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Antioxidants
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Innovative Processing Technologies and Their Effects on Antioxidant Activity in...
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Innovative Processing Technologies and Their Effects on Antioxidant Activity in Plant-Derived Natural Products

A special issue of Antioxidants (ISSN 2076-3921). This special issue belongs to the section "Extraction and Industrial Applications of Antioxidants".

Deadline for manuscript submissions: 31 December 2026 | Viewed by 3126

Editor

Dr. Filipa Mandim

E-Mail Website
Guest Editor
CIMO, LA SusTEC, Instituto Politécnico de Bragança, Campus de Santa Apolónia, 5300-253 Bragança, Portugal
Interests: natural products; bioactive compounds; pharmacological activity; cancer chemoresistance; antioxidant and anti-inflammatory mechanisms; drug discovery; functional foods; molecular pharmacology; toxicology; biotechnology; cellular models; human health; sustainable bioproducts
Special Issues, Collections and Topics in MDPI journals

Special Issue Information

Dear Colleagues,

Extraction methodologies exert a critical influence on the qualitative and quantitative profiles of bioactive compounds in natural extracts. Parameters such as solvent type, polarity, temperature, extraction duration, and pressure directly influence the recovery of bioactive secondary metabolites, including phenolic compounds, alkaloids, terpenoids, and carotenoids. This Special Issue aims to highlight recent advances in the study of how both conventional and innovative extraction methods, such as ultrasound, microwave, and supercritical fluid-assisted extraction, impact the chemical composition, antioxidant activity, and functional potential of natural products. Studies that combine detailed chemical characterization with modern methodological approaches, including cell-based assays and other biologically relevant models, are encouraged, providing a more comprehensive understanding of antioxidant activity. Contributions exploring correlations between extraction conditions, phytochemical profiles, and functional antioxidant responses, as well as approaches to optimize yield, bioactivity, and environmental sustainability, are particularly welcome. This Special Issue invites researchers to contribute original research or review articles on natural compounds from diverse sources, including plants, mushrooms, marine organisms, and bee products. Topics of interest include chemical and biological characterization, extraction and isolation procedures, and the development of innovative applications in nutraceutical, pharmaceutical, food, or cosmetic contexts.

Dr. Filipa Mandim
Guest Editor

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All submissions that pass pre-check are peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 250 words) can be sent to the Editorial Office for assessment.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-anonymized peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Antioxidants is an international peer-reviewed open access monthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 2900 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

  • innovative extraction methodologies
  • natural antioxidants
  • oxidative stress modulations
  • cell-based and biochemical assays

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Published Papers (5 papers)

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Research

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33 pages, 10898 KB  
Article
Pilot Alkaline Extraction of Eucalyptus globulus Bark: A Natural Sustainable Solution for Wood Preservation
by Victor Ferrer, Tomás Oñate-Valdés, Cecilia Fuentealba, Gastón Bravo-Arrepol, Solange Torres, Vicente Hernández, Moisés Vásquez, Priscila Moraga-Suazo, Jorge Santos and Danilo Escobar-Avello
Antioxidants 2026, 15(6), 774; https://doi.org/10.3390/antiox15060774 - 22 Jun 2026
Viewed by 325
Abstract
In Chile, Eucalyptus globulus stands out as a significant forest species, yielding around 2 million tonnes of bark; this by-product is a valuable source of phenolic compounds. This research evaluated the valorization of E. globulus bark using alkali-assisted extraction (AAE) and obtained extracts [...] Read more.
In Chile, Eucalyptus globulus stands out as a significant forest species, yielding around 2 million tonnes of bark; this by-product is a valuable source of phenolic compounds. This research evaluated the valorization of E. globulus bark using alkali-assisted extraction (AAE) and obtained extracts intended to protect the wood against fungal degradation and ultraviolet (UV) radiation. The chemical and thermal properties of the extracts were characterized using total phenolic content (TPC), antioxidant capacity, FTIR spectroscopy, LC-LTQ-Orbitrap-MS, and thermal analyses (TGA and DSC). Pine wood samples were impregnated using the Bethel process, and their absorption, retention, leaching, UV resistance, gloss, and antifungal efficacy were evaluated. The AAE showed an extraction yield of 8.79%, almost double that of aqueous extraction, with a phenolic content of 970 mg GAE/100 g dry bark and good antioxidant capacity. The MS/MS analysis tentatively identified low-molecular-weight organic acids, phenolic acids, a hydrolyzable tannin derivative, ellagic acid, methylated flavonol glycosides, and an iridoid non-phenolic metabolite. Thermal analysis indicated greater stability of the alkaline extracts, with a mass loss of less than 10% up to 200 °C, and significant degradation between 220 and 300 °C. Leaching tests showed a lower release of polyphenols from alkali-treated wood, indicating reduced mobility and/or greater retention of the extractives within the wood structure. Biological assays demonstrated effective inhibition of stain fungi and strong resistance to brown rot. Furthermore, UV aging tests showed less color change (Delta E*) and greater resistance to surface degradation. These results demonstrate the potential of alkaline extracts from E. globulus bark as sustainable additives for wood protection. Full article
(This article belongs to the Special Issue Innovative Processing Technologies and Their Effects on Antioxidant Activity in Plant-Derived Natural Products)
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33 pages, 13645 KB  
Article
Enzyme-Assisted Ultrasonic Extraction of Flavonoids from Pinus koraiensis Needle Litterfall: Process Optimization, Component Identification, and In Vitro Bioactivity Evaluation
by Weiwei Liang, Le Ouyang, Chun Bian, Yuxin Shan and Xiufang Xia
Antioxidants 2026, 15(6), 712; https://doi.org/10.3390/antiox15060712 - 3 Jun 2026
Viewed by 285
Abstract
Flavonoids from Pinus koraiensis needle (PN) litterfall were efficiently recovered using an enzyme-assisted ultrasonic extraction (EAU) method optimized via response surface methodology (RSM). The optimal conditions (enzyme dosage 1.7%, ethanol concentration 70%, ultrasonic time 21 min, cellulase–pectinase ratio 1:3, liquid–solid ratio 40:1, enzymatic [...] Read more.
Flavonoids from Pinus koraiensis needle (PN) litterfall were efficiently recovered using an enzyme-assisted ultrasonic extraction (EAU) method optimized via response surface methodology (RSM). The optimal conditions (enzyme dosage 1.7%, ethanol concentration 70%, ultrasonic time 21 min, cellulase–pectinase ratio 1:3, liquid–solid ratio 40:1, enzymatic hydrolysis at 42.5 °C for 1 h, ultrasonic extraction at 50 °C and 150 W) yielded a total flavonoid content (TFC) of 17.08 mg rutin/g, which was significantly higher than that obtained via conventional extraction (CE). Scanning electron microscopy (SEM) confirmed that the treatment disrupted the cell wall, promoting flavonoid release. Ultra-performance liquid chromatography coupled with triple-quadrupole time-of-flight mass spectrometry (UPLC-Triple-TOF/MS) identified 60 flavonoids in the purified extract obtained under the optimal EAU conditions (OT group), including quercitrin, tiliroside, taxifolin, and procyanidin B2. Fourier-transform infrared spectroscopy (FTIR) and differential scanning calorimetry (DSC) showed higher crystallinity but slightly reduced thermal stability for OT flavonoids. Notably, compared with the purified flavonoids obtained by CE (CK1 group), the OT group achieved a higher TFC and exhibited significantly better in vitro antioxidant activity (DPPH IC50 = 71.82 μg/mL; ABTS IC50 = 28.93 μg/mL) and in vitro carbohydrate-digesting-enzyme-inhibitory activity (α-glucosidase (α-GLU) IC50 = 79.52 μg/mL; α-amylase (α-AMY) IC50 = 793.9 μg/mL), with α-AMY inhibition being approximately 8.2-fold higher. These findings suggest that enzyme-assisted ultrasonic extraction is an efficient and reliable method for recovering flavonoids from PN and may provide a theoretical reference for the development and utilization of these flavonoids. Full article
(This article belongs to the Special Issue Innovative Processing Technologies and Their Effects on Antioxidant Activity in Plant-Derived Natural Products)
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28 pages, 2842 KB  
Article
Characterization of Phenolic Profiles Using UPLC-Q-TOF-MS/MS and NMR in the Biofunctional Fraction of Korean Winter Spinach (Spinacia oleracea L.) Leaves: Evaluation of Major Phenolics and Their Bioactivities Under Optimized Extraction Conditions
by Eun Young Seo, Eun Jeong Ko, Du Yong Cho, Ye Ri Jeong, Se Hyeon Jeon, Dong Hyun Park, Mu Yeun Jang, Jeong Yoon Kim, Kye Man Cho and Jin Hwan Lee
Antioxidants 2026, 15(6), 686; https://doi.org/10.3390/antiox15060686 - 29 May 2026
Viewed by 286
Abstract
This study is the first to demonstrate fluctuations in major phenolics and biofunctional properties under various extraction conditions of Korean winter spinach (Allseason cultivar) leaves. In contrast to earlier reports on summer- or greenhouse-cultivated spinach, which mainly relied on HPLC-DAD or [...] Read more.
This study is the first to demonstrate fluctuations in major phenolics and biofunctional properties under various extraction conditions of Korean winter spinach (Allseason cultivar) leaves. In contrast to earlier reports on summer- or greenhouse-cultivated spinach, which mainly relied on HPLC-DAD or LC-MS profiling and one or two bioactivity assays, the present work combines UPLC-Q-TOF-MS/MS with NMR-based structural confirmation of three major flavone glucuronides (11–13) and integrates five complementary bioactivity assays (DPPH, ABTS, FRAP, DNA protection, and tyrosinase inhibition) within a single optimization framework. A 50% methanol extract yielded twelve phenolics (patuletin, spinacetin, spinatoside, jaceidin, and methylenedioxyflavone-glucuronide derivatives) elucidated by UPLC-Q-TOF-MS/MS, with the isolated major phenolics 11–13 further verified by NMR. Total phenols and total flavonoids of biofunctional characteristics varied significantly depending on the solvent system. The optimal extraction conditions (50% methanol, 72 h, 35 °C) resulted in the highest phenolic levels of phenolics 11–13 (total: ~6.5 mg/g) and bioactivities (DNA protection > ABTS > tyrosinase inhibition > FRAP > DPPH, at 500 μg/mL). PCA and hierarchical clustering distinguished extraction profiles, with 50–70% methanol extracts forming clear clusters. Among the isolated phenolics, phenolic 12 showed the strongest antioxidant activity (DPPH IC50 = 57.6 μM; ABTS IC50 = 21.9 μM). These findings suggest that spinach leaves are a valuable source of bioactive phenolics for nutraceutical applications under optimized extraction conditions. Full article
(This article belongs to the Special Issue Innovative Processing Technologies and Their Effects on Antioxidant Activity in Plant-Derived Natural Products)
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17 pages, 645 KB  
Article
Extraction Processing Technologies and Their Effects on Antioxidant Activity in Cinnamomum camphora (L.) J. Presl Leaves
by Myat Pwint Phyu, Yuchen Cheng, Yuri Kang, Hyunjae Jang, Seungwoong Lee and Woonjung Kim
Antioxidants 2026, 15(2), 227; https://doi.org/10.3390/antiox15020227 - 9 Feb 2026
Cited by 1 | Viewed by 1219
Abstract
This study investigated the bioactive potential of Cinnamomum camphora (L.) J. Presl (C. camphora) leaf extracts obtained using hydrothermal extraction (HE) and ultrasound-assisted extraction (UAE) with 30%, 50%, and 70% ethanol (v/v). Extracts were analyzed for their [...] Read more.
This study investigated the bioactive potential of Cinnamomum camphora (L.) J. Presl (C. camphora) leaf extracts obtained using hydrothermal extraction (HE) and ultrasound-assisted extraction (UAE) with 30%, 50%, and 70% ethanol (v/v). Extracts were analyzed for their phytochemical composition and biological activities. UAE extracts, particularly with 70% ethanol, exhibited the highest total polyphenol (363.0 ± 1.40 mg GAE/g) and flavonoid (174.5 ± 0.42 mg QE/g) contents. This extract also demonstrated strong antioxidant activities (IC50: 0.024 ± 0.001 mg/mL for DPPH; IC50: 0.363 ± 0.002 mg/mL for ABTS; 3.080 ± 0.044 M Fe2+/g for FRAP) and potent enzyme inhibition (49.3 ± 0.35% for tyrosinase; 24.8 ± 0.34% for elastase; 94.5 ± 0.12% for α-glucosidase and 77.5 ± 1.11% for lipase). Antimicrobial activity was most effective against Gram-positive bacteria, notably against Cutibacterium acnes, showing the largest inhibition zone (23.0 mm at 10 mg/disc). Overall, antioxidant, enzyme inhibition and antimicrobial activities increased significantly with increasing ethanol concentration, particularly at 70% ethanol. GC–MSD analysis revealed that both HE and UAE extracts contained phenolic acids, terpenes, triterpenes, and sesquiterpenes. Collectively, these findings indicate that the extraction method (UAE) and solvent composition (70% ethanol) influence the bioactivity profile of C. camphora leaf extracts, supporting further investigation of their relevance for cosmeceutical and functional applications. Full article
(This article belongs to the Special Issue Innovative Processing Technologies and Their Effects on Antioxidant Activity in Plant-Derived Natural Products)
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Review

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54 pages, 5582 KB  
Review
Phytochemical Diversity and Antioxidant Potential of Dracocephalum Species: Current Knowledge and Future Perspectives
by Madalina Georgiana Pantazi, Oana Cioanca, Ionut Iulian Lungu, Catalin Tanase, Silvia Robu, Denisa Batir-Marin and Monica Hancianu
Antioxidants 2026, 15(6), 771; https://doi.org/10.3390/antiox15060771 - 19 Jun 2026
Viewed by 492
Abstract
The genus Dracocephalum (Lamiaceae), comprising over 60 species predominantly distributed in Europe and Asia, has historically been used in traditional medicine and has recently attracted growing scientific interest due to its diverse pharmacological and phytochemical properties. Despite increasing pharmacological and phytochemical investigations, the [...] Read more.
The genus Dracocephalum (Lamiaceae), comprising over 60 species predominantly distributed in Europe and Asia, has historically been used in traditional medicine and has recently attracted growing scientific interest due to its diverse pharmacological and phytochemical properties. Despite increasing pharmacological and phytochemical investigations, the antioxidant potential and related bioactivities of Dracocephalum species remain fragmented across individual studies, with limited efforts to comparatively integrate evidence on phytochemical diversity, antioxidant relevance, and pharmacological variability. Therefore, this review consolidates and critically evaluates current knowledge regarding the phytochemical diversity, antioxidant potential, and therapeutic applications of Dracocephalum species, emphasizing their bioactive compounds and antioxidant-driven mechanisms. Particular attention is given to polyphenolic and phenolic constituents—including flavonoids, phenolic acids, terpenoids, and volatile compounds, with rosmarinic acid, tilianin, luteolin derivatives, and apigenin derivatives identified as key contributors to biological activity. Unlike previous reviews, which primarily focused on isolated pharmacological effects or individual species, this study provides a comparative and integrative perspective by linking phytochemical composition with antioxidant-related activities and therapeutic implications across species. By synthesizing fragmented evidence and highlighting methodological advances in chromatography, metabolomics, and comparative analyses, this review identifies current knowledge gaps and outlines future perspectives for phytopharmaceutical, nutraceutical, and functional food applications. Full article
(This article belongs to the Special Issue Innovative Processing Technologies and Their Effects on Antioxidant Activity in Plant-Derived Natural Products)
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