Phenolic compounds in peach (Prunus persica) cultivars at harvest and during fruit maturation

Six peach and six nectarine cultivars were evaluated for the phenolic content in their pulp and peel tissues. Chlorogenic acid, catechin, epicatechin, rutin and cyanidin-3-glucoside were detected as the main phenolic compounds of ripened fruits. The concentration was always higher in peel tissue, with average values ranging from 1 to 8 mg g⁻¹ dry weight (DW) depending on cultivar. Of the tested varieties, the white-flesh nectarine 'Silver Rome' emerged as the cultivar with the highest amount of total phenolics. Phenolic compounds were also profiled during fruit growth and ripening in the yellow nectarine cv. 'Stark Red Gold', which showed a decreasing concentration during fruit development in both peel and pulp tissues. Average amounts of total phenolics were approximately 25 mg g⁻¹ DW 60 days after full bloom and decreased to 3 mg g⁻¹ DW at ripening in pulp tissue. Differences among peel and pulp composition show the different dietetic and antioxidant potential of fruits consumed unpeeled and peeled.     

Effects of short-term heat stress on oxidative damage and responses of antioxidant system in Lilium longiflorum

This paper aims to determine the changes in reactive oxygen species (ROS) and the responses of the lily (Lilium longiflorum L.) antioxidant system to short-term high temperatures. Plants were exposed to three levels of heat stress (37°C, 42°C, 47°C) for 10 h when hydrogen peroxide (H₂O₂) and superoxide (O₂⁻) production rate along with membrane injury indexes, and changes in antioxidants were measured. Compared with the control (20°C), electrolyte leakage and MDA concentration varied slightly after 10 h at 37°C and 42°C, while increased significantly at 47°C. During 10 h at 37°C and 42°C, antioxidant enzyme activities, such as SOD, POD, CAT, APX and GR, were stimulated and antioxidants (AsA and GSH concentrations) maintained high levels, which resulted in low levels of O₂⁻ and H₂O₂ concentration. However, after 10 h at 47°C, SOD, APX, GR activities and GSH concentration were similar to the controls, while POD, CAT activities and AsA concentration decreased significantly as compared with the control, concomitant with significant increase in O₂⁻ and H₂O₂ concentrations. In addition, such heat-induced effects on antioxidant enzymes were also confirmed by SOD and POD isoform, as Cu/ZnSOD maintained high stability under heat stress and the intensity of POD isoforms reduced with the duration of heat stress, especially at 47°C. It is concluded that in lily plants, the oxidative damage induced by heat stress was related to the changes in antioxidant enzyme activities and antioxidants.     

Nitric oxide protects against polyethylene glycol-induced oxidative damage in two ecotypes of reed suspension cultures

Dune reed (DR) is the more tolerant ecotype of reed to environmental stresses than swamp reed (SR). Under osmotic stress mediated by polyethylene glycol (PEG-6000), the suspension culture of SR showed higher ion leakage, and more oxidative damage to the membrane lipids and proteins was observed compared with the relatively tolerant DR suspension culture. Treatment with sodium nitroprusside (SNP) can significantly alleviated PEG-induced ion leakage, thiobarbituric acid reactive substances (TBARS) and carbonyl contents increase in SR suspension culture. The levels of H(2)O(2) and O(2)(-) were reduced, and the activities of antioxidant enzymes such as superoxide dismutase (SOD), catalase (CAT) and ascorbate peroxidase (APX) were increased in both suspension cultures in the presence of SNP under osmotic stress, but lipoxygenase (LOX) activity was inhibited. 2-(4-carboxy-2-phenyl)-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide (PTIO), a specific Nitric oxide (NO) scavenger, blocked the SNP-mediated protection. Depletion of endogenous NO with PTIO strongly enhanced oxidative damage in DR compared with that of PEG treatment alone, whereas had no effect on SR. Moreover, NO production increased significantly in DR while kept stable in SR under osmotic stress. Taken together, these results suggest that PEG induced NO release in DR but not SR can effectively protect against oxidative damage and confer an increased tolerance to osmotic stress in DR suspension culture.     

Oxidative metabolism-related changes in cryogenically stored neem (Azadirachta indica A. Juss) seeds

The seeds of Azadirachta indica were successfully cryopreserved for 12 months with 45% survival following drying to 0.16gH(2)Og(-1) dry mass (DM). Highest survival (94-96%) was recorded during the first month of cryostorage. Subsequent cryopreservation up to 12 months resulted in decreasing germination. Post-thawing pre-heat treatment enhanced the recovery marginally in seeds cryopreserved from 3 to 12 months. Viability of cryostored seeds was negatively correlated with leachate conductivity and accumulation of thiobarbituric acid reactive substances (TBRS) estimated in cotyledons and axes. Leachate conductivity of imbibed seeds was low during the first month of cryostorage but increased gradually with the duration of cryostorage to a maximum after 12 months. TBRS accumulation was gradual throughout cryostorage. Relatively low amounts of active oxygen species (AOS) detected during the first month of cryostorage were closely associated with very high activities of superoxide dismutase (SOD), catalase (CAT) and ascorbate peroxidase (APX) in seeds (cotyledons and axes). Marked accumulation of AOS from 3 to 12 months was associated with decrease in antioxidant enzyme activity.     

Superoxide dismutase and total peroxidase activities in relation to drought recovery performance of mycorrhizal shrub seedlings grown in an amended semiarid soil

We studied the effect of inoculation with a mixture of three arbuscular mycorrhizal (AM) fungi (Glomus intraradices Schenck & Smith, Glomus deserticola (Trappe, Bloss. & Menge) and Glomus mosseae (Nicol & Gerd.) Gerd. & Trappe) and addition of a composted organic residue on plant growth, nutrient uptake, mycorrhizal colonisation and superoxide dismutase (SOD, EC 1.15.1.1) and total peroxidase (POX, EC 1.11.1.7) activities in shoots of Juniperus oxycedrus seedlings after well-watered, drought and recovery periods. The mycorrhizal inoculation and composted residue addition significantly increased the growth, foliar nutrients (N, P, K) and shoot water content of the plants, independent of the water regime. POX activity in control plants increased during drought (about 250% higher than under well-watered conditions) and returned to initial levels after re-watering. The seedlings inoculated with AM fungi showed the highest values of POX activity, followed by the plants grown in the amended soil, which varied little during the drought and recovery periods. Drought decreased the SOD activity in shoots of both J. oxycedrus seedlings inoculated with AM fungi and those grown with composted residue, but did not affect that of control plants. After re-watering, the SOD activity in mycorrhizal or residue-amended plants increased, showing values similar to control plants.     

Hypoglycemic and antioxidant effect of oleuropein in alloxan-diabetic rabbits

Patients with diabetes mellitus are likely to develop certain complication such as retinopathy, nephropathy and neuropathy as a result of oxidative stress and overwhelming free radicals. Treatment of diabetic patients with antioxidant may be of advantage in attenuating these complications. Oleuropein, the active constituent of olive leaf (Olea europaea), has been endowed with many beneficial and health promoting properties mostly linked to its antioxidant activity. This study aimed to evaluate the significance of supplementation of oleuropein in reducing oxidative stress and hyperglycemia in alloxan-induced diabetic rabbits. After induction of diabetes, a significant rise in plasma and erythrocyte malondialdehyde (MDA) and blood glucose as well as alteration in enzymatic and non-enzymatic antioxidants was observed in all diabetic animals. During 16 weeks of treatment of diabetic rabbits with 20 mg/kg body weight of oleuropein the levels of MDA along with blood glucose and most of the enzymatic and non-enzymatic antioxidants were significantly restored to establish values that were not different from normal control rabbits. Untreated diabetic rabbits on the other hand demonstrated persistent alterations in the oxidative stress marker MDA, blood glucose and the antioxidant parameters. These results demonstrate that oleuropein may be of advantage in inhibiting hyperglycemia and oxidative stress induced by diabetes and suggest that administration of oleuropein may be helpful in the prevention of diabetic complications associated with oxidative stress.     

Hypolipidemic and antioxidant effects of Morus alba L. (Egyptian mulberry) root bark fractions supplementation in cholesterol-fed rats

The 70% alcohol extract of the Egyptian Morus alba L. root bark was fractionated over cellulose CC eluted with water, 50% methanol and finally with 100% methanol to yield 3 fractions (MRBF-1, MRBF-2 and MRBF-3), respectively. In continuation of chromatographic purification of 70% alcohol extract fractions of the Egyptian M. alba L. root bark, 4 compounds namely: mulberroside A, 5,7,2'-trihydroxyflavanone-4'-O-beta-D-glucoside and albanols A and B were isolated from MRBF-2 for the first time from the Egyptian plant. Experimentally induced atherosclerosis was produced by feeding rats a diet enriched in coconut oil (25% by weight) and cholesterol (2% by weight) for 21 days. Then, hypercholesterolemic rats were orally administered (MRBF-1, MRBF-2 and MRBF-3 fractions) in a dose of 500 mg kg(-1) day(-1) for 15 successive days, in order to evaluate their expected hypocholesterolemic activity. Lipid profile parameters such as plasma total cholesterol, LDL-C, VLDL-C, LDL:HDL ratio and triglycerides, as well as plasma and liver lipid peroxides and glutathione-S-transferase enzyme levels, serum paraoxonase enzyme level, LDL oxidation, LDL aggregation and LDL retention, were measured. Plasma and liver glutathione-S-transferase enzyme levels were unaffected in all studied groups. The results revealed that the administration of (MRBF-2 and/or MRBF-3) fractions resulted in alleviation of atherosclerotic state. Administration of MRBF-3 significantly retained plasma and liver peroxides towards their normal levels, and also, produced significant increase in resistance towards major atherogenic modifications; namely LDL oxidation, LDL aggregation and LDL retention by 44%, 30%, and 33%, respectively. Thus, it can be concluded that the consumption of MRBF-2 and (MRBF-3, in some extent) fractions of M. alba L. root bark 70% alcohol extract may act as a potent hypocholesterolemic nutrient and powerful antioxidant via the inhibition of LDL atherogenic modifications and lipid peroxides formation in hypercholesterolemic rats.     

Caffeic acid phenethyl ester blocks free radical generation and 6-hydroxydopamine-induced neurotoxicity

Neurotoxicity induced by 6-hydroxydopamine (6-OHDA) is believed to be due, in part, to the production of reactive oxygen species (ROS). Antioxidants protect neurons against 6-OHDA-induced neurotoxicity by inhibiting free radical generation. In this study, we investigated whether or not caffeic acid phenethyl ester (CAPE) could protect neurons against 6-OHDA-induced neurotoxicity in cultured rat rostral mesencephalic neurons (RMN) and cerebellar granule neurons (CGN). We now report that exposure of RMN and CGN to 6-OHDA (40 microM for RMN and 70 microM for CGN) resulted in significant increases in free radical production and death of both neuron types. Pretreatment with CAPE (10 microM) for 2 h prevented both 6-OHDA-induced free radical generation and neurotoxicity. Furthermore, CAPE also attenuated H(2)O(2)-induced neurotoxicity. Our results strongly suggest that CAPE blocks 6-OHDA-induced neuronal death possibly by inhibiting 6-OHDA-induced free radical generation and blocking free radical-induced neurotoxicity in neurons. Both the antioxidative and neuroprotective effects of CAPE may be beneficial in the therapy for Parkinson's disease and other neurodegenerative diseases.     

Anti-plasmodial and antioxidant activities of constituents of the seed shells of Symphonia globulifera Linn f

A xanthone derivative, named gaboxanthone (1), has been isolated from the seed shells of Symphonia globulifera, together with known compounds, symphonin (2), globuliferin (3), guttiferone A (4), sistosterol, oleanolic acid and methyl citrate. The structure of the compound was assigned as 5,10-dihydroxy-8,9-dimethoxy-2,2-dimethyl-12-(3-methylbut-2-enyl) pyrano [3,2-b]xanthen-6(2H)-one, by means of spectroscopic analysis. The anti-plasmodial and antioxidant activities of the phenolic compounds were evaluated, respectively, in culture against W2 strain of Plasmodium falciparum and using the free radical scavenging activity of the DPPH radical, respectively. Compounds 1-4 were found to be active against the Plasmodium parasites (IC(50) of 3.53, 1.29, 3.86 and 3.17 microM, respectively). Guttiferone A (4) showed a potent free radical scavenging activity compared to the well-known antioxidant caffeic acid.