pectins and catechol

Diabetic wound is considered as a kind of chronic wound prone to infection and difficult to repair due to high glucose level in the blood of patients. In this research, a biodegradable self-healing hydrogel with mussel inspired bioadhesion and anti-oxidation properties is fabricated based on Schiff-base cross-linking. The hydrogel was designed from dopamine coupled pectin hydrazide (Pec-DH) and oxidized carboxymethyl cellulose (DCMC) for mEGF loading as a diabetic wound repair dressing. The Pectin and CMC as natural feedstock endowed the hydrogel with biodegradability to avoid possible side effects, while the coupled catechol structure could enhance the tissue adhesion of the hydrogel for hemostasis. The results showed the Pec-DH/DCMC hydrogel formed fast and can cover irregular wounds with good sealing effect. The catechol structure also improved the reactive oxygen species (ROS) scavenging ability of the hydrogel, which can eliminate the negative effect of ROS during wound healing. The in vivo diabetic wound healing experiment revealed the hydrogel as mEGF loading vehicle greatly enhanced the diabetic wound repairing rate in mice model. As a result, the Pec-DH/DCMC hydrogel could show advantages as EGF carrier in wound healing applications.

Topics: Animals; Anti-Bacterial Agents; Catechols; Cellulose; Cellulose, Oxidized; Diabetes Mellitus; Excipients; Hemostasis; Hydrazines; Hydrogels; Mice; Pectins; Prunella; Reactive Oxygen Species

The formation of anthocyanin-metal chelates, exhibiting intense blue colours was monitored over a period up to 10 weeks. Evaluating normalised absorption spectra in the range of 580-700 nm and their proportion of the total area under the curve (AUC), provided information about the blue colour hue, intensity and stability. Colour stability in model solutions containing commercial sugar beet pectin or an isolated pectic polysaccharide fraction (PPF) therefrom, both being naturally enriched in aluminium and ferric ions, was assessed in a pH range of 3.6-7.0. The pectic structures stabilised anthocyanin-metal chelates, and thus blue colours by efficiently preventing complex precipitation. Highest bathochromic shifts and most intense blue colours were observed in PPF model solutions containing delphinidin-3-glucoside (Dpd-3-glc), exhibiting a pyrogallol moiety in the flavylium B-ring, compared to cyanidin- (Cyd-3-glc) and petunidin-3-glucoside (Pet-3-glc), both carrying a catechol substituted B-ring. Hue and intensity of the blue colour at pH 5.0 were only insignificantly influenced by the buffer system except for citrate and phosphate buffers, which both annihilated anthocyanin-metal chelate formation. The blue colours faded following first order kinetics. Best stabilities as deduced from storage experiments performed at 20 ± 2°C in the dark were observed for Dpd-3-glc. In contrast, Cyd-3-glc displayed shortened half-life values, whereas blue Pet-3-glc chelates decomposed rapidly. These results demonstrate that the solubilisation of anthocyanin-metal chelates by pectic structures is a promising option for developing water soluble natural blue food colourants.

Topics: Anthocyanins; Beta vulgaris; Catechols; Kinetics; Pectins; Pyrogallol

Down-regulation of the enzyme hydroxycinnamoyl CoA: shikimate hydroxycinnamoyl transferase (HCT) in thale cress (Arabidopsis thaliana) and alfalfa (Medicago sativa) leads to strongly reduced lignin levels, reduced recalcitrance of cell walls to sugar release, but severe stunting of the plants. Levels of the stress hormone salicylic acid (SA) are inversely proportional to lignin levels and growth in a series of transgenic alfalfa plants in which lignin biosynthesis has been perturbed at different biosynthetic steps. Reduction of SA levels by genetically blocking its formation or causing its removal restores growth in HCT-down-regulated Arabidopsis, although the plants maintain reduced lignin levels. SA-mediated growth inhibition may occur via interference with gibberellic acid signaling or responsiveness. Our data place SA as a central component in growth signaling pathways that either sense flux into the monolignol pathway or respond to secondary cell-wall integrity, and indicate that it is possible to engineer plants with highly reduced cell-wall recalcitrance without negatively impacting growth.

Topics: Arabidopsis; Biofuels; Catechols; Cold Temperature; Down-Regulation; Gene Expression Regulation, Plant; Genotype; Lignin; Medicago sativa; Pectins; Plant Physiological Phenomena; RNA, Messenger; Salicylic Acid; Signal Transduction; Temperature