Natural Phenol Polymers: Recent Advances in Food and Health Applications

From by-products to new application opportunities: the enhancement of the leaves deriving from the fruit plants for new potential healthy products

In the last decades, the world population and demand for any kind of product have grown exponentially. The rhythm of production to satisfy the request of the population has become unsustainable and the concept of the linear economy, introduced after the Industrial Revolution, has been replaced by a new economic approach, the circular economy. In this new economic model, the concept of "the end of life" is substituted by the concept of restoration, providing a new life to many industrial wastes. Leaves are a by-product of several agricultural cultivations. In recent years, the scientific interest regarding leaf biochemical composition grew, recording that plant leaves may be considered an alternative source of bioactive substances. Plant leaves' main bioactive compounds are similar to those in fruits, i.e., phenolic acids and esters, flavonols, anthocyanins, and procyanidins. Bioactive compounds can positively influence human health; in fact, it is no coincidence that the leaves were used by our ancestors as a natural remedy for various pathological conditions. Therefore, leaves can be exploited to manufacture many products in food (e.g., being incorporated in food formulations as natural antioxidants, or used to create edible coatings or films for food packaging), cosmetic and pharmaceutical industries (e.g., promising ingredients in anti-aging cosmetics such as oils, serums, dermatological creams, bath gels, and other products). This review focuses on the leaves' main bioactive compounds and their beneficial health effects, indicating their applications until today to enhance them as a harvesting by-product and highlight their possible reuse for new potential healthy products.

Phytochemicals and bioactive constituents in food packaging - A systematic review

Designing and manufacturing functional bioactive ingredients and pharmaceuticals have grown worldwide. Consumers demand for safe ingredients and concerns over harmful synthetic additives have prompted food manufacturers to seek safer and sustainable alternative solutions. In recent years the preference by consumers to natural bioactive agents over synthetic compounds increased exponentially, and consequently, naturally derived phytochemicals and bioactive compounds, with antimicrobial and antioxidant properties, becoming essential in food packaging field. In response to societal needs, packaging needs to be developed based on sustainable manufacturing practices, marketing strategies, consumer behaviour, environmental concerns, and the emergence of new technologies, particularly bio- and nanotechnology. This critical systematic review assessed the role of antioxidant and antimicrobial compounds from natural resources in food packaging and consumer behaviour patterns in relation to phytochemical and biologically active substances used in the development of food packaging. The use of phytochemicals and bioactive compounds inside packaging materials used in food industry could generate unpleasant odours derived from the diffusion of the most volatile compounds from the packaging material to the food and food environment. These consumer concerns must be addressed to understand minimum concentrations that will not affect consumer sensory and aroma negative perceptions. The research articles were carefully chosen and selected by following the Preferred Reporting Items for Systematic Reviews (PRISMA) guidelines.

Thiol-Aldehyde Polycondensation for Bio-based Adaptable and Degradable Phenolic Polymers

Designing sustainable materials with tunable mechanical properties, intrinsic degradability, and recyclability from renewable biomass through a mild process has become vital in polymer science. Traditional phenolic resins are generally considered to be not degradable or recyclable. Here we report the design and synthesis of linear and network structured phenolic polymers using facile polycondensation between natural aldehyde-bearing phenolic compounds and polymercaptans. Linear phenolic products are amorphous with Tg between -9 °C and 12 °C. Cross-linked networks from vanillin and its di-aldehyde derivative exhibited excellent mechanical strength between 6-64 MPa. The connecting dithioacetals are associatively adaptable strong bonds and susceptible to degradation in oxidative conditions to regenerate vanillin. These results highlight the potential of biobased sustainable phenolic polymers with recyclability and selective degradation, as a complement to the traditional phenol-formaldehyde resins.

An Interdisciplinary Assessment of Biochemical and Antioxidant Attributes of Six Greek Vicia sativa L. Varieties

Common vetch (Vicia sativa L.) is one of the most cultivated feed crops with extensive agricultural diversity and numerous cultivars. This study concerns the first-time investigation of the dry plant biomass and grains of six vetch cultivars to define the detailed fingerprint of their phenolic and fatty acid content, along with their respective antioxidant potencies. The results revealed a substantial variation in the feed quality traits among the tested Vicia sativa varieties, highlighting the crucial role and influence the genotype plays in the achievement of high-quality livestock nutrition. Among the six varieties tested, Istros and M-6900 displayed a particularly intriguing phytochemical profile characterized by elevated phenolic content, significant antioxidant potency and remarkably high fatty acid indices. These findings are indicative of the great potential of these varieties to function as suitable candidates for incorporation into farm animal diets either in the form of dry biomass (hay) or as a grain feed additive.

Antioxidative Impact of Phenolics-Loaded Nanocarriers on Cytoskeletal Network Remodeling of Invasive Cancer Cells

Natural phenolic compounds have antioxidant properties owing to their free radical-scavenging capability. The combined effect of a mixture of phenolic compounds has been studied; however, the detailed investigation for finding a correlation between single phenolic molecules and antioxidant activity has not been explored. Herein, we revealed that the number of phenolic hydroxyl groups in phenolics played a central role in their antioxidant capacity. Based on the finding, tannic acid showed the most effective antioxidant potential, e.g., 76% in tannic acid versus 22% in vitamin C as a standard antioxidant component. Because cancer progression is closely related to oxidative processes at the cellular level, we further applied the surface treatment of tannic acid drug-delivery nanocarriers. Tannic acid-loaded nanocarriers reduced reactive oxygen species of cancer cells as much as 41% of vehicle treatment and remodeled cytoskeletal network. By a gelatin degradation study, TA-loaded nanocarrier-treated cells induced 44.6% reduction of degraded area than vehicle-treated cells, implying a potential of blocking invasiveness of cancer cells.

Antioxidant Silicone Elastomers without Covalent Cross-Links

Improved sustainability is associated with elastomers that readily breakdown in the environment at end of life and, as importantly, that can be reprocessed/reused long before end of life arises. We report the preparation of silicone elastomers that possess both thermoplasticity-reprocessability-and antioxidant activity. A combination of ionic and H-bonding links natural phenolic antioxidants, including catechol, pyrogallol, tannic acid, and others, to telechelic aminoalkylsilicones. The mechanical properties of the elastomers, including their processability, are intimately linked to the ratio of [ArOH]/[H2NR] that was found to be optimal when the ratio exceeded 1:1.

Fillet Fish Fortified with Algal Extracts of Codium tomentosum and Actinotrichia fragilis, as a Potential Antibacterial and Antioxidant Food Supplement

With respect to the potential natural resources in the marine environment, marine macroalgae or seaweeds are recognized to have health impacts. Two marine algae that are found in the Red Sea, Codium tomentosum (Green algae) and Actinotrichia fragilis (Red algae), were collected. Antibacterial and antioxidant activities of aqueous extracts of these algae were evaluated in vitro. Polyphenols from the extracts were determined using HPLC. Fillet fish was fortified with these algal extracts in an attempt to improve its nutritional value, and sensory evaluation was performed. The antibacterial effect of C. tomentosum extract was found to be superior to that of A. fragilis extract. Total phenolic contents of C. tomentosum and A. fragilis aqueous extract were 32.28 ± 1.63 mg/g and 19.96 ± 1.28 mg/g, respectively, while total flavonoid contents were 4.54 ± 1.48 mg/g and 3.86 ± 1.02 mg/g, respectively. Extract of C. tomentosum demonstrates the highest antioxidant activity, with an IC₅₀ value of 75.32 ± 0.07 μg/mL. The IC₅₀ of L-ascorbic acid as a positive control was 22.71 ± 0.03 μg/mL. The IC₅₀ values for inhibiting proliferation on normal PBMC cells were 33.7 ± 1.02 µg/mL and 51.0 ± 1.14 µg/mL for C. tomentosum and A. fragilis, respectively. The results indicated that both algal aqueous extracts were safe, with low toxicity to normal cells. Interestingly, fillet fish fortified with C. tomentosum extract demonstrated the greatest overall acceptance score. These findings highlight the potential of these seaweed species for cultivation as a sustainable and safe source of therapeutic compounds for treating human and fish diseases, as well as effective food supplements and preservatives instead of chemical ones after performing in vivo assays.

Recovery of Lignins with Potent Antioxidant Properties from Shells of Edible Nuts by a Green Ball Milling/Deep Eutectic Solvent (DES)-Based Protocol

Lignins are phenolic polymers endowed with potent antioxidant properties that are finding increasing applications in a variety of fields. Consequently, there is a growing need for easily available and sustainable sources, as well as for green extraction methodologies of these compounds. Herein, a ball milling/deep eutectic solvent (DES)-based treatment is reported as an efficient strategy for the recovery of antioxidant lignins from the shells of edible nuts, namely chestnuts, hazelnuts, peanuts, pecan nuts, and pistachios. In particular, preliminarily ball-milled shells were treated with 1:2 mol/mol choline chloride:lactic acid at 120 °C for 24 h, and the extracted material was recovered in 19–27% w/w yields after precipitation by the addition of 0.01 M HCl. Extensive spectroscopic and chromatographic analysis allowed for confirmation that the main phenolic constituents present in the shell extracts were lignins, accompanied by small amounts (0.9% w/w) of ellagic acid, in the case of chestnut shells. The recovered samples exhibited very promising antioxidant properties, particularly in the 2,2-diphenyl-1-picrylhydrazyl (DPPH) assay (EC₅₀ values ranging from 0.03 to 0.19 mg/mL). These results open new perspectives for the valorization of nut shells as green sources of lignins for applications as antioxidants, e.g., in the biomedical, food, and/or cosmetic sector.

Phycochemical and Biological Activities From Different Extracts of Padina antillarum (Kützing) Piccone

Seaweeds are non-vascular, photosynthetic that inhabit the coastal regions commonly within rocky intertidal or submerged reef-like habitats and have been one of the richest and most promising sources of bioactive primary and secondary metabolites with antimicrobial properties. They selectively absorb elements like Na, K, Ca, Mg, I, and Br from the seawater and accumulate them in their thalli. Padina antillarum (Kützing) Piccone is a member of Phaeophycota and has remarkable phycochemistry as well as bioactivity. The phycochemical tests of the different extracts showed the presence of alkaloids, terpenoids, saponins, tannins, steroids, and phenols. The relative percentage of Oxirane, tetradecyl (C₁₆H₃₂O), and Cyclononasiloxane (C₁₈H₅₄O₉Si₉) are higher while Tetrasiloxane (C₁₆H₅₀O₇Si₈) is lowest in Gas Chromatography - Mass Spectrometry analysis. FRAP, %inhibition, the total antioxidant value of P. antillarum was higher in methanolic extract. Hexane, chloroform extracts showed no zone of inhibition against Bacillus subtilis, Escherichia coli, Klebsiella pneumonia, Staphylococcus aureus, and Staphylococcus epidermidis. The methanolic extract of P. antillarum exhibits a maximum zone of inhibition against S. epidermidis (18.66 ± 0.09). Antifungal activity of the P. antillarum in hexane extract exhibited no zone of inhibition against Aspergillus niger and Penicillium notatum while the chloroform extract yields maximum zone (37 ± 0.012, 21.66 ± 0.03). Diabetes mellitus is one of the most familiar chronic diseases associated with carbohydrate metabolism. It is also an indication of co-morbidities such as obesity, hypertension, and hyperlipidemia which are metabolic complications of both clinical and experimental diabetes. The treatment of P. antillarum methanol extract in mice reduced the body weight loss, low level of triglycerides, and elevated HDL cholesterol level as compared to diabetic mice.

Phytochemical and Potential Properties of Seaweeds and Their Recent Applications: A Review

Since ancient times, seaweeds have been employed as source of highly bioactive secondary metabolites that could act as key medicinal components. Furthermore, research into the biological activity of certain seaweed compounds has progressed significantly, with an emphasis on their composition and application for human and animal nutrition. Seaweeds have many uses: they are consumed as fodder, and have been used in medicines, cosmetics, energy, fertilizers, and industrial agar and alginate biosynthesis. The beneficial effects of seaweed are mostly due to the presence of minerals, vitamins, phenols, polysaccharides, and sterols, as well as several other bioactive compounds. These compounds seem to have antioxidant, anti-inflammatory, anti-cancer, antimicrobial, and anti-diabetic activities. Recent advances and limitations for seaweed bioactive as a nutraceutical in terms of bioavailability are explored in order to better comprehend their therapeutic development. To further understand the mechanism of action of seaweed chemicals, more research is needed as is an investigation into their potential usage in pharmaceutical companies and other applications, with the ultimate objective of developing sustainable and healthier products. The objective of this review is to collect information about the role of seaweeds on nutritional, pharmacological, industrial, and biochemical applications, as well as their impact on human health.

Effects of Functional Phenolics Dietary Supplementation on Athletes' Performance and Recovery: A Review

In recent years, many efforts have been made to identify micronutrients or nutritional strategies capable of preventing, or at least, attenuating, exercise-induced muscle damage and oxidative stress, and improving athlete performance. The reason is that most exercises induce various changes in mitochondria and cellular cytosol that lead to the generation of reactive species and free radicals whose accumulation can be harmful to human health. Among them, supplementation with phenolic compounds seems to be a promising approach since their chemical structure, composed of catechol, pyrogallol, and methoxy groups, gives them remarkable health-promoting properties, such as the ability to suppress inflammatory processes, counteract oxidative damage, boost the immune system, and thus, reduce muscle soreness and accelerate recovery. Phenolic compounds have also already been shown to be effective in improving temporal performance and reducing psychological stress and fatigue. Therefore, the aim of this review is to summarize and discuss the current knowledge on the effects of dietary phenolics on physical performance and recovery in athletes and sports practitioners. Overall, the reports show that phenolics exert important benefits on exercise-induced muscle damage as well as play a biological/physiological role in improving physical performance.

Emerging Chemical Diversity and Potential Applications of Enzymes in the DMSO Reductase Superfamily

Molybdenum- and tungsten-dependent proteins catalyze essential processes in living organisms and biogeochemical cycles. Among these enzymes, members of the dimethyl sulfoxide (DMSO) reductase superfamily are considered the most diverse, facilitating a wide range of chemical transformations that can be categorized as oxygen atom installation, removal, and transfer. Importantly, DMSO reductase enzymes provide high efficiency and excellent selectivity while operating under mild conditions without conventional oxidants such as oxygen or peroxides. Despite the potential utility of these enzymes as biocatalysts, such applications have not been fully explored. In addition, the vast majority of DMSO reductase enzymes still remain uncharacterized. In this review, we describe the reactivities, proposed mechanisms, and potential synthetic applications of selected enzymes in the DMSO reductase superfamily. We also highlight emerging opportunities to discover new chemical activity and current challenges in studying and engineering proteins in the DMSO reductase superfamily. Expected final online publication date for the Annual Review of Biochemistry, Volume 91 is June 2022. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.

Condensed Tannins, a Viable Solution To Meet the Need for Sustainable and Effective Multifunctionality in Food Packaging: Structure, Sources, and Properties

Condensed tannins (CT) have been the focus of increasing interest in the last years as a result of their potent biological properties, which have prompted their use in the food and feed sector as functional ingredients. The possible exploitation of these compounds as multifunctional additives for the implementation of active food packaging has also been recently appreciated. In this perspective, an overview of the structural features, accessible sources, methods of analysis, and functional properties of CT is provided, with the aim of critically emphasizing the opportunities offered by this widespread class of natural phenolic compounds for the rational design of multifunctional and sustainable food packaging materials.

Seaweeds as a Fermentation Substrate: A Challenge for the Food Processing Industry

Seaweeds are gaining momentum as novel and functional food and feed products. From whole consumption to small bioactive compounds, seaweeds have remarkable flexibility in their applicability, ranging from food production to fertilizers or usages in chemical industries. Regarding food production, there is an increasing interest in the development of novel foods that, at the same time, present high nutritious content and are sustainably developed. Seaweeds, because they require no arable land, no usage of fresh water, and they have high nutritious and bioactive content, can be further explored for the development of newer and functional food products. Fermentation, especially performed by lactic acid bacteria, is a method used to produce functional foods. However, fermentation of seaweed biomass remains an underdeveloped topic that nevertheless demonstrates high potential for the production of new alimentary products that hold and further improve the organoleptic and beneficial properties that these organisms are characterized for. Although further research has to be deployed in this field, the prebiotic and probiotic potential demonstrated by fermented seaweed can boost the development of new functional foods.

Cancer Cell Preferential Penetration and pH-Responsive Drug Delivery of Oligorutin

We report herein a novel delivery system, derived from the facile enzymatic synthesis of oligorutin (OR), for cancer cell targeting and pH-responsive drug delivery. In this study, we demonstrate that OR could preferentially penetrate cancer cells via the lipid raft-mediated endocytosis pathway, and cell membrane cholesterol was critical to the internalization of OR. The accumulation of OR in the tumor region was further confirmed by an in vivo biodistribution study. Considering the tumor-targeting property of OR, a pH-responsive drug delivery system (OR-BTZ) was developed by covalent conjugation of the catechol groups on OR with antitumor drug bortezomib (BTZ) through a pH-sensitive borate ester bond. OR-BTZ exerted cytotoxicity as well as inhibition of the migration and invasion to hepatoma carcinoma cells and showed no apparent cytotoxicity with liver normal cells. The OR-BTZs also presented significant therapeutic efficacy and low systematic toxicity in the murine hepatocellular carcinoma model. To our knowledge, this study presents the first attempt to exploit the potential of oligoflavonoids for cancer cell-targeted drug delivery and will motivate the development of flavonoids and their derivatives as a new type of biomaterials for tumor-targeted therapy.

An Overview to the Health Benefits of Seaweeds Consumption

Currently, seaweeds are gaining major attention due to the benefits they give to our health. Recent studies demonstrate the high nutritional value of seaweeds and the powerful properties that seaweeds' bioactive compounds provide. Species of class Phaeophyceae, phylum Rhodophyta and Chlorophyta possess unique compounds with several properties that are potential allies of our health, which make them valuable compounds to be involved in biotechnological applications. In this review, the health benefits given by consumption of seaweeds as whole food or by assumption of bioactive compounds trough natural drugs are highlighted. The use of seaweeds in agriculture is also highlighted, as they assure soils and crops free from chemicals; thus, it is advantageous for our health. The addition of seaweed extracts in food, nutraceutical, pharmaceutical and industrial companies will enhance the production and consumption/usage of seaweed-based products. Therefore, there is the need to implement the research on seaweeds, with the aim to identify more bioactive compounds, which may assure benefits to human and animal health.

Environmental Impact on Seaweed Phenolic Production and Activity: An Important Step for Compound Exploitation

Seaweeds are a potential source of bioactive compounds that are useful for biotechnological applications and can be employed in different industrial areas in order to replace synthetic compounds with components of natural origin. Diverse studies demonstrate that there is a solid ground for the exploitation of seaweed bioactive compounds in order to prevent illness and to ensure a better and healthier lifestyle. Among the bioactive algal molecules, phenolic compounds are produced as secondary metabolites with beneficial effects on plants, and also on human beings and animals, due to their inherent bioactive properties, which exert antioxidant, antiviral, and antimicrobial activities. The use of phenolic compounds in pharmaceutical, nutraceutical, cosmetics, and food industries may provide outcomes that could enhance human health. Through the production of healthy foods and natural drugs, bioactive compounds from seaweeds can help with the treatment of human diseases. This review aims to highlight the importance of phenolic compounds from seaweeds, the scope of their production in nature and the impact that these compounds can have on human and animal health through nutraceutical and pharmaceutical products.

Acid Treatment Enhances the Antioxidant Activity of Enzymatically Synthesized Phenolic Polymers

Phenolic polymers produced by enzymatic oxidation under biomimetic and eco-friendly reaction conditions are usually endowed with potent antioxidant properties. These properties, coupled with the higher biocompatibility, stability and processability compared to low-molecular weight phenolic compounds, open important perspectives for various applications. Herein, we report the marked boosting effect of acid treatment on the antioxidant properties of a series of polymers obtained by peroxidase-catalyzed oxidation of natural phenolic compounds. Both 2,2-diphenyl-1-picrylhydrazyl (DPPH) and ferric reducing/antioxidant power (FRAP) assays indicated a remarkable increase in the antioxidant properties for most phenolic polymers further to the acid treatment. In particular, up to a ca. 60% decrease in the EC50 value in the DPPH assay and a 5-fold increase in the Trolox equivalents were observed. Nitric oxide- and superoxide-scavenging assays also indicated highly specific boosting effects of the acid treatment. Spectroscopic evidence suggested, in most cases, that the occurrence of structural modifications induced by the acid treatment led to more extended π-electron-conjugated species endowed with more efficient electron transfer properties. These results open new perspectives toward the design of new bioinspired antioxidants for application in food, biomedicine and material sciences.

Synthesis and Evaluation of Antioxidant Activities of Novel Hydroxyalkyl Esters and Bis-Aryl Esters Based on Sinapic and Caffeic Acids

Novel hydroxyalkyl esters and bis-aryl esters were synthesized from sinapic and caffeic acids and aliphatic α,ω-diols of increasing chain lengths from 2 to 12 carbon atoms. Then, their antiradical reactivity (DPPH assay) and their antioxidant activity in a model oil-in-water emulsion (CAT assay) were evaluated. All the esters showed lower antiradical activities compared to their corresponding phenolic acid. This decrease was associated with the steric hindrance in hydroxyalkyl esters, and intramolecular interactions in bis-aryl esters. Regarding the two bis-aryl esters series in emulsion, the antioxidant capacity was improved with alkyl chain lengthening up to four carbons, after which it decreased for longer chains. This "cutoff" effect was not observed for both hydroxyalkyl esters series for which the alkyl chain lengthening results in a decrease of the antioxidant activity.

Role of Antioxidant Molecules and Polymers in Prevention of Bacterial Growth and Biofilm Formation

Background:

Antioxidants are multifaceted molecules playing a crucial role in several cellular functions. There is by now a well-established knowledge about their involvement in numerous processes associated with aging, including vascular damage, neurodegenerative diseases and cancer. An emerging area of application has been lately identified for these compounds in relation to the recent findings indicating their ability to affect biofilm formation by some microbial pathogens, including Staphylococcus aureus, Streptococcus mutans, and Pseudomonas aeruginosa.

Methods:

A structured search of bibliographic databases for peer-reviewed research literature was performed using a focused review question. The quality of retrieved papers was appraised using standard tools.

Results:

One hundred sixty-five papers extracted from pubmed database and published in the last fifteen years were included in this review focused on the assessment of the antimicrobial and antibiofilm activity of antioxidant compounds, including vitamins, flavonoids, non-flavonoid polyphenols, and antioxidant polymers. Mechanisms of action of some important antioxidant compounds, especially for vitamin C and phenolic acids, were identified.

Conclusion:

The findings of this review confirm the potential benefits of the use of natural antioxidants as antimicrobial/antibiofilm compounds. Generally, gram-positive bacteria were found to be more sensitive to antioxidants than gram-negatives. Antioxidant polymeric systems have also been developed mainly derived from functionalization of polysaccharides with antioxidant molecules. The application of such systems in clinics may permit to overcome some issues related to the systemic delivery of antioxidants, such as poor absorption, loss of bioactivity, and limited half-life. However, investigations focused on the study of antibiofilm activity of antioxidant polymers are still very limited in number and therefore they are strongly encouraged in order to lay the foundations for application of antioxidant polymers in treatment of biofilm-based infections.

Hydrolyzable vs. Condensed Wood Tannins for Bio-based Antioxidant Coatings: Superior Properties of Quebracho Tannins

Tannins have always been the subject of great interest for their countless properties, first of all their ability to produce functional coatings on a variety of materials. We report herein a comparative evaluation of the antioxidant properties of wood tannin-based coated substrates. In particular, nylon membrane filters were functionalized with chestnut (hydrolyzable) or quebracho (condensed) tannins by dip coating under different conditions. The efficiency of functionalization was evaluated by the 2,2-diphenyl-1-picrylhydrazyl (DPPH) and ferric reducing/antioxidant power (FRAP) assays, which invariably highlighted the superior ability of condensed tannins to induce the formation of a functional and robust coating. The results of the antioxidant assays revealed also the deleterious effects of aerial or enzymatic oxidation conditions on substrate functionalization, being more significant in the case of hydrolyzable tannins. On the other hand, the use of oxidizing conditions allowed to obtain more stable coatings, still exhibiting good antioxidant properties, in the case of condensed tannins. The presence of iron ions did not lead to a significant improvement of the coating efficiency for either tannins. The systematic approach used in this work provides novel and useful information for the optimal exploitation of tannins in antioxidant functional coatings.

Seaweed's Bioactive Candidate Compounds to Food Industry and Global Food Security

The world population is continuously growing, so it is important to keep producing food in a sustainable way, especially in a way that is nutritious and in a sufficient quantity to overcome global needs. Seaweed grows, and can be cultivated, in seawater and generally does not compete for arable land and freshwater. Thus, the coastal areas of the planet are the most suitable for seaweed production, which can be an alternative to traditional agriculture and can thus contribute to a reduced carbon footprint. There are evolving studies that characterize seaweed's nutritional value and policies that recognize them as food, and identify the potential benefits and negative factors that may be produced or accumulated by seaweed, which are, or can be, dangerous for human health. Seaweeds have a high nutritional value along with a low caloric input and with the presence of fibers, proteins, omega 3 and 6 unsaturated fatty acids, vitamins, and minerals. Moreover, several seaweed sub-products have interesting features to the food industry. Therefore, the focus of this review is in the performance of seaweed as a potential alternative and as a safe food source. Here described is the nutritional value and concerns relating to seaweed consumption, and also how seaweed-derived compounds are already commercially explored and available in the food industry and the usage restrictions to safeguard them as safe food additives for human consumption.

Seaweed Phenolics: From Extraction to Applications

Seaweeds have attracted high interest in recent years due to their chemical and bioactive properties to find new molecules with valuable applications for humankind. Phenolic compounds are the group of metabolites with the most structural variation and the highest content in seaweeds. The most researched seaweed polyphenol class is the phlorotannins, which are specifically synthesized by brown seaweeds, but there are other polyphenolic compounds, such as bromophenols, flavonoids, phenolic terpenoids, and mycosporine-like amino acids. The compounds already discovered and characterized demonstrate a full range of bioactivities and potential future applications in various industrial sectors. This review focuses on the extraction, purification, and future applications of seaweed phenolic compounds based on the bioactive properties described in the literature. It also intends to provide a comprehensive insight into the phenolic compounds in seaweed.

From winery waste to bioactive compounds and new polymeric biocomposites: A contribution to the circular economy concept

The paper aims at optimising and validating possible routes toward the full valorisation of grape agrowaste to produce bioactive molecules and new materials. Starting from Merlot red pomace, phenol complex mixtures were successfully extracted by using two different approaches. Extracts obtained by solvent-based (SE) technique contained up to 46.9 gGAeq/kgDW of total phenols. Depending on the used solvent, the prevalence of compounds belonging to different phenol families was achieved. Pressurized liquid extraction (PLE) gave higher total phenol yields (up to 79 gGAeq/kgDW) but a lower range of extracted compounds. All liquid extracts exerted strong antioxidant properties. Moreover, both SE and PLE extraction solid residues were directly exploited (between 5 and 20% w/w) to prepare biocomposite materials by direct mixing via an eco-friendly approach with PHBV polymer. The final composites showed mechanical characteristics similar to PHVB matrix. The use of pomace residues in biocomposites could therefore bring both to the reduction of the cost of the final material, as a lower amount of costly PHBV is used. The present research demonstrated the full valorisation of grape pomace, an agrowaste produced every year in large amounts and having a significant environmental impact.

Tannins in Food: Insights into the Molecular Perception of Astringency and Bitter Taste

Astringency and bitterness are organoleptic properties widely linked to tannin compounds. Due to their significance to food chemistry, the food industry, and to human nutrition and health, these tannins' taste properties have been a line of worldwide research. In recent years, significant advances have been made in understanding the molecular perception of astringency pointing to the contribution of different oral key players. Regarding bitterness, several polyphenols have been identified has new agonists of these receptors. This review summarizes the last data about the knowledge of these taste properties perceived by tannins. Ultimately, tannins' astringency and bitterness are hand-in-hand taste properties, and future studies should be adapted to understand how the proper perception of one taste could affect the perception of the other one.

Antioxidant Properties of Agri-food Byproducts |and Specific Boosting Effects of Hydrolytic Treatments

Largely produced agri-food byproducts represent a sustainable and easily available source of phenolic compounds, such as lignins and tannins, endowed with potent antioxidant properties. We report herein the characterization of the antioxidant properties of nine plant-derived byproducts. 2,2-Diphenyl-1-picrylhydrazyl (DPPH) and ferric reducing/antioxidant power (FRAP) assays indicated the superior activity of pomegranate peels and seeds, grape pomace and pecan nut shell. An increase in the antioxidant potency was observed for most of the waste materials following a hydrolytic treatment, with the exception of the condensed tannin-rich pecan nut shell and grape pomace. UV-Vis and HPLC investigation of the soluble fractions coupled with the results from IR analysis and chemical degradation approaches on the whole materials allowed to conclude that the improvement of the antioxidant properties was due not only to removal of non-active components (mainly carbohydrates), but also to structural modifications of the phenolic compounds. Parallel experiments run on natural and bioinspired model phenolic polymers suggested that these structural modifications positively impacted on the antioxidant properties of lignins and hydrolyzable tannins, whereas significant degradation of condensed tannin moieties occurred, likely responsible for the lowering of the reducing power observed for grape pomace and pecan nut shell. These results open new perspectives toward the exploitation and manipulation of agri-food byproducts for application as antioxidant additives in functional materials.

Natural Phenolic Compounds for Health, Food and Cosmetic Applications

Based on their potent antioxidant properties, natural phenolic compounds have gained more and more attention for their possible exploitation as food supplements, as well as functional ingredients in food and in the cosmetic industry [...].

Bioactive Phenolic Compounds From Agri-Food Wastes: An Update on Green and Sustainable Extraction Methodologies

Phenolic compounds are broadly represented in plant kingdom, and their occurrence in easily accessible low-cost sources like wastes from agri-food processing have led in the last decade to an increase of interest in their recovery and further exploitation. Indeed, most of these compounds are endowed with beneficial properties to human health (e.g., in the prevention of cancer and cardiovascular diseases), that may be largely ascribed to their potent antioxidant and scavenging activity against reactive oxygen species generated in settings of oxidative stress and responsible for the onset of several inflammatory and degenerative diseases. Apart from their use as food supplements or as additives in functional foods, natural phenolic compounds have become increasingly attractive also from a technological point of view, due to their possible exploitation in materials science. Several extraction methodologies have been reported for the recovery of phenolic compounds from agri-food wastes mostly based on the use of organic solvents such as methanol, ethanol, or acetone. However, there is an increasing need for green and sustainable approaches leading to phenolic-rich extracts with low environmental impact. This review addresses the most promising and innovative methodologies for the recovery of functional phenolic compounds from waste materials that have appeared in the recent literature. In particular, extraction procedures based on the use of green technologies (supercritical fluid, microwaves, ultrasounds) as well as of green solvents such as deep eutectic solvents (DES) are surveyed.

Pecan (Carya illinoinensis (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 (EC₅₀ = 0.004 mg/mL). PNSE was initially tested as an inhibitor of mushroom tyrosinase, exhibiting a quite low IC₅₀ value (0.055 mg/mL) against the enzyme diphenolase activity, suggesting its use in enzymatic browning inhibition. The anthocyanin stabilization properties were evaluated under accelerated aging conditions of both pure pigments and commercial fruit juices, and PNSE was found to be effective at concentrations (0.05 mg/mL) at which well-known stabilizers such as chlorogenic and ferulic acids proved to fail. PNSE also performed well in the stabilization of spray-dried anthocyanins for use as a food colorant, increasing the half-life of blackberry anthocyanins up to 20%. In order to explore the possibility of using PNSE as a functional additive for active packaging, polylactic acid (PLA) films containing PNSE were prepared by solvent casting, and no substantial alteration of the mechanical properties was found on addition of the extract up to 10% w/w. The films showed remarkable antioxidant properties (DDPH reduction >60% with a 3% w/w loading, at a dose of 1 mg/mL in the DPPH solution) and delayed the onset of browning of apple smoothies (ca. 30% inhibition with a 10% w/w loading). These results highlight the exploitation of PNS as a low-cost polyphenol source for food industry applications.

Natural Tannin Wood Extracts as a Potential Food Ingredient in the Food Industry

Wood extracts are one of the most important natural sources of industrially obtained tannins. Their use in the food industry could be one of the biggest (most important) recent innovations in food science as a result of their multiple (many) possible applications. The use of tannin wood extracts (TWEs) as additives directly added in foods or in their packaging meets an ever-increasing consumer demand for innovative approaches to sustainability. The latest research is focusing on new ways to include them directly in food, to take advantage of their specific actions to prevent individual pathological conditions. The present review begins with the biology of TWEs and then explores their chemistry, specific sensorial properties, and current application in food production. Moreover, this review is intended to cover recent studies dealing with the potential use of TWEs as a starting point for novel food ingredients.

Technological Application of Tannin-Based Extracts

Tannins are polyphenolic compounds naturally found in vegetables. Their presence in nature has prompted their historical use in many different ways. The revision of their traditional utilization has allowed their further modification aiming for an industrial application. Sometimes these modifications have implied the addition of harmful substances such as formaldehyde, classified as a carcinogen of category B1. In other cases, these natural tannins have been replaced by synthetic compounds that threaten human and animal health and damage the environment. Therefore, currently, both academy and industry are searching for the substitution of these unsafe complexes by the increasing inclusion of tannins, natural molecules that can be obtained from several and diverse renewable resources, modified using harmless additives. To achieve promising results, cost-efficient and eco-friendly extraction methods have been designed. Once these green alternatives have been isolated, they have been successfully applied to many fields with very assorted aims of utilization such as coagulants, adhesives, floatation agents, tannings, dyes, additives, or biomolecules. Therefore, this review offers a global vision of the full process that involves the tannin’s technological application including an overview of the most relevant tannin sources, effective extraction methods, and their utilization in very diverse fields.

Analysis of the Application Potential of Coffee Oil as an Ilmenite Flotation Collector

Coffee grounds are the most significant production waste in the coffee industry and contain about 15% coffee oil. Coffee oil is rich in fatty acids and polyphenols, which have great application potential in the flotation of oxidized minerals. In this study, coffee oil as a green flotation collector for ilmenite was investigated by micro-flotation, zeta potential measurement, and foam stability analysis. The results of zeta potential reveal that both coffee oil and MOH can be adsorbed on the ilmenite surface at pH 6.7, and the chemical adsorption mode is dominant. However, when the pH is 2.8, the adsorption capacity of coffee oil on the ilmenite surface is much larger than that of MOH. The pH value of the pulp has little effect on the foam properties in the coffee oil solution and has a great influence on the foaming performance and foam stability of the MOH solution. When coffee oil is used as a collector, the grade of TiO2 in ilmenite concentrate is increased from 21.68% to 46.83%, and the recovery is 90.22%, indicating that the potential of coffee oil in the application of ilmenite flotation is large.

Exhausted Woods from Tannin Extraction as an Unexplored Waste Biomass: Evaluation of the Antioxidant and Pollutant Adsorption Properties and Activating Effects of Hydrolytic Treatments

Exhausted woods represent a byproduct of tannin industrial production processes and their possible exploitation as a source of antioxidant compounds has remained virtually unexplored. We herein report the characterization of the antioxidant and other properties of practical interest of exhausted chestnut wood and quebracho wood, together with those of a chestnut wood fiber, produced from steamed exhausted chestnut wood. 2,2-Diphenyl-1-picrylhydrazyl (DPPH) and ferric reducing/antioxidant power (FRAP) assays indicated good antioxidant properties for all the materials investigated, with exhausted chestnut wood, and, even more, chestnut wood fiber exhibiting the highest activity. High efficiency was observed also in the superoxide scavenging assay. An increase of the antioxidant potency was observed for both exhausted woods and chestnut wood fiber following activation by hydrolytic treatment, with an up to three-fold lowering of the EC₅₀ values in the DPPH assay. On the other hand, exhausted quebracho wood was particularly effective as a nitrogen oxides (NO_x) scavenger. The three materials proved able to adsorb methylene blue chosen as a model of organic pollutant and to remove highly toxic heavy metal ions like cadmium from aqueous solutions, with increase of the activity following the hydrolytic activation. These results open new perspectives toward the exploitation of exhausted woods as antioxidants, e.g., for active packaging, or as components of filtering membranes for remediation of polluted waters.

Human Bitter Taste Receptors Are Activated by Different Classes of Polyphenols

Polyphenols may contribute directly to plant-based foodstuffs flavor, in particular to astringency and bitterness. In this work, the bitterness of a small library of polyphenols from different classes [procyanidin dimers type B, ellagitannins (punicalagin, castalagin, and vescalagin) and phenolic acid ethyl esters (protocatechuic, ferulic, and vanillic acid ethyl esters] was studied by a cell-based assay. The bitter taste receptors (TAS2Rs) activated by these polyphenols and the half-maximum effective concentrations (EC₅₀) of each agonist-TAS2Rs pair were determined. Computational methodologies were used to understand the polyphenol molecular region responsible for receptor activation and to get insights into the type of bonds established in the agonist-TAS2Rs pairs. The results show the combinatorial pattern of TAS2Rs activation. TAS2R5 seems to be the only receptor exhibiting a bias toward the activation by condensed tannins, while TAS2R7 seems more tuned for hydrolyzable (ellagi)tannins. Additionally, at the concentrations usually found for these compounds in foodstuffs, they can actively contribute to bitter taste, especially ellagitannins.

Disentangling structure-dependent antioxidant mechanisms in phenolic polymers by multiparametric EPR analysis

Excellent and selective correlations between the electron-transfer (ET) or hydrogen atom transfer (HAT) capacity (DPPH and lipid peroxidation inhibition assays) and EPR indices of π-electron spin delocalization delineate specific structural determinants of antioxidant activity in biomimetic phenolic polymers.

Valuable Compound Extraction, Anaerobic Digestion, and Composting: A Leading Biorefinery Approach for Agricultural Wastes

In a society where the environmental conscience is gaining attention, it is necessary to evaluate the potential valorization options for agricultural biomass to create a change in the perception of the waste agricultural biomass from waste to resource. In that sense, the biorefinery approach has been proposed as the roadway to increase profit of the agricultural sector and, at the same time, ensure environmental sustainability. The biorefinery approach integrates biomass conversion processes to produce fuels, power, and chemicals from biomass. The present review is focused on the extraction of value-added compounds, anaerobic digestion, and composting of agricultural waste as the biorefinery approach. This biorefinery approach is, nevertheless, seen as a less innovative configuration compared to other biorefinery configurations, such as bioethanol production or white biotechnology. However, any of these processes has been widely proposed as a single operation unit for agricultural waste valorization, and a thoughtful review on possible single or joint application has not been available in the literature up to now. The aim is to review the previous and current literature about the potential valorization of agricultural waste biomass, focusing on valuable compound extraction, anaerobic digestion, and composting of agricultural waste, whether they are not, partially, or fully integrated.

Tannic Acid-Lung Fluid Assemblies Promote Interaction and Delivery of Drugs to Lung Cancer Cells

Lung cancer (LC) is one of the leading causes of death in both men and women in the United States. Tannic acid (TA), a water-soluble polyphenol, exhibits a wide range of biological activities. TA has received much attention as a promising compound in the biomaterial and drug delivery fields. Lung fluid (LF) is a major barrier for distribution of drugs to the lungs. Therefore, the purpose of this study was to examine TA interaction with LF for effective delivery of anti-cancer drug molecules via pulmonary delivery. The extent of adsorption of LF proteins by TA was revealed by fluorescence quenching in fluorescence spectroscopy. The presence of LF in TA-LF complexes was noticed by the presence of protein peaks at 1653 cm-1. Both protein dot and SDS-PAGE analysis confirmed LF protein complexation at all TA concentrations employed. A stable particle TA-LF complex formation was observed through transmission electron microscopy (TEM) analysis. The complexation pattern measured by dynamic light scattering (DLS) indicated that it varies depending on the pH of the solutions. The degree of LF presence in TA-LF complexes signifies its interactive behavior in LC cell lines. Such superior interaction offered an enhanced anti-cancer activity of drugs encapsulated in TA-LF complex nanoformulations. Our results indicate that TA binds to LF and forms self-assemblies, which profoundly enhance interaction with LC cells. This study demonstrated that TA is a novel carrier for pharmaceutical drugs such as gemcitabine, carboplatin, and irinotecan.

Inhibition of Protein Aggregation by Several Antioxidants

Amyloid fibril formation is a shared property of all proteins; therefore, model proteins can be used to study this process. We measured protein aggregation of the model amyloid-forming protein stefin B in the presence and absence of several antioxidants. Amyloid fibril formation by stefin B was routinely induced at pH 5 and 10% TFE, at room temperature. The effects of antioxidants NAC, vitamin C, vitamin E, and the three polyphenols resveratrol, quercetin, and curcumin on the kinetics of fibril formation were followed using ThT fluorescence. Concomitantly, the morphology and amount of the aggregates and fibrils were checked by transmission electron microscopy (TEM). The concentration of the antioxidants was varied, and it was observed that different modes of action apply at low or high concentrations relative to the binding constant. In order to obtain more insight into the possible mode of binding, docking of NAC, vitamin C, and all three polyphenols was done to the monomeric form of stefin B.

Anti-Amyloid Aggregation Activity of Black Sesame Pigment: Toward a Novel Alzheimer's Disease Preventive Agent

Black sesame pigment (BSP) represents a low cost, easily accessible material of plant origin exhibiting marked antioxidant and heavy metal-binding properties with potential as a food supplement. We report herein the inhibitory properties of the potentially bioaccessible fraction of BSP following simulated gastrointestinal digestion against key enzymes involved in Alzheimer's disease (AD). HPLC analysis indicated that BSP is transformed under the pH conditions mimicking the intestinal environment and the most abundant of the released compounds was identified as vanillic acid. More than 80% inhibition of acetylcholinesterase-induced aggregation of the β-amyloid Aβ1-40 was observed in the presence of the potentially bioaccessible fraction of BSP, which also efficiently inhibited self-induced Aβ1-42 aggregation and β-secretase (BACE-1) activity, even at high dilution. These properties open new perspectives toward the use of BSP as an ingredient of functional food or as a food supplement for the prevention of AD.

Hybrid PCL/CaCO3 scaffolds with capabilities of carrying biologically active molecules: Synthesis, loading and in vivo applications

Designing advanced biomaterials for tissue regeneration with drug delivery and release functionalities remains a challenge in regenerative medicine. In this research, we have developed novel composite scaffolds based on polymeric polycaprolactone fibers coated with porous calcium carbonate structures (PCL/CaCO₃) for tissue engineering and have shown their drug delivery and release in rats. In vivo biocompatibility tests of PCL/CaCO₃ scaffolds were complemented with in vivo drug release study, where tannic acid (TA) was used as a model drug. Release of TA from the scaffolds was realized by recrystallization of the porous vaterite phase of calcium carbonate into the crystalline calcite. Cell colonization and tissue vascularization as well as transplantability of developed PCL/CaCO₃+TA scaffolds were observed. Detailed study of scaffold transformations during 21-day implantation period was followed by scanning electron microscopy and X-ray diffraction studies before and after in vivo implantation. The presented results demonstrate that PCL/CaCO₃ scaffolds are attractive candidates for implants in bone regeneration and tissue engineering with a possibility of loading biologically active molecules and controlled release.