL), oxolinic (OXO), and piromidic (PIR) acids in catfish tissue was applied to salmon and shrimp muscle. Identities of all 4 residues in salmon and shrimp were confirmed by gas chromatography/mass spectrometry (GC/MS). The tissue is homogenized with acetone, the acetone extract is defatted with hexane, and the quinolones are extracted into chloroform. The extract is further purified by first partitioning into base and then back-extracting from a solution acidified to pH 6.0. Analytes are determined by LC with simultaneous UV and fluorescence detection. Muscle tissue was fortified with each quinolone at 5, 10, 20, 40, and 80 ng/g. Average recoveries and relative standard deviations (RSDs) for salmon, which represent an average of the 5 levels for each analyte, ranged from 75.9 to 90.8% and from 2.25 to 6.40%, respectively. Average recoveries and RSDs for shrimp ranged from 81.3 to 91.2% and from 7.34 to 10.7%, respectively. Identities of OXO, FLU, NAL, and PIR were confirmed in extracts of salmon and shrimp tissue fortified at 10 ng/g by determination of decarboxylated quinolones by GC/MS. Four diagnostic ions were monitored for OXO, FLU, and PIR, and 5 ions were monitored for NAL. All ion relative abundances were within 10% of those calculated for standard decarboxylated quinolones. Optimum conditions for decarboxylation and GC/MS confirmation are given.

A liquid chromatographic (LC) method is described for the simultaneous determination of the triazine herbicides, simazine (SIM), atrazine (ATZ), and propazine (PRO) in the 12.5-100 ppb range in catfish. The herbicides are extracted from catfish homogenates with ethyl acetate, followed by solvent partitioning between acetonitrile and petroleum ether and additional cleanup on a C18 cartridge. A Supelcosil LC-18-DB column is used for LC separation, and UV determination is at 220 nm. The isocratic mobile phase is a mixture of methanol, acetonitrile, and water. Mean recoveries from catfish were 88.7, 96.9, and 91.7%; standard deviations were 6.84, 7.78, and 6.26%; and coefficients of variation were 7.72, 8.03, and 6.82% for SIM, ATZ, and PRO, respectively.

A liquid chromatographic (LC) method was developed for the determination of flunixin (FNX) in raw bovine milk. The milk was acidified and mixed with silica gel, and the mixture was packed into a chromatographic column. The column was defatted with water-saturated dichloromethane-hexane (30 + 70, v/v), and the analyte was eluted with EtOAc. The EtOAc extract was washed with water at pH 3.5, the water was discarded, and the EtOAc layer was then extracted with 0.1M NaOH. The aqueous layer was drained, passed through a primed C18 solid-phase extraction (SPE) column, and eluted with EtOAc. The EtOAc layer was dried under N2, taken up in a solution of MeOH-(5 mM tetrabutylammonium [TBA]-H2PO4 + 2 mM NaOH) (50 + 50), sonicated, and filtered. FNX was determined by LC using a C18 column (ODS Hypersil), a mobile phase mixture of 58% A (MeOH) and 42% B (5 mM TBA-H2PO4 + 2 mM NaOH), and a diode-array ultraviolet detector at 285 nm. FNX was determined in raw milk at 5 spiking levels (5, 10, 20, 40, and 80 ng drug/mL milk). Absolute recoveries ranged from 69.6 to 74.4%, and relative standard deviations ranged from 1.1 to 6.9%. The limit of quantitation was 1.7 ng drug/mL milk. A lactating cow was dosed intravenously (2.2 mg/kg) with flunixin meglumine (Banamine) to generate incurred milk residues. FNX residues ranged from 7.34 ng/mL at 16 h postdose to 1.74 ng/mL at 24 h postdose. Both levels were obtained with additional beta-glucuronidase treatment (almost no incurred drug was detected at these low levels without the enzyme treatment).(ABSTRACT TRUNCATED AT 250 WORDS)

To determine residues of malachite green (MG) and its metabolite, leucomalachite green (LMG), in catfish tissue, analytes are extracted with acetonitrile-buffer and the extract is partitioned into methylene chloride. Final cleanup and isolation are performed on neutral alumina solid-phase extraction (SPE) and propylsulfonic acid cation-exchange SPE columns before analysis by liquid chromatography with visible detection. PbO2 postcolumn oxidation is performed by isocratic elution with a buffered mobile phase from a cyano column. Recoveries and relative standard deviations (RSDs) from fortified catfish tissues were 72.9% (RSD, 1.92%; 23 ppb), 75.5% (RSD, 6.85%; 11 ppb), and 69.6% (RSD, 6.93%; 5.7 ppb) for MG and 87.4% (RSD, 2.92%; 21 ppb), 88.1% (RSD, 5.94%; 10 ppb), and 82.6% (RSD, 11.5%; 5.3 ppb) for LMG. The method was applied to MG-incurred catfish at depuration times of 0, 2, 4, 8, and 24 h. Average levels of residual MG and LMG in the 24 h depuration catfish tissue were 73.4 and 289 ppb, respectively.

A liquid chromatographic (LC) method is described for the determination of 5-100 ppb halofuginone hydrobromide (HFG) in eggs. HFG as the free base is extracted from eggs with ethyl acetate. The extract is cleaned up on an acidic Celite 545 column. A Waters C18 column is used for LC separation with UV determination at 243 nm. The isocratic mobile phase is a mixture of water-acetonitrile-ammonium acetate buffer (12 + 5 + 3) and acetic acid. The interassay average recovery from eggs was 90.4%, with a standard deviation of 5.11 and a relative standard deviation of 5.65%.

WAIS-R and NEO Personality Inventory (NEO-PI) scores obtained from 85 rehabilitation clients of the Evaluation and Development Center of Southern Illinois University's Rehabilitation Institute were utilized to examine the relationship between psychometric intelligence and personality. Correlational analyses revealed that the NEO-PI Openness domain and its six facets significantly correlated with WAIS-R FSIQ, VIQ, PIQ, and 9 of the 11 subtests. Multiple regression analyses showed that the five NEO-PI domains accounted for significant proportions of WAIS-R, FSIQ, VIQ, and PIQ score variance. The NEO-PI Openness domain was found to be the best predictor of WAIS-R FSIQ, VIQ, and PIQ scores. The study concludes with a discussion of the meaning and implications of the findings and suggestions for future research.

An interlaboratory study of a gas chromatographic method for determining chloramphenicol (CAP) residues in shrimp was conducted. An internal standard (Istd), the meta isomer of CAP, was added to the shrimp, and the treated shrimp were homogenized with ethyl acetate. The ethyl acetate extract was defatted with hexane, and the CAP was partitioned into ethyl acetate from an aqueous salt solution. The ethyl acetate was evaporated, and the dried residue was treated with Sylon, a trimethylsilyl derivatizing agent, to yield the trimethylsilyl derivative of CAP. A portion of the solution containing the derivative was injected into a gas chromatograph equipped with an electron capture detector. Levels of fortified and incurred CAP were calculated from the peak area ratio of standard CAP to Istd. Recoveries of CAP from tissue directly fortified at 5 ppb were 102% (within-laboratory relative standard deviation [RSDr] = 5.6%), 104% (RSDr = 5.5%), and 108% (RSDr = 6.3%) from Laboratories 1, 2, and 3, respectively. Incurred-CAP residues at 5 and 10 ppb levels were also determined, with the following results: Laboratory 1: composite A, 4.56 ppb (RSDr = 14.0%); composite B, 8.38 ppb (RSDr = 11.6%); Laboratory 2: composite A, 4.17 ppb (RSDr = 12.5%); composite B, 8.90 ppb (RSDr = 5.60%); Laboratory 3: composite A, 4.66 ppb (RSDr = 14.9%); composite B, 11.0 ppb (RSDr = 11.8%).

A liquid chromatographic (LC) method is described for the simultaneous determination of xylazine (XY) and its major metabolite, 2,6-dimethylaniline (2,6-DMA), in bovine and swine kidney in the 25-100 ppb range. XY and 2,6-DMA are extracted from kidney with chloroform, followed by cleanup on an acidic Celite 545 column. A mu Bondapak phenyl column is used for LC separation with UV determination at 225 nm. The mobile phase is a mixture of acetonitrile, water, sodium acetate, and acetic acid. Mean recoveries from bovine kidney were 78.3% for XY, with a standard deviation (SD) of 7.45 and a coefficient of variation (CV) of 9.51%, and 87.2% for 2,6-DMA, with an SD of 8.38 and a CV of 9.61%. Mean recoveries from swine kidney were 80.8% for XY, with an SD of 5.92 and a CV of 7.33%, and 86.7% for 2,6-DMA, with an SD of 6.16 and a CV of 7.10%.

A liquid chromatographic (LC) method is described for the determination of chlortetracycline hydrochloride (CTC) in poultry/swine and ruminant feeds in the 10-100 ppm range and in premix. CTC is extracted from ground feed/premix with acidified acetone, and the extract is filtered through a Millex-HV filter or disposable C18 column. The filtrate is partitioned with methylene chloride when additional cleanup is necessary. A Nova-Pak C18 column is used for LC separation with determination at 370 nm. The average recovery of CTC from premix was 95% with a standard deviation (SD) of 1.70 and a coefficient of variation (CV) of 1.79%. The overall average recovery from feeds was 77% with an SD of 3.18 and a CV of 4.10%.

A collaborative study of the determination of mercury in fish has been completed in which wet oxidation of fish tissue in nitric acid, using vanadium as a catalyst, is compared with the AOAC official final action digestion technique, 25.103-25.105, involving a nitric-perchloric acid mixture. The study used tuna fish samples of known mercury content and included spike recovery studies in which methyl mercury solutions of known composition were provided to each laboratory. The study was designed to provide recovery information that bracketed the regulatory level of mercury in fish. The results indicate that the proposed digestion method is at least as precise and accurate as the AOAC method. The proposed method is also more rapid and less hazardous. It has been adopted as official first action.