Balázs Dankó

In vitro Anti-diabetic Activity and Chemical Characterization of an Apolar Fraction of Morus alba Leaf Water Extract

The tea from the white mulberry (Morus alba L.) leaf is a worldwide known traditional medicine of type II diabetes. Here, we report the investigation of the dichloromethane‐soluble fraction obtained in a 0.24% m/m yield from the hot water extract of mulberry leaves. A significant, dose‐dependent activity was found by means of the 24‐h glucose consumption of fully differentiated adipocytes both in the absence and presence of insulin. The fraction was characterized by HPLC‐DAD, GC‐MS and GC‐FID. The main constituent (40.3% by means of GC‐FID) was isolated and identified as loliolide by EIMS, HRESIMS and NMR spectroscopy. In the active fraction benzyl alcohol, ethyl benzoate, t‐cinnamic acid, p‐hydroxyacetophenone, t‐coniferyl alcohol and synapil alcohol were also identified by GC‐MS and quantified by GC‐FID (0.7, 1.3, 1.5, 2.9, 7.5 and 2.6%, respectively). Copyright

Exposure of Chlorpromazine to 266 nm Laser Beam Generates New Species with Antibacterial Properties: Contributions to Development of a New Process for Drug Discovery

Introduction Phenothiazines when exposed to white light or to UV radiation undergo a variety of reactions that result in degradation of parental compound and formation of new species. This process is slow and may be sped up with exposure to high energy light such as that produced by a laser. Methods Varying concentrations of Chlorpromazine Hydrochloride (CPZ) (2–20 mg/mL in distilled water) were exposed to 266 nm laser beam (time intervals: 1–24 hrs). At distinct intervals the irradiation products were evaluated by spectrophotometry between 200–1500 nm, Thin Layer Chromatography, High Pressure Liquid Chromatography (HPLC) - Diode Array Detection, HPLC tandem mass spectrometry, and for activity against the CPZ sensitive test organism Staphylococcus aureus ATCC 25923. Results CPZ exposure to 266 nm laser beam of given energy levels yielded species, whose number increased with duration of exposure. Although the major species produced were Promazine (PZ), hydroxypromazine or PZ sulfoxide, and CPZ sulfoxide, over 200 compounds were generated with exposure of 20 mg/mL of CPZ for 24 hrs. Evaluation of the irradiation products indicated that the bioactivity against the test organism increased despite the total disappearance of CPZ, that is due, most probably, to one or more new species that remain yet unidentified. Conclusions Exposure of CPZ to a high energy (6.5 mJ) 266 nm laser beam yields rapidly a large number of new and stable species. For biological grade phenothiazines (in other words knowing the impurities in the samples: solvent and solute) this process may be reproducible because one can control within reasonably low experimental errors: the concentration of the parent compound, the laser beam wavelength and average energy, as well as the duration of the exposure time. Because the process is “clean” and rapid, it may offer advantages over the pyrogenically based methods for the production of derivatives.

Direct Semi-Synthesis of the Anticancer Lead-Drug Protoapigenone from Apigenin, and Synthesis of Further New Cytotoxic Protoflavone Derivatives

Protoapigenone, a natural flavonoid possessing an unusual p-quinol moiety on its B-ring, is a novel prospective anticancer agent with low toxicity that is currently in development. The first economical, one-step synthesis of protoapigenone from apigenin is described on up to gram scale. 13 new 1′-O-alkylflavone analogs were also synthesized, either from apigenin or β-naphthoflavone. The in vitro cytotoxic activity of each compound was tested on six human cancer cell lines (HepG2, Hep3B, Ca9-22, A549, MCF-7 and MDA-MB-231). In the case of 1′-O-alkyl-protoapigenone derivatives, structure-activity relationships were found depending on the side-chain, and protoapigenone 1′-O-butyl ether was found to exert significantly stronger activity against three of the cell lines (Hep3B, MCF-7 and MDA-MB-231) than its non-substituted analog, protoapigenone itself. In contrast to this, all β-naphthoflavone derivatives bearing the same pharmacophore on their B-ring showed decreased cytotoxic activities when substituted with an O-alkyl side-chain at position 1′, comparing to that of the non-substituted compound.

Protoflavones: a class of unusual flavonoids as promising novel anticancer agents.

Protoflavones represent a less widespread, unique class of natural flavonoids with a non-aromatic B-ring and a hydroxyl group at C-1′. Due to their recently discovered anticancer activity, these compounds have gotten into the focus of biomedical research during the past few years. The present review aims to give a brief summary on the available literature data on this special class of flavonoids, including their occurrence in plants and their bioactivity. A special emphasis is given on the anticancer potential of these compounds. Attempts for the development of certain synthetic/semi-synthetic protoflavone analogs as anticancer drugs, and structure–activity relationships are also discussed.

Bioactive constituents of Cirsium japonicum var. australe.

Cirsium japonicum var. australe, used as a folk medicine in Taiwan, has been employed traditionally in the treatment of diabetes and inflammatory symptoms. Bioactivity-guided fractionation of its ethanolic extract, utilizing centrifugal partition chromatography monitored by DPPH-TLC analysis, led to the isolation of three new acetylenic phenylacrylic acid esters (1-3) and two new polyacetylenes (4 and 5), together with seven known compounds (6-12). The structures of 1-5 were elucidated by spectroscopic methods including 1D and 2D NMR techniques. The absolute configurations of 4 and 7 were determined utilizing Moshers method and ECD/CD experiments. The DPPH scavenging activity of the constituents isolated from the C. japonicum var. australe ethanolic extract was evaluated. The potential antidiabetic activity of some of the isolates was evaluated using in vitro cellular glucose uptake and oil red staining assays.

Biological Evaluation of Products Formed from the Irradiation of Chlorpromazine with a 266 nm Laser Beam

Varying concentrations of Chlorpromazine Hydrochloride (CPZ) were exposed to a 266 nm laser beam for varying periods of time ranging from 4 to 24 hrs and the products of irradiation were evaluated for activity against a panel of bacteria that consisted of representatives of Gram-positives and Gram-negatives that expressed different degrees of efflux pump activity, and compared to the parental unexposed compound with prolonged irradiation, whereas the antibacterial activity of the product against Staphylococcus aureus and Escherichia coli strains was many folds greater, no activity against their efflux pumps was noted. The activity of the products of irradiation against Salmonella enterica serovar Enteritidis was slight. However, the products of prolonged irradiation of CPZ produced increasingly significant concentration dependent inhibition of efflux by the Salmonella strains.

Lower antioxidative capacity of multidrug-resistant cancer cells confers collateral sensitivity to protoflavone derivatives

AbstractPurposeMultidrug resistance (MDR) may develop due to a series of adaptive responses under a new stress conditions, such as chemotherapy. Novel strategies are urgently needed to fight MDR in cancer, and chemotherapeutics that are selective for MDR cancer cells offer a promising approach. Certain protoflavones were previously found to have potential in this regard.MethodsCytotoxicity of six protoflavones was assessed in different P-glycoprotein overexpressing MDR cancer cell lines and in their non-MDR counterparts. The impacts of compound 5, 6-methylprotoflavone previously published and a new derivative, 6-bromoprotoflavone (compound 6), on the cell cycle distribution were evaluated, and 6 was also studied for its potential to regulate the intracellular antioxidative capacity.Results Protoflavones showed a significant cytotoxicity against all cancer cell lines and selectivity toward MDR cancer cells adapted to conventional chemotherapeutics. Inverse sensitivity versus MDR selectivity pattern was observed. Treatment with H2O2 showed that MDR cancer cells are more vulnerable to oxidative stress. Compounds 5 and 6 significantly decreased the portion of MDR cells in the G1 phase. The levels of reactive oxygen and nitrogen species (ROS/RNS) between MDR and non-MDR cells significantly differed upon exposure to 6, accompanied by changes in the glutathione (GSH) levels and in the expression of manganese superoxide dismutase (MnSOD), glutathione-S-transferase π (GST π) and hypoxia-inducible factor-1α (HIF-1α).ConclusionsOur results suggest that MDR cancer cells can be more vulnerable to the pro-oxidative activity of protoflavones due to an impaired antioxidative defense that might arise during the adaptation processes provoked by chemotherapy.

Rapid, laser-induced conversion of 20-hydroxyecdysone – A follow-up study on the products obtained

We have recently reported the set-up of an experimental system for the laser-induced photochemical modification of bioactive substances, where two ecdysteroids, 20-hydroxyecdysone (20E) and its diacetonide derivative served as probes. As a direct continuation of our previous work, three new compounds together with five other ecdysteroid derivatives, have been identified from the novel, laser-induced photo-transformation reaction of 20E. The structures and NMR signal assignment were established by comprehensive one- and two-dimensional NMR spectroscopy supported by mass spectroscopy. Possible ways for the formation of each species is also discussed. Similar to their parental compound, the products obtained are potentially bioactive and worthy for further investigations; due to the low yields, however, a different approach for their higher scale production is suggested.

Anti-inflammatory Activities of Eleven Centaurea Species Occurring in the Carpathian Basin

Our study aimed at the identification of anti‐inflammatory activities of different fractions of C. sadleriana extract after per os administration in rats, the identification of the active compounds of the plant and the investigation of the in vitro anti‐inflammatory activities of Centaurea species native to or cultivated in the Carpathian Basin. The aerial parts of Centaurea sadleriana Janka have been used in Hungarian folk medicine to treat the wounds of sheep. Methanol extract of C. sadleriana was fractioned by solvent‐solvent partitioning. The n‐hexane fraction was further fractionated and the anti‐inflammatory activities of certain subfractions were confirmed in vivo in rats. The n‐hexane and chloroform fraction of the methanol extract of C. sadleriana exhibited remarkable COX‐1 and COX‐2 inhibiting effects in vitro. Chromatographic separation of the fractions led to the identification of the active subfractions and 11 compounds (α‐linolenic acid, γ‐linolenic acid, stigmasterol, β‐sitosterol, campesterol, vanillin, pectolinarigenin, salvigenin, hispidulin, chrysoeriol and apigenin). The in vitro screening for anti‐inflammatory activities of further Centaurea species occurring in the Carpathian Basin (C. adjarica, C. bracteata, C. cataonica, C. cynaroides, C. dealbata, C. indurata, C. macrocephala, C. melitensis, C. nigrescens, C. ruthenica) revealed considerable COX‐1 and COX‐2 inhibitory activities. Because C. sadleriana is an endangered species native only to the Carpathian Basin, the investigation of more prevalent species is reasonable. Copyright

Synthesis and SAR Study of Anticancer Protoflavone Derivatives: Investigation of Cytotoxicity and Interaction with ABCB1 and ABCG2 Multidrug Efflux Transporters

There is a constant need for new therapies against multidrug‐resistant (MDR) cancer. Natural compounds are a promising source of novel anticancer agents. We recently showed that protoflavones display activity in MDR cancer cell lines that overexpress the P‐glycoprotein (P‐gp) drug efflux pump. In this study, 52 protoflavones, including 22 new derivatives, were synthesized and tested against a panel of drug‐sensitive parental cells and their MDR derivatives obtained by transfection with the human ABCB1 or ABCG2 genes, or by adaptation to chemotherapeutics. With the exception of protoapigenone, identified as a weak ABCG2 substrate, all protoflavones bypass resistance conferred by these two transporters. The majority of the compounds were found to exhibit mild to strong (up to 13‐fold) selectivity against the MCF‐7Dox and KB‐V1 cell lines, but not to transfected MDR cells engineered to overexpress the MDR transporters. Our results suggest that protoflavones can overcome MDR cancer by evading P‐gp‐mediated efflux.