Special Issue "Polyphenols in Plants"

A special issue of Plants (ISSN 2223-7747). This special issue belongs to the section "Phytochemistry".

Deadline for manuscript submissions: 31 December 2021.

Special Issue Editors

Dr. Simon Vlad Luca
E-Mail Website
Guest Editor
TUM School of Life Sciences, Technical University of Munich, 85354 Freising, Germany
Interests: natural products; medicinal plants; phytochemistry; metabolite profiling; high-resolution mass spectrometry; downstream processing; liquid–liquid chromatography; centrifugal partition chromatography; countercurrent chromatography; anti-inflammatory; anticancer
Dr. Adriana Trifan
E-Mail Website
Guest Editor
Department of Pharmacognosy, Faculty of Pharmacy, Grigore T. Popa University of Medicine and Pharmacy Iasi, 700115 Iasi, Romania
Interests: pharmacognosy; phytochemistry; high-resolution mass spectrometry; gas chromatography; antimicrobials; anticancer; anti-inflammatory
Special Issues, Collections and Topics in MDPI journals
Dr. Gokhan Zengin
E-Mail Website
Guest Editor
Department of Biology, Science Faculty, Selcuk University, Konya 42130, Turkey
Interests: characterization of plant extracts; phenolic compounds; antioxidant capacity; enzyme inhibitory mechanisms and assays

Special Issue Information

Dear Colleagues,

Polyphenols are a very large class of specialized metabolites synthesized by plants for protection against bacteria, fungi and insect attacks. To date, more than 8000 naturally occurring phenolic compounds have been reported in plants. Ubiquitously found in foods and herbal medicines, polyphenols possess a plethora of biological effects (antioxidant, cancer chemopreventive, antimicrobial, anti-inflammatory, cardio-vasculo-protective, immunomodulatory, etc.). These potent bioactivities render them interesting alternatives for pharmaceutical and medical applications. Due to their versatile benefits with regard to human health, research studies focusing on plant-derived polyphenols have considerably increased in recent years.

Therefore, this Special Issue welcomes the submission of articles (original research papers, reviews, perspectives, hypotheses, opinions, modeling approaches and methods) that focus on plant polyphenols and their extraction from plant materials, phytochemical analysis of polyphenol-rich plant extracts with the use of advanced chromatographic and spectrometric techniques, isolation and purification of plant polyphenols, polyphenols in the prevention and management of modern diseases, pharmacokinetics, biotransformation and bioactivity of plant polyphenols, bioactivity evaluation of agro-industrial by-products rich in polyphenolics, management of polyphenols in wastes, importance of plant polyphenols in medicine and food, and preclinical and clinical findings on plant polyphenols.

Dr. Simon Luca
Dr. Adriana Trifan
Dr. Gokhan Zengin
Guest Editors

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 papers will be 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 100 words) can be sent to the Editorial Office for announcement on this website.

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. Plants 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 1800 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

  • Polyphenols
  • Extraction of polyphenols
  • Analysis of polyphenols
  • Purification of polyphenols
  • Bioactivity of polyphenols
  • Pharmacokinetics of polyphenols
  • Polyphenols and modern diseases
  • Polyphenols and by-products
  • Waste polyphenols

Published Papers (6 papers)

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Research

Article
Honokiol and Magnolol: Insights into Their Antidermatophytic Effects
Plants 2021, 10(11), 2522; https://0-doi-org.brum.beds.ac.uk/10.3390/plants10112522 (registering DOI) - 19 Nov 2021
Viewed by 360
Abstract
Dermatophyte infections represent a significant public health concern, with an alarming negative impact caused by unsuccessful therapeutic regimens. Natural products have been highlighted as a promising alternative, due to their long-standing traditional use and increasing scientific recognition. In this study, honokiol and magnolol, [...] Read more.
Dermatophyte infections represent a significant public health concern, with an alarming negative impact caused by unsuccessful therapeutic regimens. Natural products have been highlighted as a promising alternative, due to their long-standing traditional use and increasing scientific recognition. In this study, honokiol and magnolol, the main bioactives from Magnolia spp. bark, were investigated for their antidermatophytic activity. The antifungal screening was performed using dermatophyte standard strains and clinical isolates. The minimal inhibitory concentration (MIC) and the minimal fungicidal concentration (MFC) were determined in accordance with EUCAST-AFST guidelines, with minor modifications. The effects on ergosterol biosynthesis were assessed in Trichophyton rubrum cells by HPLC-DAD. Putative interactions with terbinafine against T. rubrum were evaluated by the checkerboard method. Their impact on cells’ viability and pro-inflammatory cytokines (IL-1β, IL-8 and TNF-α) was shown using an ex vivo human neutrophils model. Honokiol and magnolol were highly active against tested dermatophytes, with MIC and MFC values of 8 and 16 mg/L, respectively. The mechanism of action involved the inhibition of ergosterol biosynthesis, with accumulation of squalene in T. rubrum cells. Synergy was assessed for binary mixtures of magnolol with terbinafine (FICI = 0.50), while honokiol-terbinafine combinations displayed only additive effects (FICI = 0.56). In addition, magnolol displayed inhibitory effects towards IL-1β, IL-8 and TNF-α released from lipopolysaccharide (LPS)-stimulated human neutrophils, while honokiol only decreased IL-1β secretion, compared to the untreated control. Overall, honokiol and magnolol acted as fungicidal agents against dermatophytes, with impairment of ergosterol biosynthesis. Full article
(This article belongs to the Special Issue Polyphenols in Plants)
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Article
The Bark of Picea abies L., a Waste from Sawmill, as a Source of Valuable Compounds: Phytochemical Investigations and Isolation of a Novel Pimarane and a Stilbene Derivative
Plants 2021, 10(10), 2106; https://0-doi-org.brum.beds.ac.uk/10.3390/plants10102106 - 04 Oct 2021
Viewed by 441
Abstract
In this work, the sawmill waste from Picea abies debarking was considered as source of valuable phytoconstituents. The extraction was performed using different ethanol/water mixtures, and characterization was obtained by LC-MSn. This latter revealed flavonoid glycosides, lignans, and procyanidins. Extraction with [...] Read more.
In this work, the sawmill waste from Picea abies debarking was considered as source of valuable phytoconstituents. The extraction was performed using different ethanol/water mixtures, and characterization was obtained by LC-MSn. This latter revealed flavonoid glycosides, lignans, and procyanidins. Extraction with organic solvents (dichloromethane and methanol) and chromatographic separations of the obtained extracts by silica column followed by semi-preparative HPLC led to the isolation of polyphenols and terpenoids such as 21α-metoxy-serrat-14-en-3-one, 21α-hydroxy-serrat-14-en-3-one, pinoresinol, dehydroabietic acid, 15-hydroxy-dehydroabietic acid, 7-oxo-dehydroabietic acid, pimaric acid, 9β-pimara-7,15-dien-19-ol, 13-epi-manoyl oxide, taxifolin-3′-O-glucopyranoside, trans-astringin, and piceasides. Piceaside V and 9β-pimara-7-keto-19β-olide, two novel compounds identified for the first time in P. abies bark, were isolated, and their structures were elucidated using 1D and 2D NMR and MS techniques. The polyphenolic composition of the methanolic portion was also investigated using LC-MSn, and the piceaside content was estimated. To assess the antioxidant activity of main constituents, semi-preparative HPLC was performed on the methanolic extract, and the obtained fractions were assayed by using the DPPH test. Overall, this work shows the potential usefulness of P. abies bark as a source of valuable phytochemicals. Full article
(This article belongs to the Special Issue Polyphenols in Plants)
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Article
Influence of the Post-Harvest Storage Time on the Multi-Biological Potential, Phenolic and Pyrrolizidine Alkaloid Content of Comfrey (Symphytum officinale L.) Roots Collected from Different European Regions
Plants 2021, 10(9), 1825; https://0-doi-org.brum.beds.ac.uk/10.3390/plants10091825 - 02 Sep 2021
Viewed by 639
Abstract
Comfrey (Symphytum officinale L.) roots are well-known bioactive ingredients included in various cosmeceutical and pharmaceutical preparations. In this study, the influence of the post-harvest storage on the chemico-biological potential of roots collected from different European regions and stored for up to six [...] Read more.
Comfrey (Symphytum officinale L.) roots are well-known bioactive ingredients included in various cosmeceutical and pharmaceutical preparations. In this study, the influence of the post-harvest storage on the chemico-biological potential of roots collected from different European regions and stored for up to six months was investigated. Total phenolic content (TPC) and total phenolic acid content (TPAC) were spectrophotometrically estimated, whereas the levels of individual phenolic and pyrrolizidine alkaloidal markers were determined by HPLC-DAD and HPLC-MS/MS, respectively. The changes in the biological potential was tracked via antioxidant (DPPH, ABTS, CUPRAC, and FRAP) and anti-enzymatic (cholinesterase, tyrosinase, glucosidase, and amylase) assays. TPC and TPAC varied from 6.48–16.57 mg GAE/g d.w. root and from 2.67–9.03 mg CAE/g, respectively. The concentration of the four phenolics (rosmarinic acid, globoidnan A, globoidnan B, rabdosiin) and six pyrrolizidine alkaloids generally showed maximum values at 1–3 months, after which their levels significantly decreased. With respect to the bioassays, the samples showed a wide range of antioxidant and anti-enzymatic effects; however, a direct storage time–bioactivity relationship was not observed. Similar conclusions were also revealed by the multivariate and correlation analyses. Our study could improve the current knowledge of the shelf-life properties of comfrey-based products and enhance their industrial exploitation. Full article
(This article belongs to the Special Issue Polyphenols in Plants)
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Article
Phytochemical Composition, Antioxidant, and Enzyme Inhibition Activities of Methanolic Extracts of Two Endemic Onosma Species
Plants 2021, 10(7), 1373; https://0-doi-org.brum.beds.ac.uk/10.3390/plants10071373 - 05 Jul 2021
Viewed by 765
Abstract
Onosma species have been used as a dye for hundreds of years due to their dark red pigments. These species have also been used by mankind in the treatment of various diseases since ancient times. This work analyzed the phytochemical composition in methanol [...] Read more.
Onosma species have been used as a dye for hundreds of years due to their dark red pigments. These species have also been used by mankind in the treatment of various diseases since ancient times. This work analyzed the phytochemical composition in methanol extract of two endemic Onosma species (O. lycaonica and O. papillosa). Methanolic extract of these species varied in the content of flavonoids and phenolics. The flavonoids were found higher in O. papillosa [32.9 ± 0.3 mg QEs (quercetin equivalent)/g extracts] while the phenolics were higher in O. lycaonica [43.5 ± 1.5 mg GAEs (gallic acid equivalent)/g extracts]. ESI-MS/MS (electrospray ionization-mass spectrometry) revealed the presence of 25 compounds in O. lycaonica and 24 compounds in O. papillosa. The former was richer than the latter for apigenin, luteolin, eriodictyol, pinoresinol, apigenin 7-glucoside, rosmarinic acid, luteolin 7-glucoside, ferulic acid, vanillin, caffeic acid, 4-hydroxybenzoic acid, (+)-catechin3,4-dihydroxyphenylacetic acid. The O. papillosa exhibited low EC50 (1.90 ± 0.07 mg/mL) which indicated its strong phosphomolybdenum scavenging activity as compared to O. lycaonica. However, the O. lycaonica showed low IC50 or EC50 for 1,1-diphenyl-2-picrylhydrazyl (DPPH), 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS+), cupric reducing antioxidant power (CUPRAC), ferric reducing antioxidant power (FRAP) and ferrous ion chelating activity, as compared to O. papillosa. The results proved the presence of potent antioxidant compounds in O. lycaonica. Further, the plant extracts significantly varied for enzyme inhibition of acetylcholinesterase (AChE) and butyrylcholinesterase (BChE), but the plant extracts did not significantly differ for inhibition of α-glucosidase, α-amylase, and tyrosinase. Onosma species deserve further research towards developing novel drugs to treat oxidative diseases. Full article
(This article belongs to the Special Issue Polyphenols in Plants)
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Article
Chemical Profiling and Biological Evaluation of Nepeta baytopii Extracts and Essential Oil: An Endemic Plant from Turkey
Plants 2021, 10(6), 1176; https://0-doi-org.brum.beds.ac.uk/10.3390/plants10061176 - 09 Jun 2021
Cited by 1 | Viewed by 894
Abstract
Nepeta baytopii is a poorly studied, endemic Nepeta species (Lamiaceae) of Turkey. For the first time, the biological activities (antioxidant, enzyme inhibition, and cytotoxicity properties) of the hexane, ethyl acetate, methanol, water/methanol, and water extracts and essential oil prepared from N. [...] Read more.
Nepeta baytopii is a poorly studied, endemic Nepeta species (Lamiaceae) of Turkey. For the first time, the biological activities (antioxidant, enzyme inhibition, and cytotoxicity properties) of the hexane, ethyl acetate, methanol, water/methanol, and water extracts and essential oil prepared from N. baytopii aerial parts were assessed. Hydro-methanol (41.25 mg gallic acid equivalent (GAE)/g) and water extracts (50.30 mg GAE/g), respectively showed the highest radical scavenging (94.40 and 129.22 mg Trolox equivalent (TE)/g, for 2,2-diphenyl-1-picrylhydrazyl radical and 2,2-azino-bis (3-ethylbenzothiazoline-6-sulfonic acid radical scavenging assays) and reducing (229.37 and 129.55 mg TE/g, for ferric-reducing antioxidant power and cupric-reducing antioxidant capacity assays) capacities in vitro. An interestingly high inhibition was observed for ethyl acetate extract against butyrylcholinesterase (10.85 mg galantamine equivalent/g). The methanol extract showed high cytotoxicity (31.7%) against HepG2 cells. Caryophyllene oxide was identified in high concentrations in the essential oil (39.3%). Luteolin and apigenin and their derivatives were identified from the methanol and water extracts. The results obtained from this study highlighted that the abundance of highly bioactive compounds from Nepeta baytopii ensures the multiple biological activities of the tested extracts, and this suggests a potential use in the pharmaceutical and nutraceutical fields, and therefore should be investigated further. Full article
(This article belongs to the Special Issue Polyphenols in Plants)
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Article
LC-MS/MS Profiles and In Vitro Biological Activities of Extracts of an Endemic Species from Turkey: Stachys cretica ssp. anatolica
Plants 2021, 10(6), 1054; https://0-doi-org.brum.beds.ac.uk/10.3390/plants10061054 - 25 May 2021
Cited by 1 | Viewed by 761
Abstract
Background: Genus Stachys is one of the largest of the Lamiaceae family, having around 300 different plant species inhabiting areas with temperate and warm climates. The Stachys species in Turkey are represented with 81 taxa; 51 of them being endemic. Plants of [...] Read more.
Background: Genus Stachys is one of the largest of the Lamiaceae family, having around 300 different plant species inhabiting areas with temperate and warm climates. The Stachys species in Turkey are represented with 81 taxa; 51 of them being endemic. Plants of the Stachys genus have been known for their biological activity and their use in ethnomedicine. Methods: The dominant components of S. cretica ssp. anatolica aqueous and methanol extracts were studied with the LC-MS/MS technique. Results: Chlorogenic acid, apigenin-7-glucoside and verbascoside present as the dominant polyphenols found in studied extracts. The prominent biological activity of the studied S. cretica ssp. anatolica methanol and aqueous extracts showed strong antioxidant activity and inhibition of enzymes tyrosinase and α-amylase, involved in skin disorders and diabetes mellitus type II. Conclusions: This study has proven that the aqueous and methanol extracts of S. cretica ssp. anatolica have prominent antioxidant activity, due to a high abundance of polyphenols. The strong antioxidant properties of S. cretica ssp. anatolica extracts show promising application for the pharmaceutical, food, and cosmetics industries. Full article
(This article belongs to the Special Issue Polyphenols in Plants)
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