Plant Polyphenols: Structure, Occurrence and Bioactivity

Puerarin-A Promising Flavonoid: Biosynthesis, Extraction Methods, Analytical Techniques, and Biological Effects

Flavonoids, a variety of plant secondary metabolites, are known for their diverse biological activities. Isoflavones are a subgroup of flavonoids that have gained attention for their potential health benefits. Puerarin is one of the bioactive isoflavones found in the Kudzu root and Pueraria genus, which is widely used in alternative Chinese medicine, and has been found to be effective in treating chronic conditions like cardiovascular diseases, liver diseases, gastric diseases, respiratory diseases, diabetes, Alzheimer's disease, and cancer. Puerarin has been extensively researched and used in both scientific and clinical studies over the past few years. The purpose of this review is to provide an up-to-date exploration of puerarin biosynthesis, the most common extraction methods, analytical techniques, and biological effects, which have the potential to provide a new perspective for medical and pharmaceutical research and development.

Using Subcritical Water to Obtain Polyphenol-Rich Extracts with Antimicrobial Properties

The use of green extraction methods that meet the criteria of sustainable and environmentally friendly technologies has been increasing in recent decades due to their many benefits. In this respect, extracts obtained using subcritical water are also gaining increased attention because of their potential antioxidant and antimicrobial properties. Their antimicrobial activity is mainly due to the presence of various polyphenolic compounds. Although the exact mechanism of the antibacterial action of polyphenolic compounds has not yet been fully investigated and described, polyphenols are known to affect the bacterial cell at several cellular levels; among other things, they cause changes and ruptures in the cell membranes of the bacterial cell, affect the inactivation of bacterial enzymes and damage bacterial DNA. The difference in the strength of the antimicrobial activity of the extracts is most likely a result of differences in their lipophilicity and in the number and position of hydroxyl groups and double bonds in the chemical structure of polyphenols. By changing the extraction conditions, especially the temperature, during subcritical water extraction, we affect the solubility of the compounds we want to extract. In general, as the temperature increases, the solubility of polyphenolic compounds also increases, and the reduction of the surface tension of subcritical water at higher temperatures also enables faster dissolution of polyphenolic compounds. Different bacterial strains have different sensitivity to different extracts. However, extracts obtained with subcritical water extraction demonstrate strong antimicrobial activity compared to extracts obtained with conventional methods.

A narrative review on therapeutic potential of naringenin in colorectal cancer: Focusing on molecular and biochemical processes

Colorectal cancer (CRC) is a common and highly metastatic cancer affecting people worldwide. Drug resistance and unwanted side effects are some of the limitations of current treatments for CRC. Naringenin (NAR) is a naturally occurring compound found in abundance in various citrus fruits such as oranges, grapefruits, and tomatoes. It possesses a diverse range of pharmacological and biological properties that are beneficial for human health. Numerous studies have highlighted its antioxidant, anticancer, and anti-inflammatory activities, making it a subject of interest in scientific research. This review provides a comprehensive overview of the effects of NAR on CRC. The study's findings indicated that NAR: (1) interacts with estrogen receptors, (2) regulates the expression of genes related to the p53 signaling pathway, (3) promotes apoptosis by increasing the expression of proapoptotic genes (Bax, caspase9, and p53) and downregulation of the antiapoptotic gene Bcl2, (4) inhibits the activity of enzymes involved in cell survival and proliferation, (5) decreases cyclin D1 levels, (6) reduces the expression of cyclin-dependent kinases (Cdk4, Cdk6, and Cdk7) and antiapoptotic genes (Bcl2, x-IAP, and c-IAP-2) in CRC cells. In vitro CDK2 binding assay was also performed, showing that the NAR derivatives had better inhibitory activities on CDK2 than NAR. Based on the findings of this study, NAR is a potential therapeutic agent for CRC. Additional pharmacology and pharmacokinetics studies are required to fully elucidate the mechanisms of action of NAR and establish the most suitable dose for subsequent clinical investigations.

A mechanistic review of the pharmacological potential of narirutin: a dietary flavonoid

Flavanones, a type of polyphenol, are found in substantial amounts in citrus fruits. When high- or moderate-dose orange juice consumption occurs, flavanones make up a significant portion of the total polyphenols in plasma. Disaccharide derivative narirutin, mainly dihydroxy flavanone, is found in citrus fruits. The substantial chemotherapeutic potential of narirutin has been amply demonstrated by numerous experimental studies. Consequently, the purpose of this study is to compile the research that has already been done showing narirutin to be a promising anticancer drug, with its mechanism of action being documented in treatment plans for various cancer forms. Narirutin functions in a variety of cancer cells by regulating several pathways that include cell cycle arrest, apoptosis, antiangiogenic, antimetastatic, and DNA repair. Narirutin has been shown to modify many molecular targets linked to the development of cancer, including drug transporters, cell cycle mediators, transcription factors, reactive oxygen species, reactive nitrogen species, and inflammatory cytokines. Taken together, these reviews offer important new information about narirutin's potential as a potent and promising drug candidate for use in medicines, functional foods, dietary supplements, nutraceuticals, and other products targeted at improving the treatment of cancer.

Inhibition of pro-inflammatory cytokines by selected southern African medicinal plants in LPS-stimulated RAW 264.7 macrophages

ETHNOPHARMACOLOGICAL RELEVANCE

Bark is frequently used in southern African traditional medicine to treat inflammation, yet it remains to be rigorously examined for its immunological and anti-inflammatory activity.

AIM OF THE STUDY

Barks obtained from ten important and popular southern Africa plants were evaluated for their anti-inflammatory and immunomodulatory properties against the secretion of some pro-inflammatory cytokines (interleukin (IL)-1β, IL-6, tumour necrosis factor-α (TNF-α), and interferon-gamma (IFN-γ) as well as chemokines (monocyte chemoattractant protein 1 (MCP-1) and macrophage inflammatory protein (MIP)-2) in murine RAW 264.7 macrophages.

MATERIALS AND METHODS

The inhibitory effects of aqueous and ethanol extracts were determined using cytokine multiplex-bead assays in lipopolysaccharide (LPS)-stimulated and unstimulated RAW 264.7 cells.

RESULTS

Overall, the ethanol extracts were more potent cytokine inhibitors compared to the aqueous extracts. The LPS-stimulated cells treated with the ethanol extracts of Erythrina lysistemon Hutch., Pterocelastrus rostratus Walp. Syzygium cordatum Hochst. ex Krauss and Warburgia salutaris (G. Bertol.) Chiov., demonstrated significant (p < 0.005) inhibition up to 85% of IL-1β, IL-6, and TNF-α secretion compared to the LPS control. Additionally, P. rostratus and S. cordatum aqueous bark extracts substantially decreased the secretion of all the tested cytokines and chemokines. Chemical investigation of the S. cordatum extract resulted in the identification of four ellagic acid derivatives: ellagic acid 4-O-α-rhamnopyranoside (1), ellagic acid 4-O-α-4″-acetylrhamnopyranoside (2), 3-O-methylellagic acid 4'-O-α-3″-O-acetylrhamnopyranoside (3) and 3-O-methylellagic acid 4'-O-α-4″-O-acetylrhamnopyranoside (4), along with mixtures of ellagic acid 4-O-α-2″-acetylrhamnopyranoside (5), ellagic acid 4-O-α-3″-acetylrhamnopyranoside (6) and ellagic acid (7). Their structures were confirmed by mass spectrometry, NMR spectroscopy, and comparison with data from literature.

CONCLUSION

The cytokine inhibition properties of most of the medicinal plants screened herein are reported for the first time. Our results provide insights into the mechanism of action by which the selected southern African medicinal plants regulate inflammation.

Comprehensive Extraction and Chemical Characterization of Bioactive Compounds in Tepals of Crocus sativus L

Crocus sativus L. is largely cultivated because it is the source of saffron, a well-appreciated and valued spice, not only for its culinary use but also because of its significant biological activities. Stigmas are the main product obtained from flowers, but in addition, tepals, largely considered a waste product, represent a big source of flavonoids and anthocyanins. This study aimed to delve into the phytochemical composition of saffron tepals and investigate whether the composition was influenced by the extraction technique while investigating the main analytical techniques most suitable for the characterization of tepal extracts. The research focuses on flavonoids, a class of secondary metabolites, and their health benefits, including antioxidant, anti-inflammatory, and anticancer properties. Flavonoids occur as aglycones and glycosides and are classified into various classes, such as flavones, flavonols, and flavanones. The most abundant flavonoids in tepals are kaempferol glycosides, followed by quercetin and isorhamnetin glycosides. Overall, this review provides valuable insights into the potential uses of tepals as a source of bioactive compounds and their applications in various fields, promoting a circular and sustainable economy in saffron cultivation and processing.

Flavonoids: Overview of Biosynthesis, Biological Activity, and Current Extraction Techniques

Recently, increased attention has been paid to natural sources as raw materials for the development of new added-value products. Flavonoids are a large family of polyphenols which include several classes based on their basic structure: flavanones, flavones, isoflavones, flavonols, flavanols, and anthocyanins. They have a multitude of biological properties, such as anti-inflammatory, antioxidant, antiviral, antimicrobial, anticancer, cardioprotective, and neuroprotective effects. Current trends of research and development on flavonoids relate to identification, extraction, isolation, physico-chemical characterization, and their applications to health benefits. This review presents an up-to-date survey of the most recent developments in the natural flavonoid classes, the biological activity of representative flavonoids, current extraction techniques, and perspectives.

Invasive Alien Species as a Potential Source of Phytopharmaceuticals: Phenolic Composition and Antimicrobial and Cytotoxic Activity of Robinia pseudoacacia L. Leaf and Flower Extracts

Black locust (Robinia pseudoacacia L.), an invasive tree in Europe, commonly known for its negative impact on biodiversity, is a rich source of phenolic compounds recognized in traditional medicine. Since the metabolite profile depends on the environment and climate, this study aimed to provide the first LC-MS phytochemical screening of the black locust from the Istria region (Croatia). The compounds were extracted from leaves and flowers with 70% ethanol and 80% methanol. Total phenolics (TP) and flavonoids (TF), as well as antioxidant capacity (AC) measured by ABTS (17.49-146.41 mg TE/g DW), DPPH (24.67-118.49 mg TE/g DW), and FRAP (7.38-77.53 mg TE/g DW) assays, were higher in leaf than in flower extracts. Higher TP and total non-flavonoid (TNF) values were displayed in ethanolic than in methanolic extracts. In total, 64 compounds were identified, of which flavonols (20) and hydroxycinnamic acid derivatives (15) were the most represented. Flavanols such as catechin dominated in leaf extracts, followed by flavonols, with kaempferol glucuronyl rhamnosyl hexosides as the main compound, respectively. Flower extracts had the highest share of flavones, followed by ellagitannins, with luteolin dirhamnosyl hexosides and vescalagin, respectively, being predominant. The extracts had good quorum sensing, biofilm formation prevention, and eradicating capacity. The results provided new insights into the phytochemical properties of R. pseudoacacia as the first step toward its potential pharmaceutical use.

Green Assessment of Phenolic Acid Composition and Antioxidant Capacity of Advanced Potato Mutant Lines through UPLC-qTOF-MS/MS Quantification

Potatoes are one of the most consumed crops worldwide. They contain a high amount of bioactive compounds such as phenolic compounds and vitamins with important antioxidant activities, which makes this crop of high biological value for human health. The goal of this research was to biochemically evaluate polyphenol levels and antioxidant capacities in parent and control genotypes compared to advanced mutant potato lines in the M₁V₈ generation. This will reveal the genetic changes that result from induced mutagenesis. The quantified compounds and the evaluated antioxidant activity boost the health benefits of consuming the improved mutant potatoes. In the present study, the phenolic composition and antioxidant activity of eighteen mutant and initial potato genotypes were analyzed by UPLC-qTOF-MS/MS and the ORAC method, respectively. In each of the hybrid combinations, mutant lines with an improved phenolic compound profile were observed. Representative samples from the third hybrid combination had notable increases in phenolic compound concentrations, as well as the presence of metabolites not found in the parental lines. With one exception, the remaining nine mutants showed significantly higher antioxidant capacities. The results will be used in future potato breeding programs, with participation of the valuable mutant lines containing new phenolic substances not present in the initial genotypes.

A Review of Classification, Biosynthesis, Biological Activities and Potential Applications of Flavonoids

Flavonoids represent the main class of plant secondary metabolites and occur in the tissues and organs of various plant species. In plants, flavonoids are involved in many biological processes and in response to various environmental stresses. The consumption of flavonoids has been known to reduce the risk of many chronic diseases due to their antioxidant and free radical scavenging properties. In the present review, we summarize the classification, distribution, biosynthesis pathways, and regulatory mechanisms of flavonoids. Moreover, we investigated their biological activities and discuss their applications in food processing and cosmetics, as well as their pharmaceutical and medical uses. Current trends in flavonoid research are also briefly described, including the mining of new functional genes and metabolites through omics research and the engineering of flavonoids using nanotechnology. This review provides a reference for basic and applied research on flavonoid compounds.

Monitoring the curing efficiency of a plant-based green engineered additive on caprine skin: a spectroscopic and chemometric novel approach

Environmental sustainability in industrial processing is one of the most fundamental requirements for sustainable development. The leather industry is known for its vast environmental pollution. But, green engineering may occur a paradigm shift in this sector. Plant-based goatskins curing is a cutting-edge green technology that holds the concept of pollution reduction through prevention on the upper stream of leather processing. The successful and rapid monitoring of the efficiency of this technology is the foremost demand for mass-level applications. In this study, ATR-FTIR spectroscopy was employed to monitor this technology's efficiency using a plant Polygonum hydropiper. Chemometrics was also applied to extract information from spectral data leading to an understanding of the inherent effect of studying preservatives on goatskins collagen chemistry. 10% plant-paste +5% NaCl, 10% plant-paste +10% NaCl, and 15% plant-paste +5% NaCl on goatskin were assessed by ATR-FTIR on 0th, 10th, and 30th days of preservation. The Spectral peak fitting (R² = 0.99) area of amide I and II of collagen peptide bands revealed 2.73 to 1.33 times more structural suitability of studied goatskins than the control. Principal component analysis and Hierarchical cluster analysis showed that, after 30 days of curing, 15% paste +5% salt-rubbed goatskin collagen matrix significantly (around 50%) interacted with P. hydropiper. The interaction was superficial, as it happened before the opening up of collagen fibers. In conclusion, ATR-FTIR spectroscopy with Chemometrics can be an effective tool in evaluating the efficiency of goatskin curing and understanding the entire effect on collagen chemistry quickly.

Characterization of some Fagaceae kernels nutritional composition for potential use as novel food ingredients

The present study attempts to characterise Fagaceae kernels as a promising source of nutritional compounds for potential use as novel food ingredients. Thus, the proximate and mineral composition of some kernels (beech achene-BA, sessile oak acorn-SOA, turkey oak acorn-TOA, and red oak acorn-ROA), total phenolic content, individual polyphenols, and cytotoxicity of their aqueous extracts, respectively, the fatty acid composition of kernel oils were investigated using physicochemical and analytical techniques. Results revealed that BAK is rich in lipid and protein, OAKs in carbohydrates. All tested kernels contain high oleic-linoleic acid oils. BAK is abundant in phenolic acids, OAKs in hydrolysable tannins. Only BA and SOA kernels exert cytotoxicity against human fibroblasts. In all kernels, macroelements are dominated by K and microelements by Cu, Mn, and Fe. In conclusion, BA and OA kernels could be alternatively used as protein-rich, respectively, starch-rich ingredients in food.

A mini-review on plant-derived phenolic compounds with particular emphasis on their possible applications and beneficial uses in aquaculture

The use of most antibiotics has been restricted and banned in finfish and shrimp farms due to several reasons comprising their long-lasting persistence in aquatic environments, relatively high prices, and their ability to promote the existence of antibiotic-resistant bacteria. Hence, finding economical, natural, and environmentally safe alternatives is of great importance. The use of polyphenols, polyphenol-rich plants, and plant-derived phenolic compounds for promoting aquatic animal health and welfare could be from the effective strategies for developing aquafeed and maintaining the sustainability of the aquaculture industry. Several plants are gorgeous in various bioactive functional ingredients known as phytochemicals and polyphenols. Phenolic compounds could be successfully used as natural immunostimulants in order to raise the immunity of finfish and shrimp species against several bacterial, viral, and parasitic infections and thus may replace the use of antimicrobial agents. Besides their potential roles for improvement of the growth performance, intestinal health, and enhancing the antioxidant capacity of the treated animals. Even though the trend of using plant-derived phenolic compounds is a new and leading era for the improvement of the functionality of aquafeed and the development of the aquaculture industry, there are fundamental needs and necessities to describe a clear understanding of their modes of action and potential roles in the improvement of the production rates, antioxidant activity, immune status, and disease resistance of farmed fish and shrimp.

Seaweed metabolomics: A review on its nutrients, bioactive compounds and changes in climate change

Seaweed, an important food resource in several Asian countries, contains various metabolites, including sugars, organic acids, and amino acids; however, their content is affected by prevailing environmental conditions. This review discusses seaweed metabolomics, especially the distribution of primary and functional secondary metabolites (e.g., carotenoids, polyphenols) in seaweed. Additionally, the effects of global warming on seaweed metabolite profile changes are discussed. For example, high temperatures can increase amino acid levels in seaweeds. Overall, understanding the effects of global warming on seaweed metabolite profiles can be useful for evaluating the nutritional composition of seaweeds as food. This review provides an overview of recent applications of metabolomics in seaweed research as well as a perspective on the nutrient content and cultivation of seaweeds under climate change scenarios.

Naringin and Naringenin Polyphenols in Neurological Diseases: Understandings from a Therapeutic Viewpoint

The glycosides of two flavonoids, naringin and naringenin, are found in various citrus fruits, bergamots, tomatoes, and other fruits. These phytochemicals are associated with multiple biological functions, including neuroprotective, antioxidant, anticancer, antiviral, antibacterial, anti-inflammatory, antiadipogenic, and cardioprotective effects. The higher glutathione/oxidized glutathione ratio in 3-NP-induced rats is attributed to the ability of naringin to reduce hydroxyl radical, hydroperoxide, and nitrite. However, although progress has been made in treating these diseases, there are still global concerns about how to obtain a solution. Thus, natural compounds can provide a promising strategy for treating many neurological conditions. Possible therapeutics for neurodegenerative disorders include naringin and naringenin polyphenols. New experimental evidence shows that these polyphenols exert a wide range of pharmacological activity; particular attention was paid to neurodegenerative diseases such as Alzheimer's and Parkinson's diseases, as well as other neurological conditions such as anxiety, depression, schizophrenia, and chronic hyperglycemic peripheral neuropathy. Several preliminary investigations have shown promising evidence of neuroprotection. The main objective of this review was to reflect on developments in understanding the molecular mechanisms underlying the development of naringin and naringenin as potential neuroprotective medications. Furthermore, the configuration relationships between naringin and naringenin are discussed, as well as their plant sources and extraction methods.

Effect of quercetin and Abelmoschus esculentus (L.) Moench on lipids metabolism and blood glucose through AMPK-α in diabetic rats (HFD/STZ)

Phosphoenolpyruvate carboxykinase (PEPCK) is a key enzyme in the glyconeogenesis pathway. The AMP-activated protein kinase alpha (AMPK-α) pathway regulates PEPCK, which itself is activated by the AMP/ATP ratio and liver kinase B1 (KB1). The Abelmoschus esculentus (L.) Moench (okra) plant contains a large amount of quercetin that can function as an agonist or an antagonist. The aim of this study was to examine the effects of quercetin flavonoid and A. esculentus extract on the level of AMPK-α expression and associated metabolic pathways. The findings demonstrate that metformin, quercetin, and okra extract may significantly raise AMPK-α levels while significantly lowering PEPCK and hormone-sensitive lipase (HSL) levels, in addition to improving glucose and lipid profiles. By stimulating KB1, these substances increased AMPK-α activation. Additionally, AMPK-α activation improved insulin resistance and Glucose transporter type 4 (GLUT4) gene expression levels. Since AMPK-α maintains energy balance and its activity has not been reported to be inhibited so far, it could be a potent therapeutic target. PRACTICAL APPLICATIONS: The development of effective AMPK-α agonists and antagonists holds promise for the treatment of metabolic disorders like diabetes. Dietary polyphenols are a valuable source for developing new drugs. However, due to the lack of understanding of the underlying mechanisms of their effect on cells, their use in the treatment of diabetes is controversial. In addition to chemicals that have medicinal benefits, chemists are searching for less harmful substances. Using plants containing bioactive chemicals for this purpose can be a good alternative to chemical drugs.

Phenolic Compounds and Antioxidant Activity of Rice–Tartary Buckwheat Composite as Affected by In Vitro Digestion

The present study aimed to evaluate the phenolic compounds and antioxidant activity of rice–tartary buckwheat composite (RTBC) as affected by in vitro digestion to explore the structure-activity relationship of the release of total phenolic content (TPC) and total flavonoid content (TFC) with the antioxidant activity of RTBC during in vitro oral, gastric, and intestinal digestion stages. The release of TPC and TFC from RTBC increased significantly after in vitro digestion ( $P<0.05$ ), and the change of antioxidant activity was consistent with that of TPC and TFC. Compared with the initial stage of digestion, the antioxidant activity of RTBC was increased after digestion ( $P<0.05$ ), and there was a strong correlation between antioxidant activity and the release of TPC and TFC (0.954 < R < 0.997; $P<0.05$ ). The phenolic compounds released in the oral, gastric, and intestinal digestion stages varied, and eight phenolic compounds were identified by UPLC-Triple-TOF/MS, namely, quercetin-3-O-robinoside-7-O-sophoroside, quercetin-3-O-neohesperidoside-7-O-glucoside, forsythobiflavone A, forsythobiflavone B, quercetin-3-O-rutinoside-7-O-glucoside, rutin, isoquercetin, and ferulic acid. These results indicated that in vitro digestion significantly increases the release of phenolic compounds and flavonoids from RTBC and there is a higher antioxidant activity after digestion than before digestion. The phenolic compounds released after digestion of RTBC are beneficial to health protection.

Prospective multifunctional roles and pharmacological potential of dietary flavonoid narirutin

Plant-based phytochemicals are now being used to treat plenty of physiological diseases. Herbal drugs have gained popularity in recent years because of their strength, purity, and cheap cost-effectiveness. Citrus fruits contain significant amounts of flavanones, which falls to the category of polyphenols. Flavanones occupy a major fraction of the total polyphenols present in the plasma when orange juice is taken highly or in moderate states. Narirutin is a disaccharide derivative available in citrus fruits, primarily dihydroxy flavanone. From a pharmacological viewpoint, narirutin is a bioactive phytochemical with therapeutic efficacy. Many experimental researches were published on the use of narirutin. Anticancer activity, neuroprotection, stress relief, hepatoprotection, anti-allergic activity, antidiabetic activity, anti-adipogenic activity, anti-obesity action, and immunomodulation are a couple of the primary pharmacological properties. Narirutin also has antioxidant, and anti-inflammatory activities. The ultimate goal of this review is to provide the current scenario of pharmacological research with narirutin; to make a better understanding for therapeutic potential of narirutin, as well as its biosynthesis strategies and side effects. Extensive literature searches and studies were undertaken to determine the pharmacological properties of narirutin.

Seaweeds' pigments and phenolic compounds with antimicrobial potential

Recently, there has been increased interest in the development of novel antimicrobial compounds for utilization in a variety of sectors, including pharmaceutical, biomedical, textile, and food. The use, overuse, and misuse of synthetic compounds or derivatives have led to an increase of pathogenic microorganisms gaining resistance to the traditional antimicrobial therapies, which has led to an increased need for alternative therapeutic strategies. Seaweed are marine organisms that can be cultivated sustainably, and they are a source of polar molecules, such as pigments and phenolic compounds, which demonstrated antimicrobial potential. This review focuses on current knowledge about pigments and phenolic compounds isolated from seaweeds, their chemical characteristics, antimicrobial bioactivity, and corresponding mechanism of action.

Role of polyphenols in combating Type 2 Diabetes and insulin resistance

Compromised carbohydrate metabolism leading to hyperglycemia is the primary metabolic disorder of non-insulin-dependent diabetes mellitus. Reformed digestion and altered absorption of carbohydrates, exhaustion of glycogen stock, enhanced gluconeogenesis and overproduced hepatic glucose, dysfunction of β-cell, resistance to insulin in peripheral tissue, and impaired insulin signaling pathways are essential reasons for hyperglycemia. Although oral anti-diabetic drugs like α-glucosidase inhibitors, sulfonylureas and insulin therapies are commonly used to manage Type 2 Diabetes (T2D) and hyperglycemia, natural compounds in diet also play a significant role in combating the effect of diabetes. Due to their vast bioavailability and anti-hyperglycemic effect with least or no side effects, polyphenolic compounds have gained wide popularity. Polyphenols such as flavonoids and tannins play a significant role in carbohydrate metabolism by inhibiting key enzymes responsible for the digestion of carbohydrates to glucose like α-glucosidase and α-amylase. Several polyphenols such as resveratrol, epigallocatechin-3-gallate (EGCG) and quercetin enhanced glucose uptake in the muscle and adipocytes by translocating GLUT4 to plasma membrane mainly by the activation of the AMP-activated protein kinase (AMPK) pathway. This review provides an insight into the protective role of polyphenols in T2D, highlighting the aspects of insulin resistance.

LC–DAD–MS Phenolic Characterisation of Six Invasive Plant Species in Croatia and Determination of Their Antimicrobial and Cytotoxic Activity

Invasive plants’ phytochemicals are important for their invasiveness, enabling them to spread in new environments. However, these chemicals could offer many pharmaceutical compounds or active ingredients for herbal preparations. This study provides the first LC–MS phytochemical screening of six invasive alien plant species (IAPS) in the Istria region (Croatia): Ailanthus altissima, Ambrosia artemisiifolia, Conyza canadensis, Dittrichia viscosa, Erigeron annuus, and Xanthium strumarium. The study aims to identify and quantify the phenolic content of their leaf extracts and assess their antimicrobial and cytotoxic potential. A total of 32 species-specific compounds were recorded. Neochlorogenic, chlorogenic, and 5-p-coumaroylquinic acids, quercetin-3-glucoside, and kaempferol hexoside were detected in all the tested IAPS. Hydroxycinnamic acid derivatives were the main components in all the tested IAPS, except in E. annuus, where flavanones dominated with a share of 70%. X. strumarium extract had the best activity against the tested bacteria, with an average MIC value of 0.11 mg/mL, while A. altissima and X. strumarium extracts had the best activity against the tested fungi, with an average MIC value of 0.21 mg/mL in both cases. All the plant extracts studied, except X. strumarium, were less cytotoxic than the positive control. The results provided additional information on the phytochemical properties of IAPS and their potential for use as antimicrobial agents.

Efficacy of flavonoids on biomarkers of type 2 diabetes mellitus: a systematic review and meta-analysis of randomized controlled trials

A systematic review and meta-analysis of 28 randomized controlled trials (RCTs) to assess the efficacy of flavonoids intake on key biomarkers related to Type 2 diabetes mellitus was conducted. The mean difference (MD) with 95% confidence intervals (95% CI) was pooled using a random-effects model. Significant reduction in fasting glucose (MD: -0.22, 95% CI: -0.34 to -0.09, p = 0.0013), hemoglobin A1c (HbA1c) (MD: -0.26, 95% CI: -0.46 to -0.05, p = 0.021), homeostasis model assessment of insulin resistance (HOMA-IR) (MD: -0.40, 95% CI: -0.66 to -0.15, p = 0.0039), triglyceride (TG) (MD: -0.13, 95% CI: -0.21 to -0.05, p = 0.002), total cholesterol (TC) (MD: -0.14, 95% CI: -0.21 to -0.08, p = 0.0002), and low density lipoprotein-C (LDL-C) (MD: -0.15; 95% CI: -0.24 to -0.07, p = 0.0009) were observed in intervention group compare to placebo at the end of trial. Moreover, flavonoid intake had negative but non-significant effect on insulin (MD: -0.46), 2 h-postprandial glucose (2 h-PPG) (MD: -0.22), homeostasis model assessment of β-cell function (HOMA-β) (MD: -2.81), and insignificantly increased high-density lipoprotein-C (HDL-C) (MD: 0.03). In conclusion, flavonoid intake has modest but statistically significant benefits in glucose metabolism, insulin sensitivity, and lipid metabolism, especially for significantly lowing fasting blood glucose, HOMA-IR, HbA1c, TG, TC, and LDL-C.

Polyphenolic Characterization and Antioxidant Capacity of Laurus nobilis L. Leaf Extracts Obtained by Green and Conventional Extraction Techniques

Laurus nobilis L. is an evergreen Mediterranean shrub whose leaves have been known for various health-promoting effects mainly attributed to polyphenols. Microwave- (MAE) and ultrasound-assisted extraction (UAE) are green extraction techniques that enable effective isolation of polyphenols from plant material. Therefore, the aim of this research was to optimize the extraction conditions of MAE (ethanol percentage, temperature, extraction time, microwave power) and UAE (ethanol percentage, extraction time, amplitude) of polyphenols from Laurus nobilis L. leaves and to assess their polyphenolic profile by ultra performance liquid chromatography- tandem mass spectrometry (UPLC-MS/MS) and antioxidant capacity by oxygen radical absorbance capacity (ORAC) assay. Optimal MAE conditions were 50% ethanol, 80 °C, 10 min and 400 W. Optimal UAE conditions were 70% ethanol, 10 min and 50% amplitude. Spectrophotometric analysis showed the highest total phenolic content in the extracts was obtained by MAE, compared to conventional heat-reflux extraction (CRE) and UAE. The polyphenolic profile of all obtained extracts included 29 compounds, with kaempferol and quercetin glycosides being the most abundant. UPLC-MS/MS showed the highest total phenolic content in the extracts obtained by CRE. ORAC assay showed the highest antioxidant capacity in extracts obtained by CRE, which is in agreement with the polyphenolic profile determined by UPLC-MS/MS.

Blueberry as an Attractive Functional Fruit to Prevent (Pre)Diabetes Progression

Prediabetes, a subclinical impairment between euglycemia and hyperglycemia, is a risk factor for the development of type 2 diabetes mellitus (T2DM) and associated micro- and macrovascular complications. Lifestyle therapy, the first-line treatment of prediabetes, includes physical exercise and dietary regimens enriched in phytochemicals with health-related properties. Blueberries (Vaccinium spp.), given their pleasant taste and great abundance in beneficial phytochemicals, have gained public interest all over the world. Along with a high antioxidant activity, this functional fruit is also well-recognized due to its hypoglycemic and insulin-sensitizing effects and has been recommended for overt T2DM management. Yet blueberries target several other pathophysiological traits, namely gut microbiota dysbiosis and hepatic dysmetabolism, that ensue when prediabetes begins and for which pharmacological interventions tend to be delayed. In this work, we revisited preclinical data from in vitro assays, animal models and human studies, aiming to disclose the potential mechanisms by which blueberries may be a fruitful source of phytochemicals able to prevent (pre)diabetes progression. Collectively, future efforts should focus on longer-term studies with standardized interventions and readouts, particularly in humans, that will hopefully bring more robust evidence and concrete guidance for blueberries' effective use in prediabetes.

The Potential Role of Flavonoids in Ameliorating Diabetic Cardiomyopathy via Alleviation of Cardiac Oxidative Stress, Inflammation and Apoptosis

Diabetic cardiomyopathy is one of the major mortality risk factors among diabetic patients worldwide. It has been established that most of the cardiac structural and functional alterations in the diabetic cardiomyopathy condition resulted from the hyperglycemia-induced persistent oxidative stress in the heart, resulting in the maladaptive responses of inflammation and apoptosis. Flavonoids, the most abundant phytochemical in plants, have been reported to exhibit diverse therapeutic potential in medicine and other biological activities. Flavonoids have been widely studied for their effects in protecting the heart against diabetes-induced cardiomyopathy. The potential of flavonoids in alleviating diabetic cardiomyopathy is mainly related with their remedial actions as anti-hyperglycemic, antioxidant, anti-inflammatory, and anti-apoptotic agents. In this review, we summarize the latest findings of flavonoid treatments on diabetic cardiomyopathy as well as elucidating the mechanisms involved.

Environmental Impact on Seaweed Phenolic Production and Activity: An Important Step for Compound Exploitation

Seaweeds are a potential source of bioactive compounds that are useful for biotechnological applications and can be employed in different industrial areas in order to replace synthetic compounds with components of natural origin. Diverse studies demonstrate that there is a solid ground for the exploitation of seaweed bioactive compounds in order to prevent illness and to ensure a better and healthier lifestyle. Among the bioactive algal molecules, phenolic compounds are produced as secondary metabolites with beneficial effects on plants, and also on human beings and animals, due to their inherent bioactive properties, which exert antioxidant, antiviral, and antimicrobial activities. The use of phenolic compounds in pharmaceutical, nutraceutical, cosmetics, and food industries may provide outcomes that could enhance human health. Through the production of healthy foods and natural drugs, bioactive compounds from seaweeds can help with the treatment of human diseases. This review aims to highlight the importance of phenolic compounds from seaweeds, the scope of their production in nature and the impact that these compounds can have on human and animal health through nutraceutical and pharmaceutical products.

Phytochemicals of Conocarpus spp. as a Natural and Safe Source of Phenolic Compounds and Antioxidants

Optimization of the extraction conditions of polyphenolic compounds for different parts of the Damas species, Conocarpus lancifolius and Conocarpus erectus, grown under UAE conditions was studied. The combination of ethanol concentration (50, 75, and 100%), temperature (45, 55, and 65 °C) and time (1, 2, and 3 h) was used by applying the Response Surface Methodology. The data showed that the extracts (n = 90) contained phenolic compounds, flavonoids, and tannins, and were free of alkaloids. Changing the extraction conditions had a significant effect on the detection of phytosterols, saponins, and glycosides and on the solubility of vanillic acid, p-coumaric acid, sinapic acid, t-ferulic acid, rutin hydrate, protocatechuic acid, quercetin, and flavone. The data reveal that the roots and leaves of C. erectus and the leaves and fruits of C.lancifolius are the most important plant parts from which to extract these compounds. This study draws attention to the unordinary use of Conocarpus spp. as a source of natural food additive.

Food Bioactive Compounds and Emerging Techniques for Their Extraction: Polyphenols as a Case Study

Experimental studies have provided convincing evidence that food bioactive compounds (FBCs) have a positive biological impact on human health, exerting protective effects against non-communicable diseases (NCD) including cancer and cardiovascular (CVDs), metabolic, and neurodegenerative disorders (NDDs). These benefits have been associated with the presence of secondary metabolites, namely polyphenols, glucosinolates, carotenoids, terpenoids, alkaloids, saponins, vitamins, and fibres, among others, derived from their antioxidant, antiatherogenic, anti-inflammatory, antimicrobial, antithrombotic, cardioprotective, and vasodilator properties. Polyphenols as one of the most abundant classes of bioactive compounds present in plant-based foods emerge as a promising approach for the development of efficacious preventive agents against NCDs with reduced side effects. The aim of this review is to present comprehensive and deep insights into the potential of polyphenols, from their chemical structure classification and biosynthesis to preventive effects on NCDs, namely cancer, CVDs, and NDDS. The challenge of polyphenols bioavailability and bioaccessibility will be explored in addition to useful industrial and environmental applications. Advanced and emerging extraction techniques will be highlighted and the high-resolution analytical techniques used for FBCs characterization, identification, and quantification will be considered.

The Effects of Domestication on Secondary Metabolite Composition in Legumes

Legumes are rich in secondary metabolites, such as polyphenols, alkaloids, and saponins, which are important defense compounds to protect the plant against herbivores and pathogens, and act as signaling molecules between the plant and its biotic environment. Legume-sourced secondary metabolites are well known for their potential benefits to human health as pharmaceuticals and nutraceuticals. During domestication, the color, smell, and taste of crop plants have been the focus of artificial selection by breeders. Since these agronomic traits are regulated by secondary metabolites, the basis behind the genomic evolution was the selection of the secondary metabolite composition. In this review, we will discuss the classification, occurrence, and health benefits of secondary metabolites in legumes. The differences in their profiles between wild legumes and their cultivated counterparts will be investigated to trace the possible effects of domestication on secondary metabolite compositions, and the advantages and drawbacks of such modifications. The changes in secondary metabolite contents will also be discussed at the genetic level to examine the genes responsible for determining the secondary metabolite composition that might have been lost due to domestication. Understanding these genes would enable breeding programs and metabolic engineering to produce legume varieties with favorable secondary metabolite profiles for facilitating adaptations to a changing climate, promoting beneficial interactions with biotic factors, and enhancing health-beneficial secondary metabolite contents for human consumption.

Seaweed Phenolics: From Extraction to Applications

Seaweeds have attracted high interest in recent years due to their chemical and bioactive properties to find new molecules with valuable applications for humankind. Phenolic compounds are the group of metabolites with the most structural variation and the highest content in seaweeds. The most researched seaweed polyphenol class is the phlorotannins, which are specifically synthesized by brown seaweeds, but there are other polyphenolic compounds, such as bromophenols, flavonoids, phenolic terpenoids, and mycosporine-like amino acids. The compounds already discovered and characterized demonstrate a full range of bioactivities and potential future applications in various industrial sectors. This review focuses on the extraction, purification, and future applications of seaweed phenolic compounds based on the bioactive properties described in the literature. It also intends to provide a comprehensive insight into the phenolic compounds in seaweed.

Understanding the Composition, Biosynthesis, Accumulation and Transport of Flavonoids in Crops for the Promotion of Crops as Healthy Sources of Flavonoids for Human Consumption

Flavonoids are a class of polyphenolic compounds that naturally occur in plants. Sub-groups of flavonoids include flavone, flavonol, flavanone, flavanonol, anthocyanidin, flavanol and isoflavone. The various modifications on flavonoid molecules further increase the diversity of flavonoids. Certain crops are famous for being enriched in specific flavonoids. For example, anthocyanins, which give rise to a purplish color, are the characteristic compounds in berries; flavanols are enriched in teas; and isoflavones are uniquely found in several legumes. It is widely accepted that the antioxidative properties of flavonoids are beneficial for human health. In this review, we summarize the classification of the different sub-groups of flavonoids based on their molecular structures. The health benefits of flavonoids are addressed from the perspective of their molecular structures. The flavonoid biosynthesis pathways are compared among different crops to highlight the mechanisms that lead to the differential accumulation of different sub-groups of flavonoids. In addition, the mechanisms and genes involved in the transport and accumulation of flavonoids in crops are discussed. We hope the understanding of flavonoid accumulation in crops will guide the proper balance in their consumption to improve human health.

Review of Structural Features and Binding Capacity of Polyphenols to Gluten Proteins and Peptides In Vitro: Relevance to Celiac Disease

Polyphenols have been extensively studied due to their beneficial effects on human health, particularly for the prevention and treatment of diseases related to oxidative stress. Nevertheless, they are also known to have an anti-nutritional effect in relation to protein metabolism. This effect is a consequence of its binding to digestive enzymes and/or protein substrates. Dietary gluten is the main trigger of celiac disease, a common immune-based disease of the small intestine and for which the only treatment available is the adherence to a gluten-free diet. Recent studies have addressed the use of dietary polyphenols to interact with gluten proteins and avoid its downstream deleterious effects, taking the advantage of the anti-nutritive nature of polyphenols by protein sequestering. Flavonoids, coumarins and tannins have shown the ability to form insoluble complexes with gluten proteins. One of the most promising molecules has been epigallocatechin-3-gallate, which through its binding to gliadins, was able to reduce gliadins digestibility and its ability to stimulate monolayer permeability and transepithelial transport of immunodominant peptides in cell models. This review focuses on the structural features and binding capacity of polyphenols to gluten proteins and peptides, and the prospects of developing an adjuvant therapy in celiac disease.

Ruminal fermentation, microbial population and lipid metabolism in gastrointestinal nematode-infected lambs fed a diet supplemented with herbal mixtures

The aim of this study was to evaluate the effects of medicinal herbal mixtures rich in phenolic, flavonoid and alkaloid compounds on ruminal fermentation and microbial populations, and fatty acid (FA) concentrations and lipid oxidation in tissues of lambs infected with the gastrointestinal nematode (GIN) parasite (Haemonchus contortus). Parallel in vitro and in vivo studies were performed using two different herbal mixtures (Mix1 and Mix2). The in vitro study was conducted in a 2 (infection status; non-infected versus infected) × 3 (diets; control, Mix1 and Mix2) factorial design. In the in vivo study, 24 lambs were equally divided into four treatments: non-infected lambs fed a control diet, infected lambs fed the control diet, infected lambs fed a diet with Mix1 and infected lambs fed a diet with Mix2. Herbal mixtures (100 g dry matter (DM)/d) were added to the basal diets of meadow hay (ad libitum) and a commercial concentrate (500 g DM/d). The experimental period lasted for 70 days. Ruminal fermentation characteristics and methane production were not affected by infection in vivo or in vitro. Both herbal mixture supplementation increased total volatile fatty acid (VFA) concentrations (P < 0.01) and DM digestibility (P < 0.01) in vitro. Archaea population was slightly diminished by both herbal mixtures (P < 0.05), but they did not lower methane production in vitro or in vivo (P > 0.05). Infection of H. contortus or herbal mixtures modulated FA proportion mainly in the liver, especially the long chain FA proportion. Concentrations of thiobarbituric acid reactive substances (TBARS) in serum were significantly higher after 70 days post-infection in the infected lambs. Herbal Mix1 supplementation reduced TBARS concentrations in meat after seven days of storage. In conclusion, supplementing of herbal mixtures to the diets of GIN parasite infected lambs did not affect the basic ruminal fermentation parameters. Herbal mixtures may improve few FA proportions mainly in liver as well as decrease lipid oxidation in meat.

Plant Fibers and Phenolics: A Review on Their Synthesis, Analysis and Combined Use for Biomaterials with New Properties

Devising environmental-friendly processes in biotechnology is a priority in the current economic scenario. We are witnessing a constant and steady push towards finding sustainable solutions to societal challenges by promoting innovation-driven activities minimizing the environmental impact and valorizing natural resources. In bioeconomy, plants are among the most important renewable sources of both fibers (woody and cellulosic) and phytochemicals, which find applications in many industrial sectors, spanning from the textile, to the biocomposite, medical, nutraceutical, and pharma sectors. Given the key role of plants as natural sources of (macro)molecules, we here provide a compendium on the use of plant fibers functionalized/impregnated with phytochemicals (in particular phenolic extracts). The goal is to review the various applications of natural fibers functionalized with plant phenolics and to valorize those plants that are source of both fibers and phytochemicals.

Health Benefits of Polyphenols and Carotenoids in Age-Related Eye Diseases

Oxidative stress and inflammation play a critical role in the initiation and progression of age-related ocular abnormalities as cataract, glaucoma, diabetic retinopathy, and macular degeneration. Therefore, phytochemicals with proven antioxidant and anti-inflammatory activities, such as carotenoids and polyphenols, could be of benefit in these diseases. We searched PubMed and Web of Science databases for original studies investigating the benefits of different carotenoids and polyphenols in age-related ophthalmic diseases. Our results showed that several polyphenols (such as anthocyanins, Ginkgo biloba, quercetin, and resveratrol) and carotenoids (such as lutein, zeaxanthin, and mezoxanthin) have shown significant preventive and therapeutic benefits against the aforementioned conditions. The involved mechanisms in these findings include mitigating the production of reactive oxygen species, inhibiting the tumor necrosis factor-α and vascular endothelial growth factor pathways, suppressing p53-dependent apoptosis, and suppressing the production of inflammatory markers, such as interleukin- (IL-) 8, IL-6, IL-1a, and endothelial leucocyte adhesion molecule-1. Consumption of products containing these phytochemicals may be protective against these diseases; however, adequate human data are lacking. This review discusses the role and mechanisms of polyphenols and carotenoids and their possible synergistic effects on the prevention and treatment of age-related eye diseases that are induced or augmented by oxidative stress and inflammation.

TDDFT calculations and photoacoustic spectroscopy experiments used to identify phenolic acid functional biomolecules in Brazilian tropical fruits in natura

Time-dependent density functional theory (TDDFT) calculations of electronic transitions have been widely used to determine molecular structures. The excitation wavelengths and oscillator strengths obtained with the hybrid exchange-correlation functional B3LYP in conjunction with the ADZP basis set are employed to simulate the UV-Vis spectra of eight phenolic acids. Experimental and theoretical UV-Vis spectra reported previously in the literature are compared with our results. The fast, sensitive and non-destructive technique of photoacoustic spectroscopy (PAS) is used to determine the UV-Vis spectra of four Brazilian tropical fresh fruits in natura. Then, the PAS along with the TDDFT results are for the first time used to investigate and identify the presence of phenolic acids in the fruits studied in this work. This theoretical method with this experimental technique show to be a powerful and cheap tool to detect the existence of phenolic acids in fruits, vegetables, cereals, and grains. Comparison with high performance liquid chromatography results, when available, is also carried out.

Polyphenols in Colorectal Cancer: Current State of Knowledge including Clinical Trials and Molecular Mechanism of Action

Polyphenols have been reported to have wide spectrum of biological activities including major impact on initiation, promotion, and progression of cancer by modulating different signalling pathways. Colorectal cancer is the second most major cause of mortality and morbidity among females and the third among males. The objective of this review is to describe the activity of a variety of polyphenols in colorectal cancer in clinical trials, preclinical studies, and primary research. The molecular mechanisms of major polyphenols related to their beneficial effects on colorectal cancer are also addressed. Synthetic modifications and other future directions towards exploiting of natural polyphenols against colorectal cancer are discussed in the last section.

The promise of marine molecules as cosmetic active ingredients

The marine environment represents an underexploited resource for the discovery of novel products, despite its high level of biological and chemical diversity. With increasing awareness of the harmful effects of chronic ultraviolet exposure, and a universal desire to improve cosmetic appearance, the market for new cosmetic ingredients is growing, and current trends have generated a greater demand for products sourced from the environment. A growing number of novel molecules from marine flora and fauna exhibit potent and effective dermatological activities. Secondary metabolites isolated from macroalgae, including carotenoids and polyphenols, have demonstrated antioxidant, anti-ageing and anti-inflammatory activities. In addition, marine extremophilic bacteria have recently been shown to produce bioactive exopolymeric molecules, some of which have been commercialized. Available data on their activities show significant antioxidant, moisturizing and anti-ageing activities, but a more focussed investigation into their mechanisms and applications is required. This review surveys the reported biological activities of an emerging and growing portfolio of marine molecules that show promise in the treatment of cosmetic skin problems including ultraviolet damage, ageing and cutaneous dryness.

Facile preparation of poly(methylene blue) modified carbon paste electrode for the detection and quantification of catechin

Free radicals are formed as byproducts of metabolism, and are highly unstable due to the presence of unpaired electrons. They readily react with other important cellular components such as DNA causing them damage. Antioxidants such as (+)-catechin (CAT), neutralize free radicals in the blood stream. Hence there is a need for detection and quantification of catechin concentration in various food sources and beverages. Electro-oxidative properties of catechin were investigated using cyclic voltammetry (CV) and differential pulse voltammetry (DPV). A carbon paste working electrode modified by electropolymerizing methylene blue (MB) was fabricated. Field emission scanning electron microscopy (FESEM) and atomic force microscopy (AFM) techniques were used to study the surface morphology of the electrode. Quasi-reversible electron transfer reaction occurred at +0.260V through a diffusion controlled process. In comparison to the bare carbon paste electrode (CPE), there was a significant 5.3 times increment in anodic current sensitivity at the modified electrode at physiological pH. Our findings indicate that for the electro-oxidation of CAT, CPE is a better base material for electropolymerization of MB compared to glassy carbon electrode (GCE). Nyquist plot followed the theoretical shape, indicating low interfacial charge transfer resistance of 0.095kΩ at the modified electrode. Calibration plots obtained by DPV were linear in two ranges of 1.0×10^-3 to 1.0×10^-6 and 1.0×10^-7 to 0.1×10^-8M. The limit of detection (LOD) and limit of quantification (LOQ) was 4.9nM and 14nM respectively. Application of the developed electrode was demonstrated by detecting catechin in green tea and spiked fruit juice with satisfactory recoveries. The sensor was stable, sensitive, selective and reproducible.

Immunomodulatory Activity of Leaf Infusions of Selected Cornaceae Species on Human Leukocytes

Particular Cornus species are known for their edible fruits and their leaves are used as a tea in some countries. In the present study, the immunomodulatory activity of water infusions of leaves of Cornus mas (CM), C. kousa (CK), C. alba (CA), C. flaviramea (CF), C. coreana (CC) and C. amomum (CU) was tested on human leukocytes. Phagocytic and antimicrobial activity was determined for concentrations of 0.17 and 0.25 mg.mL−1. All samples significantly enhanced the phagocytic activity of cells. Samples at the concentration of 0.17 mg.mL−1 were in all cases, except CK, slightly more effective than those at 0.25 mg.mL−1. The strongest bactericidal ( E. coli) and also candidacidal ( C. albicans) activity was exerted by CM at 0.25 mg.mL−1. The most potent samples at the lower concentration were CF (for E. coli) and CK (for C. albicans). CC and CU were antimicrobially non-effective.