Effects of oxidative modification on textural properties and gel structure of pork myofibrillar proteins

Isolated myofibrillar protein (MP) was treated by the oxidation system of FeCl₃ (0.01 mM) at four different H₂O₂ concentrations (0, 1, 10, 20 mM). The oxidation degree was determined by measuring the carbonyl and total sulphydryl values. The structure and physicochemical properties of MP gels were investigated by water holding capacity (WHC) evaluation, sodium dodecyl sulfate-polyacryl amide gel electrophoresis (SDS-PAGE), texture profile analysis (TPA), Raman spectroscopy, and NMR transverse relaxation (T₂). The results of carbonyls and total sulphydryls indicated that oxidation degree of MP increased with increasing H₂O₂ concentration. TPA showed that moderate oxidation (10 mM H₂O₂) could improve the hardness, springiness, gumminess and cohesiveness of MP gels, but not contribute to the maintenance of their WHC, probably due to severe depolymerization of MPs, unfolding of α-helix, exposure of the hydrophobic groups and the migration of protein-associated water (T_2b) and intra-myofibrillar water (T₂₁) to the longer relaxation time.

Fermented non-digestible fraction from combined nixtamalized corn (Zea mays L.)/cooked common bean (Phaseolus vulgaris L.) chips modulate anti-inflammatory markers on RAW 264.7 macrophages

Chronic non-communicable diseases (NCDs) are low-level inflammation processes affected by several factors including diet. It has been reported that mixed whole grain and legume consumption, e.g. corn and common bean, might be a beneficial combination due to its content of bioactive compounds. A considerable amount would be retained in the non-digestible fraction (NDF), reaching the colon, where microbiota produce short-chain fatty acids (SCFAs) and phenolic compounds (PC) with known anti-inflammatory effect. The aim of this study was to estimate the anti-inflammatory potential of fermented-NDF of corn-bean chips (FNDFC) in RAW 264.7 macrophages. After 24 h, FNDFC produced SCFAs (0.156-0.222 mmol/l), inhibited nitric oxide production > 80% and H₂O₂ > 30%, up-regulated anti-inflammatory cytokines (I-TAC, TIMP-1) > 2-fold, and produced angiostatic and protective factors against vascular/tissue damage, and amelioration of tumor necrosis factor signalling and inflammatory bowel disease. These results confirm the anti-inflammatory potential derived from healthy corn-bean chips.

Immunomodulatory potential of hesperetin and chrysin through the cellular and humoral response

Flavonoids are polyphenols frequently consumed in the diet they have been suggested to exert a number of beneficial actions on human health, including anti-inflammatory activity. This study investigated the immunomodulatory effects of two flavonoids, Chrysin and Hesperetin. The effects of flavonoids on B and T cell proliferation were assessed on splenocytes stimulated or not with mitogens. However, their effects on cytotoxic T lymphocyte (CTL) and natural killer (NK) activities were assessed in splenocytes co-incubated with target cells. We report for the first time that both tested flavonoids enhance lymphocyte proliferation at 3.12μM. Chrysin significantly inhibited lipopolysaccharide (LPS) and lectin stimulated splenocyte proliferation. Whereas, hesperetin enhanced LPS and lectin stimulated splenocyte proliferation. In addition, both flavonoids significantly enhance NK cell and CTL activities. Furthermore, our study demonstrated that depending on the concentrations, flavonoid molecules affect macrophage functions by modulating their lysosomal activity and nitric oxide (NO) release, suggesting a potential anti-inflammatory effect. We conclude that flavonoids such as chrysin and hesperetin may be potentially useful for modulating immune cell functions in physiological and pathological conditions and thus a good candidate as food addition component.

Cytotoxic and antibacterial naphthoquinones from an endophytic fungus, Cladosporium sp

Objective

Endophytes have the potential to synthesize various bioactive secondary metabolites. The aim of the study was to find new cytotoxic and antibacterial metabolites from endophytic fungus, Cladosporium sp. isolated from the leaves of Rauwolfia serpentina (L.) Benth. ex Kurz. (Fam: Apocyanaceae).

Materials and methods

The endophytic fungus was grown on potato dextrose agar medium and extracted using ethyl acetate. Secondary metabolites were isolated by chromatographic separation and re-crystallization, and structures were confirmed by ¹H NMR, ¹³C NMR and mass spectroscopic data. The cytotoxicity was determined by WST-1 assay and brine shrimp lethality bioassay, while antibacterial activity was assessed by disc diffusion method.

Results

Two naphthoquinones, namely anhydrofusarubin (1) and methyl ether of fusarubin (2), were isolated from Cladosporium sp. The isolated compounds 1 and 2, by WST-1 assay against human leukemia cells (K-562) showed potential cytotoxicity with IC₅₀ values of 3.97 μg/mL and 3.58 μg/mL, respectively. Initial screening of crude ethyl acetate extract and column fractions F-8 and F-10 exhibited noticeable cytotoxicity to brine shimp nauplii with LC₅₀ values of 42.8, 1.2 and 2.1 μg/mL, respectively. Moreover, the isolated compound 2 (40 μg/disc) showed prominent activities against Staphylococcus aureus, Escherichia coli, Pseudomonas aeruginosa and Bacillus megaterium with an average zone of inhibition of 27 mm, 25 mm, 24 mm and 22 mm, respectively and the activities were compared with kanamycin (30 μg/disc).

Conclusion

Our findings indicate that anhydrofusarubin (1) and methyl ether of fusarubin (2) might be useful lead compounds to develop potential cytotoxic and antimicrobial drugs.

Thin-film amperometric multibiosensor for simultaneous determination of lactate and glucose in wine

An amperometric multi-biosensor based on lactate and glucose oxidases has been developed for determination of lactate and glucose in wine. Gold thin-film amperometric electrodes were used as multi-transducers. Analytical characteristics of the multi-biosensor developed were studied. The minimum detectable concentration was 5×10(-6) mol/l for both glucose and lactate. High reproducibility and storage stability of the multi-biosensor are demonstrated in this paper. Lactate and glucose were determined in wine, and a good correlation was obtained with concentrations determined using high-performance liquid chromatography (correlation coefficient for glucose R(2)=0.998, for lactate R(2)=0.718).