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Special Issue "Biological Activity of Secondary Metabolites"

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

Deadline for manuscript submissions: 28 February 2018

Special Issue Editors

Guest Editor
Prof. Dr. Helen D. Skaltsa

Department of Pharmacognosy and Chemistry of Natural Products, School of Pharmacy, University of Athens, 15771 Athens, Greece
Website | E-Mail
Phone: +30 210 7274593
Interests: chemistry of natural products; analytical methods; NMR; GC-MS; terpenes (iridoids, sesquiterpene lactones, triterpenes); phenolics (flavonoids, phenols, phenolic acids, lignans); essential oils; ethnopharmacology; history of pharmacy
Guest Editor
Dr. Marina Sokovic

Institute for Biological Research “Siniša Stanković”, University of Belgrade, Belgrade, Serbia
Website | E-Mail
Interests: Microfungi, macrofungi, antimcirobial activity, natural products

Special Issue Information

Dear Colleagues,

This Special Issue is related to the biological activities of natural products. Secondary metabolites are largely found in plants, marine organisms, bacteria, fungi, and insects. Natural products are used and marketed as medicines or food supplements for a number of health reasons, like the prevention or treatment of an illness or the reduction of health risks, or the maintenance of good health.

Past practices of compound drugs containing different natural ingredients predominately of plant origin were highly esteemed over centuries, but only recently are scientifically confirmed. The ethno pharmacological properties of healing plants have been used as a primary source of medicines for early drug discovery. The investigation of biological and chemical properties of natural products has, not only revealed new bioactive entities for the treatment of several diseases, but also enabled the development of synthetic organic chemistry. Natural products are the most successful source of leads for potential drug discovery and play a highly significant role in medicinal chemistry.

We particularly have interest in manuscripts dealing with the most recent research on bio-active natural products, including: Isolation and structure elucidation, metabolomic analyses, bio-assays, mechanisms of action of bioactive natural products, SAR studies, ethno-pharmacological studies.

Prof. Dr. Helen D. Skaltsa
Dr. Marina Sokovic
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. Molecules 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

  • Secondary Metabolites
  • Analytical Techniques
  • Structure elucidation
  • Biological activities
  • Predicting biological activities
  • Structure-activity relationship
  • Target-based assays
  • Ligand-based drug design
  • Ethnopharmacological studies
  • Metabolomic analysis of medicinal plants

Published Papers (8 papers)

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Research

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Open AccessArticle Comparison of Inhibitory Capacities of 6-, 8- and 10-Gingerols/Shogaols on the Canonical NLRP3 Inflammasome-Mediated IL-1β Secretion
Molecules 2018, 23(2), 466; doi:10.3390/molecules23020466
Received: 24 January 2018 / Revised: 13 February 2018 / Accepted: 20 February 2018 / Published: 21 February 2018
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Abstract
Endogenous noninfectious substances that mediate the nucleotide oligomerization domain (NOD)-like receptor family pyrin domain-containing 3 (NLRP3) inflammasome activation and interleukin (IL)-1β secretion causes inappropriate sterile inflammation and is implicated in the pathogenesis of several chronic diseases, such as type 2 diabetes mellitus, gout,
[...] Read more.
Endogenous noninfectious substances that mediate the nucleotide oligomerization domain (NOD)-like receptor family pyrin domain-containing 3 (NLRP3) inflammasome activation and interleukin (IL)-1β secretion causes inappropriate sterile inflammation and is implicated in the pathogenesis of several chronic diseases, such as type 2 diabetes mellitus, gout, atherosclerosis and Alzheimer’s disease. Consequently, dietary phytochemicals exhibiting capacities to suppress canonical NLRP3 inflammasome-mediated IL-1β secretion can be a reliable supplement to prevent such diseases. The purpose of this study was to investigate and compare the inhibitory effects of ginger phytochemicals, including 6-, 8- and 10-gingerols/shogaols on the canonical NLRP3 inflammasome-mediated IL-1β secretion in THP-1 macrophages with ordered stimulations of lipopolysaccharide (LPS) and adenosine 5′-triphosphate (ATP). At 20 μM, the 10-gingerol and all the shogaols significantly inhibited canonical IL-1β secretion. The shogaols had a more potent inhibitory capacity than that of corresponding gingerols. Increase of alkyl chain length impacted negatively the inhibitory activity of shogaols. Additionally, these effective ginger phytochemicals not only inhibited the LPS-primed expression of pro-IL-1β and NLRP3, but also decreased ATP-activated caspase-1. The results demonstrated that ginger phytochemicals, especially the most potent, 6-shogaol, might be promising for developing as an inhibitor of the canonical NLRP3 inflammasome-mediated IL-1β secretion and further applied in prevention of NLRP3 inflammasome-associated diseases. Full article
(This article belongs to the Special Issue Biological Activity of Secondary Metabolites)
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Open AccessArticle Efficacy of Compounds Isolated from the Essential Oil of Artemisia lavandulaefolia in Control of the Cigarette Beetle, Lasioderma serricorne
Molecules 2018, 23(2), 343; doi:10.3390/molecules23020343
Received: 26 December 2017 / Revised: 20 January 2018 / Accepted: 6 February 2018 / Published: 7 February 2018
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Abstract
To develop natural product resources to control cigarette beetles (Lasioderma serricorne), the essential oil from Artemisia lavandulaefolia (Compositae) was investigated. Oil was extracted by hydrodistillation of the above-ground portion of A. lavandulaefolia and analyzed using gas chromatography-mass spectrometer (GC-MS). Extracted essential
[...] Read more.
To develop natural product resources to control cigarette beetles (Lasioderma serricorne), the essential oil from Artemisia lavandulaefolia (Compositae) was investigated. Oil was extracted by hydrodistillation of the above-ground portion of A. lavandulaefolia and analyzed using gas chromatography-mass spectrometer (GC-MS). Extracted essential oil and three compounds isolated from the oil were then evaluated in laboratory assays to determine the fumigant, contact, and repellent efficacy against the stored-products’ pest, L. serricorne. The bioactive constituents from the oil extracts were identified as chamazulene (40.4%), 1,8-cineole (16.0%), and β-caryophyllene (11.5%). In the insecticidal activity assay, the adults of L. serricorne were susceptible to fumigant action of the essential oil and 1,8-cineole, with LC50 values of 31.81 and 5.18 mg/L air. The essential oil, 1,8-cineole, chamazulene, and β-caryophyllene exhibited contact toxicity with LD50 values of 13.51, 15.58, 15.18 and 35.52 μg/adult, respectively. During the repellency test, the essential oil and chamazulene had repellency approximating the positive control. The results indicated that chamazulene was abundant in A. lavandulaefolia essential oil and was toxic to cigarette beetles. Full article
(This article belongs to the Special Issue Biological Activity of Secondary Metabolites)
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Open AccessArticle Isolation and Quantification of Ginsenoside Rh23, a New Anti-Melanogenic Compound from the Leaves of Panax ginseng
Molecules 2018, 23(2), 267; doi:10.3390/molecules23020267
Received: 28 November 2017 / Revised: 23 January 2018 / Accepted: 26 January 2018 / Published: 29 January 2018
PDF Full-text (1242 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
A new ginsenoside, named ginsenoside Rh23 (1), and 20-O-β-d-glucopyranosyl-3β,6α,12β,20β,25-pentahydroxydammar-23-ene (2) were isolated from the leaves of hydroponic Panax ginseng. Compounds were isolated by various column chromatography and their structures were determined based on spectroscopic
[...] Read more.
A new ginsenoside, named ginsenoside Rh23 (1), and 20-O-β-d-glucopyranosyl-3β,6α,12β,20β,25-pentahydroxydammar-23-ene (2) were isolated from the leaves of hydroponic Panax ginseng. Compounds were isolated by various column chromatography and their structures were determined based on spectroscopic methods, including high resolution quadrupole/time of flight mass spectrometry (HR-QTOF/MS), nuclear magnetic resonance (NMR) spectroscopy, and infrared (IR) spectroscopy. To determine anti-melanogenic activity, the change in the melanin content in melan-a cells treated with identified compounds was tested. Additionally, we investigated the melanin inhibitory effects of ginsenoside Rh23 on pigmentation in a zebrafish in vivo model. Compound 1 inhibited potent melanogenesis in melan-a cells with 37.0% melanogenesis inhibition at 80 µM and also presented inhibition on the body pigmentation in zebrafish model. Although compound 2 showed slightly lower inhibitory activity than compound 1, it also showed significantly decreased melanogenesis in melan-a cell and in zebrafish model. These results indicated that compounds isolated from hydroponic P. ginseng may be used as new skin whitening compound through the in vitro and in vivo systems. Furthermore, this study demonstrated the utility of MS-based compound 1 for the quantitative analysis. Ginsenoside Rh23 (1) was found at a level of 0.31 mg/g in leaves of hydroponic P. ginseng. Full article
(This article belongs to the Special Issue Biological Activity of Secondary Metabolites)
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Open AccessArticle Agarwood Essential Oil Displays Sedative-Hypnotic Effects through the GABAergic System
Molecules 2017, 22(12), 2190; doi:10.3390/molecules22122190
Received: 8 November 2017 / Revised: 29 November 2017 / Accepted: 4 December 2017 / Published: 9 December 2017
Cited by 1 | PDF Full-text (2718 KB) | HTML Full-text | XML Full-text
Abstract
Although agarwood has been used as a tranquilizer in Asian countries for hundreds of years, the underlying pharmacological basis is still unclear. This study investigated the sedative-hypnotic effect of agarwood essential oil (AEO) using locomotor activity and pentobarbital-induced sleeping assays in mice. Single
[...] Read more.
Although agarwood has been used as a tranquilizer in Asian countries for hundreds of years, the underlying pharmacological basis is still unclear. This study investigated the sedative-hypnotic effect of agarwood essential oil (AEO) using locomotor activity and pentobarbital-induced sleeping assays in mice. Single (1-day) and multiple (7- and 14-days) administrations of 60 mg/kg AEO generated significant sedative effect on inhibiting locomotor activity and hypnotic effect on pentobarbital-induced sleeping in mice. Interestingly, prolonged AEO treatment did not result in obvious desensitization. Concoitant measurement of the levels of brain neurotransmitters using ultrafast liquid chromatography-tandem mass spectrometry (UFLC-MS/MS) indicated that AEO had no significant effect on the levels of glutamic acid (Glu) and γ-aminobutyric acid (GABA) in the brain. However, the sedative-hypnotic effects were blocked by the type A GABA (GABAA) receptor antagonists bicuculline and flumazenil. In addition, AEO significantly elevated the expression of GABAA receptor subunits and subtypes in the cerebral cortex. Furthermore, AEO increased chlorine ion (Cl) influx through GABAA receptors in human neuroblastoma cells. These results together demonstrate that AEO exerts its sedative-hypnotic effects through regulating gene expression of GABAA receptors and potentiating GABAA receptor function. Full article
(This article belongs to the Special Issue Biological Activity of Secondary Metabolites)
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Open AccessArticle HPLC-PDA-MS/MS Characterization of Bioactive Secondary Metabolites from Turraea fischeri Bark Extract and Its Antioxidant and Hepatoprotective Activities In Vivo
Molecules 2017, 22(12), 2089; doi:10.3390/molecules22122089
Received: 6 November 2017 / Revised: 21 November 2017 / Accepted: 27 November 2017 / Published: 29 November 2017
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Abstract
Turraea fischeri is an East African traditional herb, which is widely used in traditional medicine. In this study, we profiled the secondary metabolites in the methanol extract of T. fischeri bark using HPLC-PDA-ESI-MS/MS, and 20 compounds were tentatively identified. Several isomers of the
[...] Read more.
Turraea fischeri is an East African traditional herb, which is widely used in traditional medicine. In this study, we profiled the secondary metabolites in the methanol extract of T. fischeri bark using HPLC-PDA-ESI-MS/MS, and 20 compounds were tentatively identified. Several isomers of the flavonolignan cinchonain-I and bis-dihydroxyphenylpropanoid-substituted catechin hexosides dominated the extract. Robust in vitro and in vivo antioxidant properties were observed in 1,1-diphenyl-2-picrylhydrazyl radical scavenging assay (DPPH) and ferric reducing antioxidant power (FRAP) assay, and in the model organism Caenorhabditis elegans. Additionally, the extract exhibited promising hepatoprotective activities in D-galactosamine (D-GaIN) treated rats. A significant reduction in the elevated levels of aspartate aminotransferase (AST), total bilirubin, gamma-glutamyltransferase (GGT), and malondialdehyde (MDA) and increase of glutathione (GSH) was observed in rats treated with the bark extract in addition to D-galactosamine when compared with rats treated with D-galactosamine alone. In conclusion, T. fischeri is apromising candidate for health-promoting and for pharmaceutical applications. Full article
(This article belongs to the Special Issue Biological Activity of Secondary Metabolites)
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Open AccessArticle Asperflavin, an Anti-Inflammatory Compound Produced by a Marine-Derived Fungus, Eurotium amstelodami
Molecules 2017, 22(11), 1823; doi:10.3390/molecules22111823
Received: 21 September 2017 / Revised: 15 October 2017 / Accepted: 24 October 2017 / Published: 29 October 2017
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Abstract
In the present study, 16 marine-derived fungi were isolated from four types of marine materials including float, algae, animals and drift woods along with the coast of Jeju Island, Korea and evaluated for anti-inflammatory effects in lipopolysaccharide (LPS)-stimulated RAW 24.7 cells. The broth
[...] Read more.
In the present study, 16 marine-derived fungi were isolated from four types of marine materials including float, algae, animals and drift woods along with the coast of Jeju Island, Korea and evaluated for anti-inflammatory effects in lipopolysaccharide (LPS)-stimulated RAW 24.7 cells. The broth and mycelium extracts from the 16 fungi were prepared and the broth extract (BE) of Eurotium amstelodami (015-2) inhibited nitric oxide (NO) production in LPS-stimulated RAW 264.7 cells without cytotoxicity. By further bioassay-guided isolation, three compounds including asperflavin, neoechinulin A and preechinulin were successfully isolated from the BE of E. amstelodami. It was revealed that asperflavin showed no cytotoxicity up to 200 μM and significantly inhibited LPS-induced NO and PGE2 production in a dose-dependent manner. In the western blot results, asperflavin suppressed only inducible NOS (iNOS), but COX-2 were slightly down-regulated. Asperflavin was also observed to inhibit the production of pro-inflammatory cytokines including TNF-α, IL-1β, and IL-6. In conclusion, this study reports a potential use of asperflavin isolated from a marine fungus, E. amstelodami as an anti-inflammatory agent via suppression of iNOS and pro-inflammatory cytokines as well as no cytotoxicity. Full article
(This article belongs to the Special Issue Biological Activity of Secondary Metabolites)
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Open AccessArticle Inhibition of Human Kallikrein 5 Protease by Triterpenoids from Natural Sources
Molecules 2017, 22(11), 1829; doi:10.3390/molecules22111829
Received: 29 September 2017 / Revised: 16 October 2017 / Accepted: 24 October 2017 / Published: 27 October 2017
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Abstract
Stratum corneum tryptic enzyme kallikrein 5 (KLK5) is a serine protease that is involved in the cell renewal and maintenance of the skin barrier function. The excessive activation of KLK5 causes an exacerbation of dermatoses, such as rosacea and atopic dermatitis. Some triterpenoids
[...] Read more.
Stratum corneum tryptic enzyme kallikrein 5 (KLK5) is a serine protease that is involved in the cell renewal and maintenance of the skin barrier function. The excessive activation of KLK5 causes an exacerbation of dermatoses, such as rosacea and atopic dermatitis. Some triterpenoids are reported to suppress the serine proteases. We aimed to investigate whether bioactive triterpenoids modulate the KLK5 protease. Nineteen triterpenoids occurring in medicinal crude drugs were evaluated using an enzymatic assay to measure the anti-KLK5 activity. The KLK5-dependent cathelicidin peptide LL-37 production in human keratinocytes was examined using immunoprecipitation and Western blotting. Screening assays for evaluating the anti-KLK5 activity revealed that ursolic acid, oleanolic acid, saikosaponin b1, tumulosic acid and pachymic acid suppressed the KLK5 protease activity, although critical molecular moieties contributing to anti-KLK5 activity were unclarified. Ursolic acid and tumulosic acid suppressed the proteolytic processing of LL-37 in keratinocytes at ≤10 μM; no cytotoxicity was observed. Both triterpenoids were detected in the plasma of rats administered orally with triterpenoid-rich crude drug Jumihaidokuto. Our study reveals that triterpenoids, such as ursolic acid and tumulosic acid, modulate the KLK5 protease activity and cathelicidin peptide production. Triterpenoids may affect the skin barrier function via the regulation of proteases. Full article
(This article belongs to the Special Issue Biological Activity of Secondary Metabolites)
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Review

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Open AccessReview Chemical Constituents and Pharmacological Activity of Agarwood and Aquilaria Plants
Molecules 2018, 23(2), 342; doi:10.3390/molecules23020342
Received: 10 January 2018 / Revised: 28 January 2018 / Accepted: 31 January 2018 / Published: 7 February 2018
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Abstract
Agarwood, a highly precious non-timber fragrant wood of Aquilaria spp. (Thymelaeaceae), has been widely used in traditional medicine, religious rites, and cultural activities. Due to the inflated demanding and depleted natural resources, the yields of agarwood collected from the wild are shrinking, and
[...] Read more.
Agarwood, a highly precious non-timber fragrant wood of Aquilaria spp. (Thymelaeaceae), has been widely used in traditional medicine, religious rites, and cultural activities. Due to the inflated demanding and depleted natural resources, the yields of agarwood collected from the wild are shrinking, and the price is constantly rising, which restricts agarwood scientific research and wide application. With the sustainable planting and management of agarwood applied, and especially the artificial-inducing methods being used in China and Southeast Asian countries, agarwood yields are increasing, and the price is becoming more reasonable. Under this condition, illuminating the scientific nature of traditional agarwood application and developing new products and drugs from agarwood have become vitally important. Recently, the phytochemical investigations have achieved fruitful results, and more than 300 compounds have been isolated, including numerous new compounds that might be the characteristic constituents with physiological action. However, no one has focused on the new compounds and presented a summary until now. Alongside phytochemical advances, bioactivity screening and pharmacological investigation have also made a certain progress. Therefore, this review discussed the new compounds isolated after 2010, and summarized the pharmacological progress on agarwood and Aquilaria plants. Full article
(This article belongs to the Special Issue Biological Activity of Secondary Metabolites)
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