scholarly journals 3-Thienyl/benzothienylchromones. Synthesis and properties

2020 ◽  
Vol 8 (1) ◽  
pp. 174-183
Author(s):  
Natalia Gorbulenko ◽  
Tatiana Shokol ◽  
Vladimir Khilya
Keyword(s):  
Biological Activity ◽  
Transition Metals ◽  
Cyclization Reactions ◽  
Ch Activation ◽  
Oxidative Rearrangement ◽  
Testing Data ◽  
First Time

This mini-review for the first time summarizes and systematizes all the data available in the literature on the synthesis and properties of 3-thienyl/benzothienylchromones, starting from 1960. Two main approaches to the formation of target structures are presented. The conditions of cyclization reactions, oxidative rearrangement, transition metals catalyzed CH activation and annulation reactions, etc. are discussed. Testing data for some types of biological activity of a number of the 3-thienyl/benzothienylchromones and the products of their transformation into the pyrazole cycle are given.

The Pattern of Acetylation Defines the Priming Activity of Chitosan Tetramers

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 <i>β</i>-1,4-linked glucosamine (deacetylated/D) and <i>N</i>-acetylglucosamine (acetylated/A) units. To address this hypothesis, we prepared partially-acetylated chitosan oligosaccharides from a chitosan polymer (DA=35%, DP<sub>w</sub>=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 <i>bona fide</i> information-carrying molecules

The Pattern of Acetylation Defines the Priming Activity of Chitosan Tetramers

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 <i>β</i>-1,4-linked glucosamine (deacetylated/D) and <i>N</i>-acetylglucosamine (acetylated/A) units. To address this hypothesis, we prepared partially-acetylated chitosan oligosaccharides from a chitosan polymer (DA=35%, DP<sub>w</sub>=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 <i>bona fide</i> information-carrying molecules

Strategies for Oral Delivery of Metal-Saturated Lactoferrin

2019 ◽  
Vol 20 (11) ◽  
pp. 1046-1051 ◽  
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.

Organic Reactivity Control by Means of Neighboring Groups and Organometallics. A Personal Account

1994 ◽  
Vol 59 (1) ◽  
pp. 1-74 ◽  
Author(s):  
Pavel Kočovský
Keyword(s):  
Transition Metals ◽  
Cyclopropane Ring ◽  
Allylic Substitutions ◽  
Recent Developments ◽  
Cardioactive Drug ◽  
Novel Method ◽  
Metal Catalyzed ◽  
Electrophilic Additions ◽  
Near Future ◽  
First Time

This review summarizes the main topics of our research and covers the period of the last 15 years. The prime interest is focused on various ways of controlling the regio- and stereoselectivity of selected organic reactions, in particular electrophilic additions, cleavage of cyclopropane rings, and allylic substitutions by means of neighboring groups and/or transition and non-transition metals. In the first part, the factors governing the course of electrophilic additions are assessed, culminating in the formulation of selection rules for the reactivity of cyclohexene systems, and in a concise synthesis of the natural cardioactive drug, strophanthidin. These studies also contribute to a better understanding of the mechanisms of electrophilic additions. The second part describes recent developments in the stereo- and regiocontrolled cleavage of cyclopropane rings by non-transition metals (Tl and Hg), and the reactivity and transmetalation (with Pd) of the primary products. This methodology has resulted in novel routes to unique polycyclic structures, and will have synthetic applications in the near future. Evidence for the stereospecific "corner" cleavage of the cyclopropane ring has been provided for the first time for Tl and later for Hg. The third part deals with transition metal-catalyzed allylic substitution. Evidence for a new "syn" mechanism for the formation of the intermediate (π-allyl)palladium complex has been provided, which runs counter to the generally accepted "anti" mechanism. A novel method for a Pd-catalyzed allylic oxidation has been developed and employed in the synthesis of natural sesquiterpenes. The increasing importance of transition and non-transition metals for synthetic organic chemistry is demonstrated by their unique reactivity in a number of the papers included in this review.

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

2020 ◽  
Vol 9 (1) ◽  
pp. 416-428 ◽  
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.

Ion chemistry of transition metals in hydrocarbon flames. II. Cations of Sc, Ti, V, Cr, and Mn

1988 ◽  
Vol 66 (9) ◽  
pp. 2219-2228 ◽  
Author(s):  
John M. Goodings ◽  
Quang Tran ◽  
Nicholas S. Karellas
Keyword(s):  
Transition Metals ◽  
Metal Atom ◽  
Chemical Ionization ◽  
Metallic Ions ◽  
Ion Chemistry ◽  
Hydrocarbon Flames ◽  
Basic Series ◽  
First Time ◽  
Isomeric Structures

The same fuel-rich, premixed, conical, methane–oxygen flame at 2200 K and atmospheric pressure used for studies of Fe, Co, Ni, Cu, and Zn in Part I (1) is doped with the same concentration (~1 ppm) of Sc, Ti, V, Cr, and Mn to complete the first row of ten transition metals. Metallic ions of these metals and their compounds formed by chemical ionization reactions with H3O+ are observed by sampling the flame through a nozzle into a quadrupole mass spectrometer. Concentration profiles of individual and total cations are measured as a function of distance along the flame axis, and also mass spectra at a fixed point in the burnt gas. If A is the metal atom, the observed ions can be represented by four hydrate series including (a) A+•nH2O, (b) AOH+•nH2O, (c) AO+•nH2O, and (d) AO2H+•nH2O with n = 0–3 or 4, giving a maximum of four ligands around the metal atom. However, alternative isomeric structures are possible for each of the four basic series (e.g. AO+•2H2O ~ A(OH)2+•H2O ~ A(OH)3H+). The ions observed with Cr and Mn, in common with those of Fe, Co, Ni, and Cu, strongly favour series (a). On the other hand, Sc is completely different; the ions of series (c) are dominant. All four series are observed with each of Ti and V. Series (b) dominates for Ti and series (c) for V; ions from series (d) were observed for the first time. The ion chemistry of these metals is discussed in detail with emphasis on the probable chemical ionization reactions responsible for metallic ion formation. The pre-eminent role of proton transfer processes is apparent.

Synthesis, characterization, and biological activity of transition metals complexes with mefenamic acid (NSAIDs)

2015 ◽  
Vol 85 (7) ◽  
pp. 1745-1751 ◽  
Author(s):  
S. Ramzan ◽  
S. Saleem ◽  
B. Mirza ◽  
S. Ali ◽  
F. Ahmed ◽  
...  
Keyword(s):  
Biological Activity ◽  
Transition Metals ◽  
Mefenamic Acid

Farringtonite as an efficient catalyst for linear-chain α-olefin epoxidation with aqueous hydrogen peroxide

2021 ◽  
Author(s):  
Xingyu Yang ◽  
Xu Li ◽  
Jinxiang Dong
Keyword(s):  
Hydrogen Peroxide ◽  
Transition Metals ◽  
Linear Chain ◽  
Olefin Epoxidation ◽  
Aqueous Hydrogen Peroxide ◽  
Efficient Catalyst ◽  
First Time

A convenient, scalable, benign, and efficient epoxidation method based on farringtonite, without the use of transition metals, was developed for the first time.

Synthesis of Galactomannan Sulfate-Citrate

2022 ◽  
Vol 1049 ◽  
pp. 218-223
Author(s):  
Aleksandr S. Kazachenko ◽  
Yuriy N. Malyar ◽  
Anna S. Kazachenko
Keyword(s):  
Biological Activity ◽  
Ftir Spectroscopy ◽  
X Ray Diffraction ◽  
Absorption Bands ◽  
X Ray ◽  
Mixed Ester ◽  
First Time ◽  
Derivatives Of

Sulfated derivatives of polysaccharides have anticoagulant, hypolipedimic and other biological activity. In this work, a complex mixed ester of galactomannan, its sulfate-citrate, was obtained for the first time. The introduction of citrate and sulfate groups was proved by FTIR spectroscopy by the appearance of corresponding absorption bands. It was shown by X-ray diffraction that the introduction of the citrate group leads to the amorphization of the galactomannan structure.

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