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A new abietane diterpenoid, 1β, 11-epoxyabieta-12-hydroxy-8, 11, 13-triene-7-one (1), along with three known compounds (2–4), was isolated from Lycopodium complanatum. Their structures were confirmed by the analysis of 1D, 2D NMR and HRESIMS data, and comparison with previous spectral data. All compounds were tested for inhibitory activities against A549, HepG2 and MCF-7 tumor cell lines. [ABSTRACT FROM AUTHOR]

Four new prenylflavonol glycosides (1–4) along with two known analogues (5–6) were isolated from the leaves of Cyclocarya paliurus for the first time. The structures of these compounds were characterized by comprehensive analysis of 1 D, 2 D NMR, HRESIMS, UV data and enzymatic hydrolysis. In bioassays, compounds 1–4 were evaluated for inhibitory effects on xanthine oxidase (XOD) and effects on the inhibition of nitric oxide (NO) production in lipopolysaccharide (LPS) induced RAW264.7 cells. Moreover, compounds 1 and 2 showed outstanding XOD inhibitions with IC50 values of 18.16 ± 3.91 and 37.65 ± 5.67 µM, and exhibited inhibitions against LPS-induced NO production with IC50 values of 80.50 ± 3.09 and 82.28 ± 2.87 µM. [ABSTRACT FROM AUTHOR]

Three previously undescribed dammarane triterpenoid glycosides (1-3) along with five known analogues (4-8) were isolated from the leaves of Cyclocarya paliurus. Their structures and configurations were determined on the basis of comprehensive spectroscopic analyses, chemical hydrolysis and DFT GIAO 13C NMR calculation. All the isolates were evaluated cytotoxic activities against seven human cancer cell lines (MCF-7, PC-3, Du145, NCI-H1975, PC-9, SKVO3 and HepG2). Moreover, compound 4 showed a wide spectrum of cytotoxicity against human cancer cells with IC50 values ranging from 11.31 to 29.51 µM. [ABSTRACT FROM AUTHOR]

Two new robustaflavones, (±)-trichocladabiflavone A (1) and uncinatabiflavone E (2), along with seven known biflavanoids (3–9) were isolated from the 70% EtOH extract of Selaginella trichoclada. Their structures and absolute configurations were established by extensive spectroscopic and circular dichroism (CD) analyses. Compound 1 was resoluted into optically pure enantiomers (+)-1 and (−)-1 by chiral-phase HPLC. Moreover, compounds 1 and 2 exhibited moderate cytotoxicity against A549 and HepG2 human cancer cell lines. [ABSTRACT FROM AUTHOR]

One new pentacyclic triterpenoid, urs-12,16-dien-3-one (1), together with twelve known pentacyclic triterpenoids (2‒13), were isolated from the twigs and leaves of Melaleuca linariifolia. Their structures were characterized by their 1D- and 2 D-NMR spectra analysis and mass spectra studies. Furthermore, all isolated compounds were tested the inhibitory effect on proliferation of six human cancer cell lines in vitro, including NCI-H441, NCI-H460, A549, SKOV3, hela, and caki-1 cells. Among them, compounds 3, 5, 7, 9, 12, and 13 exhibited moderate antiproliferative activities with IC50 values ranging from 3.85 to 33.31 μM. [ABSTRACT FROM AUTHOR]

Two pairs of isocoumarin derivatives, (±)-rhytidhymarins A and B (1–2), one aromatic ester, rhytidhyster A (3), together with three known compounds (4–6) were isolated from fungus Rhytidhysteron sp. BZM-9. Compounds 1 and 2 are presented as racemates and resolved into optically pure enantiomers (+)-1/(−)-1 and (+)-2/(−)-2 by chiral column separation, respectively. Their planar structures were elucidated by HRESIMS, 1D and 2D NMR data and their absolute configurations were determined by X-ray crystallographic analysis and electronic circular dichroism (ECD) calculation. Compound 5 showed significant cytotoxic activity against SMMC7721 cells with an IC50 value of 0.338 μM and exhibited moderate antimicrobial activity to MRSA with a MIC value of 6.25 μg mL−1; compound 3 showed cytotoxicity against HepG2 cells with an IC50 value of 11.46 μM. [ABSTRACT FROM AUTHOR]

Nuclear magnetic resonance (NMR) chemical shift calculations are powerful tools for structure elucidation and have been extensively employed in both natural product and synthetic chemistry. However, density functional theory (DFT) NMR chemical shift calculations are usually time-consuming, while fast data-driven methods often lack reliability, making it challenging to apply them to computationally intensive tasks with a high requirement on quality. Herein, we have constructed a 54-layer-deep graph convolutional network for 13 C NMR chemical shift calculations, which achieved high accuracy with low time-cost and performed competitively with DFT NMR chemical shift calculations on structure assignment benchmarks. Our model utilizes a semiempirical method, GFN2-xTB, and is compatible with a broad variety of organic systems, including those composed of hundreds of atoms or elements ranging from H to Rn. We used this model to resolve the controversial J/K ring junction problem of maitotoxin, which is the largest whole molecule assigned by NMR calculations to date. This model has been developed into user-friendly software, providing a useful tool for routine rapid structure validation and assignation as well as a new approach to elucidate the large structures that were previously unsuitable for NMR calculations.

Two new C21 steroidal glycosides, brapreguanes A and B (1-2) were isolated from 75 % aqueous ethanol extract of Selaginella braunii Baker. Their structures were established by spectroscopic analyses (1D/2D NMR spectra and HR-ESI-MS). The absolute configurations of sugar were elucidated by enzymatic hydrolysis and GCMS analysis. In addition, all compounds were evaluated for the anti-proliferative activities against various human cancer cells in vitro. Compounds exhibited no inhibition to various human cancer cells., (© 2022 Wiley-VHCA AG, Zurich, Switzerland.)