Spirostanol Sapogenins and Saponins from Convallaria majalis L. Structural Characterization by 2D NMR, Theoretical GIAO DFT Calculations and Molecular Modeling

Two new spirostanol sapogenins (5β-spirost-25(27)-en-1β,2β,3β,5β-tetrol 3 and its 25,27-dihydro derivative, (25S)-spirostan-1β,2β,3β,5β-tetrol 4) and four new saponins were isolated from the roots and rhizomes of Convallaria majalis L. together with known sapogenins (isolated from Liliaceae): 5β-spirost-25(27)-en-1β,3β-diol 1, (25S)-spirostan-1β,3β-diol 2, 5β-spirost-25(27)-en-1β,3β,4β,5β-tetrol 5, (25S)-spirostan-1β,3β,4β,5β-tetrol 6, 5β-spirost-25(27)-en-1β,2β,3β,4β,5β-pentol 7 and (25S)-spirostan-1β,2β,3β,4β,5β-pentol 8. New steroidal saponins were found to be pentahydroxy 5-O-glycosides; 5β-spirost-25(27)-en-1β,2β,3β,4β,5β-pentol 5-O-β-galactopyranoside 9, 5β-spirost-25(27)-en-1β,2β,3β,4β,5β-pentol 5-O-β-arabinonoside 11, 5β-(25S)-spirostan-1β,2β,3β,4β,5β-pentol 5-O-galactoside 10 and 5β-(25S)-spirostan-1β,2β,3β,4β,5β-pentol 5-O-arabinoside 12 were isolated for the first time. The structures of those compounds were determined by NMR spectroscopy, including 2D COSY, HMBC, HSQC, NOESY, ROESY experiments, theoretical calculations of shielding constants by GIAO DFT, and mass spectrometry (FAB/LSI HR MS). An attempt was made to test biological activity, particularly as potential chemotherapeutic agents, using in silico methods. A set of 12 compounds was docked to the PDB structures of HER2 receptor and tubulin. The results indicated that diols have a higher affinity to the analyzed targets than tetrols and pentols. Two compounds (25S)-spirosten-1β,3β-diol 1 and 5β-spirost-25(27)-en-1β,2β,3β,4β,5β-pentol 5-O-galactoside 9 were selected for further evaluation of biological activity.

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Polyhydroxylated Steroidal Saponins from the Rhizomes of Convallaria majalis

Natural Product Communications ◽

10.1177/1934578x0700200504 ◽

2007 ◽

Vol 2 (5) ◽

pp. 1934578X0700200

Author(s):

Taro Higano ◽

Minpei Kuroda ◽

Maki Jitsuno ◽

Yoshihiro Mimaki

Keyword(s):

Spectroscopic Analysis ◽

Methanolic Extract ◽

2D Nmr ◽

Chemical Transformations ◽

Steroidal Saponins ◽

Nmr Data ◽

Spirostanol Saponins ◽

Convallaria Majalis

Six new polyhydroxylated spirostanol saponins (1–6) were isolated from the methanolic extract of the rhizomes of Convallaria majalis. On the basis of extensive spectroscopic analysis, including 2D NMR data, and a few chemical transformations, the structures of 1–6 were determined to be 1β,2β,3β-trihydroxy-5β-spirost-25(27)-en-5-yl β-D-galactopyranoside (1), (25 S)-1β,2β,3β-trihydroxy-5β-spirostan-5-yl β-D-galactopyranoside (2), 1β,2β,3β,4β-tetrahydroxy-5β-spirost-25(27)-en-5-yl β-D-galactopyranoside (3), (25 S)-1β,2β,3β,4β-tetrahydroxy-5β-spirostan-5-yl β-D-galactopyranoside (4), 1β,2β,3β,4β-tetrahydroxyspirost-25(27)-en-5-yl α-L-arabinopyranoside (5), and (25 S)-1β,2β,3β,4β-tetrahydroxy-5β-spirostan-5-yl α-L-arabinopyranoside (6), respectively.

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Steroidal Saponins from the Fruits of Cestrum ruizteranianum

Natural Product Communications ◽

10.1177/1934578x1100601209 ◽

2011 ◽

Vol 6 (12) ◽

pp. 1934578X1100601

Author(s):

Galarraga M. Elier ◽

Anne-Claire Mitaine-Offer ◽

Juan Manuel Amaro-Luis ◽

Tomofumi Miyamoto ◽

Chiaki Tanaka ◽

...

Keyword(s):

Mass Spectrometry ◽

Nmr Spectroscopy ◽

Methanolic Extract ◽

2D Nmr ◽

Steroidal Saponins ◽

2D Nmr Spectroscopy ◽

First Time

Seven spirostane and furostane-type glycosides were isolated from the aqueous methanolic extract of the fruits of Cestrum ruizteranianum and characterized mainly by 2D NMR spectroscopy and mass spectrometry. These known saponins belong to the Δ5-spirostene and Δ5-furostene series and are reported in this species for the first time.

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The Pattern of Acetylation Defines the Priming Activity of Chitosan Tetramers

10.26434/chemrxiv.8159636.v1 ◽

2019 ◽

Author(s):

Sven Basa ◽

Malathi Nampally ◽

Talita Honorato ◽

Subha Narayan Das ◽

Appa Rao Podile ◽

...

Keyword(s):

Biological Activity ◽

Degree Of Polymerization ◽

Chitosan Oligosaccharides ◽

Degree Of Acetylation ◽

Bona Fide ◽

First Time ◽

Priming Activity

The biological activity of chitosans depends on their degree of polymerization (DP) and degree of acetylation (DA). However, information could also be carried by the pattern of acetylation (PA): the sequence of β-1,4-linked glucosamine (deacetylated/D) and N-acetylglucosamine (acetylated/A) units. To address this hypothesis, we prepared partially-acetylated chitosan oligosaccharides from a chitosan polymer (DA=35%, DPw=905) using recombinant chitosan hydrolases with distinct substrate and cleavage specificities. The mixtures were separated into fractions DP4–DP12, which were tested for elicitor and priming activities in rice cells. We confirmed that both activities were influenced by DP, <a>but also observed apparent DA-dependent priming activity, with the ADDD+DADD fraction proving remarkably effective</a>. We then compared all four mono-acetylated tetramers prepared using different chitin deacetylases and observed significant differences in priming activity. This demonstrates for the first time that PA influences the biological activity of chitosans, which can now be recognized as bona fide information-carrying molecules

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The Pattern of Acetylation Defines the Priming Activity of Chitosan Tetramers

10.26434/chemrxiv.8159636 ◽

2019 ◽

Author(s):

Sven Basa ◽

Malathi Nampally ◽

Talita Honorato ◽

Subha Narayan Das ◽

Appa Rao Podile ◽

...

Keyword(s):

Biological Activity ◽

Degree Of Polymerization ◽

Chitosan Oligosaccharides ◽

Degree Of Acetylation ◽

Bona Fide ◽

First Time ◽

Priming Activity

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Strategies for Oral Delivery of Metal-Saturated Lactoferrin

Current Protein and Peptide Science ◽

10.2174/1389203720666190513085839 ◽

2019 ◽

Vol 20 (11) ◽

pp. 1046-1051 ◽

Cited By ~ 1

Author(s):

Przemysław Gajda-Morszewski ◽

Klaudyna Śpiewak-Wojtyła ◽

Maria Oszajca ◽

Małgorzata Brindell

Keyword(s):

Biological Activity ◽

Oral Delivery ◽

Therapeutic Potential ◽

Structure And Function ◽

The Difference ◽

And Function ◽

First Time

Lactoferrin was isolated and purified for the first time over 50-years ago. Since then, extensive studies on the structure and function of this protein have been performed and the research is still being continued. In this mini-review we focus on presenting recent scientific efforts towards the elucidation of the role and therapeutic potential of lactoferrin saturated with iron(III) or manganese(III) ions. The difference in biological activity of metal-saturated lactoferrin vs. the unmetalated one is emphasized. The strategies for oral delivery of lactoferrin, are also reviewed, with particular attention to the metalated protein.

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In vitro biological activity of Hydroclathrus clathratus and its use as an extracellular bioreductant for silver nanoparticle formation

Green Processing and Synthesis ◽

10.1515/gps-2020-0043 ◽

2020 ◽

Vol 9 (1) ◽

pp. 416-428 ◽

Cited By ~ 1

Author(s):

Raghad R. Alzahrani ◽

Manal M. Alkhulaifi ◽

Nouf M. Al-Enazi

Keyword(s):

Biological Activity ◽

Unsaturated Fatty Acids ◽

Multidrug Resistant ◽

Chemical Components ◽

Resistant Bacteria ◽

Transmission Electron ◽

Hydroclathrus Clathratus ◽

Adaptive Nature ◽

First Time

AbstractThe adaptive nature of algae results in producing unique chemical components that are gaining attention due to their efficiency in many fields and abundance. In this study, we screened the phytochemicals from the brown alga Hydroclathrus clathratus and tested its ability to produce silver nanoparticles (AgNPs) extracellularly for the first time. Lastly, we investigated its biological activity against a variety of bacteria. The biosynthesized nanoparticles were characterized by UV-visible spectroscopy, Fourier-transform infrared spectroscopy, dynamic light scattering, transmission electron microscopy, and energy-dispersive spectroscopy. The biological efficacy of AgNPs was tested against eighteen different bacteria, including seven multidrug-resistant bacteria. Phytochemical screening of the alga revealed the presence of saturated and unsaturated fatty acids, sugars, carboxylic acid derivatives, triterpenoids, steroids, and other components. Formed AgNPs were stable and ranged in size between 7 and 83 nm and presented a variety of shapes. Acinetobacter baumannii, Staphylococcus aureus, Methicillin-resistant S. aureus (MRSA), and MDR A. baumannii were the most affected among the bacteria. The biofilm formation and development assay presented a noteworthy activity against MRSA, with an inhibition percentage of 99%. Acknowledging the future of nano-antibiotics encourages scientists to explore and enhance their potency, notably if they were obtained using green, rapid, and efficient methods.

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Insights on forming N,O-coordinated Cu single-atom catalysts for electrochemical reduction CO2 to methane

Nature Communications ◽

10.1038/s41467-020-20769-x ◽

2021 ◽

Vol 12 (1) ◽

Author(s):

Yanming Cai ◽

Jiaju Fu ◽

Yang Zhou ◽

Yu-Chung Chang ◽

Qianhao Min ◽

...

Keyword(s):

Energy Barrier ◽

Active Sites ◽

Theoretical Calculations ◽

High Energy ◽

Single Atom ◽

Faradaic Efficiency ◽

High Energy Barrier ◽

Catalytic Sites ◽

Electron Reduction ◽

First Time

AbstractSingle-atom catalysts (SACs) are promising candidates to catalyze electrochemical CO2 reduction (ECR) due to maximized atomic utilization. However, products are usually limited to CO instead of hydrocarbons or oxygenates due to unfavorable high energy barrier for further electron transfer on synthesized single atom catalytic sites. Here we report a novel partial-carbonization strategy to modify the electronic structures of center atoms on SACs for lowering the overall endothermic energy of key intermediates. A carbon-dots-based SAC margined with unique CuN2O2 sites was synthesized for the first time. The introduction of oxygen ligands brings remarkably high Faradaic efficiency (78%) and selectivity (99% of ECR products) for electrochemical converting CO2 to CH4 with current density of 40 mA·cm-2 in aqueous electrolytes, surpassing most reported SACs which stop at two-electron reduction. Theoretical calculations further revealed that the high selectivity and activity on CuN2O2 active sites are due to the proper elevated CH4 and H2 energy barrier and fine-tuned electronic structure of Cu active sites.

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The SN2 reaction and its relationship with the Walden inversion, the Finkelstein and Menshutkin reactions together with theoretical calculations for the Finkelstein reaction

Structural Chemistry ◽

10.1007/s11224-021-01805-y ◽

2021 ◽

Author(s):

Ibon Alkorta ◽

José Elguero

Keyword(s):

Linear Models ◽

Theoretical Calculations ◽

Computational Method ◽

Basis Set ◽

Free Energies ◽

Nitrogen And Phosphorus ◽

Atom Pairs ◽

Leaving Groups ◽

First Time ◽

Nitrogen Phosphorus

AbstractThis communication gives an overview of the relationships between four reactions that although related were not always perceived as such: SN2, Walden, Finkelstein, and Menshutkin. Binary interactions (SN2 & Walden, SN2 & Menshutkin, SN2 & Finkelstein, Walden & Menshutkin, Walden & Finkelstein, Menshutkin & Finkelstein) were reported. Carbon, silicon, nitrogen, and phosphorus as central atoms and fluorides, chlorides, bromides, and iodides as lateral atoms were considered. Theoretical calculations provide Gibbs free energies that were analyzed with linear models to obtain the halide contributions. The M06-2x DFT computational method and the 6-311++G(d,p) basis set have been used for all atoms except for iodine where the effective core potential def2-TZVP basis set was used. Concerning the central atom pairs, carbon/silicon vs. nitrogen/phosphorus, we reported here for the first time that the effect of valence expansion was known for Si but not for P. Concerning the lateral halogen atoms, some empirical models including the interaction between F and I as entering and leaving groups explain the Gibbs free energies.

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Chemical Constituents of the Marine Sponge Aaptos aaptos (Schmidt, 1864) and Their Cytotoxic Activity

Natural Product Communications ◽

10.1177/1934578x21993345 ◽

2021 ◽

Vol 16 (2) ◽

pp. 1934578X2199334

Author(s):

Do Thi Trang ◽

Bui Huu Tai ◽

Dan Thuy Hang ◽

Pham Hai Yen ◽

Phan Thi Thanh Huong ◽

...

Keyword(s):

Cytotoxic Activity ◽

Spectral Data ◽

Absolute Configuration ◽

Marine Sponge ◽

Chemical Constituents ◽

2D Nmr ◽

Extensive Analysis ◽

First Time ◽

Tddft Method ◽

Mcf 7

Seven compounds (1-7) were isolated from the marine sponge Aaptos aaptos living in the Vietnamese sea. Their structures were determined as 2 hours, 5 H,7 H,9 H-9 S-hydroxy-imidazo[1,5- α]pyridine-1,3-dione (1), 3-([9-methylhexadecyl]oxy)propane-1,2-diol 2, 2,3-dihydro-2,3-dioxoaaptamine (3), indol-3-aldehyde (4), methyl indole-3-carboxylate (5) 4-hydroxy-5-(indole-3-yl)−5-oxo-pentan-2-one (6), and thymidine (7) by extensive analysis of HR-ESI-MS, 1D, and 2D NMR spectral data, as well as by comparison of the spectral data with those reported in the literature. In addition, the absolute configuration of 1 was determined from the experimental ECD spectrum and comparison of this with the theoretical ECD calculations using the TDDFT method. Compounds 1 and 2 were isolated from nature for the first time. Compound 3 induced cytotoxic activity against SK-LU-1, MCF-7, HepG2, and SK-Mel-2 cell lines with IC50 values of 41.27 ± 2.63, 40.70 ± 2.65, 34.31 ± 3.43, and 36.63 ± 1.40 µM, respectively.

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Phenolic Constituents of Knautia arvensis Aerial Parts

Natural Product Communications ◽

10.1177/1934578x1100601117 ◽

2011 ◽

Vol 6 (11) ◽

pp. 1934578X1100601 ◽

Cited By ~ 1

Author(s):

Jaroslaw Moldoch ◽

Barbara Szajwaj ◽

Milena Masullo ◽

Lukasz Pecio ◽

Wieslaw Oleszek ◽

...

Keyword(s):

Chlorogenic Acid ◽

2D Nmr ◽

Spectroscopic Methods ◽

Flavone Glycoside ◽

Aerial Parts ◽

Dicaffeoylquinic Acid ◽

Phenolic Constituents ◽

First Time

A new C-6 flavone glycoside (6), together with seven known compounds, cryptochlorogenic acid (1), chlorogenic acid (2), 2- O- trans-caffeoylhydrocitric acid (3), isovitexin 7-β-D-glucopyranoside (4), 7,4′-dihydroxy-5-methoxyflavone-6- C-β-D-glucopyranoside (5), 3,5- O-dicaffeoylquinic acid (7) and 4,5- O-dicaffeoylquinic acid (8), were isolated from the aerial parts of Knautia arvensis. Their structures were elucidated by extensive spectroscopic methods including 1D- (1H, 13C and TOCSY) and 2D-NMR (DQF-COSY, HSQC, HMBC) experiments, as well as ESIMS analysis. Compounds 1, 3-5 and 8 are reported for the first time in Knautia arvensis.

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