Biological Potential and Medical Use of Secondary Metabolites

A special issue of Medicines (ISSN 2305-6320).

Deadline for manuscript submissions: closed (28 February 2019) | Viewed by 114627

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cE3c—Centre for Ecology, Evolution and Environmental Changes, Azorean Biodiversity Group, University of Azores, Rua Mãe de Deus, 9501-801 Ponta Delgada, Portugal
Interests: bioactive natural compounds; secondary metabolites; chromatographic techniques; spectroscopic techniques; natural compounds
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Dear Colleagues,

Many macro and micro species, from terrestrial and aquatic environments, produce structurally unique compounds and, in many countries, still are the primary sources of medicines. In fact, secondary metabolites are an important source of chemotherapeutic agents, but are also lead compounds for synthetic modification and optimization of biological activity. Therefore, the exploitation of secondary metabolites, or their inspired synthetic compounds, offers excellent opportunities for the pharmaceutical industry.

This Special Issue of Medicines aims to compile both original articles and reviews, covering the most recent advances on the phytochemistry, biological activities, and action mechanisms of secondary metabolites from plants, macroalgae and microorganisms. In vitro studies will be welcome, only if molecular mechanisms are well defined. In vivo studies and clinical trials or preclinical studies are not only included in the scope, but are encouraged.

As Guest Editors of this Special Issue of Medicines, we invite you to provide original research contributions, as well as review articles, related to biological activities and medicinal uses of secondary metabolites.

We look forward to receiving your contributions to this Special Issue.

Prof. Dr. Ana M. L. Seca
Dr. Diana Cláudia Pinto
Guest Editors

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Keywords

  • secondary metabolites
  • bioactive compounds
  • phytochemistry
  • biological activities
  • in vitro and in vivo studies
  • clinical trials

Published Papers (17 papers)

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Editorial

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6 pages, 251 KiB  
Editorial
Biological Potential and Medical Use of Secondary Metabolites
by Ana M. L. Seca and Diana C. G. A. Pinto
Medicines 2019, 6(2), 66; https://doi.org/10.3390/medicines6020066 - 12 Jun 2019
Cited by 49 | Viewed by 5856
Abstract
This Medicines special issue focuses on the great potential of secondary metabolites for therapeutic applications. The special issue contains 16 articles reporting relevant experimental results and overviews of bioactive secondary metabolites. Their biological effects and new methodologies that improve the lead compounds’ synthesis [...] Read more.
This Medicines special issue focuses on the great potential of secondary metabolites for therapeutic applications. The special issue contains 16 articles reporting relevant experimental results and overviews of bioactive secondary metabolites. Their biological effects and new methodologies that improve the lead compounds’ synthesis were also discussed. We would like to thank all 83 authors, from all over the world, for their valuable contributions to this special issue. Full article
(This article belongs to the Special Issue Biological Potential and Medical Use of Secondary Metabolites)

Research

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13 pages, 2752 KiB  
Article
In Vitro Evaluation of the Phytopharmacological Potential of Sargassum incisifolium for the Treatment of Inflammatory Bowel Diseases
by Mutenta N. Nyambe, Trevor C. Koekemoer, Maryna van de Venter, Eleonora D. Goosen and Denzil R. Beukes
Medicines 2019, 6(2), 49; https://doi.org/10.3390/medicines6020049 - 06 Apr 2019
Cited by 6 | Viewed by 4306
Abstract
Background: Comprised of Crohn’s disease and ulcerative colitis, inflammatory bowel diseases (IBD) are characterized by chronic inflammation of the gastro-intestinal tract, which often results in severe damage to the intestinal mucosa. This study investigated metabolites from the South African endemic alga, Sargassum incisifolium [...] Read more.
Background: Comprised of Crohn’s disease and ulcerative colitis, inflammatory bowel diseases (IBD) are characterized by chronic inflammation of the gastro-intestinal tract, which often results in severe damage to the intestinal mucosa. This study investigated metabolites from the South African endemic alga, Sargassum incisifolium, as potential treatments for IBD. Phytochemical evaluation of S. incisifolium yielded prenylated toluhydroquinones and toluquinones, from which semi-synthetic analogs were derived, and a carotenoid metabolite. The bioactivities of S. incisifolium fractions, natural products, and semi-synthetic derivatives were evaluated using various in vitro assays. Methods: Sargahydroquinoic acid isolated from S. incisifolium was converted to several structural derivatives by semi-synthetic modification. Potential modulation of IBD by S. incisifolium crude fractions, natural compounds, and sargahydroquinoic acid analogs was evaluated through in vitro anti-inflammatory activity, anti-oxidant activity, cytotoxicity against HT-29 and Caco-2 colorectal cancer cells, and PPAR-γ activation. Results: Sargahydroquinoic acid acts on various therapeutic targets relevant to IBD treatment. Conclusions: Conversion of sargahydroquinoic acid to sarganaphthoquinoic acid increases peroxisome proliferator activated receptor gamma (PPAR-γ) activity, compromises anti-oxidant activity, and has no effect on cytotoxicity against the tested cell lines. Full article
(This article belongs to the Special Issue Biological Potential and Medical Use of Secondary Metabolites)
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9 pages, 1136 KiB  
Article
Semi-Synthesis and Evaluation of Sargahydroquinoic Acid Derivatives as Potential Antimalarial Agents
by Tatenda C. Munedzimwe, Robyn L. van Zyl, Donovan C. Heslop, Adrienne L. Edkins and Denzil R. Beukes
Medicines 2019, 6(2), 47; https://doi.org/10.3390/medicines6020047 - 01 Apr 2019
Cited by 4 | Viewed by 3232
Abstract
Background: Malaria continues to present a major health problem, especially in developing countries. The development of new antimalarial drugs to counter drug resistance and ensure a steady supply of new treatment options is therefore an important area of research. Meroditerpenes have previously been [...] Read more.
Background: Malaria continues to present a major health problem, especially in developing countries. The development of new antimalarial drugs to counter drug resistance and ensure a steady supply of new treatment options is therefore an important area of research. Meroditerpenes have previously been shown to exhibit antiplasmodial activity against a chloroquinone sensitive strain of Plasmodium falciparum (D10). In this study we explored the antiplasmodial activity of several semi-synthetic analogs of sargahydroquinoic acid. Methods: Sargahydroquinoic acid was isolated from the marine brown alga, Sargassum incisifolium and converted, semi-synthetically, to several analogs. The natural products, together with their synthetic derivatives were evaluated for their activity against the FCR-3 strain of Plasmodium falciparum as well as MDA-MB-231 breast cancer cells. Results: Sarganaphthoquinoic acid and sargaquinoic acid showed the most promising antiplasmodial activity and low cytotoxicity. Conclusions: Synthetic modification of the natural product, sargahydroquinoic acid, resulted in the discovery of a highly selective antiplasmodial compound, sarganaphthoquinoic acid. Full article
(This article belongs to the Special Issue Biological Potential and Medical Use of Secondary Metabolites)
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16 pages, 1704 KiB  
Article
Antioxidant, Cytotoxic, and Antimicrobial Activities of Glycyrrhiza glabra L., Paeonia lactiflora Pall., and Eriobotrya japonica (Thunb.) Lindl. Extracts
by Jun-Xian Zhou, Markus Santhosh Braun, Pille Wetterauer, Bernhard Wetterauer and Michael Wink
Medicines 2019, 6(2), 43; https://doi.org/10.3390/medicines6020043 - 30 Mar 2019
Cited by 25 | Viewed by 5692
Abstract
Background: The phytochemical composition, antioxidant, cytotoxic, and antimicrobial activities of a methanol extract from Glycyrrhiza glabra L. (Ge), a 50% ethanol (in water) extract from Paeonia lactiflora Pall. (Pe), and a 96% ethanol extract from Eriobotrya japonica (Thunb.) Lindl. (Ue) were investigated. Methods: [...] Read more.
Background: The phytochemical composition, antioxidant, cytotoxic, and antimicrobial activities of a methanol extract from Glycyrrhiza glabra L. (Ge), a 50% ethanol (in water) extract from Paeonia lactiflora Pall. (Pe), and a 96% ethanol extract from Eriobotrya japonica (Thunb.) Lindl. (Ue) were investigated. Methods: The phytochemical profiles of the extracts were analyzed by LC-MS/MS. Antioxidant activity was evaluated by scavenging 2,2-diphenyl-1-picrylhydrazyl (DPPH) and 2,2′-azino-bis (3-ethylbenzothiazoline-6-sulphonic acid) (ABTS) radicals and reducing ferric complexes, and the total phenolic content was tested with the Folin–Ciocalteu method. Cytotoxicity was determined with a 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay in murine macrophage RAW 264.7 cells. Antimicrobial activity of the three plant extracts was investigated against six bacterial strains with the broth microdilution method. Results: Only Pe showed high antioxidant activities compared to the positive controls ascorbic acid and (−)-epigallocatechin gallate (EGCG) in DPPH assay; and generally the antioxidant activity order was ascorbic acid or EGCG > Pe > Ue > Ge. The three plant extracts did not show strong cytotoxicity against RAW 264.7 cells after 24 h treatment with IC50 values above 60.53 ± 4.03 μg/mL. Ue was not toxic against the six tested bacterial strains, with minimal inhibitory concentration (MIC) values above 5 mg/mL. Ge showed medium antibacterial activity against Acinetobacter bohemicus, Kocuria kristinae, Micrococcus luteus, Staphylococcus auricularis, and Bacillus megaterium with MICs between 0.31 and 1.25 mg/mL. Pe inhibited the growth of Acinetobacter bohemicus, Micrococcus luteus, and Bacillus megaterium at a MIC of 0.08 mg/mL. Conclusions: The three extracts were low-cytotoxic, but Pe exhibited effective DPPH radical scavenging ability and good antibacterial activity; Ue did not show antioxidant or antibacterial activity; Ge had no antioxidant potential, but medium antibacterial ability against five bacteria strains. Pe and Ge could be further studied for their potential to be developed as antioxidant or antibacterial candidates. Full article
(This article belongs to the Special Issue Biological Potential and Medical Use of Secondary Metabolites)
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10 pages, 1268 KiB  
Article
Antiproliferative Activity of (-)-Rabdosiin Isolated from Ocimum sanctum L.
by Alexandros Flegkas, Tanja Milosević Ifantis, Christina Barda, Pinelopi Samara, Ourania Tsitsilonis and Helen Skaltsa
Medicines 2019, 6(1), 37; https://doi.org/10.3390/medicines6010037 - 12 Mar 2019
Cited by 11 | Viewed by 5675
Abstract
Background: Ocimum sanctum L. (holy basil; Tulsi in Hindi) is an important medicinal plant, traditionally used in India. Methods: The phytochemical study of the nonpolar (dichloromethane 100%) and polar (methanol:water; 7:3) extracts yielded fourteen compounds. Compounds 6, 7, 9, 11 [...] Read more.
Background: Ocimum sanctum L. (holy basil; Tulsi in Hindi) is an important medicinal plant, traditionally used in India. Methods: The phytochemical study of the nonpolar (dichloromethane 100%) and polar (methanol:water; 7:3) extracts yielded fourteen compounds. Compounds 6, 7, 9, 11, 12, and 13, along with the methanol:water extract were evaluated for their cytotoxicity against the human cancer cell lines MCF-7, SKBR3, and HCT-116, and normal peripheral blood mononuclear cells (PBMCs). Results: Five terpenoids, namely, ursolic acid (1), oleanolic acid (2), betulinic acid (3), stigmasterol (4), and β-caryophyllene oxide (5); two lignans, i.e., (-)-rabdosiin (6) and shimobashiric acid C (7); three flavonoids, luteolin (8), its 7-O-β-D-glucuronide (9), apigenin 7-O-β-D-glucuronide (10); and four phenolics, (E)-p-coumaroyl 4-O-β-D-glucoside (11), 3-(3,4-dihydroxyphenyl) lactic acid (12), protocatechuic acid (13), and vanillic acid (14) were isolated. Compound 6 was the most cytotoxic against the human cancer lines assessed and showed very low cytotoxicity against PBMCs. Conclusions: Based on these results, the structure of compound 6 shows some promise as a selective anticancer drug scaffold. Full article
(This article belongs to the Special Issue Biological Potential and Medical Use of Secondary Metabolites)
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8 pages, 473 KiB  
Article
Development and Validation of an HPLC-PDA Method for Biologically Active Quinonemethide Triterpenoids Isolated from Maytenus chiapensis
by Vito Alessandro Taddeo, Ulises Guardado Castillo, Morena Lizette Martínez, Jenny Menjivar, Ignacio Antonio Jiménez, Marvin José Núñez and Isabel López Bazzocchi
Medicines 2019, 6(1), 36; https://doi.org/10.3390/medicines6010036 - 07 Mar 2019
Cited by 10 | Viewed by 3673
Abstract
Background: Quinonemethide triterpenoids, known as celastroloids, constitute a relatively small group of biologically active compounds restricted to the Celastraceae family and, therefore, they are chemotaxonomic markers for this family. Among this particular type of metabolite, pristimerin and tingenone are considered traditional medicines [...] Read more.
Background: Quinonemethide triterpenoids, known as celastroloids, constitute a relatively small group of biologically active compounds restricted to the Celastraceae family and, therefore, they are chemotaxonomic markers for this family. Among this particular type of metabolite, pristimerin and tingenone are considered traditional medicines in Latin America. The aim of this study was the isolation of the most abundant celastroloids from the root bark of Maytenus chiapensis, and thereafter, to develop an analytical method to identify pristimerin and tingenone in the Celastraceae species. Methods: Pristimerin and tingenone were isolated from the n-hexane-Et2O extract of the root bark of M. chiapensis through chromatographic techniques, and were used as internal standards. Application of a validated RP HPLC-PDA method was developed for the simultaneous quantification of these two metabolites in three different extracts, n-hexane-Et2O, methanol, and water, to determine the best extractor solvent. Results: Concentration values showed great variation between the solvents used for extraction, with the n-hexane–Et2O extract being the richest in pristimerin and tingenone. Conclusions: M. chiapensis is a source of two biologically active quinonemethide triterpenoids. An analytical method was developed for the qualification and quantification of these two celastroloids in the root bark extracts of M. chiapensis. The validated method reported herein could be extended and be useful in analyzing Celastraceae species and real commercial samples. Full article
(This article belongs to the Special Issue Biological Potential and Medical Use of Secondary Metabolites)
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10 pages, 830 KiB  
Article
Assessment of Artemisinin Contents in Selected Artemisia Species from Tajikistan (Central Asia)
by Sodik Numonov, Farukh Sharopov, Aminjon Salimov, Parviz Sukhrobov, Sunbula Atolikshoeva, Ramazon Safarzoda, Maidina Habasi and Haji Akber Aisa
Medicines 2019, 6(1), 23; https://doi.org/10.3390/medicines6010023 - 31 Jan 2019
Cited by 33 | Viewed by 6068
Abstract
Background: Central Asia is the center of origin and diversification of the Artemisia genus. The genus Artemisia is known to possess a rich phytochemical diversity. Artemisinin is the shining example of a phytochemical isolated from Artemisia annua, which is widely used in [...] Read more.
Background: Central Asia is the center of origin and diversification of the Artemisia genus. The genus Artemisia is known to possess a rich phytochemical diversity. Artemisinin is the shining example of a phytochemical isolated from Artemisia annua, which is widely used in the treatment of malaria. There is great interest in the discovery of alternative sources of artemisinin in other Artemisia species. Methods: The hexane extracts of Artemisia plants were prepared with ultrasound-assisted extraction procedures. Silica gel was used as an adsorbent for the purification of Artemisia annua extract. High-performance liquid chromatography with ultraviolet detection was performed for the quantification of underivatized artemisinin from hexane extracts of plants. Results: Artemisinin was found in seven Artemisia species collected from Tajikistan. Content of artemisinin ranged between 0.07% and 0.45% based on dry mass of Artemisia species samples. Conclusions: The artemisinin contents were observed in seven Artemisia species. A. vachanica was found to be a novel plant source of artemisinin. Purification of A. annua hexane extract using silica gel as adsorbent resulted in enrichment of artemisinin. Full article
(This article belongs to the Special Issue Biological Potential and Medical Use of Secondary Metabolites)
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13 pages, 453 KiB  
Article
Xanthine Oxidase Inhibitory Potential, Antioxidant and Antibacterial Activities of Cordyceps militaris (L.) Link Fruiting Body
by Tran Ngoc Quy and Tran Dang Xuan
Medicines 2019, 6(1), 20; https://doi.org/10.3390/medicines6010020 - 29 Jan 2019
Cited by 14 | Viewed by 6626
Abstract
Background: Cordyceps militaris is a medicinal mushroom and has been extensively used as a folk medicine in East Asia. In this study, the separation of constituents involved in xanthine oxidase (XO) inhibitory, antioxidant and antibacterial properties of C. militaris was conducted. Methods: The [...] Read more.
Background: Cordyceps militaris is a medicinal mushroom and has been extensively used as a folk medicine in East Asia. In this study, the separation of constituents involved in xanthine oxidase (XO) inhibitory, antioxidant and antibacterial properties of C. militaris was conducted. Methods: The aqueous residue of this fungus was extracted by methanol and then subsequently fractionated by hexane, chloroform, ethyl acetate and water. The ethyl acetate extract possessed the highest XO inhibitory and antioxidant activities was separated to different fractions by column chromatography. Each fraction was then subjected to anti-hyperuricemia, antioxidant and antibacterial assays. Results: The results showed that the CM8 fraction exhibited the strongest XO inhibitory activity (the lowest IC50: 62.82 μg/mL), followed by the CM10 (IC50: 68.04 μg/mL) and the CM7 (IC50: 86.78 μg/mL). The level of XO inhibition was proportional to antioxidant activity. In antibacterial assay, the CM9 and CM11 fractions showed effective antibacterial activity (MIC values: 15–25 mg/mL and 10–25 mg/mL, respectively). Results from gas chromatography-mass spectrometry (GC-MS) analyses indicated that cordycepin was the major constituent in the CM8 and CM10 fractions. Conclusions: This study revealed that C. militaris was beneficial for treatment hyperuricemia although in vivo trials on compounds purified from this medicinal fungus are needed. Full article
(This article belongs to the Special Issue Biological Potential and Medical Use of Secondary Metabolites)
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35 pages, 7265 KiB  
Article
Protein Targets of Frankincense: A Reverse Docking Analysis of Terpenoids from Boswellia Oleo-Gum Resins
by Kendall G. Byler and William N. Setzer
Medicines 2018, 5(3), 96; https://doi.org/10.3390/medicines5030096 - 31 Aug 2018
Cited by 10 | Viewed by 8252
Abstract
Background: Frankincense, the oleo-gum resin of Boswellia trees, has been used in traditional medicine since ancient times. Frankincense has been used to treat wounds and skin infections, inflammatory diseases, dementia, and various other conditions. However, in many cases, the biomolecular targets for frankincense [...] Read more.
Background: Frankincense, the oleo-gum resin of Boswellia trees, has been used in traditional medicine since ancient times. Frankincense has been used to treat wounds and skin infections, inflammatory diseases, dementia, and various other conditions. However, in many cases, the biomolecular targets for frankincense components are not well established. Methods: In this work, we have carried out a reverse docking study of Boswellia diterpenoids and triterpenoids with a library of 16034 potential druggable target proteins. Results: Boswellia diterpenoids showed selective docking to acetylcholinesterase, several bacterial target proteins, and HIV-1 reverse transcriptase. Boswellia triterpenoids targeted the cancer-relevant proteins (poly(ADP-ribose) polymerase-1, tankyrase, and folate receptor β), inflammation-relevant proteins (phospholipase A2, epoxide hydrolase, and fibroblast collagenase), and the diabetes target 11β-hydroxysteroid dehydrogenase. Conclusions: The preferential docking of Boswellia terpenoids is consistent with the traditional uses and the established biological activities of frankincense. Full article
(This article belongs to the Special Issue Biological Potential and Medical Use of Secondary Metabolites)
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Review

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11 pages, 349 KiB  
Review
Nanoemulsions of Essential Oils: New Tool for Control of Vector-Borne Diseases and In Vitro Effects on Some Parasitic Agents
by Javier Echeverría and Ricardo Diego Duarte Galhardo de Albuquerque
Medicines 2019, 6(2), 42; https://doi.org/10.3390/medicines6020042 - 27 Mar 2019
Cited by 48 | Viewed by 5423
Abstract
The control of infectious/parasitic diseases is a continuing challenge for global health, which in turn requires new methods of action and the development of innovative agents to be used in its prevention and/or treatment. In this context, the control of vectors and intermediate [...] Read more.
The control of infectious/parasitic diseases is a continuing challenge for global health, which in turn requires new methods of action and the development of innovative agents to be used in its prevention and/or treatment. In this context, the control of vectors and intermediate hosts of etiological agents is an efficient method in the prevention of human and veterinary diseases. In later stages, it is necessary to have bioactive compounds that act efficiently on the agents that produce the disease. However, several synthetic agents have strong residual effects in humans and other animals and cause environmental toxicity, affecting fauna, flora and unbalancing the local ecosystem. Many studies have reported the dual activity of the essential oils (EOs): (i) control of vectors that are important in the cycle of disease transmission, and (ii) relevant activity against pathogens. In general, EOs have an easier degradation and cause less extension of environmental contamination. However, problems related to solubility and stability lead to the development of efficient vehicles for formulations containing EOs, such as nanoemulsions. Therefore, this systematic review describes several studies performed with nanoemulsions as carriers of EOs that have larvicidal, insecticidal, repellent, acaricidal and antiparasitic activities, and thus can be considered as alternatives in the vector control of infectious and parasitic diseases, as well as in the combat against etiological agents of parasitic origin. Full article
(This article belongs to the Special Issue Biological Potential and Medical Use of Secondary Metabolites)
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21 pages, 687 KiB  
Review
Mitragyna speciosa: Clinical, Toxicological Aspects and Analysis in Biological and Non-Biological Samples
by Vânia Meireles, Tiago Rosado, Mário Barroso, Sofia Soares, Joana Gonçalves, Ângelo Luís, Débora Caramelo, Ana Y. Simão, Nicolás Fernández, Ana Paula Duarte and Eugenia Gallardo
Medicines 2019, 6(1), 35; https://doi.org/10.3390/medicines6010035 - 04 Mar 2019
Cited by 34 | Viewed by 10300
Abstract
The abuse of psychotropic substances is a well-known phenomenon, and many of them are usually associated with ancestral traditions and home remedies. This is the case of Mitragyna speciosa (kratom), a tropical tree used to improve work performance and to withstand great heat. [...] Read more.
The abuse of psychotropic substances is a well-known phenomenon, and many of them are usually associated with ancestral traditions and home remedies. This is the case of Mitragyna speciosa (kratom), a tropical tree used to improve work performance and to withstand great heat. According to several published studies, the main reasons for kratom consumption involve improving sexual performance and endurance, but also social and recreational uses for the feeling of happiness and euphoria; it is also used for medical purposes as a pain reliever, and in the treatment of diarrhea, fever, diabetes, and hypertension. However, this plant has gained more popularity amongst young people over the last years. Since it is available on the internet for purchase, its use is now widely as a drug of abuse, namely as a new psychoactive substance, being a cheaper alternative to opioids that does not require medical prescription in most countries. According to internet surveys by the European Monitoring Centre for Drugs and Drug Addiction in 2008 and 2011, kratom was one of the most widely supplied new psychoactive substances. The composition of kratom is complex; in fact, more than 40 different alkaloids have been identified in Mitragyna speciosa so far, the major constituent being mitragynine, which is exclusive to this plant. Besides mitragynine, alkaloids such as corynantheidine and 7-hydroxamitragynine also present pharmacological effects, a feature that may be attributed to the remaining constituents as well. The main goal of this review is not only to understand the origin, chemistry, consumption, and analytical methodologies for analysis and mechanism of action, but also the use of secondary metabolites of kratom as therapeutic drugs and the assessment of potential risks associated with its consumption, in order to aid health professionals, toxicologists, and police authorities in cases where this plant is present. Full article
(This article belongs to the Special Issue Biological Potential and Medical Use of Secondary Metabolites)
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11 pages, 270 KiB  
Review
New Approaches to Detect Biosynthetic Gene Clusters in the Environment
by Ray Chen, Hon Lun Wong and Brendan Paul Burns
Medicines 2019, 6(1), 32; https://doi.org/10.3390/medicines6010032 - 25 Feb 2019
Cited by 20 | Viewed by 6653
Abstract
Microorganisms in the environment can produce a diverse range of secondary metabolites (SM), which are also known as natural products. Bioactive SMs have been crucial in the development of antibiotics and can also act as useful compounds in the biotechnology industry. These natural [...] Read more.
Microorganisms in the environment can produce a diverse range of secondary metabolites (SM), which are also known as natural products. Bioactive SMs have been crucial in the development of antibiotics and can also act as useful compounds in the biotechnology industry. These natural products are encoded by an extensive range of biosynthetic gene clusters (BGCs). The developments in omics technologies and bioinformatic tools are contributing to a paradigm shift from traditional culturing and screening methods to bioinformatic tools and genomics to uncover BGCs that were previously unknown or transcriptionally silent. Natural product discovery using bioinformatics and omics workflow in the environment has demonstrated an extensive distribution of BGCs in various environments, such as soil, aquatic ecosystems and host microbiome environments. Computational tools provide a feasible and culture-independent route to find new secondary metabolites where traditional approaches cannot. This review will highlight some of the advances in the approaches, primarily bioinformatic, in identifying new BGCs, especially in environments where microorganisms are rarely cultured. This has allowed us to tap into the huge potential of microbial dark matter. Full article
(This article belongs to the Special Issue Biological Potential and Medical Use of Secondary Metabolites)
47 pages, 910 KiB  
Review
Cannabis and Its Secondary Metabolites: Their Use as Therapeutic Drugs, Toxicological Aspects, and Analytical Determination
by Joana Gonçalves, Tiago Rosado, Sofia Soares, Ana Y. Simão, Débora Caramelo, Ângelo Luís, Nicolás Fernández, Mário Barroso, Eugenia Gallardo and Ana Paula Duarte
Medicines 2019, 6(1), 31; https://doi.org/10.3390/medicines6010031 - 23 Feb 2019
Cited by 95 | Viewed by 22949
Abstract
Although the medicinal properties of Cannabis species have been known for centuries, the interest on its main active secondary metabolites as therapeutic alternatives for several pathologies has grown in recent years. This potential use has been a revolution worldwide concerning public health, production, [...] Read more.
Although the medicinal properties of Cannabis species have been known for centuries, the interest on its main active secondary metabolites as therapeutic alternatives for several pathologies has grown in recent years. This potential use has been a revolution worldwide concerning public health, production, use and sale of cannabis, and has led inclusively to legislation changes in some countries. The scientific advances and concerns of the scientific community have allowed a better understanding of cannabis derivatives as pharmacological options in several conditions, such as appetite stimulation, pain treatment, skin pathologies, anticonvulsant therapy, neurodegenerative diseases, and infectious diseases. However, there is some controversy regarding the legal and ethical implications of their use and routes of administration, also concerning the adverse health consequences and deaths attributed to marijuana consumption, and these represent some of the complexities associated with the use of these compounds as therapeutic drugs. This review comprehends the main secondary metabolites of Cannabis, approaching their therapeutic potential and applications, as well as their potential risks, in order to differentiate the consumption as recreational drugs. There will be also a focus on the analytical methodologies for their analysis, in order to aid health professionals and toxicologists in cases where these compounds are present. Full article
(This article belongs to the Special Issue Biological Potential and Medical Use of Secondary Metabolites)
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13 pages, 2303 KiB  
Review
Medicinal Potentialities of Plant Defensins: A Review with Applied Perspectives
by Nida Ishaq, Muhammad Bilal and Hafiz M.N. Iqbal
Medicines 2019, 6(1), 29; https://doi.org/10.3390/medicines6010029 - 19 Feb 2019
Cited by 19 | Viewed by 5440
Abstract
Plant-based secondary metabolites with medicinal potentialities such as defensins are small, cysteine-rich peptides that represent an imperative aspect of the inherent defense system. Plant defensins possess broad-spectrum biological activities, e.g., bactericidal and insecticidal actions, as well as antifungal, antiviral, and anticancer activities. The [...] Read more.
Plant-based secondary metabolites with medicinal potentialities such as defensins are small, cysteine-rich peptides that represent an imperative aspect of the inherent defense system. Plant defensins possess broad-spectrum biological activities, e.g., bactericidal and insecticidal actions, as well as antifungal, antiviral, and anticancer activities. The unique structural and functional attributes provide a nonspecific and versatile means of combating a variety of microbial pathogens, i.e., fungi, bacteria, protozoa, and enveloped viruses. Some defensins in plants involved in other functions include the development of metal tolerance and the role in sexual reproduction, while most of the defensins make up the innate immune system of the plants. Defensins are structurally and functionally linked and have been characterized in various eukaryotic microorganisms, mammals, plants, gulls, teleost species of fish, mollusks, insect pests, arachnidan, and crustaceans. This defense mechanism has been improved biotechnologically as it helps to protect plants from fungal attacks in genetically modified organisms (GMO). Herein, we review plant defensins as secondary metabolites with medicinal potentialities. The first half of the review elaborates the origin, structural variations, and mechanism of actions of plant defensins. In the second part, the role of defensins in plant defense, stress response, and reproduction are discussed with suitable examples. Lastly, the biological applications of plant defensins as potential antimicrobial and anticancer agents are also deliberated. In summary, plant defensins may open a new prospect in medicine, human health, and agriculture. Full article
(This article belongs to the Special Issue Biological Potential and Medical Use of Secondary Metabolites)
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18 pages, 2414 KiB  
Review
Scabiosa Genus: A Rich Source of Bioactive Metabolites
by Diana C. G. A. Pinto, Naima Rahmouni, Noureddine Beghidja and Artur M. S. Silva
Medicines 2018, 5(4), 110; https://doi.org/10.3390/medicines5040110 - 09 Oct 2018
Cited by 18 | Viewed by 4345
Abstract
The genus Scabiosa (family Caprifoliaceae) is considered large (618 scientific plant names of species) although only 62 have accepted Latin binominal names. The majority of the Scabiosa species are widely distributed in the Mediterranean region and some Scabiosa species are used in traditional [...] Read more.
The genus Scabiosa (family Caprifoliaceae) is considered large (618 scientific plant names of species) although only 62 have accepted Latin binominal names. The majority of the Scabiosa species are widely distributed in the Mediterranean region and some Scabiosa species are used in traditional medicine systems. For instance, Scabiosa columbaria L. is used traditionally against diphtheria while S. comosa Fisch. Ex Roem. and Schult. is used in Mongolian and Tibetan traditional medical settings to treat liver diseases. The richness of Scabiosa species in secondary metabolites such as iridoids, flavonoids and pentacyclic triterpenoids may contribute to its use in folk medicine. Details on the most recent and relevant pharmacological in vivo studies on the bioactive secondary metabolites isolated from Scabiosa species will be summarized and thoroughly discussed. Full article
(This article belongs to the Special Issue Biological Potential and Medical Use of Secondary Metabolites)
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24 pages, 1105 KiB  
Review
The Current Status of the Pharmaceutical Potential of Juniperus L. Metabolites
by Wilson R. Tavares and Ana M. L. Seca
Medicines 2018, 5(3), 81; https://doi.org/10.3390/medicines5030081 - 31 Jul 2018
Cited by 21 | Viewed by 5106
Abstract
Background: Plants and their derived natural compounds possess various biological and therapeutic properties, which turns them into an increasing topic of interest and research. Juniperus genus is diverse in species, with several traditional medicines reported, and rich in natural compounds with potential for [...] Read more.
Background: Plants and their derived natural compounds possess various biological and therapeutic properties, which turns them into an increasing topic of interest and research. Juniperus genus is diverse in species, with several traditional medicines reported, and rich in natural compounds with potential for development of new drugs. Methods: The research for this review were based in the Scopus and Web of Science databases using terms combining Juniperus, secondary metabolites names, and biological activities. This is not an exhaustive review of Juniperus compounds with biological activities, but rather a critical selection taking into account the following criteria: (i) studies involving the most recent methodologies for quantitative evaluation of biological activities; and (ii) the compounds with the highest number of studies published in the last four years. Results: From Juniperus species, several diterpenes, flavonoids, and one lignan were emphasized taking into account their level of activity against several targets. Antitumor activity is by far the most studied, being followed by antibacterial and antiviral activities. Deoxypodophyllotoxin and one dehydroabietic acid derivative appears to be the most promising lead compounds. Conclusions: This review demonstrates the Juniperus species value as a source of secondary metabolites with relevant pharmaceutical potential. Full article
(This article belongs to the Special Issue Biological Potential and Medical Use of Secondary Metabolites)
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8 pages, 273 KiB  
Brief Report
Nutraceutical Characteristics of Ancient Malus x domestica Borkh. Fruits Recovered across Siena in Tuscany
by Roberto Berni, Claudio Cantini, Massimo Guarnieri, Massimo Nepi, Jean-Francois Hausman, Gea Guerriero, Marco Romi and Giampiero Cai
Medicines 2019, 6(1), 27; https://doi.org/10.3390/medicines6010027 - 18 Feb 2019
Cited by 8 | Viewed by 3062
Abstract
Background: A diet rich in fruits and vegetables contributes to lowering the risk of chronic diseases. The fruits of Malus x domestica are a rich dietary source of bioactive compounds, namely vitamins and antioxidants, with recognized action on human health protection. Tuscany is [...] Read more.
Background: A diet rich in fruits and vegetables contributes to lowering the risk of chronic diseases. The fruits of Malus x domestica are a rich dietary source of bioactive compounds, namely vitamins and antioxidants, with recognized action on human health protection. Tuscany is known for its rich plant biodiversity, especially represented by ancient varieties of fruit trees. Particularly noteworthy are the many ancient Tuscan varieties of apple trees. Methods: Sugar quantification via HPLC and spectrophotometric assays to quantify the antioxidant power and total polyphenol content revealed interesting differences in 17 old varieties of Malus x domestica Borkh. recovered in Siena (Tuscany). Results: The quantification of antioxidants, polyphenols, and the main free sugars revealed that their content in the old fruits was often superior to the widespread commercial counterparts (‘Red Delicious’ and ‘Golden Delicious’). Such differences were, in certain cases, dramatic, with 8-fold higher values. Differences were also present for sugars and fibers (pectin). Most ancient fruits displayed low values of glucose and high contents of xylitol and pectin. Conclusions: The results reported here suggest the possible use of ancient apple varieties from Siena for nutraceutical purposes and draw attention to the valorization of local old varieties. Full article
(This article belongs to the Special Issue Biological Potential and Medical Use of Secondary Metabolites)
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