No abstract

Stingless bees (Tribe Meliponini) are a diverse group of highly eusocial bees distributed throughout the tropics and subtropics. Trigona carbonaria honey, from Australia, was characterized by traditional physicochemical parameters (acidity, sugars, diastase, electrical conductivity, hydroxymethylfurfural, invertase, nitrogen, and water content) and other compositional factors (flavonoids, polyphenols, organic acids, and water activity), as well as total antioxidant capacity and radical scavenging activity. For the Australian T. carbonaria, the traditional analytical parameters were similar to those previously reported for neotropical stingless bee honey and confirm that honeys produced by Meliponini bees possess several physicochemical properties that are distinctly different from Apis mellifera honey, with higher values of moisture (26.5 +/- 0.8 g of water/100 g of honey), water activity (0.74 +/- 0.01), electrical conductivity (1.64 +/- 0.12 mS/cm), and free acidity (124.2 +/- 22.9 mEq/kg of honey) and a very low diastase activity (0.4 +/- 0.5 diastase number) and invertase activity (5.7 +/- 1.5 invertase number). The sugar spectrum was quite different from that of A. mellifera honey, with 20.3 +/- 2.9 g of maltose/100 g of honey. The values of pH (4.0 +/- 0.1), lactonic acidity (4.7 +/- 0.8 mEq/kg of honey), sucrose (1.8 +/- 0.4 g/100 g of honey), and fructose/glucose ratio (1.42 +/- 0.13) fell in the same ranges as those of A. mellifera honey. Citric (0.23 +/- 0.09) and malic (0.12 +/- 0.03) acid concentrations (in g/kg of honey) of T. carbonaria honeys were in the range described for A. mellifera honey. D-Gluconic was more concentrated (9.9 +/- 1.3 g/kg of honey), in the range of Italian Castanea, Thymus, Arbutus, and honeydew honeys. Flavonoid content was 10.02 +/- 1.59 mg of quercetin equivalents/100 g of honey, and polyphenol contents were 55.74 +/- 6.11 mg of gallic acid equivalents/100 g of honey. The antioxidant activity, expressed as percentage of 2,2'-azinobis-(3-ethylbenzothiazoline-6-sulfonic acid) cation (ABTS(*+)) decolorization, was 233.96 +/- 50.95 microM Trolox equivalents, and free radical 1,1-diphenyl-2-picrylhydrazyl (DPPH(*)) depletion was 48.03 +/- 12.58 equivalents of ascorbic acid. All reported values are averages +/- standard deviation. The antioxidant activity can represent an important added value for T. carbonaria honey, to initiate a medicinal approach for both nutritional and pharmaceutical applications, besides further physicochemical characterization.

The aim of this study was to determine the effect of aerobic exercise on uric acid (UA), total antioxidant activity (TAA), lipid hydroperoxides, and nitric oxide (NO) metabolites in human saliva. Twenty-four healthy male and female subjects were studied during a 10,000-m race. Saliva samples were collected 1 h before and immediately after exercise. The NO concentration was determined by the Griess reaction, UA by enzymatic method, TAA by the ABTS method, and lipid hydroperoxide by the ferrous iron/xylenol orange (FOX) method. A repeated measures ANOVA was used to examine the effect of aerobic exercise on salivary UA, TAA, lipid hydroperoxides, and NO metabolites. Aerobic exercise caused an increase in both salivary UA and TAA, and a decrease in salivary lipid hydroperoxide. There was no, however, change in nitrite concentration. These results suggested that aerobic exercise-induced increment in both UA and TAA seems to inhibit lipid hydroperoxide generation, a marker of oxidative stress in human saliva.

No abstract

The antioxidant effect of several polyphenolic compounds is well known. However, little is known about the antioxidant capacity of Venezuelan honey, which has a high content of polyphenolic compounds. In this work, the antioxidant capacity of a genuine honey produced in Mérida, Venezuela was studied using the ferrous iron oxidation with xylenol orange method, the thiobarbituric acid method, and the determination of antioxidant activity. We found that this honey has the capacity to decrease significantly the concentration of lipid hydroperoxides and malondialdehyde, produced during the lipid peroxidation process, in a comparable way with other widely studied antioxidants such as melatonin and vitamin E. It was found that the antioxidant activity in the 50% honey dilution, the highest concentration we tested, was equivalent to a concentration of uric acid of 0.62 mM.

Honey produced by ten stingless bee species (Melipona crinita, M. eburnea, M. grandis, M. illota, Nannotrigona melanocera, Partamona epiphytophila, Ptilotrigona lurida, Scaptotrigona polystica, Scaura latitarsis, and Tetragonisca angustula) from Peru has been characterized according to traditional physicochemical standards (color and moisture), biochemical components (flavonoids, polyphenols, nitrites, proteins), and bioactive properties (antibacterial activity, antioxidant capacity). Analytical data are also provided for a sample of Apis mellifera and an artificial honey control. For stingless bees, honey color varied between 26 and 150 mm Pfund. M. illota produced the lightest honey, while N. melanocera and T. angustula were the darkest. Moisture varied between 20.8 and 45.8 g water/100 g, confirming higher moisture for stingless bee honey than the A. mellifera honey standard of 20 g water/100 g. Flavonoids varied from 2.6 to 31.0 mg quercetin equivalents/100g, nitrites from 0.30 to 2.88 μmoles nitrites/100 g, polyphenols from 99.7 to 464.9 mg gallic acid equivalents/100g, proteins from 0.75 to 2.86 g/100 g, and the antioxidant capacity from 93.8 to 569.6 μmoles Trolox equivalents/100 g. The minimal inhibitory concentration (MIC) was slightly lower against Staphylococcus aureus (12.5-50 g/100 mL) than Escherichia coli (50 g/100 mL).

The amplification of low-density lipoprotein (LDL) peroxidation in vitro by copper and myoglobin are well-studied biochemical approaches for investigating the oxidative modification of LDL and its role in the pathogenesis of atherosclerosis. Since the acidity of the environment is increased in inflammatory sites, the aim of this study was to investigate the effects of acidic pH on the oxidisability of LDL mediated by the haem protein myoglobin in comparison with that of copper-mediated LDL oxidation. The results show that acidic pH enhances myoglobinmediated LDL oxidation as measured by conjugated dienes, lipid hydroperoxides and electrophoretic mobility, whilst a retardation is observed with copper as pro-oxidant; the mechanism probably relates to the effects of pH on the decomposition and formation of lipid hydroperoxides and the relative influences of copper ions and of myoglobin under these conditions.

Experimental evidence suggests that release of neurotransmitters in response to acute noxious stimulation and inflammation can differ in superficial and deeper dorsal horn (DH) laminae. Using two different microdialysis probes, we studied changes in levels of glutamate, aspartate, arginine and GABA in dialysates collected from the surface of the spinal cord and within the DH induced by pinching the paw or paw inflammation. In penthotal anaesthetized rats, a flexible microdialysis probe was placed on the dorsal surface of the L4-L5 or L6-S2 spinal segments. In other rats, a rigid microdialysis probe was implanted within the DH of the same segments. Samples were collected every minute before, during and after pinching the hind paw (acute pain), and every half an hour after injecting either carrageenan or saline into the same paw (inflammation-induced pain). Amino acids were measured by capillary zone electrophoresis with laser-induced fluorescence detection (CZE-LIFD). Pinching the paw induced a significant but short lasting increase in extracellular glutamate and aspartate in dialysates from the surface of the DH. Carrageenan, but not saline, injected into the paw significantly increased concentrations of glutamate, aspartate and arginine both on the surface and within the DH of L4-L5 and also within the DH of the L6-S2 segments. The GABA level was significantly increased following carrageenan only within the DH. The maximum increase on the surface was detected 60-120 min after the onset of inflammation whereas the response within the DH reached a maximum between 150 and 180 min after carrageenan. These results indicate that unlike acute mechanical noxious stimulation which enhances amino acid neurotransmitters in surface dialysate, inflammation induced neurotransmitter release in all layers of the DH suggesting sensitization of the DH.