Impact of new cyclooxygenase 2 inhibitors on human cytomegalovirus replication in vitro.

BACKGROUND: Human cytomegalovirus (HCMV) is involved in complications on immunocompromised patients. Current therapeutics are associated with several drawbacks, such as nephrotoxicity. PURPOSE: As HCMV infection affects inflammation pathways, especially prostaglandin E2 (PGE2) production via cyclooxygenase 2 enzyme (COX-2), we designed 2'-hydroxychalcone compounds to inhibit human cytomegalovirus. STUDY DESIGN: We first selected the most efficient new synthetic chalcones for their effect against COX-2-catalyzed PGE2. STUDY SAMPLE: Among the selected compounds, we assessed the antiviral efficacy against different HCMV strains, such as the laboratory strain AD169 and clinical strains (naïve or multi-resistant to conventional drugs) and toxicity on human cells. RESULTS: The most efficient and less toxic compound (chalcone 7) was tested against HCMV in combination with other antiviral molecules: artesunate (ART), baicalein (BAI), maribavir (MBV), ganciclovir (GCV), and quercetin (QUER) using Compusyn software. Association of chalcone 7 with MBV and BAI is synergistic, antagonistic with QUER, and additive with GCV and ART. CONCLUSION: These results provide a promising search path for potential bitherapies against HCMV.

New aspects of the antioxidant properties of phenolic acids: a combined theoretical and experimental approach.

Ferulic acid is widely distributed in the leaves and seeds of cereals as well as in coffee, apples, artichokes, peanuts, oranges and pineapples. Like numerous other natural polyphenols it exhibits antioxidant properties. It is known to act as a free radical scavenger by H atom transfer from the phenolic OH group. In the present joint experimental and theoretical studies we studied a new mechanism to explain such activities. Ferulic acid can indeed act by radical addition on the alpha,beta-double bond. On the basis of the identification of metabolites formed in an oxidative radiolytic solution and after DFT calculations, we studied the thermodynamic and kinetic aspects of this reaction. Addition and HAT reactions were treated as competitive reactions. The possibility of dimer formation was also investigated from a theoretical point of view; the high barriers we obtained contribute to explaining why we did not observe those compounds as major radiolytic compounds. The DPPH free radical scavenging capacity of ferulic acid and the oxidative products was measured and is discussed on the basis of DFT calculations (BDEs and spin densities).

Free radical scavenging properties of guaiacol oligomers: a combined experimental and quantum study of the guaiacyl-moiety role.

Natural polyphenols are known to exhibit a lot of different biological properties, including antioxidant activity. For some polyphenols these activities are attributed to the presence of a guaiacol moiety. In the present paper we focus on the role of this moiety. For this purpose nine different compounds were enzymatically synthesized from guaiacol. To elucidate the structure-activity relationship of these polyphenols, DFT-(PCM)B3P86/6-311+G(2d,3pd)//(PCM)B3P86/6-31+G(d,p) calculations supported the experimental DPPH free radical scavenging activities. The antioxidant activities were correlated to (i) O-H BDEs (bond dissociation enthalpies), (ii) BDE(D) (BDE of a second H atom abstraction from the phenoxyradicals), (iii) spin density, (iv) HOMO (highest occupied molecular orbital) distribution, (v) IPs (ionization potentials), (vi) DeltaG and DeltaG(#) free energies of HAT (H atom transfer), and (vii) HAT rate constants. BDE(D) appeared to be the most important descriptor to understand the free radical scavenging ability of these compounds.

Mechanisms of transformation of the antioxidant kaempferol into depsides. Gamma-radiolysis study in methanol and ethanol.

In this study, we irradiated the antioxidant kaempferol in ethanol and methanol solutions with gamma rays at doses ranging from 0.2-20 kGy. NMR and ES-MS spectroscopy were used to identify radiolysis products. Two depsides, [2-[(4'-hydroxybenzoyl)oxy]-4,6-dihydroxyphenyl](oxo) methyl acetate and [2-[(4'-hydroxybenzoyl)oxy]-4,6-dihydroxyphenyl](oxo) ethyl acetate, were the major compounds of kaempferol degradation in methanol and in ethanol, respectively. Other products formed in low concentrations were identified as [4-hydroxyphenyl](oxo) methyl acetate, [4-hydroxyphenyl](oxo) ethyl acetate, and depside [2-[(4'-hydroxybenzoyl)oxy]-4,6-dihydroxyphenyl](oxo) acetic acid. The formation of the latter was observed in both solvents. We propose degradation mechanisms that suggest that (.)CH(2)OH and CH(3)(.)CHOH, produced by solvent radiolysis, react with the 3-OH kaempferol group because of its high H-donor capacity. pi-Electron delocalization in the flavonoxy formed after the first H-transfer leads to C-ring opening and consequently to the formation of depsides. G calculation of the degradation products and of (.)CH(2)OH and CH(3)(.)CHOH radicals confirmed the proposed mechanism of kaempferol radiolysis. The rate constants for the reaction between kaempferol and these free radicals were also calculated. Formation of depside has also been observed in many studies of the oxidation of flavonoids; those studying human metabolism have suggested similar redox transformation of flavonols. The antioxidant activities of radiolysis products were evaluated and compared to those of kaempferol.

Redox reactions obtained by gamma irradiation of quercetin methanol solution are similar to in vivo metabolism.

The flavonol quercetin is one of the most well-known antioxidant flavonoids. Its antioxidant potential has been studied extensively during the last 10 years, but little is known about the metabolites formed in vivo that lead to the formation of depside and small molecules such as benzoic acids. In this study, gamma irradiation of a quercetin methanol solution was used as a model of certain oxidative reactions that occur in vivo. Qercetin at concentrations ranging from 5 x 10(-5) M to 5 x 10(-3) M, was irradiated with gamma rays at doses of 2-14 kGy. Quercetin degradation was evaluated by HPLC analysis. The major radiolytic metabolite was identified as a depside by NMR and LC-MS. Formation of 3,4-dihydroxybenzoic acid was also observed. The presence of CH3O. formed during methanol radiolysis is invoked to explain depside formation. Transformation of the 8-methoxy substituted depside (Q1) to the 8-hydroxyl substituted depside (Q2) is discussed. The antioxidant properties of quercetin metabolites are evaluated according to their capacity to decrease the EPR DPPH signal and to inhibit superoxide radical formed by the enzymatic reaction (xanthine + xanthine oxidase). For both assays, the IC50 of Q2 is twice as high as that of quercetin.

Antiproliferative, anti-aromatase, anti-17beta-HSD and antioxidant activities of lignans isolated from Myristica argentea.

Four lignans were isolated from the petrol extract of Myristica argentea mace (Myristicaceae) and their structures were elucidated by means of NMR and mass spectrometry. Although they have been previously described, NMR data are only available for threo-austrobailignan-5, which has been isolated only once, and is incomplete. Three of them, erythro-austrobailignan-6, meso-dihydroguaiaretic acid and nectandrin-B, exert an antiproliferative effect on MCF-7 cells as well as antioxidant activity on the 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical, but not the threo-austrobailignan-5. Nectandrin-B also possesses anti-17beta-hydroxysteroid dehydrogenase and anti-aromatase activities.

Free radical scavenging activities measured by electron spin resonance spectroscopy and B16 cell antiproliferative behaviors of seven plants.

In an effort to discover new antioxidant natural compounds, seven plants that grow in France (most of them in the Limousin countryside) were screened. Among these plants, was the extensively studied Vitis vinifera as reference. For each plant, sequential percolation was realized with five solvents of increasing polarities (hexane, chloroform, ethyl acetate, methanol, and water). Free radical scavenging activities were examined in different systems using electron spin resonance (ESR) spectroscopy. These assays were based on the stable free radical 1,1-diphenyl-2-picrylhydrazyl (DPPH), the hydroxyl radicals generated by a Fenton reaction, and the superoxide radicals generated by the X/XO system. Antiproliferative behavior was studied on B16 melanoma cells. ESR results showed that three plants (Castanea sativa, Filipendula ulmaria, and Betula pendula) possessed, for the most polar fractions (presence of phenolic compounds), high antioxidant activities in comparison with the Vitis vinifera reference. Gentiana lutea was the only one that presented a hydroxyl scavenging activity for the ethyl acetate and chloroform fractions. The antiproliferative test results showed that the same three plants are the most effective, but for the apolar fractions (chloroform and hexane).

Chalcones: structural requirements for antioxidant, estrogenic and antiproliferative activities.

Flavonoids are largely studied for their biological properties and particularly for their scavenging and antioxidant activities. In the present study, we first evaluated the antioxidant and the estrogenic actions of chalcones, then we tested their effects on MCF-7 cell proliferation. Chalcones are unique in the flavonoids family in lacking a heterocyclic C ring. We tested substituted chalcones with different numbers and different positions of the hydroxy groups: 2'-hydroxychalcone, 4'-hydroxychalcone, 4-hydroxychalcone, 2',4-dihydroxychalcone, isoliquiritigenin, 2',4'-dihydroxychalcone, phloretin and naringenin chalcone. For the antioxidant tests we established the importance of the alpha-beta double bond and the 6'-hydroxy group. The establishment of the structure-activity relationship for the estrogenic properties showed a correlation between the antioxidant and the estrogenic properties. The importance of conformation and hydroxy group positions observed for chalcones, having antioxidant and estrogenic properties, was also observed on MCF-7 cell growth with the same structure-activity relationship. The role of electron and hydrogen transfer in the correlation between these three biological activities was discussed.

Lipiodol ultra-fluid: an antitumor agent-in vitro study.

Lipiodol Ultra-Fluid (LUF), a contrast medium for the diagnosis and treatment of hepatocellular carcinoma (HCC), is used by hepatic intra-arterial infusion. Hepatoma cells are capable of active uptake of LUF and retaining it for prolonged periods of time. These characteristics have important therapeutic potential for the targeting of anticancer drugs and have lead us to form an intratumoral diffuser. But, before in vivo studies, we have investigated in vitro LUF effects on various cell species in order to explain and refine the lipiodol chemotherapy. The antiproliferative and cytotoxic effects of LUF on HepG2 (human hepatoma cells), MCF-7 (human breast cancer cells) murine macrophages and human hepatocytes, were assessed by Trypan blue exclusion and lactico-dehydrogenase extracellular tests. We demonstrated the dose and time-dependent antiproliferative and cytotoxic activities of LUF on cells. Cytotoxicity was different according to cells species, whether or not they had cancerous characteristics and phagocytosis function: this cytotoxicity was very significant on macrophages and was greater for cancerous cells than for human hepatocytes in primary culture. We showed in vitro, for the first time, that LUF was an antiproliferative and cytotoxic agent, because of its active uptake and selective retention which lead to cellular death due to necrosis by lipoperoxidation increase.

Inhibitory effect of curcuminoids on MCF-7 cell proliferation and structure-activity relationships.

Curcumin, demethoxycurcumin and bisdemethoxycurcumin are the yellow coloring phenolic compounds isolated from the spice turmeric. This study was part of a program correlating the biological activity and molecular structure of antitumor agents; the effect of these curcuminoids and cyclocurcumin (Cyclocur) was examined on the proliferation of MCF-7 human breast tumor cells. Curcuminoids appeared to be potent inhibitors, whereas Cyclocur was less inhibitory. To contribute to our understanding of the mechanism of antiproliferative activity of curcumin, cell cycle analysis was performed by propidium iodide staining and a flow cytometry technique. Curcumin exerts a cytostatic effect at G2/M which explains its antiproliferative activity. The presence of the diketone moiety in the curcumin molecule seems to be essential for the inhibitory activity.

The effect of gamma radiation on the degradation of salbutamol.

The use of ionizing radiation for sterilization of pharmaceuticals is now a well established technology. Degradation of salbutamol was investigated after gamma irradiation using HPLC and ESR spectroscopy. HPLC evidenced the formation of radiolytic products after gamma irradiation. Salbutamol showed a degradation of nearly 2% at 25 kGy. Sterilization of salbutamol in the liquid state appeared not technically feasible. Simulation of the increase of free radicals versus dose was performed using linear and polynomial regression. These radicals could be detected even after a storage period of more than 12 months.

1,4,5-trialkyl imidazole system anti-inflammatory properties of new substituted derivatives.

In an investigation of the anti-inflammatory properties of five-membered ring nitrogen-containing heterocyclic compounds, two series of derivatives of imidazole were prepared by altering the sites of substitution and by joining aliphatic chains to the nitrogen atom in the 1 position of the imidazole ring. Some of them were more potent inhibitors of carrageenan-induced edema than indomethacin. An electron spin resonance study indicated that these compounds possess anti-radical activity.