Flavonoids: Secondary Metabolites with Multifunctional Biological Properties

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

Deadline for manuscript submissions: closed (30 November 2021) | Viewed by 36739

Special Issue Editors


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Guest Editor
Department of Chemical, Biological, Pharmaceutical and Environmental Science, University of Messina, 98168 Messina, Italy
Interests: antimicrobials; nutraceuticals; in vitro digestion; nutrients and phytochemicals release; gut health
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Special Issue Information

Dear Colleagues,

Flavonoids are promising secondary metabolites with several biological properties. The search for molecules which are able to increase organism wellness and to reduce the incidence of chronic diseases is starting to shed light on this class of compounds, along with their low toxicity and side effects. Significant progress has been made over the past few decades as far as the promising properties of flavonoids are concerned, but a lot must still be investigated due to the unquestionable link of these molecules with the well-being of organisms (both the producers and the consumers). There is an abundant class of secondary metabolites present in fruits and vegetables and their agro-industrial transformation products (such as beverages, soft and energy drinks, jams, and so on). These compounds can modulate the intracellular signal cascade and, in addition to their antioxidant activity, they can be utilized to promote cell survival or death with a well-defined target of action. USDA, NIH and several other government and health agencies encourage people to eat a variegated and healthy balanced diet, mainly rich in fruits and vegetables, taking into account the potential health promoting properties of the natural compounds present in these complex matrices. Among these molecules, flavonoids are one of the most interesting and representative molecules, produced by plants to enhance their wellness and to overcome environmental and biological stresses. These molecules, for instance, protect plants against fungi and insects’ infections, or from UV radiation, changes in salinity, or temperature. Taken together, these characteristics make the daily assumptions of vegetables a natural defence weapon to maintain the organisms in a healthy state. Plants are complex matrices of flavonoids, and their synergistic action can further increase their potentiality on living organisms, occasionally with effects which are difficult to obtain with pure compounds. Moreover, they showed inhibitory or stimulatory effects on key metabolic enzymes influencing gene expressions, cellular properties and signaling pathways.  This Special Issue aims to collect the recent update on biological potentials and identify novel compounds belonging to this class of molecules. Therefore, it can be considered a landmark for experts in the field.

Prof. Dr. Davide Barreca
Dr. Giuseppina Mandalari
Guest Editors

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Keywords

  • flavonoids
  • antioxidants
  • free radicals
  • activation/block of signal cascade
  • antioxidant modulation of key metabolic enzymes
  • oxidative stress
  • hydrogen atom transfer
  • single electron transfer
  • antioxidant assays
  • biological potentials
  • antimicrobial activity
  • antiviral potential
  • environmental and biological stresses
  • protection against fungi and insects infections
  • protection against UV radiation, changes in salinity or temperature
  • anticancer activity antiaggregrative activity
  • anti-inflammatory activity

Published Papers (7 papers)

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Research

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14 pages, 1580 KiB  
Article
Phytochemical Characterization and Evaluation of Biological Activities of Egyptian Carob Pods (Ceratonia siliqua L.) Aqueous Extract: In Vitro Study
by Wael Sobhy Darwish, Abada El Sayed Khadr, Maher Abd El Naby Kamel, Mabrouk A. Abd Eldaim, Ibrahim El Tantawy El Sayed, Hamed Mohamed Abdel-Bary, Sami Ullah and Doaa Ahmed Ghareeb
Plants 2021, 10(12), 2626; https://doi.org/10.3390/plants10122626 - 29 Nov 2021
Cited by 12 | Viewed by 3154
Abstract
Ceratonia siliqua (Carob) is an evergreen Mediterranean tree, and carob pods are potentially nutritive and have medicinal value. The present study was carried out to estimate the possible biological activities of phytochemical-characterized carob pod aqueous extract (CPAE). The phytochemical contents of CPAE were [...] Read more.
Ceratonia siliqua (Carob) is an evergreen Mediterranean tree, and carob pods are potentially nutritive and have medicinal value. The present study was carried out to estimate the possible biological activities of phytochemical-characterized carob pod aqueous extract (CPAE). The phytochemical contents of CPAE were determined by using colorimetric methods and HPLC. In addition, the free radical scavenging properties and anti-diabetic, anti-hemolytic, and antimicrobial activities were estimated by using standardized in vitro protocols. The phytochemical analysis revealed that CPAE was rich in polyphenols, flavonoids, and alkaloids, where it contained a significant amount of gallic acid, catechin, and protocatechuic acid. Furthermore, CPAE exhibited strong antioxidant activity where it prevented the formation of 2, 2-Diphenyl-1-picryl hydrazyl, hydroxyl, and nitric oxide free radicals. Additionally, it had a potent inhibitory effect against digestive enzymes (amylase, maltase, sucrase, and lactase). Moreover, CPAE exhibited anti-Staph aureus, anti-Escherichia coli, anti-Candida albicans, and anti-herpes simplex type I virus (HSV-I). Finally, CPAE protected the erythrocyte membrane from hypotonic solution-induced hemolysis. Altogether, CPAE could be regarded as an interesting source of biologically active antioxidant, anti-diabetic, and antimicrobial preparation for a potential application in pharmaceutical and food supplement fields. Full article
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18 pages, 9620 KiB  
Article
Assessment and Classification of Volatile Profiles in Melon Breeding Lines Using Headspace Solid-Phase Microextraction Coupled with Gas Chromatography-Mass Spectrometry
by Drishti Majithia, Rita Metrani, Nitin Dhowlaghar, Kevin M. Crosby and Bhimanagouda S. Patil
Plants 2021, 10(10), 2166; https://doi.org/10.3390/plants10102166 - 13 Oct 2021
Cited by 8 | Viewed by 3414
Abstract
Cucumis melo L is one of the most commercial and economical crops in the world with several health beneficial compounds as such carotenoids, amino acids, vitamin A and C, minerals, and dietary fiber. Evaluation of the volatile organic compounds (VOCs) in different melon [...] Read more.
Cucumis melo L is one of the most commercial and economical crops in the world with several health beneficial compounds as such carotenoids, amino acids, vitamin A and C, minerals, and dietary fiber. Evaluation of the volatile organic compounds (VOCs) in different melon (Cucumis melo L.) breeding lines provides useful information for improving fruit flavor, aroma, and antimicrobial levels. In this study, the VOCs in 28 melon breeding lines harvested in 2019 were identified and characterized using head space solid-phase microextraction (HS-SPME) coupled with gas chromatography-mass spectrometry (GC-MS). This identified 113 VOCs with significant differences in composition and contents of among the breeding lines, including 15 esters, 27 aldehydes, 35 alcohols, 14 ketones, 4 acids, 10 hydrocarbons, 5 sulfurs, and 3 other compounds. The highest average contents of all the VOCs were found in BL-30 (13,973.07 µg/kg FW) and the lowest were in BL-22 (3947.13 µg/kg FW). BL-9 had high levels of carotenoid-derived VOCs. The compounds with the highest contents were benzaldehyde, geranylacetone, and β-ionone. Quality parameters such as color and sugar contents of melons were also measured. All the melon color readings were within the typical acceptable range. BL-22 and BL-14 had the highest and lowest sugar contents, respectively. Principal component analysis (PCA) produced diverse clusters of breeding lines based on flavor and aroma. BL-4, BL-7, BL-12, BL-20, and BL-30 were thus selected as important breeding lines based on their organoleptic, antimicrobial, and health-beneficial properties. Full article
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21 pages, 1525 KiB  
Article
Nutritional Composition and Health Benefits of Various Botanical Types of Melon (Cucumis melo L.)
by Shivapriya Manchali, Kotamballi N. Chidambara Murthy, Vishnuvardana and Bhimanagouda S. Patil
Plants 2021, 10(9), 1755; https://doi.org/10.3390/plants10091755 - 24 Aug 2021
Cited by 23 | Viewed by 5854
Abstract
Characterizing the diverse melon cultivars for nutrition aids in crop improvement and promoting a healthy diet. Here, we used in vitro assays to characterize the nutritional qualities and health-beneficial effects of 30 melon (Cucumis melo L.) genotypes, including 10 improved cultivars, 16 [...] Read more.
Characterizing the diverse melon cultivars for nutrition aids in crop improvement and promoting a healthy diet. Here, we used in vitro assays to characterize the nutritional qualities and health-beneficial effects of 30 melon (Cucumis melo L.) genotypes, including 10 improved cultivars, 16 landraces, and 4 wild types collected from different parts of India. Two landraces (Sidoota and Alper Green) had the highest (12.20 and 11.25) total soluble solids (TSS) contents. The Sidoota and Pappusa landraces had high reducing sugar contents (2.84 and 2.81 mg g−1 fresh weight [FW]). The highest polyphenols contents (22.0 mg g−1 FW) were observed in the landraces Mage Kaayi-2, Budamekaayi, and Small Melon. Reflecting on the primary and secondary metabolite contents, the Mekke Kaayi and Giriyala landraces exhibited high 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging activity (97.6 and 91% at 100 μg mL−1). Additionally, seven of the landraces showed significant nitric oxide (NO) induction activity (>80% inhibition at 200 μg mL−1), indicating their potential health benefits, and seven showed considerable angiotensin-converting enzyme (ACE) inhibition activity (highest in Kashi Madhu), indicating their potential usefulness in reducing hypertension. Genotypes with high health beneficial compounds identified in this study can be used for breeding improved melon cultivars to promote these fruits as well as a healthy diet. Full article
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13 pages, 2419 KiB  
Article
Himalayan Ficus palmata L. Fruit Extract Showed In Vivo Central and Peripheral Analgesic Activity Involving COX-2 and Mu Opioid Receptors
by Devesh Tewari, Pawan Gupta, Sweta Bawari, Archana N. Sah, Davide Barreca, Maryam Khayatkashani and Hamid Reza Khayat Kashani
Plants 2021, 10(8), 1685; https://doi.org/10.3390/plants10081685 - 16 Aug 2021
Cited by 7 | Viewed by 3602
Abstract
Analgesic drugs like morphine and non-steroidal anti-inflammatory drugs exhibit several harmful effects. Here, we show for the first time the analgesic activity of Ficus palmata L. fruit extract (FPFE) on different analgesic rat models along with the in silico studies of some of [...] Read more.
Analgesic drugs like morphine and non-steroidal anti-inflammatory drugs exhibit several harmful effects. Here, we show for the first time the analgesic activity of Ficus palmata L. fruit extract (FPFE) on different analgesic rat models along with the in silico studies of some of the main phytochemicals of this plant. We performed in vivo pain models, along with in silico docking studies against the active site of COX-2 protein and mu-opioid receptors. A significant (p < 0.05) analgesic effect of FPFE was observed, and it was found that rutin has good pose and score as compared to diclofenac and morphinan antagonist (X-ligand), and psoralen has binding affinity almost equal to diclofenac, but a lower binding affinity as compared to rutin. The results proved that F. palmata fruits have the potential to ameliorate painful conditions. Full article
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15 pages, 1553 KiB  
Article
Optimization of Extraction Solvent and Fast Blue BB Assay for Comparative Analysis of Antioxidant Phenolics from Cucumis melo L.
by Varsha Ravindranath, Jashbir Singh, Guddarangavvanahally K. Jayaprakasha and Bhimanagouda S. Patil
Plants 2021, 10(7), 1379; https://doi.org/10.3390/plants10071379 - 06 Jul 2021
Cited by 9 | Viewed by 3062
Abstract
Melon (Cucumis melo L.) fruits contain multiple health-promoting compounds, including phenolic compounds, which are antioxidants. Accurate measurement of antioxidant activities and total phenolic contents (TPCs) require an efficient solvent extraction. In this study, we evaluated free radical scavenging activity and TPC of [...] Read more.
Melon (Cucumis melo L.) fruits contain multiple health-promoting compounds, including phenolic compounds, which are antioxidants. Accurate measurement of antioxidant activities and total phenolic contents (TPCs) require an efficient solvent extraction. In this study, we evaluated free radical scavenging activity and TPC of melon extracts extracted with 22 different solvent combinations. The DPPH scavenging activities were high in 100% methanolic (39.48 ± 0.36 µg g−1) and 80% methanolic extracts (38.99 ± 0.44 µg g−1). Similarly, the ABTS scavenging activities were high in 100% methanolic (315.11 ± 10.38 µg g−1) and 80% methanol extracts (297.39 ± 14.98 µg g−1). The Folin–Ciocalteu (F–C) assay is typically used to measure TPC but may be affected by interference from sugars and other compounds. Therefore, we optimized an assay for TPC using Fast Blue (FB) salt and developed a standard operating procedure for microplate analysis using FB. Our analysis of standard samples and comparisons with the F–C assay suggested that the optimized FB assay could be used to measure TPC in fruit and juice samples. Moreover, we successfully detected six phenolic compounds in methanol extracts of melon by LC-HR-QTOF/MS. Full article
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19 pages, 2821 KiB  
Article
High Throughput Profiling of Flavonoid Abundance in Agave lechuguilla Residue-Valorizing under Explored Mexican Plant
by Zoé P. Morreeuw, David Castillo-Quiroz, Leopoldo J. Ríos-González, Raúl Martínez-Rincón, Norma Estrada, Elda M. Melchor-Martínez, Hafiz M. N. Iqbal, Roberto Parra-Saldívar and Ana G. Reyes
Plants 2021, 10(4), 695; https://doi.org/10.3390/plants10040695 - 03 Apr 2021
Cited by 15 | Viewed by 3187
Abstract
Agave lechuguilla waste biomass (guishe) is an undervalued abundant plant material with natural active compounds such as flavonoids. Hence, the search and conservation of flavonoids through the different productive areas have to be studied to promote the use of this agro-residue [...] Read more.
Agave lechuguilla waste biomass (guishe) is an undervalued abundant plant material with natural active compounds such as flavonoids. Hence, the search and conservation of flavonoids through the different productive areas have to be studied to promote the use of this agro-residue for industrial purposes. In this work, we compared the proportion of total flavonoid content (TFC) among the total polyphenolics (TPC) and described the variation of specific flavonoid profiles (HPLC-UV-MS/MS) of guishe from three locations. Descriptive environmental analysis, using remote sensing, was used to understand the phytochemical variability among the productive regions. Furthermore, the effect of extractive solvent (ethanol and methanol) and storage conditions on specific flavonoid recovery were evaluated. The highest TPC (16.46 ± 1.09 GAE/g) was observed in the guishe from region 1, which also had a lower normalized difference water index (NDWI) and lower normalized difference vegetation index (NDVI). In contrast, the TFC was similar in the agro-residue from the three studied areas, suggesting that TFC is not affected by the studied environmental features. The highest TFC was found in the ethanolic extracts (6.32 ± 1.66 QE/g) compared to the methanolic extracts (3.81 ± 1.14 QE/g). Additionally, the highest diversity in flavonoids was found in the ethanolic extract of guishe from region 3, which presented an intermedia NDWI and a lower NDVI. Despite the geo-climatic induced variations of the phytochemical profiles, the results confirm that guishe is a valuable raw material in terms of its flavonoid-enriched bioactive extracts. Additionally, the bioactive flavonoids remain stable when the conditioned agro-residue was hermetically stored at room temperature in the dark for nine months. Finally, the results enabled the establishment of both agro-ecological and biotechnological implications. Full article
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Review

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21 pages, 6129 KiB  
Review
Pistachio Nuts (Pistacia vera L.): Production, Nutrients, Bioactives and Novel Health Effects
by Giuseppina Mandalari, Davide Barreca, Teresa Gervasi, Michael A. Roussell, Bob Klein, Mary Jo Feeney and Arianna Carughi
Plants 2022, 11(1), 18; https://doi.org/10.3390/plants11010018 - 22 Dec 2021
Cited by 49 | Viewed by 13003
Abstract
Epidemiological and clinical studies have indicated positive outcomes related to tree nut consumption. Here, we review the production, nutrient, phytochemical composition and emerging research trends on the health benefits of pistachio nuts (Pistacia vera L.). Pistachios are a good source of protein, [...] Read more.
Epidemiological and clinical studies have indicated positive outcomes related to tree nut consumption. Here, we review the production, nutrient, phytochemical composition and emerging research trends on the health benefits of pistachio nuts (Pistacia vera L.). Pistachios are a good source of protein, fiber, monounsaturated fatty acids, minerals and vitamins, as well as carotenoids, phenolic acids, flavonoids and anthocyanins. Polyphenols in pistachios are important contributors to the antioxidant and anti-inflammatory effect, as demonstrated in vitro and in vivo through animal studies and clinical trials. The antimicrobial and antiviral potential of pistachio polyphenols has also been assessed and could help overcome drug resistance. Pistachio consumption may play a role in cognitive function and has been associated with a positive modulation of the human gut microbiota and beneficial effects on skin health. Pistachio polyphenol extracts may affect enzymes involved in glucose regulation and so type 2 diabetes. Taken together, these data demonstrate the health benefits of including pistachios in the diet. Further studies are required to investigate the mechanisms involved. Full article
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