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.

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.

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.

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.

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.

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.