Antioxidant Capacity, Nitrite and Nitrate Content in Beetroot-Based Dietary Supplements.

Due to the high content of bioactive substances, beetroot and its preserves might be a valuable constituent of a diet. Research into the antioxidant capacity and content of nitrate (III) and (V) in beetroot-based dietary supplements (DSs) worldwide is limited. The Folin-Ciocalteu method, CUPRAC, DPPH, and Griess methods were used to determine total antioxidant capacity, total phenolic content, nitrites, and nitrates content in fifty DSs and twenty beetroot samples. Moreover, the safety of products was evaluated because of the concentration of nitrites, nitrates, and the correctness of labelling. The research showed that a serving of fresh beetroot provides significantly more antioxidants, nitrites, and nitrates than most daily portions of DSs. Product P9 provided the highest dose of nitrates (169 mg/daily dose). However, in most cases, the consumption of DSs would be associated with a low health value. The acceptable daily intake was not exceeded in the cases of nitrites (0.0015-0.55%) and nitrates (0.056-48%), assuming that the supplementation followed the manufacturer's recommendation. According to European and Polish regulations, 64% of the products tested did not meet all the requirements for labelling food packaging. The findings point to the need for tighter regulation of DSs, as their consumption might be dangerous.

Commercial plant extracts may act as antioxidants or pro-oxidants in cosmetic emulsions based on argan oil.

Cosmetic emulsions containing plant extracts should be tested in a range of temperatures from 5°C to 40°C to be sure that they will be stable during general use by consumers and that plant extracts used as antioxidants do not accelerate oxidative degradation of their oil base. The oxidative stability of argan oil-in-water emulsions containing 1% and 5% commercial acerola, willow, and rose extracts [or 0.01% butylhydroxytoluene (BHT)], stored at 5°C and 20°C for 6 months and at 40°C for 4 weeks, was monitored by the determination of peroxide content. The antioxidant or pro-oxidant activities of extracts or BHT in emulsions were expressed as the protection factor (PF) and inhibition of peroxide formation (Ip). At the end of storage, 5% willow, 0.01% BHT, 1% willow, and 5% acerola were the most protective for emulsions stored at 5°C. At 20°C, the most effective was 0.01% BHT, 5% rose, and 5% acerola. At 40°C, inhibition of peroxide formation calculated for 1% rose, 5% acerola, and 0.01 % BHT was similar. Altogether, the results show that some plant extracts, depending on storage conditions, may act as pro-oxidants, whereas the others can be applied as natural antioxidants instead of synthetic BHT.

Hippophae rhamnoides L. Fruits Reduce the Oxidative Stress in Human Blood Platelets and Plasma.

Effects of the phenolic fraction from Hippophae rhamnoides fruits on the production of thiobarbituric acid reactive substances (TBARS, a marker of lipid peroxidation) and the generation of superoxide anion (O2 (-∙)) in human blood platelets (resting platelets and platelets stimulated by a strong physiological agonist, thrombin) were studied in vitro. We also examined antioxidant properties of this fraction against human plasma lipid peroxidation and protein carbonylation induced by a strong biological oxidant, hydrogen peroxide (H2O2) or H2O2/Fe (a donor of hydroxyl radicals). The tested fraction of H. rhamnoides (0.5- 50 µg/mL; the incubation time: 15 and 60 min) inhibited lipid peroxidation induced by H2O2 or H2O2/Fe. The H. rhamnoides phenolic fraction inhibited not only plasma lipid peroxidation, but also plasma protein carbonylation stimulated by H2O2 or H2O2/Fe. Moreover, the level of O2 (-∙) in platelets significantly decreased. In comparative experiments, the H. rhamnoides fraction was a more effective antioxidant than aronia extract or grape seed extract (at the highest tested concentration, 50 µg/mL). The obtained results suggest that H. rhamnoides fruits may be a new, promising source of natural compounds with antioxidant and antiplatelet activity beneficial not only for healthy people, but also for those with oxidative stress-associated diseases.