Synthesis and Biological Activity of Novel O-Alkyl Derivatives of Naringenin and Their Oximes

Antimicrobial Activity of Chalcones with a Chlorine Atom and Their Glycosides

Chalcones, secondary plant metabolites, exhibit various biological properties. The introduction of a chlorine and a glucosyl substituent to the chalcone could enhance its bioactivity and bioavailability. Such compounds can be obtained through a combination of chemical and biotechnological methods. Therefore, 4-chloro-2'-hydroxychalcone and 5'-chloro-2'-hydroxychalcone were obtained by synthesis and then glycosylated in two filamentous fungi strains cultures, i.e., Isaria fumosorosea KCH J2 and Beauveria bassiana KCH J1.5. The main site of the glycosylation of both compounds by I. fumosorosea KCH J2 was C-2' and C-3 when the second strain was utilized. The pharmacokinetics of these compounds were predicted using chemoinformatics tools. Furthermore, antimicrobial activity tests were performed. Compounds significantly inhibited the growth of the bacteria strains Escherichia coli 10536, Staphylococcus aureus DSM 799, and yeast Candida albicans DSM 1386. Nevertheless, the bacterial strain Pseudomonas aeruginosa DSM 939 exhibited significant resistance to their effects. The growth of lactic acid bacteria strain Lactococcus acidophilus KBiMZ 01 bacteria was moderately inhibited, but strains Lactococcus rhamnosus GG and Streptococcus thermophilus KBM-1 were completely inhibited. In summary, chalcones substituted with a chlorine demonstrated greater efficacy in inhibiting the microbial strains under examination compared to 2'-hydroxychalcone, while aglycones and their glycosides exhibited similar effectiveness.

Interaction of selected alkoxy naringenin oximes with model and bacterial membranes

Naringenin is a flavonoid found in many fruits and herbs, most notably in grapefruits. In recent years, this compound and its derivatives have been of great interest due to their high biological activity, including fungicidal and bactericidal effects, also in relation to multidrug-resistant bacteria. Membrane interactions of naringenin oxime (NO) and its 7-O-alkyl (7-alkoxy) derivatives, such as methyl (7MENO), ethyl (7ETNO), isopropyl (7IPNO), n-butyl (7BUNO) and n-pentyl (7PENO) were studied. Thermotropic properties of model membranes were investigated via differential scanning calorimetry (DSC), the influence on lipid raft mimicking giant unilamellar vesicles (GUVs) via fluorescence microscopy, and membrane permeability via measuring calcein leakage from liposomes. Molecular calculations supplemented the study. The influence of naringenin oximes on two strains of multidrug resistant bacteria: Staphylococcus aureus KJ and Enterococcus faecalis 37VRE was also investigated. In DSC studies all compounds reduced the temperature and enthalpy of main phase transition and caused disappearing of the pretransition. NO was the least active. The reduction in the area of surface domains in GUVs was observed for NO. Compounds NO and 7BUNO resulted in very low secretion of calcein from liposomes (permeability < 3 %). The highest results were observed for 7MENO (88.4 %) and 7IPNO (78.5 %). When bacterial membrane permeability was investigated all compounds caused significant release of propidium iodide from S. aureus (31.6-87.0 % for concentration 128 μg/mL). In the case of E. faecalis, 7ETNO (75.7 %) and NO (28.8 %) were the most active. The rest of the tested compounds showed less activity (permeability < 13.9 %). The strong evidence was observed that antibacterial activity of the tested compounds may be associated with their interaction with bacterial membrane.

Towards non-target proactive food safety: identification of active compounds in convenience tomato products by ten-dimensional hyphenation with integrated simulated gastrointestinal digestion

Current strategies for non-target food screening focus mainly on known hazardous chemicals (adulterants, residues, contaminants, packaging migrants, etc.) instead of bioactive constituents in general and exclude the biological effect detection. To widen the perspective, a more proactive non-target effect-directed strategy is introduced to complement food safety in order to detect not only known but also unknown bioactive compounds. The developed 10-dimensional hyphenation included on-surface digestion (1D), planar chromatographic separation (2D), visualization using white light (3D), UV light (4D), fluorescence light (5D), effect-directed assay analysis (6D), heart-cut zone elution to an orthogonal reversed phase column chromatography including online desalting (7D) with subsequent diode array detection (8D), high-resolution mass spectrometry (9D), and fragmentation (10D). Metabolism, i.e., intestinal digestion of each sample, was simulated and integrated on the same adsorbent surface to study any changes in the compound profiles. As proof of principle, nine convenience tomato products and a freshly prepared tomato soup were screened via five different planar assays in a non-targeted mode. Non-digested and digested samples were compared side by side. In their effect-directed profiles, 14 bioactive compounds from classes of lipids, plant hormones, spices, and pesticides were identified. In particular, bioactive compounds coming from the lipid class were increased by gastrointestinal digestion, while spices and pesticides remained unaffected. With regard to food safety, the determination of the two dinitrophenol herbicides dinoterb and dinoseb in highly processed tomato products should be given special attention. The hyphenation covered a broad analyte spectrum and showed robust and reliable results.

Biological activities of naringenin: A narrative review based on in vitro and in vivo studies

Naringenin (4',5,7-trihydroxyflavonone) is a phytochemical mainly found in citrus fruits. It is a promising phytochemical for human health because of its beneficial effects. This review aims to present comprehensive information on naringenin biological activities along with its action mechanisms and explain the pharmacokinetic properties of naringenin. This study involves a comprehensive literature review of in vitro and in vivo studies examining the effects of naringenin. Naringenin has antidiabetic, anticancer, antimicrobial, antiobesity, gastroprotective, immunomodulator, cardioprotective, nephroprotective, and neuroprotective properties. These properties are primarily attributed to its antioxidant and anti-inflammatory activities. The most important antioxidant activities of naringenin including free radical scavenging and preventing lipid peroxidation. Naringenin can increase the concentration of antioxidant enzymes and inhibit metal chelation and various pro-oxidant enzymes. Anti-inflammatory activities of naringenin are associated with decreased mitogen-activated protein kinase activities and nuclear factor kappa B by modulating the expression and release of proinflammatory cytokine and enzymes. In vitro and in vivo studies show that naringenin has promising biological activities for a variety of diseases. More research must be conducted on the bioactivities of naringenin, and to determine its optimum dose. In addition, the efficiency of naringenin must be examined with enhanced bioavailability methods to be able to increase its therapeutic effect.

Antiproliferative Activity and Impact on Human Gut Microbiota of New O-Alkyl Derivatives of Naringenin and Their Oximes

Naringenin is a 5,7,4′-trihydroxyflavanone naturally occurring mainly in citrus fruits, characterized by a wide spectrum of biological activity. Chemical modifications based on alkylation and oximation in most cases increase its bioactivity. The aim of our research was to evaluate the antiproliferative activity and influence on selected representatives of the human gut microbiota of new synthesized O-alkyl derivatives (A1–A10) and their oximes (B1–B10), which contain hexyl, heptyl, octyl, nonyl and undecyl chains attached to the C-7 or to both the C-7 and C-4′ positions in naringenin. To the best of our knowledge, compounds A3, A4, A6, A8–A10 and B3–B10 have not been described in the scientific literature previously. The anticancer activity was tested on human colon cancer cell line HT-29 and mouse embryo fibroblasts 3T3-L1 using the sulforhodamine B (SRB) and 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-2H-tetrazolium bromide (MTT) assays. We also determined the impacts of all compounds on the growth of Gram-positive and Gram-negative bacterial strains, such as Staphylococcus aureus, Enterococcus faecalis and Escherichia coli. The antimicrobial activity was expressed in terms of minimal inhibitory concentrations (MIC) and minimal bactericidal concentrations (MBC) values. For 7,4′-di-O-hexylnaringenin (A2), 7-O-undecylnaringenin (A9) and their oximes (B2, B9), which were safe for microbiota (MIC > 512 µg/mL) and almost all characterized by high cytotoxicity against the HT-29 cell line (A2: IC₅₀ > 100 µg/mL; A9: IC₅₀ = 17.85 ± 0.65 µg/mL; B2: IC₅₀ = 49.76 ± 1.63 µg/mL; B9: IC₅₀ = 11.42 ± 1.17 µg/mL), apoptosis assays were performed to elucidate their mechanisms of action. Based on our results, new compound B9 induced an apoptotic process via caspase 3/7 activation, which proved its potential as an anticancer agent.

Naringenin and Its Derivatives-Health-Promoting Phytobiotic against Resistant Bacteria and Fungi in Humans

Naringenin is a trihydroxyflavanone present in large amount in different citrus fruits, e.g., oranges, pomelos, grapefruits, but also in tomatoes, fenugreek and coffee. It has a wide range of pharmacological and biological effects beneficial to human health. Its antioxidant, anti-cancer, anti-inflammatory, antifungal and antimicrobial activity is frequently reported in scientific literature. In this review we presented the current state of knowledge on the antimicrobial activity of naringenin and its natural and synthetic derivatives as a phytobiotic against resistant Gram-positive and Gram-negative bacteria as well as fungi in humans. Most of the data reported here have been obtained from in vitro or in vivo studies. Over the past few years, due to the overuse of antibiotics, the occurrence of bacteria resistant to all available antibiotics has been growing. Therefore, the main focus here is on antibiotic resistant strains, which are a significant, worldwide problem in the treatment of infectious diseases. The situation is so alarming that the WHO has listed microbial resistance to drugs on the list of the 10 most important health problems facing humanity. In addition, based on scientific reports from recent years, we described the potential molecular mechanism of action of these bioflavonoids against pathogenic strains of microorganisms. As plant-derived substances have been pushed out of use with the beginning of the antibiotic era, we hope that this review will contribute to their return as alternative methods of preventing and treating infections in the epoch of drug resistance.

Controlled Synthesis of Luminescent Xanthene Dyes and Use of Ionic Liquid in Thermochromic Reaction

In this study, we demonstrate six novel xanthene derivatives and their spectroscopic and chemical properties. The presented synthesis examination allowed us to obtain two different compounds during one step, with open and closed lactone rings substituted with different length alkyl chains. Increasing the reaction efficiency to 77% was obtained using the microwave-assisted method. Moreover, the modification of O-alkylation synthesis in an ecofriendly way using a ball mill led to achieving exclusively one opened ring product. All of the synthesized compounds showed different spectroscopic behaviors in comparison with the different organic dyes; the typical concentration quenching of luminescence was not observed. The relationship between the length of the alkyl chain and the time of luminescence decay is presented. Synthetized closed forms of dyes turned out to be promising leuco dyes. For the first time, an ionic liquid was used as a developer of synthesized xanthene derivatives (as leuco dyes), which led to obtaining an irreversible thermochromic marker.

Compendium of naringenin: potential sources, analytical aspects, chemistry, nutraceutical potentials and pharmacological profile

Naringenin is flavorless, water insoluble active principle belonging to flavanone subclass. It exhibits a diverse pharmacological profile as well as divine nutraceutical values. Although several researchers have explored this phytoconstituent to evaluate its promising properties, still it has not gained recognition at therapeutic levels and more clinical investigations are still required. Also the neutraceutical potential has limited marketed formulations. This compilation includes the description of reported therapeutic potentials of naringenin in variety of pathological conditions alongwith the underlying mechanisms. Details of various analytical investigations carried on this molecule have been provided along with brief description of chemistry and structural activity relationship. In the end, various patents filed and clinical trial data has been provided. Naringenin has revealed promising pharmacological activities including cardiovascular diseases, neuroprotection, anti-diabetic, anticancer, antimicrobial, antiviral, antioxidant, anti-inflammatory and anti-platelet activity. It has been marketed in the form of nanoformulations, co-crystals, solid dispersions, tablets, capsules and inclusion complexes. It is also available in various herbal formulations as nutraceutical supplement. There are some pharmacokinetic issue with naringenin like poor absorption and low dissolution rate. Although these issues have been sorted out upto certain extent still further research to investigate the bioavailability of naringenin from herbal supplements and its clinical efficacy is essential.

Molecular Recognition of Citroflavonoids Naringin and Naringenin at the Active Site of the HMG-CoA Reductase and DNA Topoisomerase Type II Enzymes of Candida spp. and Ustilago maydis

Two agents from natural sources, citroflavonoids naringin and naringenin, can target enzymes in pathogenic yeasts responsible for hospital infections and crop failure. The aim of this study was to examine the molecular recognition site for naringin and naringenin on the HMGR and TOPOII enzymes of eleven Candida species and one phytopathogen, U. maydis, and evaluate yeast susceptibility to these flavonoids. The HMGR and TOPOII enzymes were analyzed in silico. The alignment of the two enzymes in the twelve pathogenic organisms with the corresponding enzyme of Homo sapiens revealed highly conserved amino acid sequences. Modeling studies of the enzymes indicated highly conserved structures. According to molecular docking simulations, both citroflavonoids recognized the amino acid residues of the active site of the enzymes. Binding energy values were higher for naringin (-10.75 and -9.38 kcal/mol, respectively) than simvastatin on HMGR (-9.9) and curcumin on TOPOII (-8.37). The appraisal of twenty-nine virtual mutations provided evidence of probable mechanisms of resistance (high binding energy) or susceptibility (low energy) to the drugs and emphasized the role of key residues. An in vitro susceptibility evaluation of the twelve yeasts demonstrated that the two flavonoids have similar or better MIC values than those reported for the reference compounds, obtaining the lowest with Candida dubliniensis (2.5 µg/ml) and U. maydis (5 µg/ml). Based on the present findings, naringin and naringenin could possibly be effective for treating diseases caused by pathogenic yeasts of the Candida species and U. maydis, presumably by inhibition of their HMGR and TOPOII enzymes.

SUPPLEMENTARY INFORMATION

The online version contains supplementary material available at 10.1007/s12088-021-00980-0.

FDA-Approved Oximes and Their Significance in Medicinal Chemistry

Despite the scientific advancements, organophosphate (OP) poisoning continues to be a major threat to humans, accounting for nearly one million poisoning cases every year leading to at least 20,000 deaths worldwide. Oximes represent the most important class in medicinal chemistry, renowned for their widespread applications as OP antidotes, drugs and intermediates for the synthesis of several pharmacological derivatives. Common oxime based reactivators or nerve antidotes include pralidoxime, obidoxime, HI-6, trimedoxime and methoxime, among which pralidoxime is the only FDA-approved drug. Cephalosporins are β-lactam based antibiotics and serve as widely acclaimed tools in fighting bacterial infections. Oxime based cephalosporins have emerged as an important class of drugs with improved efficacy and a broad spectrum of anti-microbial activity against Gram-positive and Gram-negative pathogens. Among the several oxime based derivatives, cefuroxime, ceftizoxime, cefpodoxime and cefmenoxime are the FDA approved oxime-based antibiotics. Given the pharmacological significance of oximes, in the present paper, we put together all the FDA-approved oximes and discuss their mechanism of action, pharmacokinetics and synthesis.

Synthesis and Evaluation of the Acetylcholinesterase Inhibitory Activities of Some Flavonoids Derived from Naringenin

Alzheimer's disease (AD) is an irreversible neurodegenerative disease that affects many older people adversely. AD has been putting a huge socioeconomic burden on the healthcare systems of many developed countries with aging populations. The need for new therapies that can halt or reverse the progression of the disease is now extremely great. A research approach in the finding new treatment for AD that has attracted much interest from scientists for a long time is the reestablishment of cholinergic transmission through inhibition of acetylcholinesterase (AChE). Naringenin is a flavonoid with the potential inhibitory activity against AChE. From naringenin, many other flavonoid derivatives, such as flavanones and chalcones, can be synthesized. In this study, by applying the Williamson method, nine flavonoid derivatives were synthesized, including four flavanones and five chalcones. The evaluation of AChE inhibitory activity by the Ellman method showed that there were four substances (2, 4, 5, and 7) with relatively good biological activities (IC₅₀ < 100 μM), and these biological activities were better than that of naringenin. The molecular docking revealed that strong interactions with amino acid residue Ser200 of the catalytic triad and those of the peripheral region of the enzyme were crucial for strong effects against AChE. Compound 7 had the strongest AChE inhibitory activity (IC₅₀ 13.0 ± 1.9 μM). This substance could be used for further studies.

Methylation of Cyanidin-3-O-Glucoside with Dimethyl Carbonate

The approach presented in this study is the first for the hemisynthesis of methylated anthocyanins. It was possible to obtain cyanidin-3-O-glucoside derivatives with different degrees of methylation. Cautious identification of 4′-, 5-, and 7-OH monomethylated derivatives was also accomplished. The methylation agent used was the “green chemical” dimethyl carbonate (DMC), which is characterized by low human and ecological toxicity. The influence of the temperature, reaction time, and amount of the required diazabicyclo[5.4.0]undec-7-en (DBU) catalyst on the formation of the products was examined. Compared to conventional synthesis methods for methylated flavonoids using DMC and DBU, the conditions identified in this study result in a reduction of reaction time, and an important side reaction, so-called carboxymethylation, was minimized by using higher amounts of catalyst.

Novel Fluorinated 7-Hydroxycoumarin Derivatives Containing an Oxime Ether Moiety: Design, Synthesis, Crystal Structure and Biological Evaluation

A series of fluorinated 7-hydroxycoumarin derivatives containing an oxime ether moiety have been designed, synthesized and evaluated for their antifungal activity. All the target compounds were determined by ¹H-NMR, ¹³C-NMR, FTIR and HR-MS spectra. The single-crystal structures of compounds 4e, 4h, 5h and 6c were further confirmed using X-ray diffraction. The antifungal activities against Botrytis cinerea (B. cinerea), Alternariasolani (A. solani), Gibberella zeae (G. zeae), Rhizoctorzia solani (R. solani), Colletotrichum orbiculare (C. orbiculare) and Alternaria alternata (A. alternata) were evaluated in vitro. The preliminary bioassays showed that some of the designed compounds displayed the promising antifungal activities against the above tested fungi. Strikingly, the target compounds 5f and 6h exhibited outstanding antifungal activity against B. cinerea at 100 μg/mL, with the corresponding inhibition rates reached 90.1 and 85.0%, which were better than the positive control Osthole (83.6%) and Azoxystrobin (46.5%). The compound 5f was identified as the promising fungicide candidate against B. cinerea with the EC₅₀ values of 5.75 μg/mL, which was obviously better than Osthole (33.20 μg/mL) and Azoxystrobin (64.95 μg/mL). Meanwhile, the compound 5f showed remarkable antifungal activities against R. solani with the EC₅₀ values of 28.96 μg/mL, which was better than Osthole (67.18 μg/mL) and equivalent to Azoxystrobin (21.34 μg/mL). The results provide a significant foundation for the search of novel fluorinated 7-hydroxycoumarin derivatives with good antifungal activity.

Multi-Therapeutic Potential of Naringenin (4',5,7-Trihydroxyflavonone): Experimental Evidence and Mechanisms

Extensive research has been carried out during the last few decades, providing a detailed account of thousands of discovered phytochemicals and their biological activities that have the potential to be exploited for a wide variety of medicinal purposes. These phytochemicals, which are pharmacologically important for clinical use, primarily consist of polyphenols, followed by terpenoids and alkaloids. There are numerous published reports indicating the primary role of phytochemicals proven to possess therapeutic potential against several diseases. However, not all phytochemicals possess significant medicinal properties, and only some of them exhibit viable biological effects. Naringenin, a flavanone found in citrus fruits, is known to improve immunity, repair DNA damage, and scavenge free radicals. Despite the very low bioavailability of naringenin, it is known to exhibit various promising biological properties of medicinal importance, including anti-inflammatory and antioxidant activities. This review focuses on the various aspects related to naringenin, particularly its physicochemical, pharmacokinetic, and pharmacodynamic properties. Furthermore, various pharmacological activities of naringenin, such as anticancer, antidiabetic, hepatoprotective, neuroprotective, cardioprotective, nephroprotective, and gastroprotective effects, have been discussed along with their mechanisms of action.

Antimicrobial O-Alkyl Derivatives of Naringenin and Their Oximes Against Multidrug-Resistant Bacteria

New antimicrobial agents are needed to address infections caused by multidrug-resistant bacteria. Here, we are reporting novel O-alkyl derivatives of naringenin and their oximes, including novel compounds with a naringenin core and O-hexyl chains, showing activity against clinical strains of clarithromycin-resistant Helicobacter pylori, vancomycin-resistant Enterococcus faecalis, methicillin-resistant Staphylococcus aureus, and beta-lactam-resistant Acinetobacter baumannii and Klebsiella pneumoniae. The minimum inhibitory concentrations (MICs), which provide a quantitative measure of antimicrobial activity, were in the low microgram range for the selected compounds. Checkerboard assays for the most active compounds in combination with antibiotics revealed interactions that varied from synergistic to neutral.

Effect of Naringenin and Its Derivatives on the Probing Behavior of Myzus persicae (Sulz.)

Substances that alter insect behavior have attracted a lot of attention as potential crop protection agents. Naringenin (5,7,4′-trihydroxyflavanone) is a naturally occurring bioactive flavanone. We evaluated the influence of naringenin on aphid activities during individual phases of probing and feeding and the effect of structural modifications of naringenin on its activity towards aphids. We monitored the probing behavior of Myzus persicae (Sulz.) (Hemiptera: Aphididae) using the Electrical Penetration Graph (EPG) technique. The chemical modifications were the substitution of hydrogen atoms with methyl, ethyl or pentyl groups and the replacement of the carbonyl group in naringenin and its derivatives with an oxime moiety. Depending on the substituents, the activity of naringenin-derived compounds varied in potency and mode of action. Naringenin was an attractant of moderate activity, which enhanced sap ingestion. The naringenin derivative with two methyl groups—7,4′-di-O-methylnaringenin—was a deterrent, which hindered aphid probing in non-phloem tissues. Naringenin oxime derivatives with methyl substituents—7,4′-di-O-methylnaringenin oxime, 7-O-methylnaringenin oxime, and 5,7,4′-tri-O-methylnaringenin oxime—and the derivative with a pentyl substituent—7-O-pentylnaringenin oxime—were strong attractants which stimulated aphid probing in non-phloem tissues and the ingestion of phloem sap.

Different substituent effects on the supramolecular arrays in some (E)-halo- and nitro-benzaldehyde oximes: confirmation of attractive π(C=N)···π(phenyl) interactions

The crystal structures and Hirshfeld surface analyses are reported for four aldoximes, (E)-X–C6H4CH=N–OH [X = 3-Cl (1), 4-F (2), 2-O2N (3) and 4-O2N (4)]. The strong classical O–H · · · N hydrogen bonds involving the oxime group generate C(3) chains in compound 1, in contrast to the R2 2(6) dimers formed in compounds 2–4; such arrangements have been shown to be the most frequently found for oximes other than salicylaldoximes (2-hydroxybenzaldehyde oximes). In general, weaker intermolecular interactions involving the X substituents, as well as C–H · · · O and π · · · π interactions have significant effects on the supramolecular arrays generated in the aggegation. A further important interaction in compound 1, and to a lesser extent in compound 4, is a π(C=N) · · · π(phenyl) molecular stacking. A data base search has indicated that short Cg(C=N) · · · Cg(phenyl) distances, <3.3 Å (Cg = centre of gravity), have been found in various compounds, including other oximes. A theoretical study was carried out starting from the crystal structure data of compound 1, with optimisation at the BLYP-D3/def2-DZVP level, as well as at the higher PBE0/ma-def2-TZVP level. Breakdown of the interaction energy into separate contributions was achieved using SAPT (using the jun-cc-pvdz basis set). Overall, the calculations indicate that the π(C=N) ·· · π(phenyl) interaction is attractive, with a magnitude of 14–18 kJ mol−1.

Novel O-alkyl Derivatives of Naringenin and Their Oximes with Antimicrobial and Anticancer Activity

In our investigation, we concentrated on naringenin (NG)—a widely studied flavanone that occurs in citrus fruits. As a result of a reaction with a range of alkyl iodides, 7 novel O-alkyl derivatives of naringenin (7a–11a, 13a, 17a) were obtained. Another chemical modification led to 9 oximes of O-alkyl naringenin derivatives (7b–13b, 16b–17b) that were never described before. The obtained compounds were evaluated for their potential antibacterial activity against Escherichia coli, Staphylococcus aureus, and Bacillus subtilis. The results were reported as the standard minimal inhibitory concentration (MIC) values and compared with naringenin and its known O-alkyl derivatives. Compounds 4a, 10a, 12a, 14a, 4b, 10b, 11b, and 14b were described with MIC of 25 µg/mL or lower. The strongest bacteriostatic activity was observed for 7-O-butylnaringenin (12a) against S. aureus (MIC = 6.25 µg/mL). Moreover, the antitumor effect of flavonoids was examined on human colon cancer cell line HT-29. Twenty-six compounds were characterized as possessing an antiproliferative activity stronger than that of naringenin. The replacement of the carbonyl group with an oxime moiety significantly increased the anticancer properties. The IC₅₀ values below 5 µg/mL were demonstrated for four oxime derivatives (8b, 11b, 13b and 16b).

The Therapeutic Potential of Naringenin: A Review of Clinical Trials

Naringenin is a flavonoid belonging to flavanones subclass. It is widely distributed in several Citrus fruits, bergamot, tomatoes and other fruits, being also found in its glycosides form (mainly naringin). Several biological activities have been ascribed to this phytochemical, among them antioxidant, antitumor, antiviral, antibacterial, anti-inflammatory, antiadipogenic and cardioprotective effects. Nonetheless, most of the data reported have been obtained from in vitro or in vivo studies. Although some clinical studies have also been performed, the main focus is on naringenin bioavailability and cardioprotective action. In addition, these studies were done in compromised patients (i.e., hypercholesterolemic and overweight), with a dosage ranging between 600 and 800 μM/day, whereas the effect on healthy volunteers is still debatable. In fact, naringenin ability to improve endothelial function has been well-established. Indeed, the currently available data are very promising, but further research on pharmacokinetic and pharmacodynamic aspects is encouraged to improve both available production and delivery methods and to achieve feasible naringenin-based clinical formulations.

The Anti-Candida albicans Agent 4-AN Inhibits Multiple Protein Kinases

Small molecules containing quinone and/or oxime moieties have been found as promising anti-fungal agents. One of them is 4-AN, a recently reported potent anti-Candida compound, which inhibits the formation of hyphae, decreases the level of cellular phosphoproteome, and finally shows no toxicity towards human erythrocytes and zebrafish embryos. Here, further research on 4-AN is presented. The results revealed that the compound: (i) Kills Candida clinical isolates, including these with developed antibiotic resistance, (ii) affects mature biofilm, and (iii) moderately disrupts membrane permeability. Atomic force microscopy studies revealed a slight influence of 4-AN on the cell surface architecture. 4-AN was also shown to inhibit multiple various protein kinases, a characteristic shared by most of the ATP-competitive inhibitors. The presented compound can be used in novel strategies in the fight against candidiasis, and reversible protein phosphorylation should be taken into consideration as a target in designing these strategies.

Crystal structures and Hirshfeld surfaces of four meth-oxy-benzaldehyde oxime derivatives, 2-MeO-XC6H3C=NOH (X = H and 2-, 3- and 4-MeO): different conformations and hydrogen-bonding patterns

The crystal structures of four (E)-meth-oxy-benzaldehyde oxime derivatives, namely (2-meth-oxy-benzaldehyde oxime, 1, 2,3-di-meth-oxy-benzaldehyde oxime, 2, 4-di-meth-oxy-benzaldehyde oxime, 3, and 2,5-di-meth-oxy-benzaldehyde oxime, 4, are discussed. The arrangements of the 2-meth-oxy group and the H atom of the oxime unit are s-cis in compounds 1-3, but in both independent mol-ecules of compound 4, the arrangements are s-trans. There is also a difference in the conformation of the two mol-ecules in 4, involving the orientations of the 2- and 5-meth-oxy groups. The primary inter-molecular O-H(oxime)⋯O(hy-droxy) hydrogen bonds generate C(3) chains in 1 and 2. In contrast, in compound 3, the O-H(oxime)⋯O(hy-droxy) hydrogen bonds generate symmetric R 2 2(6) dimers. A more complex dimer is generated in 4 from the O-H(oxime)⋯O(hy-droxy) and C-H(2-meth-oxy)⋯O(hy-droxy) hydrogen bonds. In all cases, further inter-actions, C-H⋯O and C-H⋯π or π-π, generate three-dimensional arrays. Hirshfeld surface and fingerprint analyses are discussed.

Cascade biotransformation of dehydroepiandrosterone (DHEA) by Beauveria species

Beauveria bassiana is an entomopathogenic fungus used as a biological control agent. It is a well-known biocatalyst for the transformation of steroid compounds. Hydroxylations at the 7α or 11α position and oxidation to D-homo lactones are described in the literature. In our study, we examined the diversity of metabolism of five different B. bassiana strains and compared them to already known pathways. According to the literature, 7α and 11α-hydroxy derivatives as well as 3β,11α-dihydroxy-17a-oxa-D-homo-androst-5-en-17-one have been observed. Here we describe new DHEA metabolic pathways and two products not described before: 3β-hydroxy-17a-oxa-D-homo-androst-5-en-7,17-dione and 3β,11α-dihydroxyandrost-5-en-7,17-dione. We also used for the first time another species from this genus, Beauveria caledonica, for steroid transformation. DHEA was hydroxylated at the 7α, 7β and 11α positions and then reactions of oxidation and reduction leading to 3β,11α-dihydroxyandrost-5-en-7,17-dione were observed. All tested strains from the Beauveria genus effectively transformed the steroid substrate using several different enzymes, resulting in cascade transformation.

Synthesis, Cancer-Selective Antiproliferative and Apoptotic Effects of Some (±)-Naringenin Cycloaminoethyl Derivatives

Naringenin is a naturally occurring flavonoid and due to its broad spectrum of biological activities, including anticancer properties, has attracted scientific attention in recent years. To contribute to these studies, we synthesized some new (±)-naringenin cyclic aminoethyl derivatives, analyzed the cytotoxic and anti-proliferative properties of them via 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-2H-tetrazolium bromide (MTT) assay, and mitochondrial apoptosis signaling response and gene expressions belong to caspase-3 depended apoptosis as biomarkers in both healthy and cancer cell lines. Our results suggest that some of our naringenin derivatives are potential anticancer agents with a selective death potential and targeting properties for mitochondrial apoptosis signaling against at least human cervix and breast cancer.