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Special Issue "Plant Extracts: Technologies, Characterizations and Applications"

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

Deadline for manuscript submissions: 15 September 2021.

Special Issue Editors

Dr. Soran Maria Loredana
E-Mail Website
Guest Editor
National Institute for Research and Development of Isotopicand Molecular Technologies, Cluj-Napoca, Romania
Interests: obtaining, characterization, and application of plant extracts; extraction techniques of plant extracts; plant extracts chromatographic techniques; the influence of stress factors on plants; nanomaterials; water
Prof. Dr. Lucian Copolovici
E-Mail Website
Guest Editor
Technical and Natural Sciences Department, Faculty of Food Engineering, Tourism and Environmental Protection, Aurel Vlaicu University, Institute for Research, Development and Innovation in Technical and Natural Sciences, 310330 Arad, Romania
Interests: volatile organic compounds; environmental engineering; environmental science; environmental health; plants metabolites
Special Issues and Collections in MDPI journals

Special Issue Information

Dear Colleagues,

Plant extracts have been increasingly used in the last years in various fields, such as medicine, food industry, cosmetic industry, and agriculture, because of their properties (e.g., antioxidant properties, antimicrobial activity, and so on). The plant extracts can be used in different forms, namely: free, encapsulated, and as a powder, depending on applications. In this Special Issue, we invite investigators to contribute with original research articles, as well as review articles that are related to the technologies, characterizations, and applications of plant extracts. Potential topics include, but are not limited to, the following:

  • New techniques for obtaining of plant extracts with high content of bioactive compounds
  • Characterization of plant extracts obtained in different conditions
  • Applications of bioactive compounds extracted

Dr. Soran Maria Loredana
Prof. Dr. Lucian Copolovici
Guest Editors

Manuscript Submission Information

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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-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Molecules is an international peer-reviewed open access semimonthly 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 2000 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

  • Plant extracts
  • Extracts characterization
  • Bioactive compounds isolation
  • Applications of bioactive compounds

Published Papers (7 papers)

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Research

Article
Content of Carotenoids, Violaxanthin and Neoxanthin in Leaves of Triticum aestivum Exposed to Persistent Environmental Pollutants
Molecules 2021, 26(15), 4448; https://doi.org/10.3390/molecules26154448 - 23 Jul 2021
Viewed by 432
Abstract
Persistent pollutants such as pharmaceuticals, pesticides, musk fragrances, and dyes are frequently detected in different environmental compartments and negatively impact the environment and humans. Understanding the impacts of diffuse environmental pollutants on plants is still limited, especially at realistic environmental concentrations of contaminants. [...] Read more.
Persistent pollutants such as pharmaceuticals, pesticides, musk fragrances, and dyes are frequently detected in different environmental compartments and negatively impact the environment and humans. Understanding the impacts of diffuse environmental pollutants on plants is still limited, especially at realistic environmental concentrations of contaminants. We studied the effects of key representatives of two major classes of environmental pollutants (nine different antibiotics and six different textile dyes) on the leaf carotenoid (violaxanthin and neoxanthin) content in wheat (Triticum aestivum L.) using different pollutant concentrations and application times. The wheat plants were watered with solutions of selected environmental pollutants in two different concentrations of 0.5 mg L−1 and 1.5 mg L−1 for one week (0.5 L) and two weeks (1 L). Both categories of pollutants selected for this study negatively influenced the content of violaxanthin and neoxanthin, whereas the textile dyes represented more severe stress to the wheat plants. The results demonstrate that chronic exposure to common diffusively spread environmental contaminants constitutes significant stress to the plants. Full article
(This article belongs to the Special Issue Plant Extracts: Technologies, Characterizations and Applications)
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Article
Chemical Profile, Antioxidant Capacity, and Antimicrobial Activity of Essential Oils Extracted from Three Different Varieties (Moldoveanca 4, Vis Magic 10, and Alba 7) of Lavandula angustifolia
Molecules 2021, 26(14), 4381; https://doi.org/10.3390/molecules26144381 - 20 Jul 2021
Viewed by 526
Abstract
Chemical composition, antioxidant capacity, and antimicrobial activity of lavender essential oils (LEOs) extracted from three different varieties of Lavandula angustifolia Mill. (1-Moldoveanca 4, 2-Vis magic 10, and 3-Alba 7) have been determined. These plants previously patented in the Republic of Moldova were cultivated [...] Read more.
Chemical composition, antioxidant capacity, and antimicrobial activity of lavender essential oils (LEOs) extracted from three different varieties of Lavandula angustifolia Mill. (1-Moldoveanca 4, 2-Vis magic 10, and 3-Alba 7) have been determined. These plants previously patented in the Republic of Moldova were cultivated in an organic agriculture system in the northeastern part of Romania and then harvested in 3 consecutive years (2017–2019) to obtain the essential oils. From the inflorescences in the complete flowering stage, the LEOs were extracted by hydrodistillation. Then, their composition was analyzed by gas chromatography coupled with mass spectrometry (GC-MS) and by Fourier Transformed Infrared spectroscopy (FT-IR). The major identified constituents are as follows: linalool (1: 32.19–46.83%; 2: 29.93–30.97%; 3: 31.97–33.77%), linalyl acetate (1: 17.70–35.18%; 2: 27.55–37.13%; 3: 28.03–35.32%), and terpinen-4-ol (1: 3.63–7.70%; 2: 3.06–7.16%; 3: 3.10–6.53%). The antioxidant capacity as determined by ABTS and DPPH assays indicates inhibition, with the highest activity obtained for LEO var. Alba 7 from 2019. The in vitro antimicrobial activities of the LEOs and combinations were investigated as well, by using the disk diffusion method and minimum inhibitory concentration (MIC) against the Gram-positive bacterial strain Staphylococcus aureus (ATCC 6538), Gram-negative Pseudomonas aeruginosa (ATCC 27858), Escherichia coli (ATCC 25922), the yeast Candida albicans (ATCC 10231), and clinical isolates. Our results have shown that LEOs obtained from the three studied varieties of L. angustifolia manifest significant bactericidal effects against tested microorganisms (Staphylococcus aureus and Escherichia coli), and antifungal effects against Candida albicans. The mixture of LEOs (Var. Alba 7) and geranium, respectively, in tea tree EOs, in different ratios, showed a significant enhancement of the antibacterial effect against all the studied strains, except Pseudomonas aeruginosa. Full article
(This article belongs to the Special Issue Plant Extracts: Technologies, Characterizations and Applications)
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Article
The Influence of Temperature, Storage Conditions, pH, and Ionic Strength on the Antioxidant Activity and Color Parameters of Rowan Berry Extracts
Molecules 2021, 26(13), 3786; https://doi.org/10.3390/molecules26133786 - 22 Jun 2021
Viewed by 473
Abstract
Recent trends in the food industry combined with novel methods in agriculture could transform rowan into a valuable raw material with potential technological applications. Thus, the aim of this research was to investigate the content of bioactive compounds in its fruits and to [...] Read more.
Recent trends in the food industry combined with novel methods in agriculture could transform rowan into a valuable raw material with potential technological applications. Thus, the aim of this research was to investigate the content of bioactive compounds in its fruits and to assess the color and antioxidant stability of the extracts prepared from such fruits during various thermal treatments and at different pH and ionic strength values. Various spectrophotometric methods, HPLC, and capillary electrophoresis were used to quantify the concentrations of bioactive compounds—polyphenols, carotenoids, organic acids, and to assess antioxidant activity and color. The results show that rowan berries contain circa 1.34–1.47 g/100 g of polyphenols among which include catechin, epicatechin, ferulic acid methyl ester, procyanidin B1, etc.; ca 21.65 mg/100 g of carotenoids including zeaxanthin, β-cryptoxanthin, all-trans-β-carotene, and various organic acids such as malic, citric, and succinic, which result in a high antioxidant activity of 5.8 mmol TE/100 g. Results also showed that antioxidant activity exhibited high stability when the extract was subjected to various thermal treatments, pHs, and ionic strengths, while color was mainly impacted negatively when a temperature of 100 °C was employed. This data confirms the technological potential of this traditional, yet often overlooked species. Full article
(This article belongs to the Special Issue Plant Extracts: Technologies, Characterizations and Applications)
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Article
The Phytochemical Analysis of Vinca L. Species Leaf Extracts Is Correlated with the Antioxidant, Antibacterial, and Antitumor Effects
Molecules 2021, 26(10), 3040; https://doi.org/10.3390/molecules26103040 - 19 May 2021
Viewed by 682
Abstract
The phytochemical analysis of Vinca minor, V. herbacea, V. major, and V. major var. variegata leaf extracts showed species-dependent antioxidant, antibacterial, and cytotoxic effects correlated with the identified phytoconstituents. Vincamine was present in V. minor, V. major, and [...] Read more.
The phytochemical analysis of Vinca minor, V. herbacea, V. major, and V. major var. variegata leaf extracts showed species-dependent antioxidant, antibacterial, and cytotoxic effects correlated with the identified phytoconstituents. Vincamine was present in V. minor, V. major, and V. major var. variegata, while V. minor had the richest alkaloid content, followed by V. herbacea. V. major var. variegata was richest in flavonoids and the highest total phenolic content was found in V. herbacea which also had elevated levels of rutin. Consequently, V. herbacea had the highest antioxidant activity followed by V. major var. variegata. Whereas, the lowest one was of V. major. The V. minor extract showed the most efficient inhibitory effect against both Staphylococcusaureus and E. coli. On the other hand, V. herbacea had a good anti-bacterial potential only against S. aureus, which was most affected at morphological levels, as indicated by scanning electron microscopy. The Vinca extracts acted in a dose-depended manner against HaCaT keratinocytes and A375 melanoma cells and moreover, with effects on the ultrastructure, nitric oxide concentration, and lactate dehydrogenase release. Therefore, the Vinca species could be exploited further for the development of alternative treatments in bacterial infections or as anticancer adjuvants. Full article
(This article belongs to the Special Issue Plant Extracts: Technologies, Characterizations and Applications)
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Article
Antioxidant Activity and Chemical Characteristics of Supercritical CO2 and Water Extracts from Willow and Poplar
Molecules 2021, 26(3), 545; https://doi.org/10.3390/molecules26030545 - 21 Jan 2021
Cited by 2 | Viewed by 1047
Abstract
Renewable feedstock from perennial industrial crops, including those cultivated on marginal land in a short-rotation coppice system, could be an important contribution to the bioeconomy. The majority of data available on the topic are limited to the production of bioenergy from this type [...] Read more.
Renewable feedstock from perennial industrial crops, including those cultivated on marginal land in a short-rotation coppice system, could be an important contribution to the bioeconomy. The majority of data available on the topic are limited to the production of bioenergy from this type of biomass. According to the concept of bioeconomy, biomass-based bioproducts have priority over energy production. This paper characterizes the chemical composition and antioxidant activity of extracts from bark (b), wood (w) or a mixture of bark and wood (b + w) from Salix purpurea, Salix viminalis and Populus nigra obtained using supercritical carbon dioxide (scCO2), scCO2 and water (1%, w/w) or only water. Generally, a high concentration of polyphenols was obtained after extraction with scCO2 and water, while the lowest concentration was found in extracts obtained with scCO2. The highest concentration of polyphenols (p < 0.05) was obtained in an extract from P. nigra (b) (502.62 ± 9.86 mg GAE/g dry matter (d.m.)) after extraction with scCO2 and water, whereas the lowest polyphenol concentration was observed in an scCO2 extract from S. purpurea (b) (6.02 ± 0.13 mg GAE/g d.m.). The flavonoids were effectively separated by extraction with scCO2 (0.88–18.37 mg QE/g d.m.). A positive linear relationship between the antioxidant activity determined by DPPH and ABTS assays and the concentration of polyphenols was demonstrated, R2 = 0.8377 and R2 = 0.9568, respectively. It is most probable that the concentration of flavonoids, rather than the concentration of polyphenols, determines the chelating activity of Fe2+. The Fe2+-chelating activity of scCO2 extracts ranged from 75.11% (EC50 = 5.41 mg/cm3, S. purpurea, b + w) to 99.43% (EC50 = 0.85 mg/cm3, P. nigra, b + w). The lowest chelating activity was demonstrated by the extracts obtained with scCO2 and water (maximum 26.36%, S. purpurea, b + w). In extracts obtained with scCO2 and water, p-hydroxybenzoic acid (210–428 µg/g), p-coumaric acid (56–281 µg/g), saligenin (142–300 µg/g) and salicortin (16–164 µg/g) were the dominant polyphenols. All of these chemical compounds occurred mainly in the free form. The S. purpurea, S. viminalis and P. nigra biomass proved to be an attractive source of biologically active compounds for various possible applications in food, drugs or cosmetics. These compounds could be extracted using an environmentally friendly method with scCO2 and water as a co-solvent. Full article
(This article belongs to the Special Issue Plant Extracts: Technologies, Characterizations and Applications)
Communication
Adapting the Accelerated Solvent Extraction Method for Resin and Rubber Determination in Guayule Using the BÜCHI Speed Extractor
Molecules 2021, 26(1), 183; https://doi.org/10.3390/molecules26010183 - 01 Jan 2021
Cited by 1 | Viewed by 689
Abstract
Guayule (Parthenium argentatum Gray) is a promising alternative source to Hevea brasiliensis for the production of natural rubber, which can reach levels of 8–9% under industrialized farming conditions. The most common method for determining rubber concentration is by accelerated solvent extraction (ASE), [...] Read more.
Guayule (Parthenium argentatum Gray) is a promising alternative source to Hevea brasiliensis for the production of natural rubber, which can reach levels of 8–9% under industrialized farming conditions. The most common method for determining rubber concentration is by accelerated solvent extraction (ASE), a technique developed by the Dionex Corporation and almost exclusively performed with the Dionex ASE-200 or 350 systems. Herein, it is sought to apply and adapt the most common methods used in the literature for the Dionex system to another extraction platform, the BÜCHI Speed Extractor E-914. Results showed that using a sand sandwich method to confine the sample in the center and exploiting a larger cell volume (80 mL) for extraction prevents the occurrence of overpressure and problems with clogging. Under optimized conditions, the coefficient of variation was <15% for both resin quantification for samples containing 5.0–15.8% of resin and for rubber quantification for samples with 1.7–10.3% rubber content. The extraction time for resin (2 cycles of 5 min each) was smaller than for rubber (2 cycles of 20 min each). It would be interesting to carry out interlaboratory comparisons to standardize the method at an international level. Full article
(This article belongs to the Special Issue Plant Extracts: Technologies, Characterizations and Applications)
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Article
Microwave-Assisted Improved Extraction and Purification of Anticancer Nimbolide from Azadirachta indica (Neem) Leaves
Molecules 2020, 25(12), 2913; https://doi.org/10.3390/molecules25122913 - 24 Jun 2020
Cited by 2 | Viewed by 1057
Abstract
Nimbolide, a limonoid present in leaves of the neem tree (Azadirachta indica), is an anticancer compound against a panel of human cancer cell lines. The rapid process of extraction and purification of the nimbolide from the leaves of neem tree through [...] Read more.
Nimbolide, a limonoid present in leaves of the neem tree (Azadirachta indica), is an anticancer compound against a panel of human cancer cell lines. The rapid process of extraction and purification of the nimbolide from the leaves of neem tree through microwave-assisted extraction (MAE) coupled with a chromatographic technique was accomplished. The crude with a maximum content of nimbolide could be recovered from neem leaves through MAE. By using three-factors, three-level Box–Behnken design of response surface methodology (RSM), the optimal conditions for nimbolide extraction (R2 = 0.9019) were solid/liquid ratio 1:16 g/mL, microwave power 280 W, and extraction time 22 min. The enriched extract was further purified by a preparative thin-layer chromatography (PTLC), where nimbolide was obtained as 0.0336 g (0.67% yield, purity over 98%) with ethyl acetate/hexane = 4:6 in 3.0 h. Structural elucidation was performed through spectroscopic techniques, including FT-IR, 1H, and 13C-NMR. This method was simple and had a good potential for the purification of bioactive compounds from a natural product. Full article
(This article belongs to the Special Issue Plant Extracts: Technologies, Characterizations and Applications)
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