Microbiological and Chemical Transformations of Argentatin B

2003 ◽  
Vol 58 (3-4) ◽  
pp. 249-255 ◽  
Author(s):  
Galal T. Maatooq
Keyword(s):  
Pyridinium Chlorochromate ◽  
Chemical Transformations ◽  
Parthenium Argentatum ◽  
Aqueous Methanol ◽  
Isomeric Mixture ◽  
Naturally Occurring ◽  
Nocardia Corallina ◽  
Hydrochloric Acid Treatment ◽  
Equatorial Proton ◽  
Cerium Sulfate

Argentatin B is a naturally occurring tetracyclic triterpene isolated from Parthenium argentatum x P. tomentosa. It was microbiologically transformed to 16, 24-epoxycycloartan-3α, 25- diol, (isoargentatin D), by Nocardia corallina var. taoka ATCC 31338, Mycobacterium species NRRL B3683 and Septomyxa affinis ATCC 6737. The later microbe also produced 16, 24- epoxycycloartan-3β, 25-diol (argentatin D) and 1, 2-didehydroargentatin B, (isoargentatin D). Sodium hydroxide converted argentatin B to argentatin D and isoargentatin D. Hydrochloric acid treatment gave cycloartan-25-ol-3, 24-dione. Cerium sulfate/sulfuric acid/aqueous methanol induced scission of the isopropanol moiety and provided an isomeric mixture of 24-methoxy-25-27-trinorargentatin B. Oxidation of this isomeric mixture with pyridinium chlorochromate, selectively, attacked the isomer with the equatorial proton at position-24 to give the corresponding lactone, 24-oxo-25-27-trinorargentatin B. The produced compounds were characterized by spectroscopic methods.

scholarly journals Electrochemical Corey–Winter reaction. Reduction of thiocarbonates in aqueous methanol media and application to the synthesis of a naturally occurring α-pyrone

2018 ◽  
Vol 14 ◽  
pp. 547-552 ◽  
Author(s):  
Ernesto Emmanuel López-López ◽  
José Alvano Pérez-Bautista ◽  
Fernando Sartillo-Piscil ◽  
Bernardo A Frontana-Uribe
Keyword(s):  
Room Temperature ◽  
Supporting Electrolyte ◽  
Trichoderma Viride ◽  
Chemical Yield ◽  
Vitreous Carbon ◽  
Aqueous Methanol ◽  
High Chemical ◽  
Naturally Occurring ◽  
Divided Cell ◽  
Stereo Selectivity

An electrochemical version of the Corey–Winter reaction was developed giving excellent results in aqueous methanol media (MeOH/H2O (80:20) with AcOH/AcONa buffer 0.5 M as supporting electrolyte), using a reticulated vitreous carbon as cathode in a divided cell. The electrochemical version is much more environmentally friendly than the classical reaction, where a large excess of trialkyl phosphite as reducing agent and high temperatures are required. Thus, cathodic reduction at room temperature of two cyclic thiocarbonates (−1.2 to −1.4 V vs Ag/AgCl) afforded the corresponding alkenes, trans-6-(pent-1-enyl)-α-pyrone and trans-6-(pent-1,4-dienyl)-α-pyrone, which are naturally occurring metabolites isolated from Trichoderma viride and Penicillium, in high chemical yield and with excellent stereo selectivity.

scholarly journals Tailored Functionalization of Natural Phenols to Improve Biological Activity

Biomolecules ◽  
2021 ◽  
Vol 11 (9) ◽  
pp. 1325
Author(s):  
Barbara Floris ◽  
Pierluca Galloni ◽  
Valeria Conte ◽  
Federica Sabuzi
Keyword(s):  
Biological Activity ◽  
Essential Oils ◽  
Phenolic Acids ◽  
Biological Role ◽  
Chemical Transformations ◽  
Nutritional Properties ◽  
Curcumin Derivatives ◽  
Naturally Occurring ◽  
Anti Oxidant ◽  
Natural Phenols

Phenols are widespread in nature, being the major components of several plants and essential oils. Natural phenols’ anti-microbial, anti-bacterial, anti-oxidant, pharmacological and nutritional properties are, nowadays, well established. Hence, given their peculiar biological role, numerous studies are currently ongoing to overcome their limitations, as well as to enhance their activity. In this review, the functionalization of selected natural phenols is critically examined, mainly highlighting their improved bioactivity after the proper chemical transformations. In particular, functionalization of the most abundant naturally occurring monophenols, diphenols, lipidic phenols, phenolic acids, polyphenols and curcumin derivatives is explored.

scholarly journals [3+2] Cycloadditions: Part XXXV. Selective Cycloadditions of C-(4-Chlorophenyl)-N-methyl Nitrone to Cinnamic Acid Anilides

2020 ◽  
Vol 32 (8) ◽  
pp. 1886-1894
Author(s):  
Sumana Sengupta ◽  
Avijit Banerji ◽  
Thierry Prangé ◽  
Alain Neuman ◽  
Jayram Hazra
Keyword(s):  
Natural Products ◽  
Bioactive Compounds ◽  
Cinnamic Acid ◽  
Nitrogen Heterocycles ◽  
Xrd Analysis ◽  
Chemical Transformations ◽  
Nmr Studies ◽  
Naturally Occurring ◽  
Acid Anilides

[3+2] Cycloadditions of nitrones as three-atom components to alkenes yield isoxazolidine cycloadducts, which on chemical transformations can be converted to bioactive compounds. The [3+2] cycloadditions route thus provides conversion of simple natural products to more complex naturally occurring bioactive nitrogen heterocycles, and close analogues. As α,β-unsaturated amides abundantly occur as natural products, [3+2] cycloadditions of nitrones with simpler α,β-unsaturated amides were studied to get information about reactivity profiles. The reactions of C-(4-chlorophenyl)-N-methyl nitrone as three-atom component to cinnamic acid anilides were investigated. The 3,4-trans-4,5-trans-4- carboxanilido-2-methyl-3,5-diaryl isoxazolidines were the major cycloadducts; the diastereoisomeric 3,4-cis-4,5-trans-4-carboxanilido-2-methyl-3,5-diaryl isoxazolidines and regioisomeric 3,4-trans-4,5- trans-5-carboxanilido-2-methyl-3,4-diaryl isoxazolidines were obtained as minor cycloadducts. The cycloadducts were characterized by NMR studies and XRD analysis.

scholarly journals Chemical Transformations of Parthenin, a Natural Bioactive Sesquiterpenoid [1]

2009 ◽  
Vol 4 (1) ◽  
pp. 1934578X0900400
Author(s):  
Biswanath Das ◽  
G. Satyalakshmi ◽  
Nisith Bhunia ◽  
K. Ravider Reddy ◽  
V. Saidi Reddy ◽  
...  
Keyword(s):  
Vital Role ◽  
Chemical Transformations ◽  
Chemical Modifications ◽  
Naturally Occurring

Chemical modifications of parthenin, a naturally occurring bioactive sesquiterpenoid, were carried out in regio- and stereoselective manners using various inexpensive reagents to form different natural and unnatural analogues. Reactions including dehydration, reduction, alkylation, addition and hydroxylation have been studied. In some of the analogues, the α-methylene-γ-lactone moiety, which plays a vital role for bioactivity of parthenin, remained intact.

scholarly journals Cyclodextrin-based catalysts and molecular reactors

2005 ◽  
Vol 77 (11) ◽  
pp. 1865-1871 ◽  
Author(s):  
Christopher J. Easton
Keyword(s):  
Molecular Level ◽  
Electrophilic Aromatic Substitution ◽  
Chemical Transformations ◽  
Aromatic Substitution ◽  
Substitution Reactions ◽  
Naturally Occurring ◽  
Rate Of Hydrolysis ◽  
Reaction Vessels ◽  
Hydrolysis Of ◽  
Competing Reactions

The naturally occurring cyclodextrins and their derivatives have been developed as miniature reaction vessels, to manipulate the outcomes of chemical transformations at the molecular level. In this manner, the rate of hydrolysis of a phosphate triester has been enhanced by almost five orders of magnitude, and the ratios of products obtained from electrophilic aromatic substitution reactions, from competing reactions to give indigoid dyes, and from nitrile oxide cycloadditions have all been changed, by factors of up to 3500 times.

scholarly journals Computational protein design enables a novel one-carbon assimilation pathway

2015 ◽  
Vol 112 (12) ◽  
pp. 3704-3709 ◽  
Author(s):  
Justin B. Siegel ◽  
Amanda Lee Smith ◽  
Sean Poust ◽  
Adam J. Wargacki ◽  
Arren Bar-Even ◽  
...  
Keyword(s):  
Protein Design ◽  
Biosynthetic Pathway ◽  
Carbon Fixation ◽  
Carbon Assimilation ◽  
Dihydroxyacetone Phosphate ◽  
Design Tools ◽  
Chemical Transformations ◽  
Central Metabolism ◽  
Naturally Occurring

We describe a computationally designed enzyme, formolase (FLS), which catalyzes the carboligation of three one-carbon formaldehyde molecules into one three-carbon dihydroxyacetone molecule. The existence of FLS enables the design of a new carbon fixation pathway, the formolase pathway, consisting of a small number of thermodynamically favorable chemical transformations that convert formate into a three-carbon sugar in central metabolism. The formolase pathway is predicted to use carbon more efficiently and with less backward flux than any naturally occurring one-carbon assimilation pathway. When supplemented with enzymes carrying out the other steps in the pathway, FLS converts formate into dihydroxyacetone phosphate and other central metabolites in vitro. These results demonstrate how modern protein engineering and design tools can facilitate the construction of a completely new biosynthetic pathway.

Flavones as a Privileged Scaffold in Drug Discovery: Current Developments

2019 ◽  
Vol 16 (7) ◽  
pp. 968-1001
Author(s):  
Pone K. Boniface ◽  
Ferreira I. Elizabeth
Keyword(s):  
Biological Activities ◽  
Therapeutic Agents ◽  
Pharmacological Properties ◽  
Chemical Transformations ◽  
National Library ◽  
Scientific Publications ◽  
Multifactorial Diseases ◽  
Naturally Occurring ◽  
Privileged Scaffold

Background: Flavones are one of the main subclasses of flavonoids with diverse pharmacological properties. They have been reported to possess antimalarial, antimicrobial, anti-tuberculosis, anti-allergic, antioxidant, anti-inflammatory activities, among others. Objective: The present review summarizes the recent information on the pharmacological properties of naturally occurring and synthetic flavones. Method: Scientific publications referring to natural and synthetic flavones in relation to their biological activities were hand-searched in databases such as SciFinder, PubMed (National Library of Medicine), Science Direct, Wiley, ACS, SciELO, Springer, among others. Results: As per the literature, seventy-five natural flavones were predicted as active compounds with reference to their IC50 (<20 µg/mL) in in vitro studies. Also, synthetic flavones were found active against several diseases. Conclusion: As per the literature, flavones are important sources for the potential treatment of multifactorial diseases. However, efforts toward the development of flavone-based therapeutic agents are still needed. The appearance of new catalysts and chemical transformations is expected to provide avenues for the synthesis of unexplored flavones, leading to the discovery of flavones with new properties and biological activities.

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