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FIG.5: NMR OF CHALCONE SEMICARBAZONE

Sugamoto, K., Matsusita, Y., Matsui, K., Kurogi, C., Matsui, T. 2011. Synthesis and Antibacterial Activity of Chalcones Bearing Prenyl or Geranyl Groups from Angelica keiskei. Tetrahedron Letters. 67: 5346–5359.

Aspergillus niger catalyzes the synthesis of flavonoids from chalcones

A mixture of chalcones derivatives 3b-d (1 mmol) and bromine (2 ml) in chloroform (25 ml) was stirred for 1–4 h. After cooling, ethanol was added and the precipitated solid was collected by filtration. Recrystallization from ethanol afforded 2,3-dibromo-1,3-diphenyl-propan-1-one derivatives as white powder 7b-d.

Isolation of Flavonoids and a Chalcone from …

FIG. 4: NMR OF CHALCONE

Chalcones are the principal precursors for the biosynthesis of flavonoids and isoflavonoids. A three carbon α, β-unsaturated carbonyl system constitutes chalcones. Chalcones are the condensation products of aromatic aldehyde with acetophenones in attendance of catalyst. They go through an assortment of chemical reactions and are found advantageous in synthesis of pyrazoline, isoxazole and a variety of heterocyclic compounds. In synthesizing a range of therapeutic compounds, chalcones impart key role. They have showed worth mentioning therapeutic efficacy for the treatment of various diseases. Chalcone based derivatives have gained heed since they own simple structures, and diverse pharmacological actions. A lot of methods and schemes have been reported for the synthesis of these compounds. Amongst all, Aldol condensation and Claisen-Schmidt condensation still grasp high up position. Other distinguished techniques include Suzuki reaction, Witting reaction, Friedel-Crafts acylation with cinnamoyl chloride, Photo-Fries rearrangement of phenyl cinnamates etc. These inventive techniques utilize various catalysts and reagents including SOCl2 natural phosphate, lithium nitrate, amino grafted zeolites, zinc oxide, water, Na2CO3, PEG400, silicasulfuric acid, ZrCl4 and ionic liquid etc. The development of better techniques for the synthesis of α, β- unsaturated carbonyl compounds is still in high demand. In brief, we have explained the methods and catalysts used in the synthesis of chalcones along with their biological activities in a review form to provide information for the development of new-fangled processes targeting better yield, less reaction time and least side effects with utmost pharmacological properties.

In this study, a novel series of chalcones fatty acid esters 5b-e and 6b-e have been synthesized via the reaction of the respective chalcones with either palmitic or stearic acid. Another related class of compounds comprising 2,3-disubstituted chalcones 7b-d and 8b(b’)-d as well as 2-amino-6-(substituted-phenyl)-4-substitutedphenyl-nicotinonitrile derivatives 9a,c,e have been also prepared by both electrophilic and Michael addition reactions, respectively, with the corresponding chalcones. The structures of all compounds are confirmed via a wide range of spectroscopic techniques including IR, 1H and 13C NMR, and mass spectra. Significantly, all synthesized compounds have been tested for their promising antioxidant activities via utilization of 1,1-biphenyl-2-picrylhydrazyl as a free radical scavenging reagent. Surprisingly, the results demonstrated that compound 5e (68.58% at C=2 μg/ml) was more effective as an antioxidant agent than the ascorbic acid, a commonly used antioxidant. Furthermore, the role and contribution of different functional groups on the antioxidant activity of the synthesized chalcone derivatives are also probed and rationalized in terms of their electronic and structural effect.

Synthesis and Cytotoxicity of Chalcones and 5-Deoxyflavonoids

Aspergillus niger catalyzes the synthesis of flavonoids from chalcones.

A comparative assessment of these activities is shown in Table . The data (Table ) clearly indicate that compounds having a meta ester group on B ring and/or para electron-withdrawing substituent as nitro group on A ring, as proposed for compounds (5d-e and 6d-e), gave very good activity. In particular, compounds 5e and 6e showed the strongest inhibition mainly at C=2 μg/ml as illustrated in Figure . Importantly, the level of activity of these compounds is very close from the level of ascorbic acid particularly at low concentrations. The deceasing of the activities at higher concentrations could arise from the stearic bulk imparted by the long chain of the alkyl groups and by the large size of the DPPH.

In order to test the influence of double bond as well on the antioxidant activity of chalcone, we assessed the compounds obtained via addition reaction on these double bonds, i.e., compounds 7b-d and 8b(b')-d. Previous work has highlighted that electrophilic addition reaction in chalcone derivatives, having different substituents, can cause the antioxidant activity of these derivatives to decrease. Consistent with this finding, we noted that addition of bromine to chalcone compound 3c in order to form compound 7c has decreased its activity from 43.67% to 6.44% particularly, when the concentration (C) is 2 μg/ml. Interestingly, replacing the bromine by the piperidine as is the case in compound 8c has resulted in marked increase in the antioxidant activity, leading to a maximum inhibition of 34.82% at C=2 μg/ml. On the basis of the overall results, it can be concluded that the presence of double bond in chalcone structure is also important to improve the antioxidant activity [,].

Chalcones | definition of Chalcones by Medical dictionary
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Highly Efficient Synthesis of Chalcones from Poly …

The phenomena of producing heat by electromagnetic irradiation are ether by collision or by conduction and sometime by both. All the wave energy changes its polarity from positive to negative with each cycle of the wave. This cause rapid orientation and reorientation of molecule which cause heating by collision. If the charge particles of material are free to travel thorough the material (e.g. Electron in a sample of carbon) and current will induce which will travel in phase with the field. If charge particles are bound within regions of material, the electric field component will cause them to move until opposing force balancing the electric force. 9

Methods of synthesizing flavonoids and chalcones - …

Chalcone, an important intermediate of flavonoid synthetic pathway, has been shown to exhibit diverse biological and pharmacological activities such as anti- cancer, antioxidant, anti-inflammatory, etc.

Flavonoids: definition, chemical structure, classification

Flavonoids: Flavonoids are extensive group of compounds occurring in plants. They are prominent plant secondary metabolites that have been found in dietary components including fruits, vegetables, olive oil, tea and red wine. It has been observed that even a high take of plant based dietary flavonoids is safe and not associated with any adverse health effect. 13 Over 5000 naturally occurring flavonoids have been characterized from various plants. Naturally and synthetic flavonoids have attracted considerable attention because of their broad spectrum of activity.

Flavonoid biosynthesis in plants: genes and enzymes

N2 - Chalcones are the principal precursors for the biosynthesis of flavonoids and isoflavonoids. A three carbon α, β-unsaturated carbonyl system constitutes chalcones. Chalcones are the condensation products of aromatic aldehyde with acetophenones in attendance of catalyst. They go through an assortment of chemical reactions and are found advantageous in synthesis of pyrazoline, isoxazole and a variety of heterocyclic compounds. In synthesizing a range of therapeutic compounds, chalcones impart key role. They have showed worth mentioning therapeutic efficacy for the treatment of various diseases. Chalcone based derivatives have gained heed since they own simple structures, and diverse pharmacological actions. A lot of methods and schemes have been reported for the synthesis of these compounds. Amongst all, Aldol condensation and Claisen-Schmidt condensation still grasp high up position. Other distinguished techniques include Suzuki reaction, Witting reaction, Friedel-Crafts acylation with cinnamoyl chloride, Photo-Fries rearrangement of phenyl cinnamates etc. These inventive techniques utilize various catalysts and reagents including SOCl2 natural phosphate, lithium nitrate, amino grafted zeolites, zinc oxide, water, Na2CO3, PEG400, silicasulfuric acid, ZrCl4 and ionic liquid etc. The development of better techniques for the synthesis of α, β- unsaturated carbonyl compounds is still in high demand. In brief, we have explained the methods and catalysts used in the synthesis of chalcones along with their biological activities in a review form to provide information for the development of new-fangled processes targeting better yield, less reaction time and least side effects with utmost pharmacological properties.

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