Total reactive antioxidant potential (TRAP) of resinous exudates from Heliotropium species was evaluated by measuring the bleaching of stable free radicals. The antioxidant capacity of the resinous exudates in Trolox equivalents, evaluated from the bleaching of ABTS derived radical cations, ranged from 2.0 M (H. huascoense) to 5.2 M (H. stenophyllum), indicating a very high concentration of phenolic compounds. Considerably smaller values were obtained by measuring the bleaching of DPPH radicals. The ratio between the values obtained employing ABTS derived radicals and DPPH, ranged from 37 (H. megalanthum) to 4.5 (H. chenopodiaceum variety typica). The magnitude of the difference can be considered as an indication of the relative reactivity of the antioxidants present in the exudates. Similar ratios were observed when stoichiometric coefficients were evaluated for representative purified flavonoids obtained from the resinous exudates.

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Although the importance of seminal plasma in the protection of spermatozoa against reactive oxygen species is well known, only a few studies have investigated its antioxidative properties and the possible relationship between infertility and plasmatic antioxidant defences. The aim of the present study was to assess the status of the total non-enzymatic antioxidant defences of human seminal plasma. Semen samples were obtained from 101 patients consulting for infertility and 15 fertile donors. A total reactive antioxidant potential (TRAP) in seminal plasma was determined by luminol-chemiluminescence. The relationship of seminal TRAP values to lipid peroxidation was also evaluated. Our results show that semen samples from fertile controls show total antioxidant capacity at higher frequency and value than equivalent samples from suspected subfertile men. This fact as well as the inverse relationship observed between antioxidant capacity and lipid peroxidation potential strongly suggest that impaired antioxidant defences may play a role in infertile disorders.

Pre-eclampsia is a hypertensive disorder of pregnancy in which enzymatic antioxidant defenses fail and tissues are injured. This prospective case-control study evaluated whether pre-eclamptic women and their newborns show higher degrees of oxidative stress than normal pregnancies and sought to determine if this stress is related to clinical severity. Forty-four pre-eclamptic and thirty healthy pregnant women attending two hospitals in Valparaíso, Chile, were studied. The following plasmatic variables of antioxidant capacity were evaluated: glutathione peroxidase activity (GPx), total antioxidant capacity measured by oxidation of ABTS substrate (2,2'-azino-bis (3-ethylbenzthiazoline-6-sulfonic acid), and superoxide dismutase activity (SOD). malondialdehide (MDA) was measured to evaluate lipoperoxidation. The evaluation was performed at diagnosis of pre-eclampsia, delivery, 30 days and 120 days post delivery. Newborns were studied at delivery through umbilical cord blood samples. Our analysis shows that antioxidant enzyme activity (SOD, GPx, ABTS) was significantly decreased, while lipoperoxidation (MDA) was increased in both pre-eclamptic groups compared to normal pregnant women (p<0.01). Statistically significant difference was found between mild and severe pre-eclamptic groups (p<0.01), for all biochemical markers studied. Therefore, the clinical severity of this pathology is closely related to the degree of oxidative stress.

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The peroxidative metabolization of indole-3-acetic acid, a biologically important process, has been followed by EPR spectroscopy with the aim of obtaining information on the mechanism of generation of electronically excited species. The skatole-3-methylene radical detected during oxidation by horseradish peroxidase, does not appear to be involved in a major oxygen consuming process or in the generation of singlet oxygen. The chemiluminescence spectrum exhibits several maxima, which are also observed when the ethyl ester of indole-3-acetic acid is metabolized by horseradish peroxidase or by myeloperoxidase in neutrophils. When the ester is metabolically activated in either of these systems, the EPR spectrum indicates a tertiary carbon-centered radical. This radical centered on the carbon in the 3-position participates in a chemiexcitation/emissive route. Within the cell, this emissive process is responsible for a large part of the oxygen consumed. Some of the emitters originate in the cleavage of the 2,3 double bond. The ester, which is capable of penetrating into the cells, also emits with other myeloperoxidase-containing cells. This compound may have useful applications as an intracellular chemiluminescent probe for the presence of myeloperoxidase.

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