Search Results (8)

Skin aging is mainly caused by external factors like sunlight, which triggers oxidative stress and chronic inflammation. Natural halogenated flavonoids have demonstrated anti-inflammatory properties. Inspired by the macroalgae-derived bromophenol BDDE, we investigated the anti-inflammatory potential of structure-related chalcones (1–7). Chalcones 1 and 7 showed the least cytotoxicity in keratinocyte and macrophage cells. Chalcones 1, 2, 4, and 5 exhibited the most significant anti-inflammatory effects in murine macrophages after lipopolysaccharide stimulation, with chalcone 1 having the lowest IC₅₀ value (≈0.58 μM). A SNAP assay confirmed that chalcones do not exert their effects through direct NO scavenging. Symmetrical bromine atoms and 3,4-dimethoxy groups on both aromatic rings improved the anti-inflammatory activity, indicating a relevant structure–activity relationship. Chalcones 1 and 2 were selected for study to clarify their mechanisms of action. At a concentration of 7.5 μM, chalcone 2 demonstrated a rapid and effective inhibitory action on the protein levels of inducible nitric oxide synthase (iNOS), while chalcone 1 exhibited a gradual inhibitory action. Moreover, chalcone 1 effectively activated the nuclear factor erythroid 2-related factor 2 (Nrf2) pathway with around a 3.5-fold increase at the end of 24 h at 7.5 μM, highlighting its potential as a modulator of oxidative stress responses. These findings place chalcone 1 as a promising candidate for skincare products targeting inflammation and skin aging. Full article

Unlike the wide number of natural biflavonoids, natural bichalcones are a rare and even less studied class. Nevertheless, some of them have proved their interest in the fight against cancer through their cytotoxic activity against human tumor cell lines. The aim of this study was to synthesize a novel bichalcone: 3′,3‴,4,4′,4″,4‴,5′,5‴-octamethoxy-2,3″-bichalcone 1. The most efficient synthetic pathway was the Suzuki–Miyaura reaction between a boronated chalcone and a brominated one. Full article

The search for new substances of natural origin, such as flavonoids, is necessary in the fight against the growing number of diseases and bacterial resistance to antibiotics. In our research, we wanted to check the influence of flavonoids with chlorine or bromine atoms and a nitro group on pathogenic and probiotic bacteria. We synthesized flavonoids using Claisen–Schmidt condensation and its modifications, and through biotransformation via entomopathogenic filamentous fungi, we obtained their glycoside derivatives. Biotransformation yielded two new flavonoid glycosides: 8-amino-6-chloroflavone 4′-O-β-D-(4″-O-methyl)-glucopyranoside and 6-bromo-8-nitroflavone 4′-O-β-D-(4″-O-methyl)-glucopyranoside. Subsequently, we checked the antimicrobial properties of the aforementioned aglycon flavonoid compounds against pathogenic and probiotic bacteria and yeast. Our studies revealed that flavones have superior inhibitory effects compared to chalcones and flavanones. Notably, 6-chloro-8-nitroflavone showed potent inhibitory activity against pathogenic bacteria. Conversely, flavanones 6-chloro-8-nitroflavanone and 6-bromo-8-nitroflavanone stimulated the growth of probiotic bacteria (Lactobacillus acidophilus and Pediococcus pentosaceus). Our research has shown that the presence of chlorine, bromine, and nitro groups has a significant effect on their antimicrobial properties. Full article

The emergence of antibiotics-resistant bacteria has been a serious concern for medical professionals over the last decade. Therefore, developing new and effective antimicrobials with modified or different modes of action is a continuing imperative. In this context, our study focuses on evaluating the antimicrobial activity of different chemically synthesized flavonoids (FLAV) to guide the chemical synthesis of effective antimicrobial molecules. A set of 12 synthesized molecules (4 chalcones, 4 flavones and 4 flavanones), bearing substitutions with chlorine and bromine groups at the C6′ position and methoxy group at the C4′ position of the B-ring were evaluated for antimicrobial activity toward 9 strains of Gram-positive and Gram-negative bacteria and 3 fungal strains. Our findings showed that most tested FLAV exhibited moderate to high antibacterial activity, particularly against Staphylococcus aureus with minimum inhibitory concentrations (MIC) between the range of 31.25 and 125 μg/mL and that chalcones were more efficient than flavones and flavanones. The examined compounds were also active against the tested fungi with a strong structure-activity relationship (SAR). Interestingly, leakage measurements of the absorbent material at 260 nm and scanning electron microscopy (SEM) demonstrated that the brominated chalcone induced a significant membrane permeabilization of S. aureus. Full article

The effective response of antibiotics is threatened by the proliferation of micro-organisms that manifest resistance mechanisms, leading to an increase of progressively untreatable infectious diseases around the world. One solution to this problem could lie in shifting the strategy from searching for new antibacterials to discovering new compounds that potentiate the antimicrobial activity of current antibiotics, therefore reverting resistance, through the interference with several mechanisms including biofilm formation and efflux pumps (EPs). Using bis(2,3-dibromo-4,5-dihydroxybenzyl) ether (BDDE) as a template, a macroalgae brominated bromophenol with antimicrobial activity, a series of 18 chalcone derivatives was prepared and evaluated for its antimicrobial activity and potential to fight antibiotic resistance. This includes seven chalcones, six dihydrochalcones and five diarylpropanes. Among them, two chalcones exhibited interesting antifungal activity and all compounds reversed resistance to vancomycin in the environmental isolate Enterococcus faecalis B3/101. Three compounds caused a four-fold decrease in the minimum inhibitory concentration (MIC) values of vancomycin against E. faecalis. All the dihydrochalcones and diarylpropanes displayed inhibition of EPs and biofilm formation in the tested multidrug-resistant strain, suggesting that these compounds are EP inhibitors. Notably, dihydrochalcones and diarylpropanes did not show cytotoxicity in a mouse embryonic fibroblast cell line and they can potentially be regarded as hits for bacterial EP inhibition. Full article

The growing number of infectious diseases around the world threatens the effective response of antibiotics, contributing to the increase in antibiotic resistance seen as a global health problem. Currently, one of the main challenges in antimicrobial drug discovery is the search for new compounds that not only exhibit antimicrobial activity, but can also potentiate the antimicrobial activity and revert antibiotics’ resistance, through the interference with several mechanisms, including the inhibition of efflux pumps (EPs) and biofilm formation. Inspired by macroalgae brominated bromophenol BDDE with antimicrobial activity, a series of 18 chalcone derivatives, including seven chalcones (9–15), six dihydrochalcones (16–18, and 22–24) and five diarylpropanes (19–21, and 25 and 26), was prepared and evaluated for its antimicrobial activity and potential to fight antibiotic resistance. Among them, chalcones 13 and 14 showed promising antifungal activity against the dermatophyte clinical strain of Trichophyton rubrum, and all compounds reversed the resistance to vancomycin in Enterococcus faecalis B3/101, with 9, 14, and 24 able to cause a four-fold decrease in the MIC of vancomycin against this strain. Compounds 17–24 displayed inhibition of EPs and the formation of biofilm by S. aureus 272123, suggesting that these compounds are inhibiting the EPs responsible for the extrusion of molecules involved in biofilm-related mechanisms. Interestingly, compounds 17–24 did not show cytotoxicity in mouse embryonic fibroblast cell lines (NIH/3T3). Overall, the results obtained suggest the potential of dihydrochalcones 16–18 and 22–24, and diarylpropanes 19–21, 25 and 26, as hits for bacterial EPs inhibition, as they are effective in the inhibition of EPs, but present other features that are important in this matter, such as the lack of antibacterial activity and cytotoxicity. Full article

Using a routine procedure, a number of derivatives of the benzo[4,5]isothiazolo[2,3-a]pyrazine-6,6-dioxide ring system have been synthesized from readily available starting materials. A series of chalcones were synthesized, which were subsequently reacted with chlorosulfonic acid to generate chalcone sulfonyl chlorides. The chalcone sulfonyl chlorides were then treated with bromine to generate dibromo chalcone sulfonyl chlorides. These were subsequently reacted with 1,2-diaminopropane and 2-methyl-1,2-diaminopropane in boiling ethanol resulting in compounds 2–10 and 11–19 respectively, in 12–80% yields. The products were characterized by spectral analysis and the definitive structure of compound 11 was determined by X-ray crystallography. The synthesized compounds were screened for potential antibacterial properties against Bacillus subtilis, Escherichia coli, Proteus vulgaris and Staphylococcus aureus. Full article

A number of 1,2-benzothiazines have been synthesized in a three-step process. Nine chalcones 1–9 bearing methyl, fluoro, chloro and bromo substituents were chlorosulfonated with chlorosulfonic acid to generate the chalcone sulfonyl chlorides 10–18. These were converted to the dibromo compounds 19–27 through reaction with bromine in glacial acetic acid. Compounds 19–27 were reacted with ammonia, methylamine, ethylamine, aniline and benzylamine to generate a library of 45 1,2-benzothiazines 28–72. Compounds 28–72 were evaluated for their antimicrobial activity using broth microdilution techniques against two Gram-positive bacteria (Bacillus subtilis and Staphylococcus aureus) and two Gram-negative bacteria (Proteus vulgaris and Salmonella typhimurium). The results demonstrated that none of the compounds showed any activity against Gram-negative bacteria P. vulgaris and S. typhimurium; however, compounds 31, 33, 38, 43, 45, 50, 53, 55, 58, 60, 63 and 68 showed activity against Gram-positive bacteria Bacillus subtilis and Staphylococcous aureus. The range of minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) was 25–600 µg/mL, though some of the MIC and MBC concentrations were high, indicating weak activity. Structure activity relationship studies revealed that the compounds with a hydrogen atom or an ethyl group on the nitrogen of the thiazine ring exerted antibacterial activity against Gram-positive bacteria. The results also showed that the compounds where the benzene ring of the benzoyl moiety contained a methyl group or a chlorine or bromine atom in the para position showed higher antimicrobial activity. Similar influences were identified where either a bromine or chlorine atom was in the meta position. Full article