Chemopreventive and antioxidant activity of 6-substituted imidazo[2,1-b]thiazoles.

The synthesis of new imidazo[2,1-b]thiazoles bearing phenolic groups is reported. These compounds and some previously described analogs were evaluated as antioxidant agents with three chemical model systems, and cancer chemopreventive potential was examined by inhibition of NO production, TNF-α activated NFκB activity, and aromatase activity, as well as induction of QR1 and RXRE binding. Two of the test compounds, 9 and 12, displayed promising activity by inhibiting iNOS, NFκB and aromatase in dose-dependent manner, with IC50 values in low micromolar range. The same compounds activated QR1 in a bifunctional manner. When incubated with human liver microsomes, the active compounds were further hydroxylated on the parent ring system, suggesting the next logical step in the development of these promising leads will entail synthetic production of metabolites followed by additional assessment of biological activity.

Monocyclic ß-lactams as antibacterial agents: facing antioxidant activity of N-methylthio-azetidinones.

A series of N-methylthio-ß-lactams with antibacterial activity were thoroughly evaluated as antioxidants. We found that only the presence of a polyphenolic moiety anchored to the ß-lactam ring ensured an adequate antioxidant potency. New compounds, efficiently combining in one structure antioxidant and antibacterial activity, may provide a promising basis for the development of new leads useful in adverse clinical conditions such as in cystic fibrosis patients, in whom colonization by MRSA and epithelial damage by chronic pulmonary oxidative stress take place.

Phytochemical and antioxidant-related investigations on bark of Abies spectabilis (D. Don) Spach. from Nepal.

The bark of several coniferous species, a waste product of the timber industry, contains significant amounts of natural antioxidants. In our ongoing studies of Nepalese medicinal plants, we examined the bark from Abies spectabilis as the starting material for extracting antioxidant compounds. In vitro antioxidant activity evaluated by means of three antioxidant methods, namely 2,2-diphenyl-1-picrylhydrazyl (DPPH), Briggs-Rauscher oscillating reaction (BR) and Trolox Equivalent Antioxidant Capacity (TEAC) and total phenol contents with the Folin-Ciocalteau reagent; the ferrous iron chelating capacity was also assessed. The methanol extract of A. spectabilis showed significant antioxidant activity and polyphenol contents (IC(50) 4.13 µg/mL, 0.20 µg/mL eq. resorcinol, 4.22 mM eq. Trolox, 3.9 µg/g eq. gallic Acid in the DPPH, BR, TEAC and Folin-Ciocalteau tests, respectively) and weak Fe(2+) chelating capacity. Phytochemical studies were also carried out with 1D- and 2D NMR experiments and DI-ESI-MS, HPLC-DAD and LC-MSn measurements. Oligomeric C-type proanthocyanidins, mainly trimeric gallocatechin derivatives, were the most abundant compounds (16% of extract expressed as procyanindin B1). Gallocatechin oligomers (up to six units) and prodelphynidin-gallocatechin polymers were also identified in the extract. Prodelphynidin B4, cyclograndisolide and trans-docosanil ferulate were also isolated and characterized by NMR and MS spectroscopy.

In vivo anti-inflammatory effect of Rosa canina L. extract.

ETHNOPHARMACOLOGICAL RELEVANCE: Rosa canina L. is a medicinal plant largely used in traditional folk medicine. Several compounds from rose hip extracts were reported to display in vitro anti-inflammatory activities. AIM OF THE STUDY: The in vivo effects of Rosa canina extracts are still poorly investigated. In the present study the anti-inflammatory and the gastroprotective effects of a hydroalcoholic crude extract of Rosa canina fruits were tested in rat. MATERIALS AND METHODS: The anti-inflammatory activity of the extract was tested on the carrageenin-induced rat paw edema assay. The gastroprotective effect was investigated on the ethanol-induced gastric damage model. The in vitro antioxidant activity of this extract was also quantified using the Briggs-Rauscher oscillating reaction, the Trolox Equivalent Antioxidant Capacity method, and the Total Phenolic Content. RESULTS: Data show that the Rosa canina extract inhibits the development of carrageenin-induced edema; the anti-inflammatory power is similar to that of indomethacin. The antiedema effect was more significant using a higher dose of the extract. The total score expressing gastric damage was lower in Rosa canina pre-treated stomachs with respect to unpre-treated ones, although the antiulcerogenic effectiveness was not statistically significant. The antiulcerogenic effectiveness was not statistically detectable, even if the total score expressing gastric damage was lower in Rosa canina stomachs from pre-treated rats with respect to unpre-treated ones. Chemical analysis revealed that the extract owns a good antioxidant activity that may also contribute to the anti-inflammatory effects observed in vivo. CONCLUSIONS: Altogether, the present data demonstrate the anti-inflammatory property of Rosa canina suggesting its potential role as adjuvant therapeutic tool for the management of inflammatory-related diseases.

Gastroprotective effect and antioxidant properties of different Laurus nobilis L. leaf extracts.

Laurus nobilis L. (Family Lauraceae) is an evergreen tree widely distributed in the Mediterranean area and Europe. It is used in folk medicine of different countries as a stomachic and carminative as well as in treatment of gastric diseases. Extracts obtained with different methods (methanol and chloroform) from laurel leaves were evaluated for their gastroprotective activities in the rat. The antioxidant capacity of the different extracts has been also measured in vitro. In order to confirm the activities investigated, histological observations were performed. The gastric damage was significantly reduced by all extracts administered. The more effective protection was produced by chloroformic and methanolic crude extracts. The results obtained after oral administration of L. nobilis leaf extracts are in good agreement with their antioxidant capacity, confirming the relationship between pharmacological efficacy and antiradical activity. Histological evidences confirm the results evaluated with the animal procedures.

Experimental and mechanistic investigation of an iodomalonic acid-based Briggs-Rauscher oscillator and its perturbations by resorcinol.

Classic Briggs-Rauscher oscillators use malonic acid (MA) as a substrate. The first organic product is iodomalonic acid. Iodomalonic acid (IMA) can serve as a substrate also; thus, the first product in that case is diiodomalonic acid (I(2)MA). Nonoscillating iodination kinetics can be followed by absorbance at 462 nm in acidic KIO(3) so long as IMA is in substantial excess over [I(2)]. At 25 °C, simulations lead to the two most important rate laws, and related rate constant estimates are reported. I(2)MA eventually decomposes by unknown processes, but I(2), O(2), H(2)O(2), and Mn(2+) speed up that decomposition, liberating most of the iodine back to the solution. Resorcinol is an effective inhibitor of oscillations both in MA oscillators and in IMA oscillators. Response of an IMA oscillator to varying amounts of resorcinol is shown herein and is similar to that for MA-based oscillators. The inhibitory effect of resorcinol is diminished by addition of IMA to a MA-based oscillator. The iodination reaction between IMA and resorcinol is too slow (0.043 M(-1) s(-1)) to account for the decreased inhibitory effectiveness of resorcinol. Rather, the decomposition of I(2)MA is responsible for the inhibition decrease.

New isatin derivatives with antioxidant activity.

The reaction between isatin and 2,5-dimethoxyaniline is described. The main product was identified as 3,3-bis(4-amino-2,5-dimethoxyphenyl)-1,3-dihydroindol-2-one. The antioxidant activity of the compounds isolated was evaluated with two methods. Three published antitumor E-3-(2-chloro-3-indolylmethylene)1,3-dihydroindol-2-ones entered the same tests to search whether they are endowed with antioxidant activity too. 3,3-Bis(4-amino-2,5-dimethoxyphenyl)-1,3-dihydroindol-2-one and the three antitumor agents showed a good chemical antioxidant activity.

Phytochemical composition and antioxidant activity of Laurus nobilis L. leaf infusion.

Laurus nobilis L. (laurel) leaves are frequently used as a spice for cooking purposes. Folk medicine in many countries uses the infusion of the plant in stomachic and carminative remedies, as well as for the treatment of gastric diseases. Little information is available about the phytochemical composition of the infusion of dried leaves, which is a way to consume this aromatic and medicinal plant. Phytochemical investigations on the infusion were performed by high-performance liquid chromatography (HPLC) with a diode array detector (DAD) and direct electrospray ionization-tandem mass spectrometry. Several flavonoid derivatives were detected. Semipreparative HPLC from the infusion of laurel leaves isolated 10 flavonoid O-glycosides, one flavonoid C-glycoside, catechin, and cinnamtannin B1. Structures of the isolated compounds were computed on the basis of spectral measurements including high-resolution mass spectrometry spectroscopy and one- and two-dimensional nuclear magnetic resonance techniques. The amount of the flavonoids was also determined by HPLC-DAD. The antioxidant activity of the tea and the isolated compounds was also measured using two different in vitro methods: the Briggs-Rauscher oscillating reaction test, at a pH similar to that of the gastric juice, and the Trolox equivalent antioxidant capacity assay, at the pH of blood. For the infusion and the methanol extract the total phenolic content was also measured using the Folin-Ciocalteu reagent.

In vitro evaluation of the chemoprotective action mechanisms of leontopodic acid against aflatoxin B1 and deoxynivalenol-induced cell damage.

Several in vitro studies showed that free radical scavengers possess chemopreventive properties against mycotoxin-induced cell damage which are at least partially associated with the induction of phase II detoxifying enzymes and antioxidant enzymes like glutathione S-transferase (GST) and glutathione peroxidase (GPx). The aim of this project was to study the chemopreventive effects of leontopodic acid (LA), a potent natural occurring free radical scavenger isolated from the aerial parts of Leontopodium alpinum. Different mycotoxins were evaluated in two different cell lines on the basis of their specific toxicity: aflatoxin B1 (AFB1) on HepG2 cells and deoxynivalenol (DON) on U937 cells. Cell viability and reactive oxygen species concentration were determined, and the effects of pre-treatment with LA on these parameters were investigated together with the GST and GPx activity as well as the concentration of reduced glutathione. The results show that LA protects U937 cells from DON-induced cell damage but not HepG2 cells from AFB1. Moreover LA is able to enhance GPx activity in U937, but not GST activity in HepG2. We hypothesize that the increase in detoxifying enzymes is probably the main mechanism of antioxidant mediated chemoprevention.

New polyphenolic beta-lactams with antioxidant activity.

Novel 4-alkylidene-beta-lactams with a polyphenolic side chain were synthesized and evaluated as radical scavengers. We have undertaken a detailed study of the antioxidant activity in vitro with chemical and biological testing of the new beta-lactams and of the corresponding methyl polyhydroxy benzoates. Antioxidant activity of beta-lactams and methyl benzoates was measured with the Briggs-Rauscher oscillating reaction, the TEAC (Trolox( Equivalent Antioxidant Capacity) assay, and as ability to inhibit ROS (=Reactive Oxygen Species) production on myoblast H9c2 cells. The results were discussed with regard to mechanism and correlated with structural parameters.

Carnosic acid from rosemary extracts: a potential chemoprotective agent against aflatoxin B1. An in vitro study.

Since oxidative stress plays an important role in the toxicity mechanism of several mycotoxins such as aflatoxin B1 (AFB1), the use of natural or synthetic free radical scavengers could be a potential chemopreventive strategy. Carnosic acid (CA) is the major polyphenolic compound present in rosemary plants and it can also be found in sage leaves. Its free radical scavenging properties were tested with two chemical methods. It was found that it has good free radical scavenging capacity at pH 7.4. This study also found that a 24 h pre-treatment with 10, 20 and 30 microm CA led to a clear, dose-dependent protective effect on cell toxicity, reducing cell death induced by a 24 h exposure with 10 microm AFB1, respectively, by 16% (P < 0.05), 26% (P < 0.01) and 63% (P < 0.001). It was also found that a 24 h pre-treatment with 20 and 30 microm CA achieved a reduction of ROS levels, respectively, of 146% (P < 0.001) and 173% (P < 0.001) in HepG2 cells exposed to 10 microm AFB1 for 8 h. Moreover, in cells pre-incubated with 30 microm CA for 24 h the concentration of 8-OH-deoxyguanine decreased by 57% (P < 0.001) with respect to the cells exposed for 24 h to 10 microm AFB1 alone. The results obtained with the in vitro and chemical studies support the theory that AFB1 induced oxidative stress plays an important role in the cytotoxic mechanism of this mycotoxin. Furthermore these findings suggest a starting point for developing alimentary strategies in order to counteract the damage caused by AFB1 contamination in feed and food.

Antioxidant and choleretic properties of Raphanus sativus L. sprout (Kaiware Daikon) extract.

Brassica vegetables and glucosinolates contained therein are supposed to reduce the risk of cancer and to possess health-promoting properties. The benefits of a Brassica-based diet may be particularly expressed by eating sprouts, in which the glucosinolate content is higher than in mature vegetables. With this in mind, a first objective of this study was to evaluate the antioxidant properties of radish (Raphanus sativus L.) sprouts (Kaiware Daikon) extract (KDE), in which the glucosinolate glucoraphasatin (GRH), showing some antioxidant activity, is present at 10.5% w/w. The contribution of GRH to KDE's antioxidant activity was considered in two chemical assays (Trolox equivalent antioxidant capacity and Briggs-Rauscher methods). The total phenol assay by Folin-Ciocalteu reagent was performed to quantify the reducing capacity of KDE. Finally, on the basis of the putative choleretic properties of antioxidant plant extracts, the effect on the bile flow of KDE administration was investigated in an animal experimental model. The findings showed that KDE has antioxidant properties and significantly induced bile flow in rats administered 1.5 g/kg of body weight for 4 consecutive days.

Deoxypodophyllotoxin content and antioxidant activity of aerial parts of Anthriscus sylvestris Hoffm.

Deoxypodophyllotoxin content of the aerial parts of Anthriscus sylvestris Hoffm. growing at different altitudes was evaluated in comparison to the roots. The lignan accumulation in ground parts was at least double compared to aerial ones. In addition antioxidant-guided fractionation of the crude methanol extract of aerial parts was performed with the 2,2-diphenyl-1-picrylhydrazyl (DPPH) test. Active fractions contained mainly luteolin-7-O-glucoside and chlorogenic acid. Antioxidant properties of both crude extract and isolated compounds were also investigated with the Briggs-Rauscher (BR) oscillating reaction. A satisfactory agreement between the results obtained with the two methods was observed.

In vivo efficacy of different extracts of Edelweiss (Leontopodium alpinum Cass.) in animal models.

Dichloromethane, methanolic and CO(2) extracts of the aerial parts and roots of Edelweiss (Leontopodium alpinum Cass.) were investigated for their anti-inflammatory and analgesic effects after oral administration. The highest activity in rat's paw edema assay was found for the lipophilic extracts of the aerial plant parts (dose 200 mg/kg), exhibiting a swelling reduction of 72% (CO(2)-extract) and 80% (DCM-extract), respectively. Histological evaluation of the treated paws showed a significant reduction of the inflammatory response in the pre-treated specimens. On the contrary in the acetic acid-induced writhing test the dichloromethane extract of the root extract exhibited more pronounced analgesic effects than the extracts of the aerial parts, suggesting a different pattern of active compounds. As far as gastrointestinal effects are concerned, oral administration of aerial parts (hDCM 200 mg/kg) to mice induces a highly significant inhibition in gastrointestinal propulsion probably related to the presence of so far unknown compounds. Moreover, the antioxidant capacity of some extracts was studied in order to establish a possible correlation with anti-inflammatory properties.

Isolation of 4-methylthio-3-butenyl glucosinolate from Raphanus sativus sprouts (kaiware daikon) and its redox properties.

The most promising among glucosinolates (GLs) are those bearing in their aglycon an extra sulfur function, such as glucoraphasatin (4-methylthio-3-butenyl GL; GRH) and glucoraphenin (4-methylsulfinyl-3-butenyl GL; GRE). The GRE/GRH redox couple is typically met among secondary metabolites of Raphanus sativus L. and, whereas GRE prevails in seeds, GRH is the major GL in full-grown roots. During the 10 days of sprouting of R. sativus seeds, the GRE and GRH contents were determined according to the Eurpean Union official method (ISO 9167-1). In comparison to the seeds, the GRE content in sprouts decreased from about 90 to about 12 micromol g(-1) of dry weight (dw), whereas a 25-fold increase--from about 3 to 76 micromol g(-1) of dw--of the GRH content was measured. An efficient pure GRH gram-scale production process from R. sativus (kaiware daikon) sprouts resulted in significant yield improvement of up to 2.2% (dw basis). The reaction of GRH with both H2O2 and ABTS*+ radical cation was investigated. Whereas H2O2 oxidation of GRH readily resulted in complete transformation into GRE, ABTS*+ caused complete decay of the GL. Even though not directly related to its radical scavenging activity, the assessed reducing capacity of GRH suggests that R. sativus sprouts might possess potential for health benefits.

Antioxidant activity of pasteurized and sterilized commercial red orange juices.

Blood orange juice is a typical Italian product whose red color is primarily associated with anthocyanin pigments. Two orange-based products are present on the market: pasteurized pure juice with 40 days of shelf life, and sterilized beverage containing minimum 12% of concentrated fruit juice. The aim of the present paper is to verify the relationships between the antioxidant properties and the anthocyanins content in a sampling of pasteurized and sterilized commercial red orange juices. The anthocyanins composition was determined by HPLC-MS/MS, while the antioxidant activity was evaluated by the Briggs-Rauscher reaction, selected in order to acquire information at acid pH values, by three radical scavenging assays (DMPD, 2-2'-azinobis-(3-ethylenbenzothiazoline-6-sulfonic acid) diammonium salt (ABTS), DPPH), and by FRAP assay to monitor the ferric reducing power. Results showed that antioxidant activity, particularly when measured by ABTS method, is positively related to the content of anthocyanins and that the reduction of anthocyanins content, typical of commercial long-shelf life juices, leads to a remarkable loss of antioxidant power.

Wulfenia carinthiaca Jacq., antioxidant and pharmacological activities.

Relative antioxidant activities of a methanolic extract of three phenylpropanoid glycosides and three iridoid glycosides from Wulfenia carinthiaca were evaluated using the Briggs-Rauscher (BR) reaction method. This method is based on the inhibitory effects by antioxidants on oscillations of the BR reaction. The total extract showed a certain antioxidant activity with respect to resorcinol chosen as standard. The three phenylpropanoid glycosides showed a very high relative antioxidant activity while iridoid glycosides had practically no activity. These experimental results were confirmed by empirical calculations based on the BDE (Bond Dissociation Enthalpy) theory. The total phenolic content was also measured for the phenylpropanoid glycosides using the Folin-Ciocalteu reagent. The obtained values as gallic acid equivalents were in perfect agreement with the relative antioxidant activities. From a pharmacological point of view the results obtained demonstrate that the methanolic extract of W. carinthiaca have antinociceptive and antiedematogenic effects in the different models adopted. The plant extract produced a significant inhibition, dose related, of the rat paw edema induced by carrageenin. The anti-inflammatory activity is probably due to the phenylpropanoid compounds present in the plant. The histological sections of paw tissue in animals treated with Wulfenia carinthiaca extract confirmed the anti-inflammatory effects. The results of the antinociceptive assay indicated a significant reduction on the number of abdominal writhes of mice, induced by acetic acid.

Polyphenols from Polygala spp. and their antioxidant activity.

Members of Polygalaceae are known to contain a variety of different polyphenolic compounds such as xanthones, flavonoids, and biphenyl derivatives. Here, we report the isolation and structural characterization of two new phenol derivatives, named alpestrin (= 3,3',5'-trimethoxy[1,1'-biphenyl]-4-ol; 10) and alpestriose A (= 6-O-benzoyl-1-O-{6-O-acetyl-3-O-[(4-hydroxy-3,5-dimethoxyphenyl)prop-2-enoyl]-beta-D-fructofuranosyl}-alpha-D-glucopyranoside; 11), and of four known compounds (12-15) from the MeOH extract of Polygala alpestris. The relative in vitro antioxidant activities of these compounds, in comparison with other phenolic substances from Polygala vulgaris, were evaluated by means of the Briggs-Rauscher (BR) oscillating reaction, a method based on the inhibitory effects of antioxidant free-radical scavengers. The experimental antioxidant-activity values (relative to resorcinol as a standard) were compared with those calculated on the basis of the bond-dissociation enthalpies. The structure/activity relationships for the compounds examined are also discussed.

Evaluation of antioxidant activity of some natural polyphenolic compounds using the Briggs-Rauscher reaction method.

A new method based on the inhibitory effects of antioxidants on the oscillations of the hydrogen peroxide, acidic iodate, malonic acid, and Mn(II)-catalyzed system (known as the Briggs-Rauscher reaction), was used for the evaluation of antioxidative capacity. With this method, which works near the pH of the fluids in the stomach (pH approximately 2), a group of natural compounds present in fruits and vegetables or in medicinal plants assumed to have antioxidant capacity, was tested successfully. The aim of the present study is to evaluate the antioxidative properties of some active principles contained in vegetables and aromatic plants, namely, cynarin (from Cynara scolymus), rosmarinic acid (from Rosmarinus officinalis), echinacoside (from Echinacea species), puerarin (from Pueraria lobata), and oleuropein (from Olea europea). Also studied with the Briggs-Rauscher reaction method was the antioxidant activity of cyanidin 3-O-beta-glucopyranoside (from Citrus aurantium) in order to compare the results with those obtained by other methods. The conclusions on the dependency of the antioxidative activity on the pH of the testing system are given.