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Special Issue "Recovery of Phytochemicals from Forest Materials"

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

Deadline for manuscript submissions: closed (31 August 2020).

Special Issue Editors

Prof. Dr. Daniel Granato
grade Website
Guest Editor
Natural Resources Institute Finland (Luke), Helsinki, Finland
Interests: reactive oxygen species; inflammation; antioxidants; multivariate data analysis; phenolic compounds; statistical optimization; food chemistry; analytical methods; phenolic compounds; food fraud
Special Issues and Collections in MDPI journals
Dr. Petri Kilpeläinen
Website
Guest Editor
Natural Resources Institute Finland (Luke), Helsinki, Finland
Interests: hot water extraction; tannins; carbohydrates; forest and agricultural biomasses; films; food emulsions; cosmetics; paints; industrial side-streams; isotope analysis; GC–—FID/MS; anaerobic digestion

Special Issue Information

Dear Colleagues,

Wood and wood bark are important sources of phytochemicals. As demand for renewable natural resources has increased, research on the use of bark phytochemicals has increased as well. Polyphenols extracted from wood or wood bark have bioactive properties that could be utilized in the food and pharmaceutical industry. Extracted and purified compounds could also be exploited as platform chemicals for the chemical industry, since some natural compounds are difficult to synthesize. Technical formulas with crude extracts or compounds purified from extracts can be used in different applications. Mixtures of extracted phytochemicals could, in some cases, have a synergistic effect against certain pathogens or pests. Extraction following characterization and bioactivity of extracts are important steps to verify that compounds are safe and can be used. Robust and verified analytical methods are an important part of the research toolbox. Therefore, new approaches in analytical methods can identify potentially harmful compounds and allow the creation of products that increase the wellbeing and health of consumers.

Following an international trend in using industrial byproducts and taking into account the need to find sustainable uses of different fruit side streams, this Special Issue is dedicated to providing new scientific and technological applications for bioactive compounds from forest materials. Additionally, other chemical compounds with applications in the food, feed, cosmetic, and chemical industries will be considered. These studies may include analytical methods used to assess the chemical composition of forest side streams, bioactivity as assessed by in vitro and in vivo protocols, evaluation of extracting technologies, and comparison between matrices. The use of these bioactive-rich extracts in different applications (pharmaceutical products, food models, etc.) will be a matter of interest.

The Special Issue will cover original research and review articles, according to the Author Guidelines.

Prof. Daniel Granato
Dr. Petri Kilpeläinen
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

  • Extraction technologies
  • Analytical methods
  • Bioactive compounds
  • Side streams
  • Biological activities
  • Application of bioactives in creams
  • Foods and pharmaceutical products
  • Phenolic compounds

Published Papers (10 papers)

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Research

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Open AccessArticle
Assessment of Insecticidal Activity of Benzylisoquinoline Alkaloids from Chilean Rhamnaceae Plants against Fruit-Fly Drosophila melanogaster and the Lepidopteran Crop Pest Cydia pomonella
Molecules 2020, 25(21), 5094; https://doi.org/10.3390/molecules25215094 - 03 Nov 2020
Abstract
The Chilean plants Discaria chacaye, Talguenea quinquenervia (Rhamnaceae), Peumus boldus (Monimiaceae), and Cryptocarya alba (Lauraceae) were evaluated against Codling moth: Cydia pomonella L. (Lepidoptera: Tortricidae) and fruit fly Drosophila melanogaster (Diptera: Drosophilidae), which is one of the most widespread and destructive primary [...] Read more.
The Chilean plants Discaria chacaye, Talguenea quinquenervia (Rhamnaceae), Peumus boldus (Monimiaceae), and Cryptocarya alba (Lauraceae) were evaluated against Codling moth: Cydia pomonella L. (Lepidoptera: Tortricidae) and fruit fly Drosophila melanogaster (Diptera: Drosophilidae), which is one of the most widespread and destructive primary pests of Prunus (plums, cherries, peaches, nectarines, apricots, almonds), pear, walnuts, and chestnuts, among other. Four benzylisoquinoline alkaloids (coclaurine, laurolitsine, boldine, and pukateine) were isolated from the above mentioned plant species and evaluated regarding their insecticidal activity against the codling moth and fruit fly. The results showed that these alkaloids possess acute and chronic insecticidal effects. The most relevant effect was observed at 10 µg/mL against D. melanogaster and at 50 µg/mL against C. pomonella, being the alteration of the feeding, deformations, failure in the displacement of the larvae in the feeding medium of D. melanogaster, and mortality visible effects. In addition, the docking results show that these type of alkaloids present a good interaction with octopamine and ecdysone receptor showing a possible action mechanism. Full article
(This article belongs to the Special Issue Recovery of Phytochemicals from Forest Materials)
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Open AccessArticle
Clonal Variation in the Bark Chemical Properties of Hybrid Aspen: Potential for Added Value Chemicals
Molecules 2020, 25(19), 4403; https://doi.org/10.3390/molecules25194403 - 25 Sep 2020
Abstract
This study aims to promote comprehensive utilization of woody biomass by providing a knowledgebase on the utility of aspen bark as a new alternative source for fossil-based chemicals. The research focused on the analysis of clonal variation in: (1) major chemical components, i.e., [...] Read more.
This study aims to promote comprehensive utilization of woody biomass by providing a knowledgebase on the utility of aspen bark as a new alternative source for fossil-based chemicals. The research focused on the analysis of clonal variation in: (1) major chemical components, i.e., hemicelluloses, cellulose, and lignin; (2) extraneous materials, i.e., bark extractives, and suberic acid; (3) condensed tannins content and composition; and (4) screening differences in antioxidative properties and total phenolic content of hot water extracts and ethanol-water extracts of hybrid aspen bark. Results of this study, the discovery of clonal variation in utilizable chemicals, pave the way for further research on added-value potential of under-utilized hybrid aspen and its bark. Clonal variation was found in notable part of chemicals with potential for utilization. Based on the results, an appropriate bark raw material can be selected for tailored processing, thus improving the resource efficiency. The results also indicate that by applying cascade processing concepts, bark chemical substances could be more efficiently utilized with more environmentally friendly methods. Full article
(This article belongs to the Special Issue Recovery of Phytochemicals from Forest Materials)
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Open AccessArticle
Fate of Antioxidative Compounds within Bark during Storage: A Case of Norway Spruce Logs
Molecules 2020, 25(18), 4228; https://doi.org/10.3390/molecules25184228 - 15 Sep 2020
Abstract
Softwood bark is an important by-product of forest industry. Currently, bark is under-utilized and mainly directed for energy production, although it can be extracted with hot water to obtain compounds for value-added use. In Norway spruce (Picea abies [L.] Karst.) bark, condensed [...] Read more.
Softwood bark is an important by-product of forest industry. Currently, bark is under-utilized and mainly directed for energy production, although it can be extracted with hot water to obtain compounds for value-added use. In Norway spruce (Picea abies [L.] Karst.) bark, condensed tannins and stilbene glycosides are among the compounds that comprise majority of the antioxidative extractives. For developing feasible production chain for softwood bark extractives, knowledge on raw material quality is critical. This study examined the fate of spruce bark tannins and stilbenes during storage treatment with two seasonal replications (i.e., during winter and summer). In the experiment, mature logs were harvested and stored outside. During six-month-storage periods, samples were periodically collected for chemical analysis from both inner and outer bark layers. Additionally, bark extractives were analyzed for antioxidative activities by FRAP, ORAC, and H2O2 scavenging assays. According to the results, stilbenes rapidly degraded during storage, whereas tannins were more stable: only 5–7% of the original stilbene amount and ca. 30–50% of the original amount of condensed tannins were found after 24-week-storage. Summer conditions led to the faster modification of bark chemistry than winter conditions. Changes in antioxidative activity were less pronounced than those of analyzed chemical compounds, indicating that the derivatives of the compounds contribute to the antioxidative activity. The results of the assays showed that, on average, ca. 27% of the original antioxidative capacity remained 24 weeks after the onset of the storage treatment, while a large variation (2–95% of the original capacity remaining) was found between assays, seasons, and bark layers. Inner bark preserved its activities longer than outer bark, and intact bark attached to timber is expected to maintain its activities longer than a debarked one. Thus, to ensure prolonged quality, no debarking before storage is suggested: outer bark protects the inner bark, and debarking enhances the degradation. Full article
(This article belongs to the Special Issue Recovery of Phytochemicals from Forest Materials)
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Open AccessArticle
Sprouts and Needles of Norway Spruce (Picea abies (L.) Karst.) as Nordic Specialty—Consumer Acceptance, Stability of Nutrients, and Bioactivities during Storage
Molecules 2020, 25(18), 4187; https://doi.org/10.3390/molecules25184187 - 12 Sep 2020
Abstract
Developing shoots, i.e., sprouts, and older needles of Norway spruce (Picea abies (L.) Karst.) have traditionally been used for medicinal purposes due to the high content of vitamins and antioxidants. Currently, sprouts are available as, for example, superfood and supplements. However, end-product [...] Read more.
Developing shoots, i.e., sprouts, and older needles of Norway spruce (Picea abies (L.) Karst.) have traditionally been used for medicinal purposes due to the high content of vitamins and antioxidants. Currently, sprouts are available as, for example, superfood and supplements. However, end-product quality and nutritive value may decline in the value-chain from raw material sourcing to processing and storage. We studied (1) impacts of different drying and extraction methods on nutritional composition and antioxidative properties of sprouts and needles, (2) differences between sprouts and needles in nutritional composition and microbiological quality, and (3) production scale quality of the sprouts. Additionally, (4) sprout powder was applied in products (ice-cream and sorbet) and consumer acceptance was evaluated. According to our results, older needles have higher content of dry matter, energy, and calcium, but lower microbial quality than sprouts. Sprouts showed a higher concentration of vitamin C, magnesium, potassium, and phosphorus than older needles. Freeze-drying was the best drying method preserving the quality of both sprouts and needles, e.g., vitamin C content. The antioxidative activity of the sprout extracts were lower than that of needles. Ethanol-water extraction resulted in a higher content of active compounds in the extract than water extraction. Sensory evaluation of food products revealed that on average, 76% of consumers considered sprout-containing products very good or good, and a creamy product was preferred over a water-based sorbet. Full article
(This article belongs to the Special Issue Recovery of Phytochemicals from Forest Materials)
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Open AccessArticle
Optimization and Characterization of Microwave-Assisted Hydro-Distillation Extraction of Essential Oils from Cinnamomum camphora Leaf and Recovery of Polyphenols from Extract Fluid
Molecules 2020, 25(14), 3213; https://doi.org/10.3390/molecules25143213 - 14 Jul 2020
Abstract
In this study, the efficiency of microwave-assisted hydro-distillation (MAHD) to extract essential oil from Cinnamomum camphora leaf, and the recovery of polyphenols from extract fluid were investigated. The effects of microwave power, liquid-to-material ratio, and extraction time on the extraction efficiency were studied [...] Read more.
In this study, the efficiency of microwave-assisted hydro-distillation (MAHD) to extract essential oil from Cinnamomum camphora leaf, and the recovery of polyphenols from extract fluid were investigated. The effects of microwave power, liquid-to-material ratio, and extraction time on the extraction efficiency were studied by a single factor test as well as the response surface methodology (RSM) based on the central composite design method. The optimal extraction conditions were a microwave power of 786.27 W, liquid-to-material ratio of 7.47:1 mL/g, and extraction time of 35.57 min. The yield of essential oil was 3.26 ± 0.05% (w/w), and the recovery of polyphenols was 4.97 ± 0.02 mg gallic acid equivalent/g dry weight under the optimal conditions. Furthermore, the comprehensive two-dimensional gas chromatography-time-of-flight mass spectrometry (GC×GC-TOFMS) was used to characterize the essential oils of fresh and fallen leaves, and 159 individual compounds were tentatively identified, accounting for more than 89.68 and 87.88% of the total contents, respectively. The main ingredients include sabinene, l-β-pinene, β-myrcene, α-terpineol, 3-heptanone, and β-thujene, as well as δ-terpineol and 3-heptanone, which were first identified in C. camphora essential oil. In conclusion, the MAHD method could extract essential oil from C. camphora with high efficiency, and the polyphenols could be obtained from the extract fluid at the same time, improving the utilization of C. camphora leaf. Full article
(This article belongs to the Special Issue Recovery of Phytochemicals from Forest Materials)
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Open AccessArticle
Lignans in Knotwood of Norway Spruce: Localisation with Soft X-ray Microscopy and Scanning Transmission Electron Microscopy with Energy Dispersive X-ray Spectroscopy
Molecules 2020, 25(13), 2997; https://doi.org/10.3390/molecules25132997 - 30 Jun 2020
Abstract
Lignans are bioactive compounds that are especially abundant in the Norway spruce (Picea abies L. Karst.) knotwood. By combining a variety of chromatographic, spectroscopic and imaging techniques, we were able to quantify, qualify and localise the easily extractable lignans in the xylem [...] Read more.
Lignans are bioactive compounds that are especially abundant in the Norway spruce (Picea abies L. Karst.) knotwood. By combining a variety of chromatographic, spectroscopic and imaging techniques, we were able to quantify, qualify and localise the easily extractable lignans in the xylem tissue. The knotwood samples contained 15 different lignans according to the gas chromatography-mass spectrometry analysis. They comprised 16% of the knotwood dry weight and 82% of the acetone extract. The main lignans were found to be hydroxymatairesinols HMR1 and HMR2. Cryosectioned and resin-embedded ultrathin sections of the knotwood were analysed with scanning transmission X-ray microscopy (STXM). Cryosectioning was found to retain only lignan residues inside the cell lumina. In the resin-embedded samples, lignan was interpreted to be unevenly distributed inside the cell lumina, and partially confined in deposits which were either readily present in the lumina or formed when OsO4 used in staining reacted with the lignans. Furthermore, the multi-technique characterisation enabled us to obtain information on the chemical composition of the structural components of knotwood. A simple spectral analysis of the STXM data gave consistent results with the gas chromatographic methods about the relative amounts of cell wall components (lignin and polysaccharides). The STXM analysis also indicated that a torus of a bordered pit contained aromatic compounds, possibly lignin. Full article
(This article belongs to the Special Issue Recovery of Phytochemicals from Forest Materials)
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Open AccessArticle
Effects of Ultrasound-Assisted Extraction and Solvent on the Phenolic Profile, Bacterial Growth, and Anti-Inflammatory/Antioxidant Activities of Mediterranean Olive and Fig Leaves Extracts
Molecules 2020, 25(7), 1718; https://doi.org/10.3390/molecules25071718 - 09 Apr 2020
Cited by 3
Abstract
Mediterranean plants, such as fig and olive leaves, are well-known to exert beneficial effects in humans because of the presence of a wide range of bioactive compounds. However, scarce information regarding the impact of extraction methods, such as ultrasound and types of solvents, [...] Read more.
Mediterranean plants, such as fig and olive leaves, are well-known to exert beneficial effects in humans because of the presence of a wide range of bioactive compounds. However, scarce information regarding the impact of extraction methods, such as ultrasound and types of solvents, on their profile of antioxidant and anti-inflammatory compounds is provided. In addition, no information is available on the effects of extraction methods and solvents on the inhibition of pathogenic bacteria or promoting probiotic growth. In this scenario, this study was aimed to study the effects of ultrasound-assisted extraction (UAE) and solvent on the phenolic profile (Triple TOF-LC-MS/MS), antioxidant and anti-inflammatory compounds of olive and fig leaves. Results showed that UAE extracted more carotenoids compared to conventional extraction, while the conventional extraction impacted on higher flavonoids (olive leaves) and total phenolics (fig leaves). The antioxidant capacity of aqueous extract of fig leaves was three times higher than the extract obtained with ethanol for conventional extraction and four times higher for UAE. In general terms, hydroethanolic extracts presented the highest bacterial growth inhibition, and showed the highest anti-inflammatory activity. In conclusion, these side streams can be used as sources of bioactive compounds for further development of high-added-value products. Full article
(This article belongs to the Special Issue Recovery of Phytochemicals from Forest Materials)
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Open AccessArticle
Tannins of Conifer Bark as Nordic Piquancy—Sustainable Preservative and Aroma?
Molecules 2020, 25(3), 567; https://doi.org/10.3390/molecules25030567 - 28 Jan 2020
Cited by 4
Abstract
Bark of Norway spruce and Scots pine trees contain large amounts of condensed tannins. Tannins extracted with hot water could be used in different applications as they possess antioxidative and antimicrobial activities. The use of bark tannins as e.g., food preservatives calls for [...] Read more.
Bark of Norway spruce and Scots pine trees contain large amounts of condensed tannins. Tannins extracted with hot water could be used in different applications as they possess antioxidative and antimicrobial activities. The use of bark tannins as e.g., food preservatives calls for increases in our knowledge of their antioxidative activities when applied in foodstuffs. To assess the ability of bark tannins to prevent lipid oxidation, hot water extracts were evaluated in a liposome model. Isolated tannins were also applied in dry-cured, salty meat snacks either as liquid extracts or in dry-powder form. Consumer acceptance of the snacks was tested by a sensory evaluation panel where outlook, odor, taste, and structure of the snacks were evaluated and compared to a commercial product without tannin ingredients. Our results show that conifer bark tannin-rich extracts have high capacity to prevent lipid oxidation in the liposome model. The efficacies of pine and spruce bark extracts were ten to hundred folds higher, respectively, than those of phenolic berry extracts. The bark extracts did not significantly influence the odor or taste of the meat snacks. The findings indicate that bark extracts may be used as sustainable food ingredients. However, more research is needed to verify their safety. Full article
(This article belongs to the Special Issue Recovery of Phytochemicals from Forest Materials)
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Open AccessArticle
The Hydrophobicity of Lignocellulosic Fiber Network Can Be Enhanced with Suberin Fatty Acids
Molecules 2019, 24(23), 4391; https://doi.org/10.3390/molecules24234391 - 01 Dec 2019
Cited by 1
Abstract
Suberin fatty acids were extracted from outer bark of Silver birch (Betula pendula Roth.) using an isopropanolic sodium hydroxide solution. Laboratory sheets composed of lignocellulosic fiber networks were prepared from unbleached and unrefined softwood kraft pulp and further impregnated with suberin fatty [...] Read more.
Suberin fatty acids were extracted from outer bark of Silver birch (Betula pendula Roth.) using an isopropanolic sodium hydroxide solution. Laboratory sheets composed of lignocellulosic fiber networks were prepared from unbleached and unrefined softwood kraft pulp and further impregnated with suberin fatty acid monomers and cured with maleic anhydride in ethanol solution. The treatment resulted in hydrophobic surfaces, in which the contact angles remained over 120 degrees during the entire measurement. The fiber network also retained its water vapor permeability and enhanced fiber–fiber bonding resulted in improved tensile strength of the sheets. Scanning electron microscopy (SEM) images revealed that the curing agent, together with suberin fatty acids, was evenly distributed on the fiber surfaces and smoothing occurred over the wrinkled microfibrillar structure. High concentrations of the curing agent resulted in globular structures containing betulinol derivates as revealed with time-of-flight secondary ion mass spectrometry (ToF-SIMS). Also, the larger amount of suberin fatty acid monomers slightly impaired the optical properties of sheets. Full article
(This article belongs to the Special Issue Recovery of Phytochemicals from Forest Materials)
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Review

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Open AccessFeature PaperReview
Value-Added Compound Recovery from Invasive Forest for Biofunctional Applications: Eucalyptus Species as a Case Study
Molecules 2020, 25(18), 4227; https://doi.org/10.3390/molecules25184227 - 15 Sep 2020
Abstract
From ancient times, the medicinal properties of the different Eucalyptus species are well known. In fact, plants from this family have been used in folk medicine as antiseptics, and to treat different ailments of the upper respiratory tract such as sinus congestion, common [...] Read more.
From ancient times, the medicinal properties of the different Eucalyptus species are well known. In fact, plants from this family have been used in folk medicine as antiseptics, and to treat different ailments of the upper respiratory tract such as sinus congestion, common cold, or influenza. Moreover, other biological activities were described for Eucalyptus species such as antioxidant and antimicrobial properties. In the last few decades, numerous investigations revealed that the compounds responsible for these properties are secondary metabolites that belonging to the group of phenolic compounds and are present in different parts of the plants such as leaves, bark, wood, fruits, and stumps. The increasing demand for natural compounds that can substitute synthetic antioxidants and the increase in resistance to traditional antibiotics have boosted the intense search for renewable natural sources containing substances with such bioactivities, as well as greener extraction technologies and avant-garde analytical methods for the identification of the target molecules. The literature data used in this paper were collected via Scopus (2001–2020) using the following search terms: Eucalyptus, extraction methods, phenolic compounds, and biological activities. This review collects the main studies related to the recovery of value-added compounds from different Eucalyptus species, as well as their biofunctional applications. Full article
(This article belongs to the Special Issue Recovery of Phytochemicals from Forest Materials)
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