Tumor cell growth suppression by chalcone (1,3-diphenyl-2-propen-1-one)

Regulatory effects of 4-methoxychalcone on adipocyte differentiation through PPARγ activation and reverse effect on TNF-α in 3T3-L1 cells

Chalcones, the biosynthetic precursors of flavonoids and isoflavonoids abundant in edible plants, possess a number of pharmacological properties, and there is growing evidence that chalcone derivatives inhibit TNF-α mediated insulin resistance. The aim of the present study was to define the effects of 4-methoxychalcone (4-MC) on adipocyte differentiation and to determine the underlying molecular mechanism. We investigated the effects of 4-MC on adipocyte differentiation and lipid accumulation, and expression of adipogenic genes in 3T3-L1 cells. Additionally, treatment with 4-MC significantly increased the PPARγ-induced transcriptional activity and 4-MC also enhanced the DNA binding affinity of PPARγ to the proliferator-activated receptor response elements (PPRE) at target promoters. Next, we tested the effect of 4-MC on the inhibition induced by TNF-α on adipocyte differentiation. Treatment with 4-MC enhanced the lipid accumulation and strongly up-regulated the expression of adipogenic markers, including PPARγ, aP2, FAS, and adiponectin during adipocyte differentiation. Finally, 4-MC attenuated the inhibitory effect of TNF-α on adipocyte differentiation and adiponectin expression and subsequently regulated the expression and secretion of various adipokines that are involved in insulin sensitivity. This study clearly demonstrates that 4-MC enhanced adipocyte differentiation, in part, by its potent effects on PPARγ activation and by its reverse effect on TNF-α.

Study of DNA interactions with cyclic chalcone derivatives by spectroscopic techniques

A series of chalcone derivatives (1-4) were studied. The interaction between these ligands and calf thymus DNA was studied with UV-vis spectrophotometry, fluorescence and circular dichroism spectroscopy. The binding constants K were estimated at 0.5-4.6×10(5) M(-1). All these measurements indicated that the compounds behave as effective DNA-intercalating agents. Electrophoretic separation proved that ligands inhibited topoisomerase I at a concentration of 60 μM.

Dipolar relaxation in a lipid bilayer detected by a fluorescent probe, 4″-dimethylaminochalcone

The dynamic behavior of polar molecules in egg phosphatidylcholine (PC) bilayers has been studied using a membrane fluorescent probe, 4''-dimethylaminochalcone (DMAC). Time and spectrally resolved fluorescence spectroscopy of DMAC incorporated in PC liposomes, as compared to studies of the probe in organic solvents, shows the existence of two independent populations, associated with different extent and speed of dipolar solvent relaxation. The first DMAC population represents approximately 69% of the fluorescence-emitting molecules, has a short fluorescence decay time (0.32 ns) and undergoes Stokes shift of 80 nm. The remaining 31% fraction of DMAC molecules has a decay time of 0.74 ns and undergoes a high (106 nm) Stokes shift. A fraction of the shift, ca. 24 nm for the first and 46 nm for the second population, is attributed to the fast (<0.1 ns) rotational relaxation of nearby dipolar molecules, which might be water. This two-state model accounts well for the detailed fluorescence properties of DMAC in egg PC, i.e. its broadened steady-state spectrum, its average fluorescence quantum yield and its complex wavelength-dependent fluorescence decays.

Electrochemical biosensor for the interaction of DNA with the alkylating agent 4,4'-dihydroxy chalcone based on guanine and adenine signals

The interaction of an alkylating agent, 4,4'-dihydroxy chalcone (DHC) with calf thymus double stranded DNA (dsDNA) and calf thymus single stranded DNA (ssDNA) was studied electrochemically based on the oxidation signals of guanine and adenine by using differential pulse voltammetry (DPV) at carbon paste electrode (CPE). As a result of the alkylation of DHC between the base pairs in dsDNA, the voltammetric signal of guanine and adenine greatly decreased. After the interaction of DHC with ssDNA, a higher decrease in the oxidation signals of guanine and adenine was observed under the same conditions. The partition coefficients of DHC at dsDNA and ssDNA modified CPEs were calculated. The interactions of DHC with synthetic polynucleotides, such as polyguanylic acid and polyadenylic acid were also observed. In addition, the detection limit and the reproducibility were determined by using DPV. The interaction of DHC with dsDNA in solution-phase was also investigated and the results were compared with the ones obtained by surface immobilized dsDNA. The application of electrochemical DNA biosensor for monitoring the DNA-alkylating agent interactions was explored.

Antitumor effect of anthocyanin fractions extracted from red soybeans and red beans in vitro and in vivo

Many bioflavonoids extracted from petals of higher plants and from fruit rinds, as well as purified flavonoids, have been reported to have antitumor effects in vitro and in vivo. Bioflavonoids extracted from red soybeans are mostly cyanin conjugated with glucose and rhamnose, whereas bioflavonoids of red beans are cyanin conjugated with rhamnose as revealed by thin-layer chromatogram. Flavonoids extracted from red soybeans were effective in inhibiting the growth of HCT-15 cells in vitro. On the other hand, flavonoids from red beans were not effective, although their hydrolyzed sugar-free forms were growth inhibitory. Sugar-bonded bioflavonoids extracted from both red soybeans and red beans were effective in prolonging the survival of Balb/C mice bearing syngeneic tumor-Meth/A cells, when they were dissolved in drinking water and given at a dose of approximately 500 micrograms/mouse/day.

Influence of flavonoids on cell cycle phase as analyzed by flow-cytometry

Flavonoids were previously reported to have cytostatic activity in vitro and in vivo. In the present study each phase of the cell cycle was observed by flow-cytometry after HCT-15 cells had been cultured with flavonoids for 2 days. In the control group, two peaks were observed on the histogram, the first peak representing double strands of DNA, and the second, tetra strands. Chalcone, which is known to be a precursor of all flavonoids, seemed to block the passage from S to G2 and M phase. Flavonone, which is freely transformed into chalcone in vivo, showed a similar histogram as chalcone. Among the anthocyanins most effective in suppressing the tumor cell growth, cyanin and pelargonidin made a mild rise between the 1st and 2nd peak suggesting block between G1 and S phase. Delphinidin gave a high percent of cells in G1 phase, suggesting prolongation of G1 phase. When quercetin or kaempherol, both of which are flavonols were added to the culture, the second peak rose significantly, indicating a block between G2 and M phases. Thus, the site of these cytostatic agents seems to differ depending on the kind of flavonoid.