This review focuses on the synthesis and biological activity of flavones and their related flavonoidic compounds: flavonols and aurones. Among the biological activities of flavones and aurones, the anticancer, antioxidant and antimicrobial properties are highlighted and detailed in this review. The most applied method for the synthesis of flavones and aurones is based on the oxidative cyclisation of o-hydroxychalcones. Depending on the reaction conditions and the structure of the precursor, in some cases several cyclization products result simultaneously: flavones, flavanones, flavonols and aurones. Based on the literature data and the results obtained in our research group, our aim is to highlight the most promising methods for the synthesis of flavones, as well as the synthetic routes for the other structurally related cyclization products, hydroxyflavones and aurones, considering that in practice it is difficult to predict which is the main or exclusive cyclisation product of o-hydroxychalcones under certain reaction conditions.

Two biotinylated derivatives of the main hop chalcone xanthohumol (1) were prepared by a one-step synthesis via esterification using biotin and 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide hydrochloride (EDC HCl) and 4-dimethylaminopyridine (DMAP) as coupling reagents. The products were characterized spectroscopically and their antiproliferative activity toward MCF-7, MCF-10A, HepG2, MDA-MB-231, 4T1 and Balb/3T3 cell lines was investigated using the SRB assay. For all three tested compounds the best activity was noted in the case of human (MCF-7) and mice (4T1) breast cancer cell lines (IC₅₀ values < 9 μM). Both biotinylated derivatives showed higher anticancer activity than xanthohumol (1) towards all types of tested breast cancer cells. Double biotinylated xanthohumol (3) proved to be the most active in inhibiting cell growth, with IC₅₀ values equal to 5.35 ± 1.5 μM for 4T1 and 8.03 ± 0.53 µM for MCF-7 cell lines. Compound 3 was also more active than 1 and 2 against liver cancer cells HepG2 (IC₅₀ = 17.37 ± 5.1 μM), while the IC₅₀ values for 1 and 2 were equal to 21.5 ± 2.7 and 22.1 ± 3.9 µM, respectively. 4‑O‑biotinylxanthohumol (2) was the second most active growth inhibitor, particularly with respect to MCF-7 (IC₅₀ = 6.19 ± 1.7 μM) and 4T1 (IC₅₀ = 6.64 ± 0.4 μM) cell lines. The antioxidant activity was evaluated using the 1.1-diphenyl-2-picrylhydrazyl radical (DPPH) method. All tested compounds (1-3) have antioxidant activity between 2.73 and 3.38 mM. It was reported for the first time that new prenylated chalcones containing the biotin moiety effectively inhibited proliferation of cancer cells in vitro.

This review provides a comprehensive and updated information on chalcones, presenting their sources, methods of identification and properties putting emphasis on applications in agricultural industry. Vast exploitation of synthetic pesticides led to the weed and pest resistance issue, causing economic loss but more importantly health risk due to pesticide overuse. Because one of the aim of the European Green Deal 2030 is the Farm to Fork strategy which targets on reducing by 50% the use of chemical pesticides by 2030, and push towards natural pesticides which are more environmentally friendly and restore natural resources, chalcones and their derivatives seem to fit perfectly. They have herbicidal, fungicidal, bactericidal and antiviral properties. Moreover, chalcones are naturally occurring substances, known for their favorable health effect for years, working on many areas. This review is complementary to the previous ones describing chalcones use in agriculture, updates them but additionally shows methods of detection.

Leishmaniasis is a group of neglected infectious, non-contagious diseases caused by parasites of the Leishmania genus which affects millions of people worldwide. The drugs available for its treatment, especially in cases of visceral leishmaniasis, are old, outdated, have serious side effects and in many cases are ineffective due to the emergence of resistant strains. In this context, the search for new candidates for more effective and safer drugs which can become new therapeutic alternatives is a constant need. In this work, 10 new chalcones were synthesized in high yields through Claisen-Schmidt condensation and were evaluated in vitro against Leishmania infantum promastigotes and amastigotes. CP04 and CP06 compounds were the most promising, respectively showing IC50 values = 13.64 ± 0.25 and 11.19 ± 0.22 against promastigotes, and IC50 = 18.92 ± 0.05 and 22.42 ± 0.05 against amastigotes. The compounds did not show cytotoxicity in erythrocytes, showing selectivity indexes greater than 74 and 90. Molecular docking studies carried out under the sterol 14-alpha demethylase (CYP-51) (PDB: 3L4D) and trypanothione reductase (PDB: 5EBK) enzymes from L. infantum evidenced the great affinity of the CP04 molecule for these targets, showing Moldock score values of -94.0758 and -50.5692 KJ/mol-1, with these values being much lower than the co-crystallized ligand energies. Molecular dynamics simulations demonstrated great stability of CP04 in its targets, thus indicating a real interaction possibility. Our findings confirm the potential that chalcones have as candidates for anti-leishmania drugs, and suggest that the CP04 compound may become a promising drug candidate to design and develop novel chalcone-based analogs for leishmaniosis therapy.