Photochemical Degradation of Short-Chain Chlorinated Paraffins in Aqueous Solution by Hydrated Electrons and Hydroxyl Radicals

Short-chain chlorinated paraffins (SCCPs) are a complex mixture of polychlorinated alkanes (C10-C13, chlorine content 40-70%), and have been categorized as persistent organic pollutants. However, there are knowledge gaps about their environmental degradation, particularly the effectiveness and mechanism of photochemical degradation in surface waters. Photochemically-produced hydrated electrons (e-(aq)) have been shown to degrade highly chlorinated compounds in environmentally-relevant conditions more effectively than hydroxyl radicals (·OH), which can degrade a wide range of organic pollutants. This study aimed to evaluate the potential for e-(aq) and ·OH to degrade SCCPs. To this end, the degradation of SCCP model compounds was investigated under laboratory conditions that photochemically produced e-(aq) or ·OH. Resulting SCCP degradation rate constants for e-(aq) were on the same order of magnitude as well-known chlorinated pesticides. Experiments in the presence of ·OH yielded similar or higher second-order rate constants. Trends in e-(aq) and ·OH SCCP model compounds degradation rate constants of the investigated SCCPs were consistent with that of other chlorinated compounds, with higher chlorine content producing in higher rate constants for e-(aq) and lower for ·OH. Above a chlorine:carbon ratio of approximately 0.6, the e-(aq) second-order rate constants were higher than rate constants for ·OH reactions. Results of this study furthermore suggest that SCCPs are likely susceptible to photochemical degradation in sunlit surface waters, facilitated by dissolved organic matter that can produce e-(aq) and ·OH when irradiated.

Exopolysaccharides from the Energy Microalga Strain Botryococcus braunii: Purification, Characterization, and Antioxidant Activity

Botryococcus braunii, a prestigious energy microalga, has recently received widespread attention because it can secrete large amounts of exopolysaccharides (EPS) with potential applications in food, cosmetics, and nutraceuticals. Unfortunately, the insufficiency of research on the bioactivity and structure–activity relationship of B. braunii EPS has impeded the downstream applications. In the present study, alcohol precipitation, deproteinization, and DEAE-cellulose column chromatography were used to extract and purify B. braunii SCS-1905 EPS. It was found that B. braunii SCS-1905 EPS were high-molecular-weight heteropolysaccharides containing uronic acid (7.43–8.83%), protein (2.30–4.04%), and sulfate groups (1.52–1.95%). Additionally, the EPS primarily comprised galactose (52.34–54.12%), glucose (34.60–35.53%), arabinose (9.41–10.32%), and minor amounts of fucose (1.80–1.99%), with the presence of a pyranose ring linked by a β-configurational glycosidic bond. Notably, the antioxidant activity of crude exopolysaccharides (CEPS) was stronger, and the half maximal inhibitory concentration (IC50) for ABTS and hydroxyl radicals was significantly lower than that of deproteinized exopolysaccharides (DEPS). Overall, this study indicated a potential application of B. braunii SCS-1905 EPS as a natural antioxidant. In summary, B. braunii EPS could be used as a potential feedstock for the production of antioxidant health foods.

Understanding the bactericidal mechanism of Cu(OH)2 nanorods in water through Mg-substitution: high production of toxic hydroxyl radicals by non-soluble particles

To date, there is still a lack of definite knowledge regarding the toxicity of Cu(OH)2 nanoparticles towards bacteria. This study was aimed at shedding light on the role played by...

ANTIOXIDANT AND ANTIRADICAL ACTIVITY IN VITRO OF EXTRACTS FROM THE LEAVES OF RUBUS CHAMAEMORUS L. (ROSACEAE)

Cloudberry (Rubus chamaemorus L.) is the leader among northern berries in the content of phenolic compounds, which can cause a wide range of biological activity. Currently, there is an increased interest in the study of the antioxidant activity of plant extracts in order to search for promising sources of raw materials for the pharmaceutical and food industries. The article presents the results of a comparative analysis of interpopulation and gender differences in antioxidant and antiradical activities in vitro of cloudberry leaf extracts growing on the territory of the Republic of Belarus. Classical spectrophotometric methods were used for determination: phosphomolibdenic method, Fe + 2-chelating activity, NO-inhibiting activity, inhibition of hydroxyl radicals (OH), method of superoxide radical inhibition in an alkaline solution of dimethylsulfoxide, DPPH, ABTS. Differences in the content of phenolic compounds and flavonoids in the alcoholic extracts of leaf blades of Rubus chamaemorus L. It was found that the population of the Bolshoi Mokh preserve possesses the highest inhibition rates of hydroxyl radicals and superoxide radicals. The maximum iron-chelating activity was exhibited by the extracts of the male plant of the Bolshoy Moh preserve. The least inhibitory activity of Rubus chamaemorus L. leaf extracts was shown to the nitrogen-oxide radical. The established values of antioxidant and antiradical activities, as well as the content of phenolic compounds and flavonoids of the leaf blades of Rubus chamaemorus L. may be important for the development of measures to preserve the species and specific populations on the southern border of the habitat.