Resonance structure contributions, flexibility, and frontier molecular orbitals (HOMO-LUMO) of pelargonidin, cyanidin, and delphinidin throughout the conformational space: application to antioxidant and antimutagenic activities.

This research refers to the study and understanding of the conformational space of the positive-charged anthocyanidin structures in relation with the known chemical reactivities and bioactivities of these compounds. Therefore, the planar (P) and nonplanar (Z) conformers of the three hydroxylated anthocyanidins pelargonidin, cyanidin, and delphinidin were analyzed throughout the conformational space at the B3LYP/6-311 ++ G** level of theory. The outcome displayed eleven new conformers for pelargonidin, fifty-four for cyanidin, and thirty-one for delphinidin. Positive-charged quinoidal structures showed a significant statistical weight in the conformational space, thus coexisting simultaneously with other resonance structures, such that under certain reaction conditions, the anthocyanidins behave as positive-charged quinoidal structures instead of oxonium salts. The calculations of the permanent dipole moment and the polarizability showed relationships with the quantity and arrangement of hydroxyls in the structure. In addition, theoretical calculations were used to analyze the frontier molecular orbitals (HOMO-LUMO) of the three anthocyanidins. The novel conception of this work lies in the fact that dipole moment, polarizability, and HOMO-LUMO values were related to the reactivity/bioactivity of these three anthocyanidins. HOMO-LUMO energy gaps were useful to explain the antioxidant activity, while the percent atom contributions to HOMO were appropriate to demonstrate the antimutagenic activity as enzyme inhibitors, as well as the steric and electrostatic requirements to form the pharmacophore. Delphinidin was the strongest antioxidant anthocyanidin, and pelargonidin the best anthocyanidin with antimutagenic activity.

Anthocyanins and Functional Compounds Change in a Third-Generation Snacks Prepared Using Extruded Blue Maize, Black Bean, and Chard: An Optimization.

The effect of extrusion cooking on bioactive compounds in third-generation snacks (TGSE) and microwave-expanded snacks (MWSE) prepared using black bean, blue maize, and chard (FBCS) was evaluated. FBCS was extruded at different moisture contents (MC; 22.2-35.7%), extrusion temperatures (ET; 102-142 °C), and screw speeds (SP; 96-171 rpm). Total anthocyanin content (TAC), contents of individual anthocyanins, viz., cyanidin-3-glucoside, malvidin-3-glucoside, pelargonidin-3-glucoside, pelargonidin-3-5-diglucoside, and delphinidin-3-glucoside chloride, total phenolic content (TPC), antioxidant activity (AA), and color parameters were determined. TAC and individual anthocyanin levels increased with the reduction in ET. ET and MC affected the chemical and color properties; increase in ET caused a significant reduction in TPC and AA. Microwave expansion reduced anthocyanin content and AA, and increased TPC. Extrusion under optimal conditions (29% MC, 111 rpm, and 120 °C) generated products with a high retention of functional compounds, with high TAC (41.81%) and TPC (28.23%). Experimental validation of optimized process parameters yielded an average error of 13.73% from the predicted contents of individual anthocyanins. Results suggest that the TGSE of FBCS obtained by combining extrusion and microwave expansion achieved significant retention of bioactive compounds having potential physiological benefits for humans.

Comparison of the bioactive potential of Roselle (Hibiscus sabdariffa L.) calyx and its by-product: Phenolic characterization by UPLC-QTOF MSE and their anti-obesity effect in vivo.

The aim of the present study was to evaluate extractable (EPP), non-extractable polyphenols (NEPP) and organic acid in Roselle by-product, as well as its potential health beneficial effects in obesity control and their complication in rats fed with high caloric diet. Roselle by-product showed a higher content of dietary fiber and NEPP than Roselle calix, which was was a better source of EPP (P < .05). The UPLC-QTOF MSE analysis allowed the tentative identification of 34 EPP, and 3 hydrolysable polyphenols (NEPP), and 2 organic acids in calyx and by-product. Rats fed with a high caloric diet supplemented with 4% of dietary fiber from by-products and Roselle calyx powder generated a reduction in body weight gain (10% and 14%), adipocytes hypertrophy (17% and 13%) and insulin resistance (48% and 59%) and hepatic steatosis (15% and 25%; respectively) compared with rats fed with a high caloric diet alone. Interestingly, even though Roselle by-product has low EPP contents showed comparable beneficial health effects than Roselle calyces. These effects could be associated with high content of dietary fiber and NEPP. Together, the results of the present study indicate that Roselle by-products could be a potential ingredient to develop functional foods against obesity and its complications.

Enhancement of antioxidant activity and physicochemical properties of yogurt enriched with concentrated strawberry pulp obtained by block freeze concentration.

Strawberry juice was concentrated using block freeze concentration process. The concentrate was used to produce two yogurts with different concentrations of cryoconcentrated strawberry pulp (15% and 30%). Total lactic acid bacteria count, physicochemical and rheological properties was evaluated during storage (7days) for all yogurts. Also, the beverages produced were compared with two commercial trademarks. It was observed that the total lactic acid bacteria count remained higher than 108CFU·mL-1 during the storage time for all beverages studied. The viscosity of the yogurts decreased when the ratio of strawberry cryoconcentrate was increased. The Power Law model was successfully applied to describe the flow of the yogurts, which had a thixotropic behaviour. The incorporation of the cryoconcentrated strawberry pulp in the yogurt resulted in a product with 3-fold more anthocyanins content and antioxidant activity. The enrichment of natural yogurt with strawberry cryoconcentrated pulp proved to be effective in the production of a beverage with higher nutritional characteristics.

Molecular mechanism of action of Pelargonidin-3-O-glucoside, the main anthocyanin responsible for the anti-inflammatory effect of strawberry fruits.

Fragaria x ananassa Duch., popularly called strawberry, is known for its worldwide consumption and important biological activities, and these effects are related to its high concentration of anthocyanins. Pelargonidin-3-O-glucoside (P3G) is a major anthocyanin found in strawberry, and was evaluated for its anti-inflammatory action in experimental models. The effect of strawberry extract and P3G, on leukocyte migration, exudation levels and many inflammatory mediators, was therefore evaluated in an in vivo model. An in vitro study was also carried out to characterize the effect of P3G on mitogen-activated protein kinases, and on nuclear transcript factors NF-κB and AP-1. The results revealed that the strawberry and P3G have important anti-inflammatory proprieties, and the anti-inflammatory mechanism of P3G involves the arrest of IkB-α activation and reduction in JNKMAPK phosphorylation. The results reinforce that strawberry fruits are functional foods that can act as an adjuvant in the treatment of inflammatory conditions.

Binding effect of proline-rich-proteins (PRPs) on in vitro antimicrobial activity of the flavonoids.

The interaction of the cyanidin, pelargonidin, catechin, myrecetin and kaempferol with casein and gelatin, as proline rich proteins (PRPs), was studied. The binding constants calculated for both flavonoid-casein and flavonoid-gelatin were fairly large (10 (5) -10 (7) M (-1) ) indicating strong interaction. Due to higher proline content in gelatin, the binding constants of flavonoid-gelatin (2.5 × 10 (5) -6.2 × 10 (7) M (-1) ) were found to be higher than flavonoid-casein (1.2 × 10 (5) -5.0 × 10 (7) M (-1) ). All the flavonoids showed significant antibacterial activity against the tested strains. Significant loss in activity was observed due to the complexation with PRPs confirming that binding effectively reduced the concentration of the free flavonoids to be available for antibacterial activity. The decline in activity was corresponding to the values of the binding constants. Though the activities of free catechin and myrecetin were higher compared to pelargonidin, cyanidin and kaempferol yet the decline in activity of catechin and myrecetin due to complexation with casein and gelatin was more pronounced.

Binding effect of proline-rich-proteins (PRPs) on in vitro antimicrobial activity of the flavonoids

The interaction of the cyanidin, pelargonidin, catechin, myrecetin and kaempferol with casein and gelatin, as proline rich proteins (PRPs), was studied. The binding constants calculated for both flavonoid-casein and flavonoid-gelatin were fairly large (105–107 M−1) indicating strong interaction. Due to higher proline content in gelatin, the binding constants of flavonoid-gelatin (2.5 × 105–6.2 × 107 M−1) were found to be higher than flavonoid-casein (1.2 × 105–5.0 × 107 M−1). All the flavonoids showed significant antibacterial activity against the tested strains. Significant loss in activity was observed due to the complexation with PRPs confirming that binding effectively reduced the concentration of the free flavonoids to be available for antibacterial activity. The decline in activity was corresponding to the values of the binding constants. Though the activities of free catechin and myrecetin were higher compared to pelargonidin, cyanidin and kaempferol yet the decline in activity of catechin and myrecetin due to complexation with casein and gelatin was more pronounced.

Binding effect of proline-rich-proteins (PRPs) on in vitro antimicrobial activity of the flavonoids

The interaction of the cyanidin, pelargonidin, catechin, myrecetin and kaempferol with casein and gelatin, as proline rich proteins (PRPs), was studied. The binding constants calculated for both flavonoid-casein and flavonoid-gelatin were fairly large (105–107 M−1) indicating strong interaction. Due to higher proline content in gelatin, the binding constants of flavonoid-gelatin (2.5 × 105–6.2 × 107 M−1) were found to be higher than flavonoid-casein (1.2 × 105–5.0 × 107 M−1). All the flavonoids showed significant antibacterial activity against the tested strains. Significant loss in activity was observed due to the complexation with PRPs confirming that binding effectively reduced the concentration of the free flavonoids to be available for antibacterial activity. The decline in activity was corresponding to the values of the binding constants. Though the activities of free catechin and myrecetin were higher compared to pelargonidin, cyanidin and kaempferol yet the decline in activity of catechin and myrecetin due to complexation with casein and gelatin was more pronounced.(AU)