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Angewandte Chemie (International Ed. in... Mar 2020The combination of electrocyclizations and cycloadditions accounts for the formation of a range of fascinating natural products. Cascades consisting of 8π...
The combination of electrocyclizations and cycloadditions accounts for the formation of a range of fascinating natural products. Cascades consisting of 8π electrocyclizations followed by a 6π electrocyclization and a cycloaddition are relatively common. We now report the synthesis of the tetramic acid PF-1018 through an 8π electrocyclization, the product of which is immediately intercepted by a Diels-Alder cycloaddition. The success of this pericyclic cascade was critically dependent on the substitution pattern of the starting polyene and could be rationalized through DFT calculations. The completion of the synthesis required the instalment of a trisubstituted double bond by radical deoxygenation. An unexpected side product formed through 4-exo-trig radical cyclization could be recycled through an unprecedented triflation/fragmentation.
Topics: Biological Products; Cyclization; Cycloaddition Reaction; Density Functional Theory; Electrochemical Techniques; Models, Molecular; Polyenes; Pyrrolidinones; Pyrrolizidine Alkaloids; Stereoisomerism
PubMed: 31788926
DOI: 10.1002/anie.201912452 -
Critical Reviews in Biotechnology Jun 2023The demand for food, feed, cosmeceutical, and nutraceutical supplements/additives from natural sources has been rapidly increasing, with expectations for a faster... (Review)
Review
The demand for food, feed, cosmeceutical, and nutraceutical supplements/additives from natural sources has been rapidly increasing, with expectations for a faster expansion than the growth of the global markets in the coming years. In this framework, a particular interest is given to carotenoids due to their outstanding antioxidant activities, particularly the xanthophylls class. Torularhodin is one of these carotenoids that stands out for its multifunctional role as: antioxidant, anticancer and antimicrobial, yet its commercial potential is still unexplored. Although most xanthophylls can be naturally found in: microbial, plant and animal sources, torularhodin is only produced by microbial species, especially red oleaginous yeast. The microbial production of xanthophylls has many advantages as compared to other natural sources, such as: the need for low production area, easier extraction, high yields (at optimum operating conditions), and low (or no) seasonal, climatic, and geographic variation dependency. Due to the importance of natural products and their relevance to the market, this review provides a comprehensive overview of the: properties, characteristics and potential health benefits of torularhodin. Moreover, the most promising developments in both upstream and downstream processing to obtain this colorant from microbial sources are considered. For this purpose, the main microorganisms used for torularhodin production are firstly reviewed, including biosynthesis pathway and torularhodin properties. Following, an overall analysis of the processing aspects related with its: extraction, separation and purification is provided. Lastly, current status and future trends of torularhodin-based processes and products such as therapeutic agents or biomaterials are discussed, indicating promising directions toward biorefinery and circular economy.
Topics: Animals; Antioxidants; Carotenoids; Xanthophylls
PubMed: 35430937
DOI: 10.1080/07388551.2022.2041540 -
Sheng Wu Gong Cheng Xue Bao = Chinese... May 2023Polyolefin plastics are a group of polymers with C-C backbone that have been widely used in various areas of daily life. Due to their stable chemical properties and poor... (Review)
Review
Polyolefin plastics are a group of polymers with C-C backbone that have been widely used in various areas of daily life. Due to their stable chemical properties and poor biodegradability, polyolefin plastic waste continues to accumulate worldwide, causing serious environmental pollution and ecological crises. In recent years, biological degradation of polyolefin plastics has attracted considerable attention. The abundant microbial resources in the nature offer the possibility of biodegradation of polyolefin plastic waste, and microorganisms capable of degrading polyolefin have been reported. This review summarizes the research progress on the biodegradation microbial resources and the biodegradation mechanisms of polyolefin plastics, presents the current challenges in the biodegradation of polyolefin plastics, and provides an outlook on future research directions.
Topics: Plastics; Polymers; Polyenes; Biodegradation, Environmental
PubMed: 37212222
DOI: 10.13345/j.cjb.221024 -
Marine Drugs May 2022Over the past few decades (covering 1972 to 2022), astounding progress has been made in the elucidation of structures, bioactivities and biosynthesis of polyene... (Review)
Review
Over the past few decades (covering 1972 to 2022), astounding progress has been made in the elucidation of structures, bioactivities and biosynthesis of polyene macrolactams (PMLs), but they have only been partially summarized. PMLs possess a wide range of biological activities, particularly distinctive fungal inhibitory abilities, which render them a promising drug candidate. Moreover, the unique biosynthetic pathways including β-amino acid initiation and pericyclic reactions were presented in PMLs, leading to more attention from inside and outside the natural products community. According to current summation, in this review, the chem- and bio-diversity of PMLs from marine and terrestrial sources are considerably rich. A systematic, critical and comprehensive overview is in great need. This review described the PMLs' general structural features, production strategies, biosynthetic pathways and the mechanisms of bioactivities. The challenges and opportunities for the research of PMLs are also discussed.
Topics: Biological Products; Biosynthetic Pathways; Polyenes
PubMed: 35736163
DOI: 10.3390/md20060360 -
Angewandte Chemie (International Ed. in... Jan 2023A catalysis-based regioselective 1,4-fluorofunctionalization of trifluoromethyl substituted 1,3-dienes has been developed to access compact, highly functionalized...
A catalysis-based regioselective 1,4-fluorofunctionalization of trifluoromethyl substituted 1,3-dienes has been developed to access compact, highly functionalized products. The process allows E,Z-mixed dienes to be processed to a single E-alkene isomer, and leverages an inexpensive and operationally convenient I(I)/I(III) catalysis platform. The first example of catalytic 1,4-difluorination is disclosed and subsequently evolved to enable 1,4-hetero-difunctionalization, which allows δ-fluoro-alcohol and amine derivatives to be forged in a single operation. The protocol is compatible with a variety of nucleophiles including fluoride, nitriles, carboxylic acids, alcohols and even water thereby allowing highly functionalized products, with a stereocenter bearing both C(sp )-F and C(sp )-CF groups, to be generated rapidly. Scalability (up to 3 mmol), and facile post-reaction modifications are demonstrated to underscore the utility of the method in expanding organofluorine chemical space.
Topics: Polyenes; Isomerism; Alkenes; Catalysis; Alcohols
PubMed: 36345795
DOI: 10.1002/anie.202214906 -
Food Research International (Ottawa,... Mar 2021The aim of this study was the use and revalorization of two persimmon by-products A and B generated in the juice production process. The by-product B resulting from a...
The aim of this study was the use and revalorization of two persimmon by-products A and B generated in the juice production process. The by-product B resulting from a pectinase enzymatic treatment of peels and pulp to optimize juice extraction was especially suitable for recovery of valuable bioactive carotenoids. The extraction solvents and solvent combinations used were: ethanol, acetone, ethanol/acetone (50:50 v/v) and ethanol/acetone/hexane (25:25:50 v/v/v). HPLC-DAD analysis detected and identified a total of nine individual carotenoids namely violaxanthin, neoxanthin, antheraxanthin, lutein, zeaxanthin, β-cryptoxanthin 5,6-epoxide, β-cryptoxanthin, α-carotene, and β-carotene. β-cryptoxanthin and β-carotene represented 49.2% and 13.2% of the total carotenoid content (TCC) in the acetone extract from by-product B. TCC contributed greatly to antioxidant activity of acetone extract derived from this by-product. Pectinase enzymatic treatment of persimmon peels and pulp followed by absolute acetone extraction of carotenoids could be an efficient method to obtain a rich extract in these compounds that could be used as nutraceutical ingredient.
Topics: Carotenoids; Diospyros; Fruit; Lutein; Zeaxanthins
PubMed: 33641941
DOI: 10.1016/j.foodres.2020.109882 -
International Journal of Molecular... Nov 2022are of great interest in the pharmaceutical industry as they produce a plethora of secondary metabolites that act as antibacterial and antifungal agents. They may... (Review)
Review
are of great interest in the pharmaceutical industry as they produce a plethora of secondary metabolites that act as antibacterial and antifungal agents. They may thrive on their own in the soil, or associate with other organisms, such as plants or invertebrates. Some soil-derived strains exhibit hemolytic properties when cultivated on blood agar, raising the question of whether hemolysis could be a virulence factor of the bacteria. In this work we examined hemolytic compound production in 23 β-hemolytic isolates; of these 12 were soil-derived, 10 were arthropod-associated, and 1 was plant-associated. An additional human-associated sp. TR1341 served as a control. Mass spectrometry analysis suggested synthesis of polyene molecules responsible for the hemolysis: candicidins, filipins, strevertene A, tetrafungin, and tetrin A, as well as four novel polyene compounds (denoted here as polyene A, B, C, and D) in individual liquid cultures or paired co-cultures. The non-polyene antifungal compounds actiphenol and surugamide A were also identified. The findings indicate that the ability of to produce cytolytic compounds (here manifested by hemolysis on blood agar) is an intrinsic feature of the bacteria in the soil environment and could even serve as a virulence factor when colonizing available host organisms. Additionally, a literature review of polyenes and non-polyene hemolytic metabolites produced by is presented.
Topics: Humans; Streptomyces; Antifungal Agents; Anti-Bacterial Agents; Polyenes; Hemolysis; Virulence Factors
PubMed: 36499372
DOI: 10.3390/ijms232315045 -
Organic & Biomolecular Chemistry Dec 2021The antioxidant capacity of β-carotene has been studied in terms of H-atom abstraction reactions using quantum chemical methods. These oxidation reactions are studied...
The antioxidant capacity of β-carotene has been studied in terms of H-atom abstraction reactions using quantum chemical methods. These oxidation reactions are studied for the all- as well as 15,15'- isomers (15) of β-carotene, as the latter is only ∼10 kJ mol less stable than the all- isomer in the gas phase and about 9 kJ mol less stable in aqueous solution. Hydrogen abstraction from the rotamers obtained through C-C single and double bond rotations has been shown to play an important role in determining the antioxidant capacity of β-carotene. Hydrogen abstraction from the C4 and C5-CH positions of the β-ionone rings and the C7 and C9 positions along the polyene chain of β-carotene by the hydroxyl radical have been studied. In the all- form the most favorable H-atom abstraction reaction occurs at the C4 position of the terminal regions of the polyene π-system of β-carotene, closely followed by hydrogen abstraction from the C5 methyl position. The H-atom abstraction reactions are more exothermic in water than in the gas phase due to solvation energies for the water product.
Topics: Antioxidants; Density Functional Theory; Molecular Conformation; beta Carotene
PubMed: 34874031
DOI: 10.1039/d1ob01723c -
Communications Biology Feb 2023This Perspective discusses how retinol catalyzes resonance energy transfer (RET) reactions pivotally important for mitochondrial energy homeostasis by protein kinase C... (Review)
Review
This Perspective discusses how retinol catalyzes resonance energy transfer (RET) reactions pivotally important for mitochondrial energy homeostasis by protein kinase C δ (PKCδ). PKCδ signals to the pyruvate dehydrogenase complex, controlling oxidative phosphorylation. The PKCδ-retinol complex reversibly responds to the redox potential of cytochrome c, that changes with the electron transfer chain workload. In contrast, the natural retinoid anhydroretinol irreversibly activates PKCδ. Its elongated conjugated-double-bond system limits the energy quantum absorbed by RET. Consequently, while capable of triggering the exergonic activating pathway, anhydroretinol fails to activate the endergonic silencing path, trapping PKCδ in the ON position and causing harmful levels of reactive oxygen species. However, physiological retinol levels displace anhydroretinol, buffer cyotoxicity and potentially render anhydroretinol useful for rapid energy generation. Intriguingly, apocarotenoids, the primary products of the mitochondrial β-carotene,9'-10'-oxygenase, have all the anhydroretinol-like features, including modulation of energy homeostasis. We predict significant conceptual advances to stem from further understanding of the retinoid-catalyzed RET.
Topics: Retinoids; Vitamin A; beta Carotene; Biology
PubMed: 36854887
DOI: 10.1038/s42003-023-04602-x -
Molecules (Basel, Switzerland) Dec 2022Carotenoid compounds are ubiquitous in nature, providing the characteristic colouring of many algae, bacteria, fruits and vegetables. They are a critical component of... (Review)
Review
Carotenoid compounds are ubiquitous in nature, providing the characteristic colouring of many algae, bacteria, fruits and vegetables. They are a critical component of the human diet and play a key role in human nutrition, health and disease. Therefore, the clinical importance of qualitative and quantitative carotene content analysis is increasingly recognised. In this review, the structural and optical properties of carotenoid compounds are reviewed, differentiating between those of carotenes and xanthophylls. The strong non-resonant and resonant Raman spectroscopic signatures of carotenoids are described, and advances in the use of Raman spectroscopy to identify carotenoids in biological environments are reviewed. Focus is drawn to applications in nutritional analysis, optometry and serology, based on in vitro and ex vivo measurements in skin, retina and blood, and progress towards establishing the technique in a clinical environment, as well as challenges and future perspectives, are explored.
Topics: Humans; Lutein; Spectrum Analysis, Raman; beta Carotene; Carotenoids; Xanthophylls; Zeaxanthins
PubMed: 36558154
DOI: 10.3390/molecules27249017