Publications by authors named "Tina Holt"

Article Synopsis
  • - The study focuses on creating diverse polyheterocycles using a method that involves light-assisted chemical reactions.
  • - It utilizes a specific process called decarboxylative aromatization, which transforms initial products from intramolecular cycloadditions of azaxylylenes.
  • - These azaxylylenes are combined with heteroaromatic compounds that have unsaturated parts to form the desired complex structures.
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The fragmentation reaction of the radical cations of 3-aryl-5-fluoroisoxazoles formed via EI-MS is described. A new rearrangement accompanied by fluorine atom migration is discovered. A mechanistic rationale for the rearrangement supporting the existence of a fluorinated benzocyclopropenyl cation was proposed based on the experimental data and quantum chemical calculations.

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The inhibitor of apoptosis protein BIRC2 regulates fundamental cell death and survival signaling pathways. Here we show that BIRC2 accumulates in the nucleus via binding of its second and third BIR domains, BIRC2 and BIRC2, to the histone H3 tail and report the structure of the BIRC2-H3 complex. RNA-seq analysis reveals that the genes involved in interferon and defense response signaling and cell-cycle regulation are most affected by depletion of BIRC2.

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Article Synopsis
  • New variants of SARS-CoV-2 and drug resistance highlight the need for novel treatments against the virus.
  • The study investigates how the E protein of SARS-CoV-2 interacts with the human protein BRD4, revealing that the E protein is modified (acetylated) and binds to BRD4.
  • Inhibitors targeting BRD4 reduce the virus's ability to infect lung cells, suggesting BRD4 could be a promising target for anti-COVID-19 therapies.
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Structurally unique halimanes EBC-232 and EBC-323, isolated from the Australian rainforest plant Croton insularis, proved considerably difficult to elucidate. The two diastereomers, which consist an unusual oxo-6,7-spiro ring system fused to a dihydrofuran, were solved by unification and consultation of five in silico NMR elucidation and prediction methods [i.e.

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Briarellins, a subset of C2-C11 cyclized cembranoids, were proposed to contain a C3-C14 ether or lactone bridge, similar to asbestinins. However, the total synthesis of the proposed structure of briarellin J revealed a misassignment. We revisited briarellins, computationally, with the help of a recently developed hybrid DFT/parametric method, DU8+, and revised the structures of briarellin C14-C3 ε-lactones to new structural types containing either a C14-C11 or C14-C12 lactone bridge.

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This manuscript describes predicted NMR shifts for the limonoid natural product xylogranatin F. The H and C NMR shifts of four diastereomers were evaluated by GIAO and hybrid DFT/parametric DU8+ methods. The results of the H and C NMR calculations for both the GIAO method and the DU8+ calculations suggest the revised structure that was recently reassigned by chemical synthesis.

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Total synthesis has been an effective and broadly practiced approach for structure validation (or revision) of complex natural products. It appears that computational methods for structure elucidation are gradually becoming a better alternative, being faster and more reliable, as found in the case of alstofolinine A.

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Article Synopsis
  • - Analysis of NMR data for natural products with oxetane groups highlights challenges in determining their structures and stereochemistry, with over 30 structures needing revisions.
  • - A new computational method, DU8+, was employed to improve accuracy in structure elucidation.
  • - Common pitfalls in identifying these compounds are outlined, and revised structures are proposed for 26 different natural products.
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NMR data for natural products containing the epoxy moiety have been revisited and reanalyzed with the help of a recently developed parametric/DFT hybrid computational method, DU8+. More than 20 structures needed revision, which points to challenges in NMR solution structure assignment for molecules possessing this structural feature. Among the revised structures are achicretin 2, acremine P, aromaticane I, artanomalide B, botryosphaerihydrofuran, chloroklotzchin, crithmifolide, crotodichogamoin A, emervaridone C, 9α,15-epoxyafricanane, fischambiguine B, grandilobalide B, guaianolide A, guatterfriesols A and B, juncenolide G, roscotane D, secoafricane 7, taccalonolides AJ and AF, and related compounds.

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