Chalcone is an aromaticketone and an enone that forms the central core for a variety of important biological compounds, which are known collectively as chalcones or chalconoids. Alternative names for chalcone include benzylideneacetophenone, phenyl styryl ketone, benzalacetophenone, β-phenylacrylophenone, γ-oxo-α,γ-diphenyl-α-propylene, and α-phenyl-β-benzoylethylene.
Chemical properties
Chalcones have two absorption maximums at 280 nm and 340 nm.
Chemical reactions
Synthesis
Chalcones can be prepared by an aldol condensation between benzaldehyde and acetophenone in the presence of sodium hydroxide as a catalyst. This reaction can be carried out without any solvent as a solid-state reaction. The reaction between substituted benzaldehydes and acetophenones can be used as an example of green chemistry in undergraduate education. In a study investigating green syntheses, chalcones were synthesized from the same starting materials in high-temperature water. Substituted chalcones were also synthesised by piperidine-mediated condensation to avoid side reactions such as multiple condensations, polymerizations, and rearrangements.
Other reactions
An example is the conjugate reduction of the enone by tributyltin hydride: 3,5-Disubstituted 1H-pyrazoles can be produced from a suitably substituted chalcone by reaction with hydrazine hydrate in the presence of elemental sulfur or sodium persulfate, or by using a hydrazone in which case an azine is produced as a by-product. The specific case for formation of 3,5-diphenyl-1H-pyrazole from chalcone itself can be represented as:
Potential pharmacology
Chalcones and their derivatives demonstrate a wide range of biological activities including anti-inflammation. Some 2′-amino chalcones are have been studied as potential antitumor agents. The therapeutic, catalytic, chemosensing, and photosensitizing potentials of various Metal -Chalcone complexes have also been reported.
Biological Target Inhibition Perspectives
Several natural and synthetic chalcones have shown anti-cancer activity due to their inhibitory potential against various targets namely ATP-binding cassette super-family G member 2, P-glycoprotein, Breast Cancer Resistance Protein, 5α-reductase, aromatase, 17-β-hydroxysteroid dehydrogenase, histone deacetylase /Sirtuin-1, proteasome, vascular endothelial growth factor, vascular endothelial growth factor receptor-2 kinase, matrix metalloproteinases -2/9, Janus kinases /Signal transducer and activator of transcription proteins signaling pathways, Cell Division Cycle-25, tubulin, cathepsin-K, topoisomerase-II, Wingless-related integration site, nuclear factor kappa-light-chain-enhancer of activated B cells, v-raf murine sarcoma viral oncogene homolog B1, mammalian target of rapamycin, etc. Chalcone molecules deserve the credit of being potential anti-diabetic candidates that act by modulating the therapeutic targets Peroxisome proliferator-activated receptor gamma, Dipeptidyl peptidase-4, α-glucosidase, Protein-tyrosine Phosphatase 1B, aldose reductase, and tissue sensitivity. Chalcones have been identified as the potential anti-infective candidates that inhibit various parasitic, malarial, bacterial, viral, and fungal targets like cruzain-1/2, trypanopain-Tb, trans-sialidase, glyceraldehyde-3-phosphate dehydrogenase, fumarate reductase, falcipain-1/2, β-hematin, topoisomerase-II, plasmepsin-II, lactate dehydrogenase, protein kinases, sorbitol-induced hemolysis, recombinant dengue virus Type 1, influenza A virus, human immunodeficiency virus, protein tyrosine phosphatase A/B, filamentous temperature-sensitive mutant Z, fatty acid syntheses, lactate/isocitrate dehydrogenase, NorA efflux pump, deoxyribonucleic acid gyrase, fatty acid synthase, chitin synthase, β--glucan synthase, etc. Chalcones are the promising candidates in inhibiting various cardiovascular, hematological and anti-obesity targets like angiotensin-converting enzyme, cholesteryl ester transfer protein, diacylglycerol acyltransferase, acyl-coenzyme A: cholesterol acyltransferase, pancreatic lipase, lipoprotein lipase, calcium /potassium channel, thromboxane, etc. Chalcone derivatives have demonstrated admirable anti-inflammatory activity due to their inhibitory potential against various therapeutic targets like cyclooxygenase, lipooxygenase, interleukins, prostaglandins, nitric oxide synthase, leukotriene D4, nuclear factor-κB, intracellular cell adhesion molecule-1, vascular cell adhesion molecule-1, monocyte chemoattractant protein-1, TLR4/MD-2, etc.
