In recent years, great interest has been focused on using natural antioxidants in food products, due to studies indicating possible adverse effects that may be related to the consumption of synthetic antioxidants. A variety of plant materials are known to be natural sources of antioxidants, such as herbs, spices, seeds, fruits and vegetables. The interest in these natural components is not only due to their biological value, but also to their economic impact, as most of them may be extracted from food by-products and under-exploited plant species. This article provides an overview of current knowledge on natural antioxidants: their sources, extraction methods and stabilization processes. In addition, recent studies on their applications in the food industry are also addressed; namely, as preservatives in different food products and in active films for packaging purposes and edible coatings.

https://www.mdpi.com/1420-3049/24/22/4132/pdf

Antioxidants of Natural Plant Origins: From Sources to Food Industry Applications.

The winemaking process generates a large amount of residues such as vine shots, stalks, grape pomace, and wine lees, which were only recently considered for exploitation of their valuable compounds. The purpose of this work was to investigate the performance of nanofiltration for the recovery of phenolic compounds, with bioactive capacity like antioxidant, from red grape pomace extract. Four membranes were compared in this study—three cellulose acetate (CA series: lab-prepared by phase inversion) and one commercial (NF90). All membranes were characterized for their hydraulic permeability and rejection coefficients to reference solutes like saccharose, glucose, raffinose, polyethylene glycol, sodium chloride, and sodium sulfate. Permeation flowrates and rejection coefficients towards total phenolics content, antioxidant activity, proanthocyanidins, glucose and fructose were measured in the nanofiltration of grape pomace extract using selected operating conditions. Among the investigated membranes, the CA400-22 exhibited the highest permeate flux (50.58 L/m2 h at 20 bar and 25 °C), low fouling index (of about 23%), the lowest rejection coefficients towards the reference solutes and the best performance in terms of separation between sugars and phenolic compounds. Indeed, the observed rejections for glucose and fructose were 19% and 12%, respectively. On the other hand, total phenolics content and proanthocyanidins were rejected for 73% and 92%, respectively.

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Recovery of Phenolic Compounds from Red Grape Pomace Extract through Nanofiltration Membranes.

Normal wound healing progresses through inflammatory, proliferative and remodeling phases in response to tissue injury. Collagen, a key component of the extracellular matrix, plays critical roles in the regulation of the phases of wound healing either in its native, fibrillar conformation or as soluble components in the wound milieu. Impairments in any of these phases stall the wound in a chronic, non-healing state that typically requires some form of intervention to guide the process back to completion. Key factors in the hostile environment of a chronic wound are persistent inflammation, increased destruction of ECM components caused by elevated metalloproteinases and other enzymes and improper activation of soluble mediators of the wound healing process. Collagen, being central in the regulation of several of these processes, has been utilized as an adjunct wound therapy to promote healing. In this work the significance of collagen in different biological processes relevant to wound healing are reviewed and a summary of the current literature on the use of collagen-based products in wound care is provided.

Collagen in Wound Healing.

Natural composite dressings based on collagen, gelatin and plant bioactive compounds for wound healing: A review.

Our previous study has revealed that silver nanoparticles (AgNPs) have potential to promote wound healing by accelerated re-epithelization and enhanced differentiation of fibroblasts. However, the effect of AgNPs on the functionality of repaired skin is unknown. The aim of this study was to explore the tensile properties of healed skin after treatment with AgNPs. Immunohistochemical staining, quantitative assay and scanning electron microscopy (SEM) were used to detect and compare collagen deposition, and the morphology and distribution of collagen fibers. Our results showed that AgNPs improved tensile properties and led to better fibril alignments in repaired skin, with a close resemblance to normal skin. Based on our findings, we concluded that AgNPs were predominantly responsible for regulating deposition of collagen and their use resulted in excellent alignment in the wound healing process. The exact signaling pathway by which AgNPs affect collagen regeneration is yet to be investigated.

Modulation of collagen alignment by silver nanoparticles results in better mechanical properties in wound healing

Polyphenols extract from grape pomace. Characterization and valorisation through encapsulation into mesoporous silica-type matrices.

In this study, we aimed to obtain gelatin from the marine snail Rapana venosa using acidic and enzymatic extraction methods and to characterize these natural products for cosmetic and pharmaceutical applications. Marine gelatins presented protein values and hydroxyproline content similar to those of commercial mammalian gelatin, but with higher melting temperatures. Their electrophoretic profile and Fourier transform infrared (FTIR) spectra revealed protein and absorption bands situated in the amide region, specific for gelatin molecule. Scanning electron microscopy (SEM) analysis showed significant differences in the structure of the lyophilized samples, depending on the type of gelatin. In vitro studies performed on human keratinocytes showed no cytotoxic effect of acid-extracted gelatin at all tested concentrations and moderate cytotoxicity of enzymatic extracted gelatin at concentrations higher than 0.5 mg/mL. Also, both marine gelatins favored keratinocyte cell adhesion. No irritant potential was recorded as the level of IL-1α and IL-6 proinflammatory cytokines released by HaCaT cells cultivated in the presence of marine gelatins was significantly reduced. Together, these data suggest that marine snails are an alternative source of gelatins with potential use in pharmaceutical and skincare products.

Physicochemical and Biological Properties of Gelatin Extracted from Marine Snail Rapana venosa.

Angiotensin-converting enzyme inhibition, antioxidant activity and cytotoxicity of bioactive peptides from fermented bovine colostrum

Bionanocomposites based on poly(lactic acid) (PLA), plasticized with commercial tributyl o-acetyl citrate (ATBC) and containing hydrolyzed collagen (HC) up to 10 wt% and silver nanoparticles (AgNPs), were prepared by a melt mixing procedure. The properties of antimicrobial PLA based formulations were investigated in terms of morphology (atomic force microscopy, AFM), mechanical, thermal (differential scanning calorimetry, DSC), spectral (by attenuated total reflectance, Fourier-transform infrared spectroscopy), cell proliferation (by flow cytometry) and immunohistochemical properties induced by collagen. The incorporation of HC into antimicrobial PLA biocomposites led to the slight reduction both in mechanical properties and the degree of crystallinity with respect to those of PLA/ATBC sample. These properties can be attributed to the smooth surface improvement of the bionanocomposite. In vitro testing using L929 fibroblasts in the presence of PLA-based bionanocomposites showed that all samples presented good biocompatibility, as it was indicated by the cell cycle distribution and DNA content analyses. Furthermore, these new biocomposites induced an increase of collagen production in vitro. Overall, PLA/HC5/AgNPs and PLA/HC10/AgNPs bionanocomposites showed very good in vitro biocompatibility, and therefore, could be considered as valuable materials for medical devices, such as tubes, catheters, drains or connectors, with a relatively long service life.

Alexandra Gaspar-Pintiliescu

Papers

Natural composite dressings based on collagen, gelatin and plant bioactive compounds for wound healing: A review.

Polyphenols extract from grape pomace. Characterization and valorisation through encapsulation into mesoporous silica-type matrices.

Physicochemical and Biological Properties of Gelatin Extracted from Marine Snail Rapana venosa.

Angiotensin-converting enzyme inhibition, antioxidant activity and cytotoxicity of bioactive peptides from fermented bovine colostrum

Effect of hydrolyzed collagen on thermal, mechanical and biological properties of poly(lactic acid) bionanocomposites