Phenolic Compounds in Foods, Plants and Related By-Products—2nd Edition

A special issue of Antioxidants (ISSN 2076-3921). This special issue belongs to the section "Natural and Synthetic Antioxidants".

Deadline for manuscript submissions: 31 May 2025 | Viewed by 16117

Special Issue Editor


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Guest Editor
School of Pharmacy, University of Camerino, Via Madonna delle Carceri, 62032 Camerino, Italy
Interests: food analysis; mass spectrometry; extraction methods; plant analysis; by-products chemical characterization; chromatography
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Special Issue Information

Dear Colleagues,

In view of the great response that we received to the previous Special Issue "Antioxidant Capacity of Phenolic Compounds in Foods, Plants and Related By-Products", we decided to revisit this topic.

Phenolic compounds are a large class of plant secondary metabolites displaying different structures. The main groups of phenolic compounds include flavonoids, phenolic acids, tannins, stilbenes, and lignans. Phenolic compounds have been found to exert various activities, such as antioxidant, anti-microbial, anti-carcinogenic, and anti-inflammatory properties, as well as the prevention of cardiovascular diseases, diabetes, and diseases associated with oxidative stress. They are synthesized in plants as a response to ecological and physiological pressures such as pathogen and insect attack, UV radiation, and wounding, and at the same time, they are also closely associated with the sensory and nutritional quality of fresh and processed food and plants. In the last few years, the reutilization of food and plant by-products has become a relevant issue as they contain a large number of phenolic compounds that can be extracted and reused.

This Special Issue aims to collect and share studies on the antioxidant capacity of phenolic compounds present in food, plants, and related by-products. In this topic, the exploitation of extraction processes, analytical methods used for their analyses, evaluation of biological activities, nutritional value, and nutraceutical/innovative applications in different economic sectors of food, plants, and related by-products rich in phenolic compounds are themes to be explored.

Dr. Giovanni Caprioli
Guest Editor

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Keywords

  • phenolic compounds
  • food and plants analyses
  • by-products chemical characterization
  • biological activities
  • valorization and recovery of by-products
  • food supplement
  • functional food
  • antioxidant activity
  • extraction methods
  • analytical methods

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Published Papers (8 papers)

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Research

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22 pages, 44544 KiB  
Article
Optimization of Phenolic Content Extraction and Effects of Drying Treatments on Physicochemical Characteristics and Antioxidant Properties of Edible Mushroom Pleurotus ostreatus (Jacq.) P. Kumm (Oyster Mushroom)
by Marcelo Villalobos-Pezos, Ociel Muñoz-Fariña, Kong Shun Ah-Hen, María Fernanda Garrido-Figueroa, Olga García-Figueroa, Alexandra González-Esparza, Luisbel González-Pérez de Medina and José Miguel Bastías-Montes
Antioxidants 2024, 13(12), 1581; https://doi.org/10.3390/antiox13121581 - 23 Dec 2024
Viewed by 4870
Abstract
Edible mushrooms have been part of the human diet for centuries. Traditionally, they have been used for culinary and medicinal purposes due to their chemical composition and nutritional value, including their high antioxidant activity attributed to key metabolites such as phenolic compounds and [...] Read more.
Edible mushrooms have been part of the human diet for centuries. Traditionally, they have been used for culinary and medicinal purposes due to their chemical composition and nutritional value, including their high antioxidant activity attributed to key metabolites such as phenolic compounds and ergothioneine. P. ostreatus mushrooms, known for their potent antioxidant activity, are prone to spoilage shortly after harvest, making preservation methods necessary. Various drying methods were evaluated to determine their effects on physicochemical characteristics, antioxidant properties, and ergothioneine content. Mushrooms were subjected to freeze-drying (FD), hot-air-drying (HAD), and microwave-vacuum-drying (MVD). The rehydration rate, color, and microstructural characteristics of extracts from fresh and dried P. ostreatus mushrooms were evaluated. Additionally, the total soluble phenolic content and antioxidant activity were assessed using DPPH and ORAC assays, along with the determination of ergothioneine content. FD and HAD at 40 °C showed the best results regarding the physicochemical characteristics. In terms of total soluble phenolic content, antioxidant activity, and ergothioneine content, the mushrooms dried using HAD at 40 °C showed the best retention of bioactive compounds. Among the evaluated methods, HAD at 40 °C proved to be a suitable alternative for processing P. ostreatus. Full article
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12 pages, 720 KiB  
Article
Quantification of Bioactive Compounds by HPLC-ESI-MS/MS and Evaluation of Antioxidant and Enzyme Inhibitory Activities of Acorn Flour Extracts
by Laura Acquaticci, Agnese Santanatoglia, Elena Vittadini, Daniela Beghelli, Antonietta La Terza, Gokhan Zengin and Giovanni Caprioli
Antioxidants 2024, 13(12), 1526; https://doi.org/10.3390/antiox13121526 - 13 Dec 2024
Viewed by 973
Abstract
This study provides the first comprehensive evaluation of the bioactive potential of acorn flour extracts (Quercus robur, Fagaceae) prepared at different temperatures (20, 60, 80 and 100 °C), focusing on polyphenolic content, antioxidant properties and enzyme inhibitory activities. Through HPLC-ESI-MS/MS analysis, [...] Read more.
This study provides the first comprehensive evaluation of the bioactive potential of acorn flour extracts (Quercus robur, Fagaceae) prepared at different temperatures (20, 60, 80 and 100 °C), focusing on polyphenolic content, antioxidant properties and enzyme inhibitory activities. Through HPLC-ESI-MS/MS analysis, 36 bioactive compounds were identified, with the extract at 60 °C showing the highest concentrations of key polyphenols, notably gallic acid (210,008.9 mg·kg−1) and ellagic acid (45,469.6 mg·kg−1). This extract also exhibited a high antioxidant activity and significant inhibition of glucosidase and acetylcholinesterase, suggesting potential benefits for diabetes management and neuroprotection. The results indicate that extraction temperature affects bioactivity, with the 60 °C extract standing out as a promising candidate for nutraceutical, pharmaceutical, and cosmeceutical applications due to its rich polyphenol profile and potent biological properties. Full article
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17 pages, 3672 KiB  
Article
Protective Effect of Resveratrol on Kidney Disease and Hypertension Against Microplastics Exposure in Male Juvenile Rats
by You-Lin Tain, Guo-Ping Chang-Chien, Shu-Fen Lin, Chih-Yao Hou and Chien-Ning Hsu
Antioxidants 2024, 13(12), 1457; https://doi.org/10.3390/antiox13121457 - 27 Nov 2024
Cited by 1 | Viewed by 1305
Abstract
Global pollution stems from the degradation of plastic waste, leading to the generation of microplastics (MPs). While environmental pollutants increase the risk of developing hypertension and kidney disease, the effects of MP exposure on these conditions in children remain unclear. Resveratrol, a phenolic [...] Read more.
Global pollution stems from the degradation of plastic waste, leading to the generation of microplastics (MPs). While environmental pollutants increase the risk of developing hypertension and kidney disease, the effects of MP exposure on these conditions in children remain unclear. Resveratrol, a phenolic compound known for its antihypertensive and renoprotective properties, has gained attention as a potential nutraceutical. This study investigates the effects of resveratrol on kidney disease and hypertension induced by MP exposure in a juvenile rat model. Three-week-old male Sprague–-Dawley (SD) rats were randomly allocated into four groups (n = 8 per group): a control group, a low-dose MP group (1 mg/L), a high-dose MP group (10 mg/L), and a high-dose MP group receiving resveratrol (50 mg/L). By 9 weeks of age, MP exposure resulted in elevated blood pressure and increased creatinine levels, both of which were mitigated by resveratrol treatment. The hypertension and kidney damage induced by high-dose MP exposure were linked to oxidative stress, which resveratrol effectively prevented. Additionally, resveratrol’s protective effects against hypertension and kidney damage were associated with increased acetic acid levels, reduced renal expression of Olfr78, and decreased expression of various components of the renin-angiotensin system (RAS). Low- and high-dose MP exposure, as well as resveratrol treatment, differentially influence gut microbiota composition. Our findings suggest that targeting oxidative stress, gut microbiota, and the RAS through resveratrol holds therapeutic potential for preventing kidney disease and hypertension associated with MP exposure. However, further research is needed to translate these results into clinical applications. Full article
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25 pages, 5673 KiB  
Article
Thymus spp. Aqueous Extracts and Their Constituent Salvianolic Acid A Induce Nrf2-Dependent Cellular Antioxidant Protection Against Oxidative Stress in Caco-2 Cells
by Carlos Martins-Gomes, Fernando M. Nunes and Amélia M. Silva
Antioxidants 2024, 13(11), 1287; https://doi.org/10.3390/antiox13111287 - 24 Oct 2024
Cited by 1 | Viewed by 1427
Abstract
The increasing incidence of colorectal cancer and inflammatory diseases poses a major health concern, with oxidative stress playing a significant role in the onset of these pathologies. Factors such as excessive consumption of sugar-rich and fatty foods, synthetic food additives, pesticides, alcohol, and [...] Read more.
The increasing incidence of colorectal cancer and inflammatory diseases poses a major health concern, with oxidative stress playing a significant role in the onset of these pathologies. Factors such as excessive consumption of sugar-rich and fatty foods, synthetic food additives, pesticides, alcohol, and tobacco contribute to oxidative stress and disrupt intestinal homeostasis. Functional foods arise as a potential tool to regulate redox balance in the intestinal tract. Herbs (such as Thymus spp.) have long been screened for their antioxidant properties, but their use as antioxidants for medicinal purposes requires validation in biological models. In this study, we addressed the potential antioxidant protection and preventive effects of extracts from two thyme species at the intestinal level, as well as their molecular mechanisms of action. Caco-2 cells were pre-exposed (4 h) to aqueous (AD) and hydroethanolic (HE) extracts of Thymus carnosus and Thymus capitellatus, followed by a recovery period in culture medium (16 h), and then treated with tert-butyl-hydroperoxide (TBHP; 4 h), before analyzing cell viability. The effect of the extracts’ main components was also analysed. Cellular oxidative stress, cell-death markers, and the expression of antioxidant-related proteins were evaluated using flow cytometry on cells pre-exposed to the AD extracts and salvianolic acid A (SAA). Results showed that pre-exposure to AD extracts or SAA reduced TBHP-induced oxidative stress and cell death, mediated by increased levels of nuclear factor erythroid 2-related factor 2 (Nrf2) protein. The protective activity of T. capitellatus AD extract was shown to be dependent on NAD(P)H quinone dehydrogenase 1 (NQO1) protein expression and on increased glutathione (GSH) content. Furthermore, ursolic acid induced cytotoxicity and low cellular antioxidant activity, and thus the presence of this triterpenoid impaired the antioxidant effect of HE extracts. Thus, AD extracts show high potential as prophylactic dietary agents, while HE extracts arise as a source of nutraceuticals with antioxidant potential. Full article
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17 pages, 3598 KiB  
Article
DNA-Protective, Antioxidant and Anti-Carcinogenic Potential of Meadowsweet (Filipendula ulmaria) Dry Tincture
by Tsvetelina Andonova, Yordan Muhovski, Elena Apostolova, Samir Naimov, Silviya Mladenova, Iliya Slavov, Ivayla Dincheva, Vasil Georgiev, Atanas Pavlov and Ivanka Dimitrova-Dyulgerova
Antioxidants 2024, 13(10), 1200; https://doi.org/10.3390/antiox13101200 - 3 Oct 2024
Cited by 3 | Viewed by 1650
Abstract
Nowadays, interest in natural antioxidants (especially phenolics) for the prevention of oxidative stress-related diseases is increasing due to their fewer side effects and more potent activity than some of their synthetic analogues. New chemical and pharmacological studies of well-known herbal substances are among [...] Read more.
Nowadays, interest in natural antioxidants (especially phenolics) for the prevention of oxidative stress-related diseases is increasing due to their fewer side effects and more potent activity than some of their synthetic analogues. New chemical and pharmacological studies of well-known herbal substances are among the current trends in medicinal plant research. Meadowsweet (Filipendula ulmaria) is a popular herb used in traditional medicine to treat various diseases (including rheumatic-, inflammatory- and tumor-related disease, etc.). The dry tincture of Filipendulae ulmariae herba, collected from the Bulgarian flora, was analyzed using the HPLC method and bioassayed for antioxidant, antiproliferative and DNA-protective activities against oxidative damage. The HPLC phenolic profile showed 12 phenolics, of which salicylic acid (18.84 mg/g dry extract), rutin (9.97 mg/g de), p-coumaric acid (6.80 mg/g de), quercetin (4.47 mg/g de), rosmarinic acid (4.01 mg/g de) and vanillic acid (3.82 mg/g de) were the major components. The high antioxidant potential of the species was confirmed by using four methods, best expressed by the results of the CUPRAC assay (10,605.91 μM TE/g de). The present study reports for the first time the highly protective activities of meadowsweet dry tincture against oxidative DNA damage and its antiproliferative effect against hepatocellular carcinoma (HepG2 cell line). Meadowsweet dry tincture possesses great potential to prevent diseases caused by oxidative stress. Full article
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22 pages, 4073 KiB  
Article
Extraction Optimization of Quercus cerris L. Wood Chips: A Comparative Study between Full Factorial Design (FFD) and Artificial Neural Network (ANN)
by Maria Ponticelli, Vittorio Carlucci, Marisabel Mecca, Luigi Todaro, Luigi Milella and Daniela Russo
Antioxidants 2024, 13(9), 1115; https://doi.org/10.3390/antiox13091115 - 14 Sep 2024
Cited by 2 | Viewed by 1205
Abstract
From a circular bio-economy perspective, biomass valorization requires the implementation of increasingly efficient extraction techniques to ensure the environmental and economic sustainability of biorefining processes. This research focuses on optimizing the specialized metabolite extraction of Turkey oak chips from Quercus cerris L. by [...] Read more.
From a circular bio-economy perspective, biomass valorization requires the implementation of increasingly efficient extraction techniques to ensure the environmental and economic sustainability of biorefining processes. This research focuses on optimizing the specialized metabolite extraction of Turkey oak chips from Quercus cerris L. by applying a 3 levels Full Factorial Design (FFD). The goal is to obtain an extract with the highest antioxidant activity [evaluated by 1,1-diphenyl-2-picryl hydrazyl (DPPH) scavenging activity and ferric reducing antioxidant power (FRAP) assays] and specialized metabolites content [measured as total phenolic content (TPC), total flavonoid content (TFC), condensed tannin content (CTC), and hydrolysable tannins content (THC)]. With this objective, three different variables were investigated and compared: temperature (20 °C, 50 °C, 80 °C), solvents EtOH/H2O (0%, 20%, 40%), and time (3 h, 6 h, 24 h), resulting in 27 different extracts. Following the FFD analysis, the optimal extractive conditions were determined to be 80 °C, 40% EtOH/H2O, and 19.8 h. Finally, the prediction ability of FFD was compared with that of artificial neural network (ANN) for DPPH scavenging activity, FRAP, and TPC data based on the coefficient of determination (R2), mean absolute error (MAE), and root mean square error (RMSE). The results indicated that ANN predictions were more precise than FFD ones; however, both methods were useful in optimizing the extraction process as they returned comparable optimized extraction parameters. Full article
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15 pages, 566 KiB  
Article
Improving the Extraction of Polyphenols from Cocoa Bean Shells by Ultrasound and Microwaves: A Comparative Study
by Vincenzo Disca, Fabiano Travaglia, Chiara Carini, Jean Daniel Coïsson, Giancarlo Cravotto, Marco Arlorio and Monica Locatelli
Antioxidants 2024, 13(9), 1097; https://doi.org/10.3390/antiox13091097 - 10 Sep 2024
Cited by 3 | Viewed by 1608
Abstract
The extraction of bioactive compounds from food by-products is one of the most important research areas for the nutraceutical, pharmaceutical, and food industries. This research aimed to evaluate the efficiency of Ultrasound-Assisted Extraction (UAE) and Microwave-Assisted Extraction (MAE), either alone or in combination, [...] Read more.
The extraction of bioactive compounds from food by-products is one of the most important research areas for the nutraceutical, pharmaceutical, and food industries. This research aimed to evaluate the efficiency of Ultrasound-Assisted Extraction (UAE) and Microwave-Assisted Extraction (MAE), either alone or in combination, of phenolic compounds from cocoa bean shells (CBSs). These extraction techniques were compared with conventional methods, such as under simple magnetic stirring and the Soxhlet apparatus. After the preliminary characterization of the gross composition of CBSs, the total polyphenol content and radical scavenging of extracts obtained from both raw and defatted cocoa bean shells were investigated. Quantification of the main polyphenolic compounds was then performed by RP-HPLC-DAD, identifying flavonoids and phenolic acids, as well as clovamide. The application of MAE and UAE resulted in a similar or superior extraction of polyphenols when compared with traditional methods; the concentration of individual polyphenols was variously influenced by the extraction methods employed. Combining MAE and UAE at 90 °C yielded the highest antiradical activity of the extract. Spectrophotometric analysis confirmed the presence of high-molecular-weight melanoidins, which were present in higher concentrations in the extracts obtained using MAE and UAE, especially starting from raw material. In conclusion, these results emphasize the efficiency of MAE and UAE techniques in obtaining polyphenol-rich extracts from CBS and confirm this cocoa by-product as a valuable biomass for the recovery of antioxidant compounds, with a view to possible industrial scale-up. Full article
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Review

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31 pages, 2352 KiB  
Review
The Role of Polyphenols in Abiotic Stress Tolerance and Their Antioxidant Properties to Scavenge Reactive Oxygen Species and Free Radicals
by Muhammad Junaid Rao and Bingsong Zheng
Antioxidants 2025, 14(1), 74; https://doi.org/10.3390/antiox14010074 - 10 Jan 2025
Cited by 2 | Viewed by 2254
Abstract
Plants have evolved complex mechanisms to cope with diverse abiotic stresses, with the phenylpropanoid pathway playing a central role in stress adaptation. This pathway produces an array of secondary metabolites, particularly polyphenols, which serve multiple functions in plant growth, development, regulating cellular processes, [...] Read more.
Plants have evolved complex mechanisms to cope with diverse abiotic stresses, with the phenylpropanoid pathway playing a central role in stress adaptation. This pathway produces an array of secondary metabolites, particularly polyphenols, which serve multiple functions in plant growth, development, regulating cellular processes, and stress responses. Recent advances in understanding the molecular mechanisms underlying phenylpropanoid metabolism have revealed complex regulatory networks involving MYB transcription factors as master regulators and their interactions with stress signaling pathways. This review summarizes our current understanding of polyphenol-mediated stress adaptations in plants, emphasizing the regulation and function of key phenylpropanoid pathway compounds. We discussed how various abiotic stresses, including heat and chilling stress, drought, salinity, light stress, UV radiation, nanoparticles stress, chemical stress, and heavy metal toxicity, modulate phenylpropanoid metabolism and trigger the accumulation of specific polyphenolic compounds. The antioxidant properties of these metabolites, including phenolic acids, flavonoids, anthocyanins, lignin, and polyphenols, and their roles in reactive oxygen species scavenging, neutralizing free radicals, membrane stabilization, and osmotic adjustment are discussed. Understanding these mechanisms and metabolic responses is crucial for developing stress-resilient crops and improving agricultural productivity under increasingly challenging environmental conditions. This review provides comprehensive insights into integrating phenylpropanoid metabolism with plant stress adaptation mechanisms, highlighting potential targets for enhancing crop stress tolerance through metabolic adjustment. Full article
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