David C. Lankin

# Publications/

Dissemination of Original NMR Data Enhances Reproducibility and Integrity in Chemical Research

Journal: Natural Product Reports (RoMEO status: Yellow) Published on
Categories: publications
Subjects: Fundamental research NMR raw data

The notion of data transparency is gaining a strong awareness among the scientific community. The availability of raw data is actually regarded as a fundamental way to advance science by promoting both integrity and reproducibility of research outcomes. Particularly, in the field of natural product and chemical research, NMR spectroscopy is a fundamental tool for structural elucidation and quantification (qNMR). As such, the accessibility of original NMR data, i.e., Free Induction Decays (FIDs), fosters transparency in chemical research and optimizes both peer review and reproducibility of reports by offering the fundamental tools to perform efficient structural verification.

Read More...

# Publications/

OpenAccess Toward Structural Correctness: Aquatolide and the Importance of 1D Proton NMR FID Archiving

Journal: Journal of Organic Chemistry (RoMEO status: White) Published on
Categories: publications
Subjects: Pharmacognosy Phytochemistry NMR FID raw data Spin simulation

The revision of the structure of the sesquiterpene aquatolide from a bicyclo[2.2.0]hexane to a bicyclo[2.1.1]hexane structure using compelling NMR data, X-ray crystallography, and the recent confirmation via full synthesis exemplify that the achievement of “structural correctness” depends on the completeness of the experimental evidence. Archived FIDs and newly acquired aquatolide spectra demonstrate that archiving and rigorous interpretation of 1D 1H NMR data may enhance the reproducibility of (bio)chemical research and curb the growing trend of structural misassignments.

Read More...

# Publications/

Subtle Chemical Shifts Explain the NMR Fingerprints of Oligomeric Proanthocyanidins with High Dentin Biomodification Potency

Journal: Journal of Organic Chemistry (RoMEO status: White) Published on
Categories: publications
Subjects: Pharmacognosy Phytochemistry Dentistry OPAC NMR

The ability of certain oligomeric proanthocyanidins (OPACs) to enhance the biomechanical properties of dentin involves collagen cross-linking of the 1.3–4.5 nm wide space via protein–polyphenol interactions. A systematic interdisciplinary search for the bioactive principles of pine bark has yielded the trimeric PAC, ent-epicatechin-(4β→8)-epicatechin-(2β→O→7,4β→8)-catechin (3), representing the hitherto most potent single chemical entity capable of enhancing dentin stiffness. Building the case from two congeneric PAC dimers, a detailed structural analysis decoded the stereochemistry, spatial arrangement, and chemical properties of three dentin biomodifiers.

Read More...

# Posters/

Chemical nano shifts explain the NMR fingerprints of dentin-enhancing oligomeric proanthocyanidins

1D NMR spectra contain a wealth of vital structural information that can enhance the description of bioactive molecules. The present study demonstrates how quantum-mechanics driven 1H iterative Full Spin Analysis (QM-HiFSA) is capable of distinguishing spectral detail that cannot be interpreted manually or visually, but provides important information of the 3D structure and bonding (re-)activity of the molecules. This approach is established by analyzing 1D NMR spectra of oligomeric proanthocyanidins (OPACs), which exhibit high dentin bioactivity, and were isolated from the inner bark of pine.

Read More...

# Posters/

Dissemination of original NMR data enhances the reproducibility of natural product research

The acquisition of 1D 1H NMR (HNMR) spectra is one of earliest steps in characterizing natural products and other organic molecules. For publication, HNMR information usually is “converted” into a table format, and sometimes spectral plots are provided. However, this transformation is lossy and frequently insufficient for unambiguous dereplication. This ambiguity can even lead to structural revision, such as in the recent case of aquatolide (1), a sesquiterpene lactone from Asteriscus aquaticus.

Read More...

# Publications/

OpenAccess Essential Parameters for Structural Analysis and Dereplication by 1H NMR Spectroscopy

Journal: Journal of Natural Products (RoMEO status: White) Published on
Categories: publications
Subjects: Pharmacognosy Phytochemistry NMR Spin simulation

The present study demonstrates the importance of adequate precision when reporting the δ and J parameters of frequency domain 1H NMR (HNMR) data. Using a variety of structural classes (terpenoids, phenolics, alkaloids) from different taxa (plants, cyanobacteria), this study develops rationales that explain the importance of enhanced precision in NMR spectroscopic analysis and rationalizes the need for reporting Δδ and ΔJ values at the 0.1–1 ppb and 10 mHz level, respectively.

Read More...