Pecan ( (Wagenh.) K. Koch) Nut Shell as an Accessible Polyphenol Source for Active Packaging and Food Colorant Stabilization.

Herein, the antioxidant and food stabilizing properties of a pecan nut shell (PNS) hydroalcoholic extract (PNSE) are reported. Chemical degradation of PNSE demonstrated the presence of condensed tannins as the main phenolic components. PNSE showed remarkable antioxidant properties in the 2,2-diphenyl-1-picrylhydrazyl (DPPH) assay (EC = 0.

From Fish Waste to Value: An Overview of the Sustainable Recovery of Omega-3 for Food Supplements.

The disposal of food waste is a current and pressing issue, urging novel solutions to implement sustainable waste management practices. Fish leftovers and their processing byproducts represent a significant portion of the original fish, and their disposal has a high environmental and economic impact. The utilization of waste as raw materials for the production of different classes of biofuels and high-value chemicals, a concept known as "biorefinery", is gaining interest in a vision of circular economy and zero waste policies.

Conjugation with Dihydrolipoic Acid Imparts Caffeic Acid Ester Potent Inhibitory Effect on Dopa Oxidase Activity of Human Tyrosinase.

Caffeic acid derivatives represent promising lead compounds in the search for tyrosinase inhibitors to be used in the treatment of skin local hyperpigmentation associated to an overproduction or accumulation of melanin. We recently reported the marked inhibitory activity of a conjugate of caffeic acid with dihydrolipoic acid, 2--lipoylcaffeic acid (LCA), on the tyrosine hydroxylase (TH) and dopa oxidase (DO) activities of mushroom tyrosinase. In the present study, we evaluated a more lipophilic derivative, 2--lipoyl caffeic acid methyl ester (LCAME), as an inhibitor of tyrosinase from human melanoma cells.

Unexpected impact of esterification on the antioxidant activity and (photo)stability of a eumelanin from 5,6-dihydroxyindole-2-carboxylic acid.

To inquire into the role of the carboxyl group as determinant of the properties of 5,6-dihydroxyindole melanins, melanins from aerial oxidation of 5,6-dihydroxyindole-2-carboxylic acid (DHICA) and its DHICA methyl ester (MeDHICA) were comparatively tested for their antioxidant activity. MALDI MS spectrometry analysis of MeDHICA melanin provided evidence for a collection of intact oligomers. EPR analysis showed g-values almost identical and signal amplitudes (ΔB) comparable to those of DHICA melanin, but spin density was one order of magnitude higher, with a different response to pH changes.

Milk thistle and olive extract: old substances with a new mission against sun-induced skin damage.

Background: Natural antioxidants represent an effective option in the prevention and/or improvement of ultraviolet radiations (UVR)-induced/aggravated skin conditions. UVR cause DNA damage in keratinocytes, directly, in the form of cyclobutane pyrimidine dimers (CPDs), or indirectly, through oxidative stress production. Failure of the repair system can result in genetic mutations primarily responsible for the initiation of NMSCs.

Structural Basis of Polydopamine Film Formation: Probing 5,6-Dihydroxyindole-Based Eumelanin Type Units and the Porphyrin Issue.

The role of 5,6-dihydroxyindole (DHI)-based oligomers, including porphyrin-like tetramers, in polydopamine (PDA) film formation was addressed by a comparative structural investigation against model polymers from DHI and its 2,7'-dimer. MALDI-MS data showed that (a) PDA is structurally different from DHI melanin and does not contain species compatible with DHI-based oligomers as primary building blocks; (b) PDA films and precipitate display a single main peak at m/ z 402 in common; (c) no species matching the range of m/ z values expected for cyclic porphyrin-type tetramers was detected in DHI melanin produced in the presence or in the absence of folic acid (FA) as templating agent, nor by oxidation of the 2,7'-dimer of DHI as putative precursor. N NMR resonances and Raman spectra predicted by extensive DFT calculations on porphyrin-type structures at various oxidation levels did not match spectral data for PDA or DHI melanin.

2--Lipoylcaffeic Acid, a Natural Product-Based Entry to Tyrosinase Inhibition via Catechol Manipulation.

Conjugation of naturally occurring catecholic compounds with thiols is a versatile and facile entry to a broad range of bioinspired multifunctional compounds for diverse applications in biomedicine and materials science. We report herein the inhibition properties of the caffeic acid- dihydrolipoic acid -conjugate, 2--lipoylcaffeic acid (LC), on mushroom tyrosinase. Half maximum inhibitory concentration (IC) values of 3.

The anti-inflammatory and antioxidant properties of 1,2-decanediol and willow bark extract in lipopolysaccharide-stimulated keratinocytes.

Background: 1,2-Decanediol (S-Mal) is an organic compound belonging to the 1,2-alkanediol family, with two hydroxyl groups located on the first and second carbon of the alkane chain, probably responsible for the enhanced anti-bacterial efficacy. The willow bark total extract (W-Mal) has been used since thousands of years as an herbal remedy for its antipyretic, analgesic, anti-inflammatory and anti-microbial activities. S-Mal is used in cosmetic preparations, whether W-Mal can be topically or systemically administered.

Eumelanin broadband absorption develops from aggregation-modulated chromophore interactions under structural and redox control.

Eumelanins, the chief photoprotective pigments in man and mammals, owe their black color to an unusual broadband absorption spectrum whose origin is still a conundrum. Excitonic effects from the interplay of geometric order and disorder in 5,6-dihydroxyindole (DHI)-based oligomeric/polymeric structures play a central role, however the contributions of structural (scaffold-controlled) and redox (π-electron-controlled) disorder have remained uncharted. Herein, we report an integrated experimental-theoretical entry to eumelanin chromophore dynamics based on poly(vinyl alcohol)-controlled polymerization of a large set of 5,6-dihydroxyindoles and related dimers.

"Fifty Shades" of Black and Red or How Carboxyl Groups Fine Tune Eumelanin and Pheomelanin Properties.

Recent advances in the chemistry of melanins have begun to disclose a number of important structure-property-function relationships of crucial relevance to the biological role of human pigments, including skin (photo) protection and UV-susceptibility. Even slight variations in the monomer composition of black eumelanins and red pheomelanins have been shown to determine significant differences in light absorption, antioxidant, paramagnetic and redox behavior, particle morphology, surface properties, metal chelation and resistance to photo-oxidative wear-and-tear. These variations are primarily governed by the extent of decarboxylation at critical branching points of the eumelanin and pheomelanin pathways, namely the rearrangement of dopachrome to 5,6-dihydroxyindole (DHI) and 5,6-dihydroxyindole-2-carboxylic acid (DHICA), and the rearrangement of 5-S-cysteinyldopa o-quinoneimine to 1,4-benzothiazine (BTZ) and its 3-carboxylic acid (BTZCA).

Reverse Engineering Applied to Red Human Hair Pheomelanin Reveals Redox-Buffering as a Pro-Oxidant Mechanism.

Pheomelanin has been implicated in the increased susceptibility to UV-induced melanoma for people with light skin and red hair. Recent studies identified a UV-independent pathway to melanoma carcinogenesis and implicated pheomelanin's pro-oxidant properties that act through the generation of reactive oxygen species and/or the depletion of cellular antioxidants. Here, we applied an electrochemically-based reverse engineering methodology to compare the redox properties of human hair pheomelanin with model synthetic pigments and natural eumelanin.