Water stress induces changes in polyphenol profile and antioxidant capacity in poplar plants (Populus spp.).

This paper is aimed to characterize young poplar plants under the influence of water stress provoked by polyethileneglycol 6000 (PEG 6000). Three polar genotypes (M1, B229, and PE19/66) were grown in hydroponics and subjected to 100 and 200 mOsm PEG 6000 during six days. Polyphenol characterization, two enzymatic markers and antioxidant capacity in leaves and roots were investigated in stressed plants. Total phenol content, ferric reducing antioxidant capacity (FRAP) and DPPH antiradical power (DPPH ARP) were determined for estimating total antioxidant capacity. Polyphenol oxidase (PPO) and phenylalanine ammonia lyase (PAL) were determined as enzymatic markers. Polyphenol characterization of poplar samples was performed by HPLC-PDA analysis. All results were subjected to correlation analysis and principal component analysis (PCA). Inspite of the decrease of total phenol content in investigated genotypes, as well as total antioxidant capacity, some of polyphenols were affected by stress like flavonoids chrysin, myricetine, kaempferol and isoferulic acid in roots of B229 genotype (Populus deltoides). Genotype B229 also showed the increase of antioxidant capacity and PAL activity in root and leaves under stress what could be the indicator of the adaptability of poplar plants to water stress. Significant positive correlations were obtained between PAL, antioxidant capacity as well as phenolic acids among themselves. Chemometric evaluation showed close interdependence between flavonoids, FRAP, DPPH antiradical power and both investigated enzymes of polyphenol metabolism, PAL and PPO.

Apple pomace: antiradical activity and antiproliferative action in HeLa and HT- 29 human tumor cell lines.

PURPOSE: Apple pomace is an easily accessible source of bioactive compounds which can be used for various purposes in the food, pharmaceutical and cosmetic industry. Six types of apple pomace extracts were tested to study their health benefits, free radical scavenging and antiproliferative activities. METHODS: The radical scavenging activity was determined by electron spin resonance (ESR) spectroscopy. Antiproliferative action was measured using MTT [3-(4,5-dimethylthiazol- 2-yl)2,5-diphenyl tetrazolium bromide] colorimetric assay in cervix epithelioid carcinoma (HeLa) and colon adenocarcinoma (HT-29) human cancer cell lines. RESULTS: All extracts suppressed the formation of 2,2-diphenyl- 1-picrylhydrazyl (DPPH○) and hydroxyl-free radical in a dose-dependent manner. In the presence of 12.5 mg/ ml Pinova, Reinders and Nectar pomace extract, the ESR DPPH○ signals vanished. The ○OH was completely scavenged in the presence of 45 mg/ml or higher concentration of the investigated extracts. Pinova and Braeburn pomace extracts showed the strongest antiproliferative activity against the investigated human cancer cell lines. Also, HeLa cells were found more sensitive than HT-29 cells to all extracts. CONCLUSION: Although the relationship between radical scavenging activities and phenolic contents or flavonol glycosides (R(2)≥0.80) was high, there were no significant correlations between the total phenolic contents or individual phenolic compounds and the antiproliferative activity.

Antioxidant and free-radical scavenging activities of Allium roseum and Allium subhirsutum.

This study was designed to examine the antioxidant and free-radical scavenging activities of two Allium species, Allium roseum and Allium subhirsutum. This study reports the results concerning bulb, stalk and leaf antioxidant enzyme activities (superoxide dismutase, catalase, guaiacol peroxidase and glutathione peroxidase), quantities of malonyldialdehyde, (*)OH and O(2) (*-) radicals and total antioxidant capacity determined by the FRAP method. Scavenging activities were determined by ESR method. The total antioxidant capacity was the highest in the leaves of Allium roseum. Among the investigated organs the leaves exhibited the highest antioxidant activities in all investigated Allium species. The highest ESR (84.61%) scavenger activity was observed in the leaves of Allium roseum.

Antioxidant and scavenger activities of Allium ursinum.

The antioxidative properties of bulb, leaf and stalk of Allium ursinum were investigated. Activities of antioxidant enzymes (superoxide dismutase, catalase, peroxidase, glutathione peroxidase), quantities of malonyldialdehyde, superoxide and hydroxyl radicals and reduced glutathione and also the contents of total flavonoids, chlorophylls a and b and carotenoids were determined. The extracts from all plant organs exhibited antioxidant activity, the highest having been observed in the leaves. Furthermore, ESR signal of PBN-OH radical adducts in the presence of leaves phosphate buffer (pH 7) extract was reduced for 87.61%.

Free radical scavenging activity of three Equisetum species from Fruska gora mountain.

The scavenger activities of Equisetum arvense, Equisetum ramosissimum and Equisetum telmateia aboveground parts phosphate buffer (pH 7) extracts were evaluated using three different methods: DPPH assay, ESR and NO radical inhibition assay. Total reducing power was determined by FRAP assay. The E. telmateia extract demonstrated the most relevant scavenger and antioxidant properties. ESR signal of DMPO-OH radical adducts in the presence of E. telmateia phosphate buffer (pH 7) extract was reduced to 98.9% which indicated that E. telmateia could be a useful source of antioxidants with huge scavenger ability.

Exploring Allium species as a source of potential medicinal agents.

It has been shown that Allium species may help to prevent tumor promotion, cardiovascular diseases and aging; all processes that are associated with free radicals. Therefore the Allium species of both cultivated species (Allium nutans L., Allium fistulosum L., Allium vineale L., Allium psekemense B. Fedtsch, Allium cepa L., Allium sativum L.) and wild species (Allium flavum L., Allium sphaerocephalum L., Allium atroviolaceum Boiss, Allium schenoprasum L., Allium vineale L., Allium ursinum L., Allium scorodoprasum L.) from various locations were investigated for their antioxidative properties. The leaves were examined for activities of antioxidative enzymes (catalase, peroxidase, superoxide-dismutase, glutathione-peroxidase), non-enzymic antioxidants (reduced glutathione and total flavonoids), content of soluble proteins, vitamin C, carotenoids, chlorophylls a and b, as well as the quantities of malonyldialdehyde and *OH and O2*- radicals. Using a contemporary spectroscopic fluorescent method, lipofuscin, 'plant age pigments' were determined. ESR spectroscopy was used to follow the decrease of oxygen radicals in the presence of extracts of Allium species in phosphate buffer (pH 7). The results showed that all Allium species had strong antioxidative properties due to their high concentration of total flavonoids, high content of carotenoids and chlorophylls, and very low concentrations of toxic oxygen radicals. ESR signals of DMPO-OH radical adducts, in the presence of Allium extracts in phosphate buffer (pH 7), were reduced by up to 94.3%.

Screening for antioxidant properties of Allium giganteum.

The antioxidative properties of bulb, leaf and stalk of Allium giganteum were investigated. Activities of antioxidant enzymes (superoxide dismutase, catalase, peroxidase, glutathione peroxidase), quantities of malonyldialdehyde, superoxide and hydroxyl radicals and reduced glutathione and also the content of total flavonoids, chlorophylls a and b, carotenoids, vitamin C and soluble proteins were determined. The highest antioxidant activity was observed in the leaves. Furthermore, ESR signal of PBN-OH radical adducts in the presence of leaves phosphate buffer (pH 7) extract was reduced for 74.19%.

Allium schoenoprasum L., as a natural antioxidant.

The present study investigated the antioxidative properties of the bulb, leaf and stalk of Allium schoenoprasum L. Activities of antioxidant enzymes (superoxide dismutase, catalase, peroxidase, glutathione peroxidase), quantities of malonyldialdehyde, superoxide and hydroxyl radicals and reduced glutathione and also the content of total flavonoids, chlorophylls a and b, carotenoids, vitamin C and soluble proteins were determined. The results indicate that extracts from all plant organs exhibited antioxidant activity. The highest antioxidant activity was observed in the leaves.

Antioxidative and antiproliferative effects of Satureja montana L. extracts.

PURPOSE: To study in vitro the antioxidative effect of 6 Satureja montana L. extracts on free radicals and their antiproliferative effect on human tumor cell lines. MATERIALS AND METHODS: The antioxidative effect of extracts on 2, 2-diphenyl-1-picryhydrazyl (DPPH) radical was investigated by electron spin resonance (ESR) spectroscopy. Cell growth effect was measured by sulforhodamine B colorimetric assay on HeLa (human cervix epidermoid carcinoma), HT-29 (human colon adenocarcinoma), and MCF-7 (human breast adenocarcinoma) cell lines. IC(50) values were calculated from the concentration response curves following 48 h exposure time. RESULTS: The antioxidative activity of extracts increased dose-dependently at mass concentrations ranging from 0.05 to 0.3 mg/ml, and decreased in the following order: n-butanol > methanol > water > ethyl acetate > petroleum ether. All extracts effected cell growth but in a different way, depending on the extract dose and cell line. Extracts exhibited antiproliferative effect on HeLa cell line with IC(50) values ranging from 0.41 to 0.84 mg/ml except petroleum ether (IC(50) >1 mg/ml). Petroleum ether and chloroform extracts stimulated proliferation of HeLa cells within a concentration range from 0.0625 to 0.125 mg/ml. No extract reduced MCF-7 cells growth by 50% even at the concentration of 1 mg/ml. Only petroleum ether and chloroform extracts induced significant growth inhibition of HT-29 cells (IC(50) was approximately 0.74 mg/ml for both extracts). Strong stimulation of HT-29 proliferation was observed within a concentration range from 0.0625 to 0.25 mg/ml for petroleum ether, n-butanol and chloroform extract, and from 0.0625 to 0.5 mg/ml for methanol and water extracts, respectively. CONCLUSION: The obtained results indicated that Satureja montana L. extracts are strong antioxidants in vitro. ESR data demonstrated that n-butanol, methanol and water Satureja montana L. extracts possess high antioxidative activity. Chloroform extract did not show any antioxidative activity. Satureja montana L. extracts selectively inhibited the growth of human tumor cells.

An investigation into the antioxidant activity of Allium nutans L.

Antioxidants are important species which possess the ability to protect the body from damage caused by free radical-induced oxidative stress. There is currently much interest in the antioxidant role of fruit, vegetables, wines and teas. In this study the antioxidant activity of leaf, bulb and root of Allium nutants L. was investigated. Biochemical parameters were also determined: activities of antioxidant enzymes (superoxide dismutase, catalase, peroxidase, glutathione peroxidase), quantities of malonyldialdehyde, superoxide and hydroxyl radicals and reduced glutathione and contents of total flavonoids, chlorophylls a and b carotenoids, vitamin C and soluble proteins. Our results indicated that Allium nutants L. exhibits antioxidant ability in all investigated plant organs. The highest antioxidant ability was observed in the leaves where all investigated antioxidant enzymes were active and quantities of malonyldialdehyde and OH. low. Reduced glutathione, pigments and carotenoids present in the leaves contribute to the high antioxidant activity. ESR investigation conducted with Allium nutans L. phosphate buffer (pH 7) extract showed that the signal DMPO-OH spin adducts in the presence of Allium nutans L. extract was reduced by 78.48%.