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Plant Waste Management: Bioactive Compounds with Therapeutic Role in Disease Prevention

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A special issue of Molecules (ISSN 1420-3049). This special issue belongs to the section "Natural Products Chemistry".

Deadline for manuscript submissions: closed (31 May 2023) | Viewed by 36421

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Prof. Dr. Ana Barros

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Centre for the Research and Technology of Agro-Environmental and Biological Sciences (CITAB), Institute for Innovation, Capacity Building and Sustainability of Agri-Food Production (Inov4Agro), University of Trás-os-Montes and Alto Douro (UTAD), Quinta de Prados, 5000-801 Vila Real, Portugal
Interests: by-products; bioactive compounds; circular economy; industrial symbiosis; HLPC-MS; spectroscopic analysis
Special Issues, Collections and Topics in MDPI journals

Dr. Irene Gouvinhas

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Centre for the Research and Technology of Agro-Environment and Biological Sciences (CITAB), Institute for Innovation, Capacity Building and Sustainability of Agri-Food Production (Inov4Agro), University of Trás-os-Montes e Alto Douro, 5000-801 Vila Real, Portugal
Interests: bioactivity; chemical characterization of natural products; identification, quantification, separation, and recovery of bioactive compounds from different food and agro-food byproducts; experimental design applied to extraction and process optimization of natural products
Special Issues, Collections and Topics in MDPI journals

Special Issue Information

Dear Colleagues,

In the scientific community, it has been well established that some plants have an important role in the prevention of some degenerative or cardiovascular diseases, resulting from their content in bioactive phytochemicals with several biological properties. Furthermore, the agro-food industry involves the production of large quantities of waste, also characterized by a valuable composition in phytochemicals with putative health-promoting qualities. Due to increasing production, disposal represents a growing problem since plant material is usually prone to microbial spoilage, thus limiting further exploitation. On the other hand, costs of drying, storage, and shipment of these materials are economically limiting factors. Therefore, agro-industrial waste is often utilized as feed or fertilizer, or as combustion feedstock for biofuels. Additionally, in light of the biological properties recently revealed, the search for natural bioactive compounds has drawn attention to these materials, namely phenolic compounds that may have an added-value to be used as an alternative to synthetic substances employed in distinct industries, such as the food, cosmetic, or pharmaceutical sectors, giving rise to sustainable agro-industrial activities.

Due to contemporary lifestyle issues, research on secondary metabolites with health-promoting effects in countering or slowing-down chronic and degenerative diseases (e.g., cancer, cardiovascular, and neurodegenerative diseases) have recognized that phenols and polyphenols are beneficial for human health, and are widespread and copious in dietary plant sources.

Taking all this into account, and considering not only the increasing trend to reduce the costs of industrial activities, but also the growing interest in the major therapeutic role that bioactive compounds from plant waste can play in disease prevention in humans, the main goal is the valorization of less-characterized plant wastes, of low commercial value, as a source of bioactive compounds with the capacity to influence health-related conditions.

Contributions to this Special Issue may cover all research aspects related to plant wastes, characterized to be all those parts from plants discarded during the agricultural and industrial processing, distribution and consumption stages of the food supply chain, which could be either edible or inedible, and that can be further processed and valorized in several ways; plant food residues (fruit and vegetable waste); characterization of their biological properties, including (but not limited to) methods for their extraction, purification, comprehensive profiling characterization, and quantification, as well as new technologies explored for more efficient extraction; beneficial biological properties that could potentially contribute to functional food and nutraceutical development; functional properties such as antioxidant, antibacterial, anticancer, antidiabetic, anti-obesity, antitumor, antiviral, anti-inflammatory, and anticoagulant properties, among others; in vitro and in vivo model systems; clinical investigations; biotechnological applications of plant wastes, such as nutraceuticals, cosmeceuticals, and pharmaceuticals. Original research papers and review articles on these different areas are welcome.

Dr. Ana Barros
Dr. Irene Gouvinhas
Guest Editors

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Keywords

Plant waste
Phytochemicals
Bioactive compounds
Biological properties
Natural products
Nutraceuticals
Added-value products Disease prevention

Published Papers (9 papers)

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Research

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17 pages, 1577 KiB

Open AccessArticle

Optimization of the Extraction Methodology of Grape Pomace Polyphenols for Food Applications

by Joana Moutinho, Irene Gouvinhas, Raúl Domínguez-Perles and Ana Barros

Molecules 2023, 28(9), 3885; https://doi.org/10.3390/molecules28093885 - 04 May 2023

Cited by 3 | Viewed by 1775

Abstract

This study aims to take advantage of the wine industry by-products and extract bioactive compounds from grape pomace by applying methodologies susceptible to be integrated easily into industrial workflows because of the association with standard instrumentation and facilities, while the main factors affecting the efficiency of the process have been optimized. The sampling consisted of two grape varieties: ‘Touriga Nacional’ and ‘Sousão’. A response surface methodology (RSM) method was used to optimize the extraction conditions based on three independent variables according to the chemical characteristics and stability/lability traits associated with polyphenols; the main bioactive phytochemical in grape pomace: solvent (50%, 70%, and 90% ethanol); temperature (20 °C, 40 °C, and 60 °C); and pH (0.5% HCl, 2% HCl, and 3.5% HCl). The phytochemical profile, as well as the radical scavenging and reducing powers were determined on 27 different samples. The highest yield and antioxidant activity corresponded to extracts obtained at 60 °C using 3.5% HCl and 70% ethanol. The values for total phenols and flavonoids were 44.93 mg of gallic acid equivalents (GAE) and 22.95 mg of catechins equivalents (CE) per gram, respectively. Concerning the evaluation of antioxidant capacity using various assays such as ABTS, DPPH, and FRAP, the results obtained were 0.30, 0.43, and 0.36 mmol of Trolox equivalent antioxidant capacity (TEAC) per gram, correspondingly. The analysis of the extract obtained with the best extraction performance using these parameters via High-Performance Liquid Chromatography–Mass Spectrometry has been also performed, allowing us to identify fourteen (14) compounds, including phenolic acids (n = 3), flavonols (n = 7), and anthocyanins (n = 4). As a result of this process, the best conditions for the production of a natural and environmentally friendly dye, not only avoiding waste but also reusing these by-products, were achieved. Full article

(This article belongs to the Special Issue Plant Waste Management: Bioactive Compounds with Therapeutic Role in Disease Prevention)

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23 pages, 2357 KiB

Open AccessArticle

Olive Pomace Phenolic Compounds Stability and Safety Evaluation: From Raw Material to Future Ophthalmic Applications

by Nikolaos Katsinas, Amalia Enríquez-de-Salamanca, Andreia Bento da Silva, Maria Rosário Bronze and Soraya Rodríguez-Rojo

Molecules 2021, 26(19), 6002; https://doi.org/10.3390/molecules26196002 - 02 Oct 2021

Cited by 6 | Viewed by 4752

Abstract

Nowadays, increasing interest in olive pomace (OP) valorization aims to improve olive’s industry sustainability. Interestingly, several studies propose a high-value application for OP extracts containing its main phenolic compounds, hydroxytyrosol and oleuropein, as therapy for ocular surface diseases. In this work, the stability and accessibility of OP total phenolic and flavonoid content, main representative compounds, and antioxidant activity were assessed under different pretreatment conditions. Among them, lyophilization and supercritical CO₂ extraction were found to increase significantly most responses measured in the produced extracts. Two selected extracts (CONV and OPT3) were obtained by different techniques (conventional and pressurized liquid extraction); Their aqueous solutions were characterized by HPLC-DAD-MS/MS. Additionally, their safety and stability were evaluated according to EMA requirements towards their approval as ophthalmic products: their genotoxic effect on ocular surface cells and their 6-months storage stability at 4 different temperature/moisture conditions (CPMP/ICH/2736/99), together with pure hydroxytyrosol and oleuropein solutions. The concentration of hydroxytyrosol and oleuropein in pure or extract solutions was tracked, and possible degradation products were putatively identified by HPLC-DAD-MS/MS. Hydroxytyrosol and oleuropein had different stability as standard or extract solutions, with oleuropein also showing different degradation profile. All compounds/extracts were safe for ophthalmic use at the concentrations tested. Full article

(This article belongs to the Special Issue Plant Waste Management: Bioactive Compounds with Therapeutic Role in Disease Prevention)

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15 pages, 1707 KiB

Open AccessArticle

Formulation Effects in the Antioxidant Activity of Extract from the Leaves of Cymbopogon citratus (DC) Stapf

by Raquel Sousa, Artur Figueirinha, Maria Teresa Batista and Maria Eugénia Pina

Molecules 2021, 26(15), 4518; https://doi.org/10.3390/molecules26154518 - 27 Jul 2021

Cited by 8 | Viewed by 2602

Abstract

Cymbopogon citratus DC (Stapf.) is a perennial grass and it is distributed around the world. It is used as a condiment for food and beverage flavouring in the form of infusions and decoctions of its dried leaves. Our previous studies have shown antioxidant, anti-inflammatory and gastroprotective activities for the infusion and its phenolic fractions. The aim of the present work was to develop oral dosage forms from a Cymbopogon citratus extract to be used as a functional food with antioxidant properties. Initially, an essential oil-free infusion was prepared, lyophilized and characterized by HPLC-PDA. Total phenols were quantified with the Folin–Ciocalteu method and the antioxidant activity was assessed by DPPH assay. Gelatine capsules containing the extract with different excipients, selected after DSC and IR trials, were prepared. A formulation exhibiting better antioxidant behaviour in a gastric environment was attained. These results suggest that the proposed formulation for this extract could be a valuable antioxidant product and, consequently, make an important contribution to “preventing” and minimizing diseases related to oxidative stress conditions. Full article

(This article belongs to the Special Issue Plant Waste Management: Bioactive Compounds with Therapeutic Role in Disease Prevention)

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19 pages, 1677 KiB

Open AccessArticle

Invasive Plant Species Biomass—Evaluation of Functional Value

by Anamarija Peter, Jana Šic Žlabur, Jona Šurić, Sandra Voća, Dubravka Dujmović Purgar, Lato Pezo and Neven Voća

Molecules 2021, 26(13), 3814; https://doi.org/10.3390/molecules26133814 - 22 Jun 2021

Cited by 7 | Viewed by 2015

Abstract

Invasive plant species (IAS), with their numerous negative ecological, health, and economic impacts, represent one of the greatest conservation challenges in the world. Reducing the negative impacts and potentially exploiting the biomass of these plant species can significantly contribute to sustainable management, protect biodiversity, and create a healthy environment. Therefore, the main objective of this study was to evaluate the nutritional potential, phytochemical status, and antioxidant capacity of nine alien invasive plant species: Abutilon theophrasti, Amaranthus retroflexus, Ambrosia artemisiifolia, Datura stramonium, Erigeron annuus, Galinsoga ciliata, Reynoutria japonica, Solidago gigantea, and Sorghum halepense. Multivariate statistical methods such as cluster and PCA were performed to determine possible connections and correlations among selected IAS depending on the phytochemical content. According to the obtained results, R. japonica was notable with the highest content of vitamin C (38.46 mg/100 g FW); while E. annuus (1365.92 mg GAE/100 g FW) showed the highest values of total polyphenolic compounds. A. retroflexus was characterized by the highest content of total chlorophylls (0.26 mg/g) and antioxidant capacity (2221.97 µmol TE/kg). Therefore, it can be concluded that the selected IAS represent nutrient-rich plant material with significant potential for the recovering of bioactive compounds. Full article

(This article belongs to the Special Issue Plant Waste Management: Bioactive Compounds with Therapeutic Role in Disease Prevention)

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15 pages, 1699 KiB

Open AccessArticle

An Insight into Kiwiberry Leaf Valorization: Phenolic Composition, Bioactivity and Health Benefits

by Ana Margarida Silva, Diana Pinto, Iva Fernandes, Victor de Freitas, María de la Luz Cádiz-Gurrea, Paulo Costa, Cristina Delerue-Matos and Francisca Rodrigues

Molecules 2021, 26(8), 2314; https://doi.org/10.3390/molecules26082314 - 16 Apr 2021

Cited by 15 | Viewed by 2149

Abstract

During kiwiberry production, different by-products are generated, including leaves that are removed to increase the fruit’s solar exposure. The aim of this work was to extract bioactive compounds from kiwiberry leaf by employing microwave-assisted extraction (MAE). Compatible food solvents (water and ethanol) were employed. The alcoholic extract contained the highest phenolic and flavonoid contents (629.48 mg of gallic acid equivalents (GAE) per gram of plant material on dry weight (dw) (GAE/g dw) and 136.81 mg of catechin equivalents per gram of plant material on dw (CAE/g dw), respectively). Oppositely, the hydroalcoholic extract achieved the highest antioxidant activity and scavenging activity against reactive oxygen and nitrogen species (IC₅₀ = 29.10 μg/mL for O₂^•−, IC₅₀ = 1.87 μg/mL for HOCl and IC₅₀ = 1.18 μg/mL for ^•NO). The phenolic profile showed the presence of caffeoylquinic acids, proanthocyanidin, and quercetin in all samples. However, caffeoylquinic acids and quercetin were detected in higher amounts in the alcoholic extract, while proanthocyanidins were prevalent in the hydroalcoholic extract. No adverse effects were observed on Caco-2 viability, while the highest concentration (1000 µg/mL) of hydroalcoholic and alcoholic extracts conducted to a decrease of HT29-MTX viability. These results highlight the MAE potentialities to extract bioactive compounds from kiwiberry leaf. Full article

(This article belongs to the Special Issue Plant Waste Management: Bioactive Compounds with Therapeutic Role in Disease Prevention)

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19 pages, 2422 KiB

Open AccessArticle

Olive Pâté by Multi-Phase Decanter as Potential Source of Bioactive Compounds of Both Nutraceutical and Anticancer Effects

by Barbara Lanza, Martina Cellini, Sara Di Marco, Emira D’Amico, Nicola Simone, Lucia Giansante, Arianna Pompilio, Giuseppina Di Loreto, Martina Bacceli, Paolo Del Re, Giovanni Di Bonaventura, Luciana Di Giacinto and Gitana Maria Aceto

Molecules 2020, 25(24), 5967; https://doi.org/10.3390/molecules25245967 - 16 Dec 2020

Cited by 14 | Viewed by 2864

Abstract

In the oil sector, a novelty in the centrifugal extraction system is represented by the multi-phase decanters (DMF) that work without adding process water and with the advantage of recovering a dried pomace and a by-product, called “pâté”, consisting of the pulp and its vegetation water, without traces of stone. The pâté has a high content of phenolic compounds, mainly represented by secoiridoids and verbascoside. The present work investigated the efficacy of two different ways of debittering (by sequential filtrations and spontaneous fermentation) of DMF pâté from three olive cultivars (Olea europaea L. “Leccino”, “Carboncella” and “Tortiglione”) to make the pâté edible, and, contemporary, investigated also the effect of its phenolic bioactive extracts on pathogenic bacteria and colon cancer cell model. Daily filtrations of pâté of the three cultivars have been shown to be more efficient in phenolic degradation. The activity of the indigenous microflora on the other hand takes a longer time to degrade the phenolic component and therefore to de-bitter it. None of pâté showed antibacterial activity. Colorimetric assay MTS for cell viability and metabolic activity tested on colon cancer cells Caco-2 and HCT116 suggest a potential beneficial effect of the dried extracts probably related to the modulation of gene expression under these treatments. Full article

(This article belongs to the Special Issue Plant Waste Management: Bioactive Compounds with Therapeutic Role in Disease Prevention)

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19 pages, 712 KiB

Open AccessArticle

Acorn Flour as a Source of Bioactive Compounds in Gluten-Free Bread

by Rita Beltrão Martins, Irene Gouvinhas, Maria Cristiana Nunes, José Alcides Peres, Anabela Raymundo and Ana I.R.N.A. Barros

Molecules 2020, 25(16), 3568; https://doi.org/10.3390/molecules25163568 - 06 Aug 2020

Cited by 25 | Viewed by 5151

Abstract

Polyphenols are important bioactive compounds whose regular ingestion has shown different positive impacts in health. Celiac patients have nutritional deficiencies, bringing many problems to their health. Thus, it is important to develop gluten-free (GF) products, such as bread, with nutritional benefits. The acorn is the fruit of holm oak and cork oak, being an underexploited resource nowadays. Its nutritional and functional characteristics are remarkable: rich in unsaturated fatty acids and fiber, vitamin E, chlorophylls, carotenoids, phenolic compounds, and antioxidant properties. The purpose of this study was to assess the use of acorn flour as a bioactive compounds source and natural GF ingredient for baking GF bread. Bread loaves were prepared with buckwheat, rice, acorn flour, and potato starch. Two levels of acorn flour (23% and 35% of the flour mixture) were tested. The physical, nutritional, and sensory characteristics of the bread were analysed, as well as the composition of phenolic compounds: total phenols, ortho-diphenols, and flavonoids. The phenolic profile was assessed by Reverse Phase–High-Performance Liquid Chromatography–Diode Array Detector (RP-HPLC-DAD). The antioxidant activity of the bread extracts was determined by 2,2-azino-bis (3-ethylbenzothiazoline-6-sulphonic acid) diammonium salt (ABTS), diphenyl-1-picrylhidrazyl radical (DPPH), and ferric reducing antioxidant power (FRAP) methodologies. Acorn flour can be considered a good source of bioactive compounds and antioxidants in GF bread. Acorn flour showed good technological properties in GF baking, improving bread nutritional and sensory characteristics. Full article

(This article belongs to the Special Issue Plant Waste Management: Bioactive Compounds with Therapeutic Role in Disease Prevention)

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13 pages, 3538 KiB

Open AccessArticle

Identification of Polyphenols from Coniferous Shoots as Natural Antioxidants and Antimicrobial Compounds

by Marcin Dziedzinski, Joanna Kobus-Cisowska, Daria Szymanowska, Kinga Stuper-Szablewska and Marlena Baranowska

Molecules 2020, 25(15), 3527; https://doi.org/10.3390/molecules25153527 - 01 Aug 2020

Cited by 31 | Viewed by 3772

Abstract

Currently, coniferous shoots are almost absent as a food ingredient despite their wide availability in many parts of the world. The aim of the study was to assess and compare the composition of selected plant metabolites, evaluate the antioxidant and antimicrobial properties of selected shoots collected in 2019 from the arboretum in Zielonka (Poland), including individual samples from Picea abies L. (PA), Larix decidua Mill (LD), Pinus sylvestris L. (PS), Pseudotsuga menziesii (PM) and Juniperus communis L. (JC). The present work has shown that aqueous extracts obtained from tested shoots are a rich source of phenols such as caffeic acid, ferulic acid, chlorogenic acid, 4-hydroxybenzoic acid and many others. Obtained extracts exhibit antioxidant and antimicrobial properties in vitro. The highest sum of the studied phenolic compounds was found in the PA sample (13,947.80 µg/g dw), while the lowest in PS (6123.57 µg/g dw). The samples were particularly rich in ferulic acid, chlorogenic acid and 4-hydroxybenzoic acid. The highest values regarding the Folin-Ciocâlteu reagent (FCR) and ferric reducing ability of plasma (FRAP) reducing ability tests, as well as the total flavonoid content assay, were obtained for the LD sample, although the LD (14.83 mg GAE/g dw) and PM (14.53 mg GAE/g dw) samples did not differ statistically in the FCR assay. With respect to free radical quenching measurements (DPPH), the PA (404.18-μM Trolox/g dw) and JC (384.30-μM Trolox/g dw) samples had the highest radical quenching ability and did not differ statistically. Generally, extracts obtained from PA and PS showed the highest antimicrobial activity against tested Gram-negative bacteria, Gram-positive bacteria and fungi. Full article

(This article belongs to the Special Issue Plant Waste Management: Bioactive Compounds with Therapeutic Role in Disease Prevention)

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Review

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34 pages, 1519 KiB

Open AccessReview

Processing Factors Affecting the Phytochemical and Nutritional Properties of Pomegranate (Punica granatum L.) Peel Waste: A Review

by Tandokazi Pamela Magangana, Nokwanda Pearl Makunga, Olaniyi Amos Fawole and Umezuruike Linus Opara

Molecules 2020, 25(20), 4690; https://doi.org/10.3390/molecules25204690 - 14 Oct 2020

Cited by 97 | Viewed by 9545

Abstract

Pomegranate peel has substantial amounts of phenolic compounds, such as hydrolysable tannins (punicalin, punicalagin, ellagic acid, and gallic acid), flavonoids (anthocyanins and catechins), and nutrients, which are responsible for its biological activity. However, during processing, the level of peel compounds can be significantly altered depending on the peel processing technique used, for example, ranging from 38.6 to 50.3 mg/g for punicalagins. This review focuses on the influence of postharvest processing factors on the pharmacological, phytochemical, and nutritional properties of pomegranate (Punica granatum L.) peel. Various peel drying strategies (sun drying, microwave drying, vacuum drying, and oven drying) and different extraction protocols (solvent, super-critical fluid, ultrasound-assisted, microwave-assisted, and pressurized liquid extractions) that are used to recover phytochemical compounds of the pomegranate peel are described. A total phenolic content of 40.8 mg gallic acid equivalent (GAE)/g DM was recorded when sun drying was used, but the recovery of the total phenolic content was higher at 264.3 mg TAE/g when pressurised liquid extraction was performed. However, pressurised liquid extraction is costly due to the high initial investment costs and the limited possibility of carrying out selective extractions of organic compounds from complex peel samples. The effects of these methods on the phytochemical profiles of pomegranate peel extracts are also influenced by the cultivar and conditions used, making it difficult to determine best practice. For example, oven drying at 60 °C resulted in higher levels of punicalin of 888.04 mg CE/kg DM compared to those obtained 40 °C of 768.11 mg CE/kg DM for the Wonderful cultivar. Processes that are easy to set up, cost-effective, and do not compromise the quality and safety aspects of the peel are, thus, more desirable. From the literature survey, we identified a lack of studies testing pretreatment protocols that may result in a lower loss of the valuable biological compounds of pomegranate peels to allow for full exploitation of their health-promoting properties in potentially new value-added products. Full article

(This article belongs to the Special Issue Plant Waste Management: Bioactive Compounds with Therapeutic Role in Disease Prevention)

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