Antioxidant activity of pea protein hydrolysates produced by batch fermentation with lactic acid bacteria

Nine Lactobacillus strains known for surface proteinase activity were chosen from our collection and tested for their ability to grow in pea seed protein-based medium, and to hydrolyze purified pea proteins in order to produce peptides with antioxidant (AO) activity. Two strains, Lactobacillus rhamnosus BGT10 and Lactobacillus zeae LMG17315, exhibited strong proteolytic activity against pea proteins. The AO activity of the pea hydrolysate fraction, MW lt 10 kDa, obtained by the fermentation of purified pea proteins with Lactobacillus rhamnosus BGT10, was tested by standard spectrophotometric assays (DPPH, ABTS, Fe3+-reducing capacity) and the recently developed direct current (DC) polarographic assay. The low molecular weight fraction of the obtained hydrolysate was separated using ion exchange chromatography, while the AO activity of eluted fractions was determined by means of a sensitive DC polarographic assay without previous concentration of samples. Results revealed that the fraction present in low abundance that contained basic peptides possessed the highest antioxidant activity. Based on the obtained results, it can be concluded that Lactobacillus rhamnosus BGT10 should be further investigated as a candidate strain for large-scale production of bioactive peptides from legume proteins

Reduction of Hg2+ by Individual Phenolics and Complex Samples and Its Application in Polarographic Antioxidant Assay

Direct current (DC) polarographic antioxidant (AO) HPMC assay based on the decrease of anodic limiting current of [Hg(O2H)(OH)] (HydroxoPerhydroxoMercury(II) Complex-HPMC), formed in alkaline solution of H2O2, at potential of mercury oxidation, occurring upon AO addition, was validated and widely used recently. Here, a novel DC polarographic assay, MRAP (Mercury Reduction Antioxidant Power), based on the decrease of Hg2+ cathodic current with addition of AOs was applied. Percentage of this decrease was plotted versus the amount of various individual phenolics or the volume of medicinal plant extracts, and the slope obtained was used to express AO activity. A high correlation between MRAP and HPMC assays was found for individual compounds (r = 0.974) and real samples (r = 0.968). MRAP was shown to be effective in the determination of AO activity of both synthetic mixtures of individual AOs and real samples containing various AOs. Agreement between the decrease of Hg2+ cathodic current and HPMC anodic current lead to the assumption that Hg2+ reduction causes a decrease in concentration of Hg2+ available for HMPC complex formation, i.e. its anodic current decrease. The validity Of MRAP assay was also confirmed through good correlation with FRAP assay

Antioxidative status and acclimatization capacity of bamboo - potential use for air quality improvement in urban areas

Phyllostachis bissetti was introduced to urban areas in Belgrade with the aim to improve the quality of air polluted by heavy traffic. Dust released from fuel combustion adsorbed on the leaves reaching up to 10% of leaf dry weight. Adsorbed dust was analyzed for its morphological structure, chemical content and prooxidant activity. SEM analysis of dust indicated the presence of particulate matter fractions PM10 and PM2.5. Determination of peroxidase levels (POD, EC 1.11.1.7), ascorbate concentration and total antioxidant capacity in the leaves showed that, overall, P. bissetii had high antioxidative potential to cope with oxidative stress under urban environmental conditions. Leaf protein and chlorophyll content accompanied by high growth rate of seedlings planted at different locations indicated excellent acclimatization capacity of P. bissetti to the heavily polluted urban areas