Publications by authors named "James McAlpine"

Objective: Investigate the bioactivity and stability of Rhodiola rosea (RR) fractions as a natural source of prodelphinidin gallate (PDg) on dentin collagen via analysis of the viscoelastic and resin-dentin adhesive properties of the dentin matrix.

Methods: The biomimicry and stability of RR subfractions (F1, F2, F3 and F4) with collagen were determined by dynamic mechanical analysis (DMA). DMA used a strain sweep method to assess the dentin matrix viscoelastic properties [storage (E'), loss (E"), and complex (E*) moduli and tan δ] after treatment, 7-, 30- and 90-days of storage in simulated body fluids (SBF).

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Article Synopsis
  • - The study focuses on proanthocyanidins (PACs) with A-type linkages, which are rare in nature due to the complex biosynthesis needed to form them, but they offer enhanced structural rigidity compared to the more common B-type linkages.
  • - Previous research suggests that PACs with more double linkages, particularly B- and AB-type, interact more effectively with dentin type I collagen, making A-type PACs promising materials for enhancing dental treatments.
  • - The researchers utilized a chemical process to convert B-type PACs into A-type analogues and confirmed their structures through spectroscopy, finding that the type of linkages affects the flexibility and conformational energy of the PACs, which is important for their
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Three unique linear oligomeric depsipeptides, designated as cavomycins A-C (-), were identified from , a gut bacterium associated with the annelid . The structures of these depsipeptides were determined through a combination of spectroscopic methods and chemical derivatization techniques, including methanolysis, the modified Mosher's method, advanced Marfey's methods, and phenylglycine methyl ester derivatization. The unique dipeptidyl residue arrangements in compounds - indicate that they are not degradation products of valinomycin.

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Flavan-3-ol monomers are the building blocks of proanthocyanidins (PACs), natural compounds from plants shown to mediate specific biologic activities on dentin. While the stereochemistry of the terminal flavan-3-ols, catechin (C) versus epicatechin (EC), impacts the biomechanical properties of the dentin matrix treated with oligomeric PACs, structure-activity relationships driving this bioactivity remain elusive. To gain insights into the modulatory role of the terminal monomers, two highly congruent trimeric PACs from Pinus massoniana only differing in the stereochemistry of the terminal unit (Trimer-C vs.

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Proanthocyanidins (PACs) are complex flavan-3-ol polymers with stunning chemical complexity due to oxygenation patterns, oxidative phenolic ring linkages, and intricate stereochemistry of their heterocycles and inter-flavan linkages. Being promising candidates for dental restorative biomaterials, trace analysis of dentin bioactive cinnamon PACs now yielded novel trimeric ( and ) and tetrameric () PACs with unprecedented - and benzoquinone motifs (benzoquinonoid PACs). Challenges in structural characterization, especially their absolute configuration, prompted the development of a new synthetic-analytical approach involving comprehensive spectroscopy, including NMR with quantum mechanics-driven H iterative functionalized spin analysis (HifSA) plus experimental and computational electronic circular dichroism (ECD).

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Given that the essence of Science is a search for the truth, one might expect that those identifying as scientists would be conscientious and observant of the demands this places on them. However, that expectation is not fulfilled universally as, not too surprisingly, egregious examples of unethical behavior appear and are driven by money, personal ambition, performance pressure, and other incentives. The reproducibility-, fact-, and truth-oriented of Science has come to face a variety of challenges.

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In botanical extracts, highly abundant constituents can mask or dilute the effects of other, and often, more relevant biologically active compounds. To facilitate the rational chemical and biological assessment of these natural products with wide usage in human health, we introduced the DESIGNER approach of Depleting and Enriching Selective Ingredients to Generate Normalized Extract Resources. The present study applied this concept to clinical Red Clover Extract (RCE) and combined phytochemical and biological methodology to help rationalize the utility of RCE supplements for symptom management in postmenopausal women.

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Background: The translation of research into healthcare practice relies on effective communication between disciplines, however strategies to address the gap between information sharing and knowledge transfer are still under exploration. Communities of Practice (CoP) are informal networks of stakeholders with shared knowledge or endeavour and present an opportunity to address this gap beyond disciplinary boundaries. However, the evidence-base supporting their development, implementation and efficacy in health is not well described.

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Monoterpenoids are integral to the chemical composition of the widely used adaptogenic dietary supplement . The present study expands the chemical space and stereochemical information about these taxon-specific constituents from the isolation and characterization of five geraniol-derived glucosides, -. While and exhibited almost identical NMR spectra and shared the same 2D structure ascribed to the 4-hydroxygeraniolglucoside previously described as rosiridin, the NMR-based Mosher ester method revealed the enantiomeric nature of their aglycone moieties.

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Investigation of a pine bark extract for bioactive proanthocyanidin oligomers resulted in the isolation of structurally related dimeric B-type procyanidin derivatives, -. This includes scalemic mixtures of gambiriin A1 () and A2 () and their newly described optical antipodes, -gambiriin A1 () and -gambiriin A2 (), respectively, as well as a racemic mixture of the newly described (-)gambiriin A5 (/). Furthermore, the study now fully characterizes the previously reported optically pure dimers gambiriin B1 () and gambirflavan D1 (), and characterized the novel B-type procyanidin trimer, (gambirifuran C1).

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Four new rufomycins, compounds -, named rufomycins 56, 57, 58, and 61, respectively, exhibiting new skeletal features, were obtained from strain MJM3502 and were fully characterized. Compounds and possess a 4-imidazolidinone ring not previously encountered in this family of cyclopeptides, thereby resulting in a [5,17] bicyclic framework. The in vitro anti- potency of compounds and is remarkable, with minimum inhibitory concentration values of 8.

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To enable translational studies, a scalable preparative isolation scheme was developed for underivatized cocoa () proanthocyanidins (PACs), affording six all-B-type oligomeric PACs, including a new tetramer . Their structures, including absolute configuration, were unambiguously established by comprehensive spectroscopic and chemical methods. Evaluation of the PACs' dentin biomodification properties employed dynamic mechanical and infrared spectroscopic analyses in dentin bioassay models.

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Aim: Grape seed extract contains a complex mixture of proanthocyanidins (PACs), a plant biopolymer used as a biomaterial to improve reparative and preventive dental therapies. Co-polymerization of PACs with type I collagen mechanically reinforces the dentin extracellular matrix. This study assessed the biocompatibility of PACs from grape seed extract on dental pulp stem cells (DPSCs) in a model simulating leaching through dentin to the pulp cavity.

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Medical devices such as peripheral intravenous cannulae (PIVC) are commonly used in the care of children across all hospital settings. However, the association between PIVC and the development of pressure injuries in this population became a concern on one Australian paediatric ward. A quality improvement project was conducted to reduce the incidence of pressure injuries in children caused by PIVCs.

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Background: A significant barrier to the access of safe abortion is the lack of trained abortion providers. Recent studies show that with appropriate education, nurses and midwives can provide abortions as safely as medical practitioners.

Aims: To examine the attitudes and practices of registered midwives (RMs) and sexual health nurses (SHNs) in Queensland toward abortion.

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To enable the further exploration of structure-activity relationships (SARs) of proanthocyanidins (PACs) with dentin biomodification abilities, was selected for scaled-up purification of mixed A-/B-type, medium-size PAC oligomers. Sequential purification by centrifugal partition chromatography (CPC), Sephadex LH-20, and semiprep HPLC chromatography yielded four underivatized tetrameric (-) and two pentameric (-) PACs. Their unambiguous structural characterization involved extensive spectral and chemical degradation approaches to show that epicatechin units are connected by plant-specific combinations of doubly linked A- and singly linked B-type interflavanyl bonds.

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Much confusion exists about the chemical composition of widely sold products that utilize the cannabidiol (CBD) acronym and related terms such as "CBD oil", "CBD plus hemp oil", "full spectrum CBD", "broad spectrum CBD", and "cannabinoids". Their rational chemical and subsequent biological assessment requires both knowledge of the chemical complexity and the characterization of significant individual constituents. Applicable to hemp preparations in general, this study demonstrates how the combination of liquid-liquid-based separation techniques, NMR analysis, and quantum mechanical-based NMR interpretation facilitates the process of natural product composition analysis by allowing specific structural characterization and absolute quantitation of cannabinoids present in such products with a large dynamic range.

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Flavonoids are a vast group of metabolites that are essential for vascular plant physiology and, thus, occur ubiquitously in plant-based/-derived foods. The solitary designation of thousands of known flavonoids hides the fact that their metabolomes are structurally highly diverse, consist of disparate subgroups, yet undergo a certain degree of metabolic interconversion. Unsurprisingly, flavonoids have been an important theme in nutrition research.

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Rufomycin and ilamycin are synonymous for the same class of cyclopeptides, currently encompassing 33 structurally characterized isolates and 9 semisynthetic derivatives. Elucidation of new structures prioritized the consolidation of the names and established the structures of four diastereoisomeric rufomycins with a 2-piperidinone, named rufomycins 4-7, including full H/C NMR assignments. The characteristic HSQC cross-peak for the CH-5, the hemiaminal carbon in amino acid #5, allows assignment of the stereocenters C-4 and C-5 within this ring.

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Article Synopsis
  • The study aimed to explore how the structure of proanthocyanidins (PACs) interacts with type I collagen in dentin by using various PACs with different degrees of polymerization.
  • Researchers used techniques like dynamic mechanical analysis and infrared spectroscopy to assess the effects of PACs on the mechanical properties of modified dentin.
  • Results showed that higher degrees of polymerization in PACs significantly improved the mechanical properties of dentin, with specific structural changes in collagen, highlighting key relationships between PAC structure and its effects on dentin.
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Off-line combination of countercurrent separation (CCS) and quantitative H NMR (qHNMR) methodologies enabled the systematic dissection and gravimetric quantification of a chemically complex crude extract (RCE). The loss-free nature and high selectivity of CCS achieved the quantitative discrimination of fatty acids (FAs), sugars, and proanthocyanidins (PACs) from ten other metabolite classes: phenylpropanoids, phenylethanoids, acyclic monoterpenoid glycosides, pinene derived glycosides, benzyl alcohol glycosides, cyanogenic glycosides, flavonoids, gallic acids, methylparabens, and cuminol glycosides. The ability of CCS to remove ("knockout") PACs completely resolved challenges with baselines that plague NMR and UHPLC analyses and produce inaccurate integral and AUC quantitation, respectively.

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Nontuberculous mycobacterial pulmonary infection is often aggravated due to antibiotic resistance issues. There is a need for development of new drugs inducing both host immune responses and antimicrobial activities. This study shows that the rufomycins 4/5/6/7 (Rufomycin 4-7), which targets ClpC1 as a subunit of caseinolytic protein complex ClpC1/ClpP1/ClpP2 of mycobacteria, exhibits a dual effect in host innate defense and antimicrobial activities against a rough morphotype of (Mabs-R), a clinically severe morphotype that causes hyperinflammation.

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The importance of Trifolium pratense L. as a dietary supplement and its use in traditional medicine prompted the preparation of a thorough metabolite profile. This included the identification and quantitation of principal constituents as well as low abundant metabolites that constitute the residual complexity (RC) of T.

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