Antioxidant Activity of Essential Oils, 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: closed (31 December 2023) | Viewed by 28392

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1. Department of Pharmacy, Faculty of Medicine and Pharmacy, University of Oradea, 410028 Oradea, Romania
2. Doctoral School of Biomedical Sciences, University of Oradea, 410087 Oradea, Romania
Interests: pharmacology; alternative therapies; biochemistry; public health; therapeutics; One Health; sustainability in health; ecology
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Special Issue Information

Dear Colleagues,

Medicine that considers natural products, many of them plant-based, is gaining more and more ground. The “return” to nature, to the remedies known for thousands of years and used in traditional medicine worldwide, comes as support for modern medicine, in the treatment and therapy of many diseases, from neurodegenerative, cardiometabolic, and respiratory up to those that affect the bone tissue and many others. In this context, essential oils (EOs) are a cornerstone in the development of these cures or of some of the classic pharmaceutical products. EOs’ components rich in bioactive compounds, their structures, their role, and beneficial effects are of great interest to chemists, biologists, and biochemists, but also for medical or pharmaceutical specialties, the field of nutrition/food, toxicology, and many more.

Considering the increased interest in such a vast field of EOs, we are pleased to welcome you to submit to this new Special Issue, which is intended to be a continuation of the fruitful first volume (https://www.mdpi.com/journal/antioxidants/special_issues/antioxidant_essential_oil).

Our goal is to collect original works or reviews focused on the chemistry of EOs, their biochemical activity (especially antioxidant EOs), and the development of new products (pharmaceutical, food, phytochemical, etc.) based on EOs, focusing also on experimental or clinical results that include aspects and results related to EOs. We look forward to your high-level scientific works.

Prof. Dr. Simona Gabriela Bungau
Prof. Dr. Delia Mirela Tit
Guest Editors

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Keywords

  • antioxidant activity
  • antioxidant mechanism
  • bioactive compounds
  • chemistry of antioxidant activity
  • essential oils
  • innovative formulations
  • plant-based products

Published Papers (10 papers)

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Research

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47 pages, 4580 KiB  
Article
In Vitro Antioxidant and In Vivo Antigenotoxic Features of a Series of 61 Essential Oils and Quantitative Composition–Activity Relationships Modeled through Machine Learning Algorithms
by Milan Mladenović, Roberta Astolfi, Nevena Tomašević, Sanja Matić, Mijat Božović, Filippo Sapienza and Rino Ragno
Antioxidants 2023, 12(10), 1815; https://doi.org/10.3390/antiox12101815 - 29 Sep 2023
Cited by 1 | Viewed by 1119
Abstract
The antioxidant activity of essential oils (EOs) is an important and frequently studied property, yet it is not sufficiently understood in terms of the contribution of EOs mixtures’ constituents and biological properties. In this study, a series of 61 commercial EOs were first [...] Read more.
The antioxidant activity of essential oils (EOs) is an important and frequently studied property, yet it is not sufficiently understood in terms of the contribution of EOs mixtures’ constituents and biological properties. In this study, a series of 61 commercial EOs were first evaluated as antioxidants in vitro, following as closely as possible the cellular pathways of reactive oxygen species (ROS) generation. Hence, EOs were assessed for the ability either to chelate metal ions, thus interfering with ROS generation within the respiratory chain, or to neutralize 2,2-diphenyl-1-picrylhydrazyl (DPPH) and lipid peroxide radicals (LOO), thereby halting lipid peroxidation, as well as to neutralize 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid cation radicals (ABTS•+) and hydroxyl radicals (OH), thereby preventing the ROS species from damaging DNA nucleotides. Showing noteworthy potencies to neutralize all of the radicals at the ng/mL level, the active EOs were also characterized as protectors of DNA double strands from damage induced by peroxyl radicals (ROO), emerging from 2,2′-azobis-2-methyl-propanimidamide (AAPH) as a source, and OH, indicating some genome protectivity and antigenotoxicity effectiveness in vitro. The chemical compositions of the EOs associated with the obtained activities were then analyzed by means of machine learning (ML) classification algorithms to generate quantitative composition–activity relationships (QCARs) models (models published in the AI4EssOil database available online). The QCARs models enabled us to highlight the key features (EOSs’ chemical compounds) for exerting the redox potencies and to define the partial dependencies of the features, viz. percentages in the mixture required to exert a given potency. The ML-based models explained either the positive or negative contribution of the most important chemical components: limonene, linalool, carvacrol, eucalyptol, α-pinene, thymol, caryophyllene, p-cymene, eugenol, and chrysanthone. Finally, the most potent EOs in vitro, Ylang-ylang (Cananga odorata (Lam.)) and Ceylon cinnamon peel (Cinnamomum verum J. Presl), were promptly administered in vivo to evaluate the rescue ability against redox damage caused by CCl4, thereby verifying their antioxidant and antigenotoxic properties either in the liver or in the kidney. Full article
(This article belongs to the Special Issue Antioxidant Activity of Essential Oils, 2nd Edition)
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21 pages, 20251 KiB  
Article
Waste Citrus limon Leaves as Source of Essential Oil Rich in Limonene and Citral: Chemical Characterization, Antimicrobial and Antioxidant Properties, and Effects on Cancer Cell Viability
by Giacomo Luigi Petretto, Giuseppe Vacca, Roberta Addis, Giorgio Pintore, Mariella Nieddu, Franca Piras, Valeria Sogos, Francesco Fancello, Severino Zara and Antonella Rosa
Antioxidants 2023, 12(6), 1238; https://doi.org/10.3390/antiox12061238 - 08 Jun 2023
Cited by 5 | Viewed by 3411
Abstract
This study investigated chemical composition, cytotoxicity in normal and cancer cells, and antimicrobial and antioxidant activity of the essential oil (EO) isolated by hydrodistillation from the discarded leaves of lemon (Citrus limon) plants cultivated in Sardinia (Italy). The volatile chemical composition [...] Read more.
This study investigated chemical composition, cytotoxicity in normal and cancer cells, and antimicrobial and antioxidant activity of the essential oil (EO) isolated by hydrodistillation from the discarded leaves of lemon (Citrus limon) plants cultivated in Sardinia (Italy). The volatile chemical composition of lemon leaf EO (LLEO) was analyzed with gas chromatography-mass spectrometry combined with flame ionization detection (GC/MS and GC/FID). The most abundant component of LLEO was limonene (260.7 mg/mL), followed by geranial (102.6 mg/mL) and neral (88.3 mg/mL). The antimicrobial activity of LLEO was tested using eight bacterial strains and two types of yeasts by a microdilution broth test. Candida albicans showed the greatest susceptibility (MIC = 0.625 μL/mL) and Listeria monocytogenes and Staphylococcus aureus were inhibited at low LLEO concentration (MIC values from 2.5 to 5 μL/mL). The C. limon leaf EO displayed radical scavenging ability (IC50 value of 10.24 mg/mL) in the 2,2-diphenyl-1-picryl-hydrazylhydrate (DPPH) assay. Furthermore, the LLEO impact on cell viability was explored by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay in cancer HeLa cells, A375 melanoma cell line, normal fibroblasts (3T3 cells), and keratinocytes (HaCaT cells). LLEO, at 24 h of incubation, significantly reduced viability from 25 μM in Hela cells (33% reduction) and A375 cells (27%), greatly affecting cell morphology, whereas this effect was found from 50 μM on 3T3 fibroblasts and keratinocytes. LLEO’s pro-oxidant effect was also established in HeLa cells by 2′,7′-dichlorodihydrofluorescein diacetate assay. Full article
(This article belongs to the Special Issue Antioxidant Activity of Essential Oils, 2nd Edition)
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22 pages, 6159 KiB  
Article
Essential Oil Composition, Antioxidant Activity and Leaf Micromorphology of Five Tunisian Eucalyptus Species
by Flavio Polito, Florinda Fratianni, Filomena Nazzaro, Ismail Amri, Habiba Kouki, Marwa Khammassi, Lamia Hamrouni, Paola Malaspina, Laura Cornara, Sana Khedhri, Benedetta Romano, Daniela Claudia Maresca, Angela Ianaro, Giuseppe Ercolano and Vincenzo De Feo
Antioxidants 2023, 12(4), 867; https://doi.org/10.3390/antiox12040867 - 03 Apr 2023
Cited by 9 | Viewed by 2617
Abstract
Eucalyptus species have been widely employed in the projects of reforestation in Tunisia. Although their ecological functions are controversial, these plants are indeed important to counteract soil erosion, and represent a fast-growing source of fuelwood and charcoal wood. In the present study, we [...] Read more.
Eucalyptus species have been widely employed in the projects of reforestation in Tunisia. Although their ecological functions are controversial, these plants are indeed important to counteract soil erosion, and represent a fast-growing source of fuelwood and charcoal wood. In the present study, we considered five Eucalyptus species, namely Eucalyptus alba, E. eugenioides, E. fasciculosa, E. robusta, and E. stoatei cultivated in the Tunisian Arboreta. The aim was to carry out the micromorphological and anatomical characterization of the leaves, the extraction and phytochemical profile of the essential oils (EOs), and the evaluation of their biological properties. Four of the EOs showed the prevalence of eucalyptol (1,8-cineole) varying from 64.4 to 95.9%, whereas a-pinene predominated in E. alba EO (54.1%). These EOs showed in vitro antioxidant activity, and reduced the oxidative cellular stress as shown by their activity on reactive oxygen species (ROS) production, and modulation of the expression of antioxidant enzymes, such as glutamate-cysteine ligase (GCL) and heme oxygenase-1 (Hmox-1). Moreover, the EOs inhibited the production of nitric oxide (NO), showing anti-inflammatory activity. The data collected suggest that these EOs may be considered a promising therapeutic strategy for inflammation-based diseases and may represent an additional value for the economy of Tunisia. Full article
(This article belongs to the Special Issue Antioxidant Activity of Essential Oils, 2nd Edition)
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11 pages, 1090 KiB  
Article
The Antioxidant Properties and Protective Capacity of Prangos trifida and Cachrys cristata Essential Oils against Cd Stress in Lunularia cruciata and Brassica napus
by Viviana Maresca, Natale Badalamenti, Vincenzo Ilardi, Maurizio Bruno and Adriana Basile
Antioxidants 2023, 12(4), 793; https://doi.org/10.3390/antiox12040793 - 24 Mar 2023
Cited by 2 | Viewed by 1180
Abstract
The genera Prangos Lindl. and Cachrys L., for a long time interpreted as a single genus but today distinct and separate, and both belonging to the majestic Apiaceae family, are species with a large distribution and are used in ethnomedicine in various countries, [...] Read more.
The genera Prangos Lindl. and Cachrys L., for a long time interpreted as a single genus but today distinct and separate, and both belonging to the majestic Apiaceae family, are species with a large distribution and are used in ethnomedicine in various countries, especially in Asian countries. In this context, we investigated the chemical characteristics and biological properties of two essential oils (EOs) obtained from different specimens, namely Cachrys cristata (Cc) and Prangos trifida (Pt). The chemical composition of the two EOs was investigated by GC-MS analysis. From gas-chromatography analyses, while the (Cc) EO was rich in β-myrcene (45.34%), allo-ocimene (10.90%), and 2,4,6-trimethylbenzaldehyde (23.47%), the (Pt) EO was characterized by moderate amounts of α-pinene (8.85%), sylvestrene (11.32%), α-phellandrene (12.14%), (Z)-β-ocimene (18.12%), and finally, p-mentha-1,3,8-triene (9.56%). Furthermore, the protective and antioxidant capacity of (Pt) and (Cc) EOs on Lunularia cruciata and Brassica napus exposed to cadmium (Cd) stress was studied. To study these possible effects, the liverwort and oilseed rape, previously pretreated with both EOs, were subsequently subjected to oxidative stress by treatment with Cd. Then, DNA damage and antioxidant enzyme activity were measured in both EOs-pretreated and untreated samples to examine EOs-induced tolerance to Cd toxicity. The results indicate that (Pt) and (Cc) EOs have antioxidant and protective capacity in modulating the redox state through the antioxidant pathway by reducing oxidative stress induced by Cd. Furthermore, B. napus was found to be a more resistant and tolerant species than L. cruciata. Full article
(This article belongs to the Special Issue Antioxidant Activity of Essential Oils, 2nd Edition)
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16 pages, 2169 KiB  
Article
Biodegradable Active Packaging Enriched with Essential Oils for Enhancing the Shelf Life of Strawberries
by Magdaléna Rusková, Alena Opálková Šišková, Katarína Mosnáčková, Custódia Gago, Adriana Guerreiro, Mária Bučková, Andrea Puškárová, Domenico Pangallo and Maria Dulce Antunes
Antioxidants 2023, 12(3), 755; https://doi.org/10.3390/antiox12030755 - 20 Mar 2023
Cited by 6 | Viewed by 2575
Abstract
The strawberry (Fragaria ananassa) is a nutrient-rich fruit with high content of health-beneficial compounds. However, strawberries are susceptible to mechanical damage and microbiological contamination which can cause changes in fruit sensory properties. These changes consequently effect on ripening and shelf life [...] Read more.
The strawberry (Fragaria ananassa) is a nutrient-rich fruit with high content of health-beneficial compounds. However, strawberries are susceptible to mechanical damage and microbiological contamination which can cause changes in fruit sensory properties. These changes consequently effect on ripening and shelf life of the strawberry. In recent years, essential oils (EOs) have been famous for their antimicrobial and antioxidant properties and are promising ecological alternatives to chemical antimicrobial substances. Nowadays, active packaging is one of several techniques developed for slowing down the metabolic processes of fresh fruits. Poly(lactic acid) (PLA) is one of the several polymers suitable for encapsulation EOs, whereas at the same time represent non-toxic, biodegradable, and compostable polymer derived from renewable resources. Suitable packaging prolongs the shelf life of fruit, keeps the products at the highest possible nutrition level, improves quality, and attracts customer attention. In the current study, we encapsulated EOs (lemongrass and oregano) into a PLA and poly(3-hydroxybutyrate) (PHB) packaging film and explored their antimicrobial and antioxidant properties. Moreover, biochemical and quality parameters for strawberry preservation and shelf-life extension were also assessed. Our tested active packaging film with EOs was proven to be useful for postharvest quality maintenance and shelf-life extension of strawberries, with PLA/PHB/ATBC + 5% lemongrass EO being slightly better than PLA/PHB/ATBC + 5% oregano EO. Full article
(This article belongs to the Special Issue Antioxidant Activity of Essential Oils, 2nd Edition)
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21 pages, 2380 KiB  
Article
GC-MS Profiling and Biomedical Applications of Essential Oil of Euphorbia larica Boiss.: A New Report
by Muddaser Shah, Faizullah Khan, Saeed Ullah, Tapan Kumar Mohanta, Ajmal Khan, Rimsha Zainab, Naseem Rafiq, Hussan Ara, Tanveer Alam, Najeeb Ur Rehman and Ahmed Al-Harrasi
Antioxidants 2023, 12(3), 662; https://doi.org/10.3390/antiox12030662 - 07 Mar 2023
Cited by 6 | Viewed by 2420
Abstract
The present study explored Euphorbia larica essential oil (ELEO) constituents for the first time, obtained via hydro-distillation by means of Gas Chromatography-Mass Spectrometry (GC-MS) profiling. The essential oil was screened in vitro against breast cancer cells, normal cell lines, α-glucosidase, carbonic anhydrase-II (CA-II), [...] Read more.
The present study explored Euphorbia larica essential oil (ELEO) constituents for the first time, obtained via hydro-distillation by means of Gas Chromatography-Mass Spectrometry (GC-MS) profiling. The essential oil was screened in vitro against breast cancer cells, normal cell lines, α-glucosidase, carbonic anhydrase-II (CA-II), free radical scavenging and in vivo analgesic and anti-inflammatory capabilities. The GC-MS screening revealed that the ELEO comprises sixty compounds (95.25%) with the dominant constituents being camphene (16.41%), thunbergol (15.33%), limonene (4.29%), eremophilene (3.77%), and β-eudesmol (3.51%). A promising antidiabetic capacity was noticed with an IC50 of 9.63 ± 0.22 μg/mL by the ELEO as equated to acarbose with an IC50 = 377.71 ± 1.34 μg/mL, while a 162.82 ± 1.24 μg/mL inhibition was observed against CA-II. Regarding breast cancer, the ELEO offered considerable cytotoxic capabilities against the triple-negative breast cancer (MDA-MB-231) cell lines, having an IC50 = 183.8 ± 1.6 μg/mL. Furthermore, the ELEO was also tested with the human breast epithelial (MCF-10A) cell line, and the findings also presumed that the ELEO did not produce any damage to the tested normal cell lines. The ELEO was effective against the Gram-positive bacteria and offered a 19.8 ± 0.02 mm zone of inhibition (ZOI) against B. atrophaeus. At the same time, the maximum resistance with 18.03 ± 0.01 mm ZOI against the fungal strain Aspergillus parasiticus was observed among the tested fungal strains. An appreciable free radical significance was observed via the DPPH assay with an IC50 = 133.53 ± 0.19 µg/mL as equated to the ABTS assay having an IC50 = 154.93 ± 0.17 µg/mL. The ELEO also offered a substantial analgesic capacity and produced 58.33% inhibition in comparison with aspirin, a 68.47% decrease in writhes, and an anti-inflammatory capability of 65.54% inhibition, as equated to the standard diclofenac sodium having 73.64% inhibition. Hence, it was concluded that the ELEO might be a natural source for the treatment of diabetes mellitus, breast cancer, analgesic, inflammatory, and antimicrobial-related diseases. Moreover, additional phytochemical and pharmacological studies are needed to isolate responsible chemical ingredients to formulate new drugs for the examined activities. Full article
(This article belongs to the Special Issue Antioxidant Activity of Essential Oils, 2nd Edition)
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23 pages, 5778 KiB  
Article
Development and Evaluation of a Novel-Thymol@Natural-Zeolite/Low-Density-Polyethylene Active Packaging Film: Applications for Pork Fillets Preservation
by Constantinos E. Salmas, Aris E. Giannakas, Vassilios K. Karabagias, Dimitrios Moschovas, Ioannis K. Karabagias, Christina Gioti, Stavros Georgopoulos, Areti Leontiou, George Kehayias, Apostolos Avgeropoulos and Charalampos Proestos
Antioxidants 2023, 12(2), 523; https://doi.org/10.3390/antiox12020523 - 19 Feb 2023
Cited by 9 | Viewed by 2126
Abstract
Sustainability, the circular economy, and the “greenhouse” effect have led the food packaging industry to use naturally available bio-compounds. The integration of such compounds in packaging films increases food safety and extends food shelf-life. The development of an active/antioxidant packaging film based on [...] Read more.
Sustainability, the circular economy, and the “greenhouse” effect have led the food packaging industry to use naturally available bio-compounds. The integration of such compounds in packaging films increases food safety and extends food shelf-life. The development of an active/antioxidant packaging film based on the widely commercially used low-density polyethylene, natural zeolite, and Thymol, a natural extract from thyme oil, is presented in this work. The obtained active films were characterized using X-Ray Diffraction, Fourier-Transform Infrared Spectroscopy, Scanning Electron Microscopy, and Differential Scanning Calorimetry techniques. The tensile strength, water–oxygen barrier properties, and total antioxidant activity were measured. Low-density polyethylene incorporated with Thymol@Natural Zeolite at a proportion of 15 wt% was the most promising material and was used as film to wrap-up pork fillets. The thiobarbituric acid (TBA) method and heme iron measurements indicated a delayed lipids oxidation using this film. A linear correlation between the TBA method and heme iron values seems to be established, which could result in a fast method to determine the degree of lipid oxidation in pork fillets. Finally, a two-stage diffusion process during Thymol release was observed, and the values of the diffusion coefficient was 2.09 × 10−7 and 1.21 × 10−8 cm2/s for each stage. The applied pseudo-second sorption model provided a rate constant k2 = 0.01647 (s−1). These results indicate the strong potential of such films to be used as food packaging materials free of E-number preservatives. Full article
(This article belongs to the Special Issue Antioxidant Activity of Essential Oils, 2nd Edition)
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23 pages, 6661 KiB  
Article
Effect-Directed, Chemical and Taxonomic Profiling of Peppermint Proprietary Varieties and Corresponding Leaf Extracts
by Antonio M. Inarejos-Garcia, Julia Heil, Patricia Martorell, Beatriz Álvarez, Silvia Llopis, Ines Helbig, Jie Liu, Bryon Quebbeman, Tim Nemeth, Deven Holmgren and Gertrud E. Morlock
Antioxidants 2023, 12(2), 476; https://doi.org/10.3390/antiox12020476 - 14 Feb 2023
Cited by 3 | Viewed by 1673
Abstract
During the development of novel, standardized peppermint extracts targeting functional applications, it is critical to adequately characterize raw material plant sources to assure quality and consistency of the end-product. This study aimed to characterize existing and proprietary, newly bred varieties of peppermint and [...] Read more.
During the development of novel, standardized peppermint extracts targeting functional applications, it is critical to adequately characterize raw material plant sources to assure quality and consistency of the end-product. This study aimed to characterize existing and proprietary, newly bred varieties of peppermint and their corresponding aqueous extract products. Taxonomy was confirmed through genetic authenticity assessment. Non-target effect-directed profiling was developed using high-performance thin-layer chromatography–multi-imaging–effect-directed assays (HPTLC–UV/Vis/FLD–EDA). Results demonstrated substantial differences in compounds associated with functional attributes, notably antioxidant potential, between the peppermint samples. Further chemical analysis by high-performance liquid chromatography–photodiode array/mass spectrometry detection (HPLC–PDA/MS) and headspace solid-phase microextraction–gas chromatography–flame ionization/MS detection (headspace SPME–GC–FID/MS) confirmed compositional differences. A broad variability in the contents of flavonoids and volatiles was observed. The peppermint samples were further screened for their antioxidant potential using the Caenorhabditis elegans model, and the results indicated concordance with observed content differences of the identified functional compounds. These results documented variability among raw materials of peppermint leaves, which can yield highly variable extract products that may result in differing effects on functional targets in vivo. Hence, product standardization via effect-directed profiles is proposed as an appropriate tool. Full article
(This article belongs to the Special Issue Antioxidant Activity of Essential Oils, 2nd Edition)
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Review

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55 pages, 748 KiB  
Review
Antioxidant Activity of Essential Oils from Pinaceae Species
by Robert Ancuceanu, Adriana Iuliana Anghel, Marilena Viorica Hovaneț, Anne-Marie Ciobanu, Beatrice Elena Lascu and Mihaela Dinu
Antioxidants 2024, 13(3), 286; https://doi.org/10.3390/antiox13030286 - 26 Feb 2024
Cited by 1 | Viewed by 1403
Abstract
With a widespread distribution throughout the Northern Hemisphere and 11 genera, Pinaceae is the largest family of Gymnosperms in the world. Essential oils are an important chemotaxonomic marker for the species of this family, although the degree of chemical and biological investigation has [...] Read more.
With a widespread distribution throughout the Northern Hemisphere and 11 genera, Pinaceae is the largest family of Gymnosperms in the world. Essential oils are an important chemotaxonomic marker for the species of this family, although the degree of chemical and biological investigation has not been the same for all genera. Essential oils from Abies and Cedrus (from the abietoid clade) or Pinus and Picea (from the pinoid clade) have been more extensively investigated with respect to their chemical composition and biological or pharmacological properties, including their antioxidant effects. Instead, essential oils from the other genera of the family have been less explored in this respect or even have not been investigated at all. This is a narrative review looking into the knowledge acquired up to date, the variability and limitations of the current methods used to estimate antioxidant effects, and multiple comparisons between EOs obtained from different genera, species, and plant parts, as well as potential applications and future directions of research and utilization of essential oils derived from Pinaceae species. Full article
(This article belongs to the Special Issue Antioxidant Activity of Essential Oils, 2nd Edition)
47 pages, 2038 KiB  
Review
Tea Tree Oil: Properties and the Therapeutic Approach to Acne—A Review
by Tânia Nascimento, Diana Gomes, Ricardo Simões and Maria da Graça Miguel
Antioxidants 2023, 12(6), 1264; https://doi.org/10.3390/antiox12061264 - 12 Jun 2023
Cited by 4 | Viewed by 8401
Abstract
Acne vulgaris is an inflammatory dermatological pathology that affects mostly young people. However, it can also appear in adulthood, mainly in women. It has a high psychosocial impact, not only at the time of active lesions but also due to the consequences of [...] Read more.
Acne vulgaris is an inflammatory dermatological pathology that affects mostly young people. However, it can also appear in adulthood, mainly in women. It has a high psychosocial impact, not only at the time of active lesions but also due to the consequences of lesions such as scarring and hyperpigmentation. Several factors are involved in the physiopathology of acne and the constant search for active ingredients is a reality, namely phytotherapeutic ingredients. Tea tree oil is an essential oil extracted from Melaleuca alternifolia (Maiden & Betch) Cheel with known antibacterial, anti-inflammatory, and antioxidant properties, making it a candidate for the treatment of acne. This review aims to describe the various properties of tea tree oil that make it a possible ingredient to use in the treatment of acne and to present several human studies that have evaluated the efficacy and safety of using tea tree oil in the treatment of acne. It can be concluded that tea tree oil has good antibacterial, anti-inflammatory, and antioxidant properties that result in a decrease in the number of inflammatory lesions, mainly papules, and pustules. However, given the diversity of study designs, it is not possible to draw concrete conclusions on the efficacy and safety of this oil in the treatment of acne. Full article
(This article belongs to the Special Issue Antioxidant Activity of Essential Oils, 2nd Edition)
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