Medicinal Plants—Natural Sources of Bioactive Secondary Metabolites

A special issue of Agronomy (ISSN 2073-4395).

Deadline for manuscript submissions: closed (28 February 2023) | Viewed by 27938

Special Issue Editors


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Guest Editor
1. Department of Pharmacognosy, Faculty of Pharmacy, University of Szeged, H-6720 Szeged, Hungary
2. Institute for Translational Medicine, Faculty of Medicine, University of Pécs, Szigeti út 12, 7624 Pécs, Hungary
Interests: phytochemistry; pharmacognosy; phytotherapy; phytochemical analysis
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Guest Editor
Center for Molecular Biosciences (CMBI), Institute of Pharmacy/Pharmacognosy, University of Innsbruck, Innrain 80-82, 6020 Innsbruck, Austria
Interests: medicinal plants; phytochemistry; natural products chemistry; drug discovery; isolation and identification of bioactive natural products
Special Issues, Collections and Topics in MDPI journals

Special Issue Information

Dear Colleagues,

The utilization of plants in the treatment of various ailments and disorders has a history as old as human antiquity. Over time, the investigation of plant constituents has led to the discovery of secondary metabolites (phytochemicals) as natural healing agents. The biological and pharmacological potencies of these compounds, which possess diverse chemical structures, are subjects of extensive investigation. Many natural drugs have hitherto been developed to treat various human diseases and disorders. The study of various plant-derived products is still one of the promising approaches to discover novel natural drugs.

This Special Issue covers a broad range of investigations in the field of medicinal plants and is particularly seeking submissions of original research and review articles. Manuscripts reporting the qualitative or quantitative composition of phytochemicals in medicinal plants, as well as the isolation, identification, and biological evaluation of herbal extracts, volatile oils, and plant secondary metabolites, are highly welcomed.

Dr. Dezső Csupor
Dr. Javad Mottaghipisheh
Guest Editors

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Keywords

  • isolation, purification, and structural elucidation of plant secondary metabolites
  • quantification and qualification analysis of plant secondary metabolites
  • bioactivity assessment of plant products in vitro and/or in vivo
  • ethnobotany and ethnopharmacological studies of medicinal plants
  • plant essential oils

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Published Papers (8 papers)

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Research

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19 pages, 7337 KiB  
Article
In Vitro Potent Anticancer, Antifungal, and Antioxidant Efficacy of Walnut (Juglans regia L.) Genotypes
by Tabasum Ara, Sabeeha Shafi, Mohammed Ghazwani, Javid Iqbal Mir, Abdul Haseeb Shah, Raies A. Qadri, Abdulrahim R. Hakami, Mohammad Khalid, Umme Hani and Shadma Wahab
Agronomy 2023, 13(5), 1232; https://doi.org/10.3390/agronomy13051232 - 27 Apr 2023
Cited by 4 | Viewed by 2872
Abstract
Walnuts are one of the healthiest foods in the world because they are one of the best sources of beneficial nutrients, minerals, and antioxidants. They also contain key sources of energy. Despite several traditional uses, the leaves of Juglans regia L. have received [...] Read more.
Walnuts are one of the healthiest foods in the world because they are one of the best sources of beneficial nutrients, minerals, and antioxidants. They also contain key sources of energy. Despite several traditional uses, the leaves of Juglans regia L. have received little attention regarding phytochemical and pharmacological potential. Thus, the current study intended to find the walnut genotypes with the greatest antioxidant, anticancer, and antifungal activity. The total polyphenolic, flavonoid, and flavanol contents of leaves from 14 walnut genotypes were determined. Genotypes that accumulate flavonoid/flavonol contents (99.8–111.93 mg/g quercetin equivalent (QE) and 101.67–111.83 mg/g QE) showed significantly higher ferric reducing antioxidant potential (FRAP) activity (128.2–148.1 μM Fe2+/g dry weight (DW)] than other genotypes. Maximum divergence in the quercetin content (0.8–1.23 mg/g) of walnut genotypes was obtained by cluster analysis. The active component, quercetin, was measured using RP-HPLC. Moreover, the extracts were investigated for antifungal and anticancer assays. We report the significant antifungal potential of walnut leaf genotypes against Candida glabrata, Candida albicans, and Candida tropicalis, with 57.7–93.6%, 26.8–51.5%, and 26.8–51.5% inhibition, respectively. The most significant antiproliferative effect was shown by Opex Culchry, which exhibited 9.4% cell viability at a concentration of 25 µL (0.75 mg) against lung (A549) cell lines. Chenovo exhibited 2.9, 6.2, and 2.2% cell viability, Opex Culchry exhibited 2, 1.5, and 2.4% cell viability, and Sulieman showed 7.6, 0.9, and 7% cell viability against the colon (HCT116) cell lines. The results showed that walnut leaves possess enormous potential as antioxidants, and as anticancer and antifungal agents. Full article
(This article belongs to the Special Issue Medicinal Plants—Natural Sources of Bioactive Secondary Metabolites)
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20 pages, 4586 KiB  
Article
Bio-Growth Stimulants Impact Seed Yield Products and Oil Composition of Chia
by Heba S. El-Desouky, Reda M. Y. Zewail, Dalia Abdel-Fattah H. Selim, Morooj M. Baakdah, Doaa Mahmoud Johari, Abeer Elhakem, Yasser S. Mostafa, Saad Alamri, Rokayya Sami, Lamiaa A. S. El-Khayat, Khandakar R. Islam, Enas S. Azab and Mohamed Y. F. Yousry
Agronomy 2022, 12(11), 2633; https://doi.org/10.3390/agronomy12112633 - 26 Oct 2022
Cited by 2 | Viewed by 1813
Abstract
Chia (Salvia hispanica L.) is a specialty crop capable of providing healthy food and metabolites. The goal of our study was to explore the possibility of expanding seed yield, oil production, and metabolites of chia in response to amino acid, barthenosteriode, and algae [...] Read more.
Chia (Salvia hispanica L.) is a specialty crop capable of providing healthy food and metabolites. The goal of our study was to explore the possibility of expanding seed yield, oil production, and metabolites of chia in response to amino acid, barthenosteriode, and algae extract treatments used as bio-stimulants. The experiment was conducted in the field in a randomized complete block design with three repeats. The treatments were (1) control (spray only with water), (2) amino acids with nutrients (2 mL/L vs. 4 mL/L), (3) brassinolide (5 mL/L vs. 10 mL/L), and algae extract (2 mL/L vs. 4 mL/L). The growth and yield measurements of chia, such as chlorophyll, carotenoids, amino acids, indoles, phenols, macro- and micronutrients, carbohydrates, total oil, and fatty acids were analyzed. The chia plants sprayed with growth stimulant materials showed increases in most studied characteristics, particularly algae extract at 4 mL/L, followed by algae extract at 2 mL/L during the first and second seasons. Meanwhile, amino acids at 4 mL/L led to the third-highest increases in most cases. Conversely, all bio-stimulant treatments decreased total phenols in leaves (mg/100 g f.w.), especially seaweed at 4 mL/L, compared to high levels in the control during both seasons. Control plants showed the lowest levels of the measurements mentioned previously when scored by barthenosteriode at 5 mL/L during the first and second seasons. GLC for fixed oil in chia showed the recognition of four biocomponents. i.e., oleic, linoleic, palmitic, and α-α linolenic acids. The main biocomponent was α-α linolenic acid and reach (49.7 to 57.9%). The application of seaweed at 4 mL/L could be exploited to improve growth, seed crop, fixed oil production, chemicals and bio-constituents, especially the fixed oil composition of chia (Salvia hispanica L.) plant. Full article
(This article belongs to the Special Issue Medicinal Plants—Natural Sources of Bioactive Secondary Metabolites)
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12 pages, 653 KiB  
Article
Salicylic Acid Spraying Affects Secondary Metabolites and Radical Scavenging Capacity of Drought-Stressed Eriocephalus africanus L.
by Noha Khalil, Sameh S. Elhady, Reem M. Diri, Mostafa I. Fekry, Mokhtar Bishr, Osama Salama and Soheir M. El-Zalabani
Agronomy 2022, 12(10), 2278; https://doi.org/10.3390/agronomy12102278 - 23 Sep 2022
Cited by 10 | Viewed by 1882
Abstract
Drought is among the most common abiotic stresses that significantly influence plants’ growth and metabolic activities. In this study, Eriocephalus africanus L. (Asteraceae) was exposed to three levels of drought stress (irrigation with 75, 50, and 25% field capacity), together with foliar spraying [...] Read more.
Drought is among the most common abiotic stresses that significantly influence plants’ growth and metabolic activities. In this study, Eriocephalus africanus L. (Asteraceae) was exposed to three levels of drought stress (irrigation with 75, 50, and 25% field capacity), together with foliar spraying of a plant hormone, salicylic acid (1, 2, and 3 mM SA), to observe the effect of drought stress and SA on its secondary metabolites. These growing conditions efficiently affected its total flavonoid and polyphenol contents (TFC and TPC, respectively). TFC and TPC increased by 53% and 35%, respectively, in stressed plants. Consequently, the radical scavenging activity improved by 140%. UPLC-ESI-MS/MS profiles of the extracts of control and stressed plants were assessed. Among identified polyphenols, 3,4-dicaffeoylquinic acid predominated in both samples, although it was detected in a greater percentage of stressed plants. Essential oils hydro-distilled from the plants showed a higher yield (1.05 ± 0.03% v/w) in stressed plants. Artemisia ketone prevailed in all oil samples’ GC/MS chromatograms, with a higher yield (42%) recorded in stressed plants. In conclusion, drought stress and SA spraying triggered the production of phenolic and essential oil components and increased the radical scavenging activity of E. africanus. Thus, agricultural conditions are optimized to provide a continuous supply of plant materials with appropriate amounts of bioactive constituents for economic industrialization. Full article
(This article belongs to the Special Issue Medicinal Plants—Natural Sources of Bioactive Secondary Metabolites)
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19 pages, 1571 KiB  
Article
Essential Oil and Polyphenolic Compounds of Flourensia cernua Leaves: Chemical Profiling and Functional Properties
by Nestor E. Aranda-Ledesma, María D. González-Hernández, Romeo Rojas, Alma D. Paz-González, Gildardo Rivera, Brenda Luna-Sosa and Guillermo C. G. Martínez-Ávila
Agronomy 2022, 12(10), 2274; https://doi.org/10.3390/agronomy12102274 - 22 Sep 2022
Cited by 6 | Viewed by 2394
Abstract
Flourensia cernua is a bush that grows in the semi-desert regions of Mexico. It has been used in traditional medicine due to its healing properties and currently represents an alternative source of bioactive molecules for different areas of the agri-food and health industries. [...] Read more.
Flourensia cernua is a bush that grows in the semi-desert regions of Mexico. It has been used in traditional medicine due to its healing properties and currently represents an alternative source of bioactive molecules for different areas of the agri-food and health industries. The objective of this study was to extract and characterize the purified polyphenolic compounds (PPCs) and essential oils (EOs) of F. cernua leaves, determine the total flavonoid content, evaluate the antioxidant activity by three different assays, and determine, for the first time, its inhibitory effect against enzymes involved in the degradation of carbohydrates (α-amylase and α-glucosidase). In addition, the analysis of functional groups (by FTIR-ATR assay) and the identification of the chemical constituents present in both essential oils and phenolic compounds were carried out by GC/MS and UPLC-QToF/MS2, respectively. The results indicate that PPCs and EOs are rich in flavonoid-type compounds. In addition, they showed potential for free-radical scavenging and the inhibition of the lipid oxidation process. The analyzed EOs and PPCs had potential against α-amylase and α-glucosidase enzymes, which are related to high blood sugar levels. FTIR-ATR analysis allowed for the identification of functional groups characteristic of polyphenolic compounds and the chemical constituents of EOs. Finally, compounds such as caryophyllene, caryophyllene oxide, and germacrene-D were identified by GC/MS assay and luteolin 7-O-rutinoside and apigenin-6-C-glucosyl-8-C-arabinoside by UPLC/QToF-MS2. The results indicate that the PPCs and EOs of F. cernua have the potential to be used as antioxidant and enzyme inhibitor agents. Full article
(This article belongs to the Special Issue Medicinal Plants—Natural Sources of Bioactive Secondary Metabolites)
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24 pages, 8099 KiB  
Article
In Vitro Regeneration of Stevia (Stevia rebaudiana Bertoni) and Evaluation of the Impacts of Growth Media Nutrients on the Biosynthesis of Steviol Glycosides (SGs)
by Asish Kumar Ghose, Siti Nor Akmar Abdullah, Muhammad Asyraf Md Hatta and Puteri Edaroyati Megat Wahab
Agronomy 2022, 12(8), 1957; https://doi.org/10.3390/agronomy12081957 - 19 Aug 2022
Cited by 7 | Viewed by 3676
Abstract
A plant tissue culture protocol from stevia was optimized for the production of planting materials and the natural sweetener, rebaudioside A. The highest survivability (88.90% ± 5.55) of explants was achieved at 15 and 30 days after culture initiation (DACI) on Murashige and [...] Read more.
A plant tissue culture protocol from stevia was optimized for the production of planting materials and the natural sweetener, rebaudioside A. The highest survivability (88.90% ± 5.55) of explants was achieved at 15 and 30 days after culture initiation (DACI) on Murashige and Skoog (MS) media by sterilization with 30% Clorox (5 min) and 10% Clorox (10 min), respectively. Supplementation of MS with 0.50 mg/L 2,4-Dichlorophenoxyacetic acid (2,4-D) and 0.10 mg/L zeatin produced 50% callus at 15 DACI while 1.50 mg/L 2,4-D and 0.10 mg/L zeatin at 30 DACI increased callus production to 76.67%. The highest shoot proliferation per callus was achieved with 10.00 mg/L 6-benzyl amino purine (BAP) in MS at 15 DACI (5.80) and 30 DACI (12.33). The longest shoots of 4.31 cm and 6.04 cm at 15 and 30 DACI, respectively, were produced using BAP (10.00 mg/L) and 1.00 mg/L naphthalene acetic acid (NAA). MS media (0.50 strength) induced 2.86 and 6.20 roots per shoot and produced 3.25 cm and 7.82 cm long roots at 15 and 30 DACI, respectively. Stevia grown on 0.25 MS accumulated the highest concentration of rebaudioside A (6.53%), which correlated with the expression level of its biosynthetic gene uridine-diphosphate-dependent (UDP)-glycosyltransferase (UGT76G1). Full article
(This article belongs to the Special Issue Medicinal Plants—Natural Sources of Bioactive Secondary Metabolites)
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9 pages, 1093 KiB  
Article
Enhancing the Accumulation of Rosavins in Rhodiola rosea L. Plants Grown In Vitro by Precursor Feeding
by Aaqib Javid, Nóra Gampe, Fulea Gelana and Zsuzsanna György
Agronomy 2021, 11(12), 2531; https://doi.org/10.3390/agronomy11122531 - 13 Dec 2021
Cited by 5 | Viewed by 3434
Abstract
Rhodiola rosea produces nearly 150 bioactive compounds. Cinnamyl alcohol glycosides (CAGs) are among the most important secondary metabolites which are specific to this plant species, exhibiting adaptogenic properties along with salidroside. However, raw material supplies for the pharmaceutical industry are hindered by limited [...] Read more.
Rhodiola rosea produces nearly 150 bioactive compounds. Cinnamyl alcohol glycosides (CAGs) are among the most important secondary metabolites which are specific to this plant species, exhibiting adaptogenic properties along with salidroside. However, raw material supplies for the pharmaceutical industry are hindered by limited access to the plant material. The species is endangered and protected in many areas: cultivation is long and ineffective. Precursor feeding has been found to be an effective strategy for improving the production of secondary metabolites in various plant tissues cultures, including in Rhodiola species. In this study, whole R. rosea plants grown in vitro were subjected to three different precursor treatments, including with trans-cinnamic acid, cinnamaldehyde and cinnamyl alcohol at 2 mM concentrations. The different treatments affected the secondary metabolite production differently. Trans-cinnamic acid did not affect the synthesis significantly, which contradicts earlier studies with cell suspensions. On the other hand, cinnamyl alcohol and cinnamaldehyde were beneficial, improving the production rate of rosin and rosavin by 13.8- and 6.9-fold, and 92.7- and 8.0-fold, respectively. The significant improvement in CAG accumulation due to cinnamaldehyde treatment was unexpected based on previous studies. In addition, cinnamaldehyde triggered the production of rosarin, which the other two treatments failed to do. The study presents the beneficial application of precursors to whole plants grown in vitro. Full article
(This article belongs to the Special Issue Medicinal Plants—Natural Sources of Bioactive Secondary Metabolites)
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Review

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16 pages, 3304 KiB  
Review
Understanding the Complex Functional Interplay between Glucosinolates and Cyanogenic Glycosides in Carica papaya
by Insyirah-Hannah Ruhaizat-Ooi, Rabiatul-Adawiah Zainal-Abidin, Nur Syatila Ab Ghani, Nor Afiqah-Aleng, Hamidun Bunawan, Norfarhan Mohd-Assaad, Zeti-Azura Mohamed-Hussein and Sarahani Harun
Agronomy 2022, 12(10), 2508; https://doi.org/10.3390/agronomy12102508 - 14 Oct 2022
Cited by 4 | Viewed by 2299
Abstract
Glucosinolates (GSLs) and cyanogenic glycosides (CGs) fulfil functions in plant defence and have been reported to be anticancer agents. Generally, GSL-containing plants do not produce CG, and vice versa, CG-containing plants do not synthesise GSLs. However, the production of both GSL and CG [...] Read more.
Glucosinolates (GSLs) and cyanogenic glycosides (CGs) fulfil functions in plant defence and have been reported to be anticancer agents. Generally, GSL-containing plants do not produce CG, and vice versa, CG-containing plants do not synthesise GSLs. However, the production of both GSL and CG compounds was observed in Carica papaya. Additionally, several studies found both GSL glucotropaeolin and CG prunasin in papaya leaves. The advancement of genome technologies can be explored to elucidate the gene functions and other molecular discoveries in plants that might relate to GSLs and CGs. This review aims to discuss the complex interplay of the rare events whereby these two compounds (GSL and CG) co-occur in a bifurcation pathway in papaya. To our knowledge, this is the first review that highlights novel GSL and CG genes in papaya. Furthermore, species-specific pathways in papaya are also discussed and comprehensively described. The transcription factors involved in regulating GSL and CG biosynthesis pathways are also discussed, accompanied by relevant bioinformatic approaches that can help discover potential regulatory genes that control the production of prunasin and glucotropaeolin in papaya. Full article
(This article belongs to the Special Issue Medicinal Plants—Natural Sources of Bioactive Secondary Metabolites)
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18 pages, 2019 KiB  
Review
Adventitious Root Culture—An Alternative Strategy for Secondary Metabolite Production: A Review
by Mehrun Nisha Khanam, Mohammad Anis, Saad Bin Javed, Javad Mottaghipisheh and Dezső Csupor
Agronomy 2022, 12(5), 1178; https://doi.org/10.3390/agronomy12051178 - 13 May 2022
Cited by 18 | Viewed by 7840
Abstract
Medicinal plants are valuable sources of botanical drugs, extracts and pure compounds. Although several species can be propagated or collected, the access to herbal material is limited in certain cases. The protection of natural habitats and biodiversity demands new sources to provide plant [...] Read more.
Medicinal plants are valuable sources of botanical drugs, extracts and pure compounds. Although several species can be propagated or collected, the access to herbal material is limited in certain cases. The protection of natural habitats and biodiversity demands new sources to provide plant secondary metabolites of medical importance. Adventitious root culture is used to harvest the secondary metabolites from the medicinally important plants, thereby offering an alternative to collection and propagation of medicinal plants. In this review, we comprehensively summarize the previously published data on the use of adventitious root cultures for numerous therapeutic plants. Adventitious roots showed elevated growth rates and production of pharmaceutically important metabolites under sterilized condition with optimized plant-growth regulators in culture media. In the present study, major influencing factors, such as the stages involved in the process of adventitious root formation, medium composition and type of growth regulators, specifically the effect of different auxins on the initiation and formation of roots, are discussed. Elicitation strategies using biotic (yeast extracts, chitosan and pectin) and abiotic factors (MJ, SA, CuSO4, AgNO3, NaCl) that affect the in vitro growth of adventitious roots and the role of bioreactors, which are new advancements in the scale-up process, are also highlighted. The development of adventitious root cultures for the production of secondary metabolites of medicinal importance is a perspective that is advantageous from ecological and economical aspects as well. Full article
(This article belongs to the Special Issue Medicinal Plants—Natural Sources of Bioactive Secondary Metabolites)
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