Nutraceutical Value of Citrus Flavanones and Their Implications in Cardiovascular Disease

Polyphenols as Therapeutics in Respiratory Diseases: Moving from Preclinical Evidence to Potential Clinical Applications

Respiratory diseases are the most common and severe health complication and a leading cause of death worldwide. Despite breakthroughs in diagnosis and treatment, few safe and effective therapeutics have been reported. Phytochemicals are gaining popularity due to their beneficial effects and low toxicity. Polyphenols are secondary metabolites with high molecular weights found at high levels in natural food sources such as fruits, vegetables, grains, and citrus seeds. Over recent decades, polyphenols and their beneficial effects on human health have been the subject of intense research, with notable successes in preventing major chronic non-communicable diseases. Many respiratory syndromes can be treated effectively with polyphenolic supplements, including acute lung damage, pulmonary fibrosis, asthma, pulmonary hypertension, and lung cancer. This review summarizes the role of polyphenols in respiratory conditions with sufficient experimental data, highlights polyphenols with beneficial effects for each, and identifies those with therapeutic potential and their underlying mechanisms. Moreover, clinical studies and future research opportunities in this area are discussed.

Ethnobotany and diversity of Citrus spp. (Rutaceae) as a source of "Kem-kem" traditional medicine used among the Karo sub-ethnic in North Sumatra, Indonesia

The Karo sub-ethnic is one of five Batak sub-ethnicities in the Karo Regency, North Sumatra Province, Indonesia. They are famous for their local knowledge about the traditional use of medicinal plants to treat various diseases. The "Kem-kem" traditional medicine is one of the traditional healing practices that involve using plants passed down through generations from their ancestors. One of the plant genus group in the Rutaceae family utilized in the traditional "Kem-kem" healing practice is a citrus known as "Rimo". This study aims to document the local knowledge about the diversity of Citrus spp. as Kem-kem's herbal medicinal plant. This study was conducted from April to July 2023 in the Kabanjahe and Berastagi districts, Karo Regency, North Sumatra. Data was collected using interviews with traditional healers, herbal medicine vendors, and direct observations at traditional markets, involving a total of 8 Citrus spp. The Karo uses "Rimo" with different local names as sources of traditional medicinal ingredients in practicing "Kem-kem". There are 15 local names comprising eight species of Citrus. Four are hybrids, i.e., Citrus x aurantiifolia (Christm.) Swingle, Citrus × aurantium L, Citrus × junos Siebold ex Yu.Tanaka, and Citrus × taitensis Risso. Two of the remaining species are recognized in infraspecific rank, one variety (Citrus medica var. sarcodactylis (Hoola van Nooten) Swingle) and one form (Citrus × aurantium f. deliciosa (Ten.) M.Hiroe). They were used as material sources for Kem-kem traditional medicine to treat at least nine health problems. There are two species with six local names included in the Least Concern (LC) category, namely C. medica (Rimo Gawang, Rimo Hantuantu, Rimo Kayu), C. medica var. sarcodactylis (Rimo Kuku Harimau), and C. medica (Rimo Telur Buaya), C. maxima (Burm.) Merr. (Rimo Malem). Nine local names are included in the Not Evaluated (NE) category, namely C. × junos (Rimo Kejaren), C. × taitensis (Rimo Jungga), C. × aurantium f. deliciosa (Rimo Keling), C. × aurantium (Rimo Kersik), Citrus hystrix DC. (Rimo Mukur), C. × taitensis (Rimo Puraga), C. × aurantium (Rimo Kalele), Citrus swinglei Burkill ex Harms (Rimo Pagar), and C. x aurantiifolia (Rimo Bunga). Rimo Kejaren (C. × junos) is a species that has the most benefits.

An Update on the Potential of Tangeretin in the Management of Neuroinflammation-Mediated Neurodegenerative Disorders

Neuroinflammation is the major cause of neurodegenerative disorders such as Alzheimer's and Parkinson's disease. Currently available drugs present relatively low efficacy and are not capable of modifying the course of the disease or delaying its progression. Identifying well-tolerated and brain-penetrant agents of plant origin could fulfil the pressing need for novel treatment techniques for neuroinflammation. Attention has been drawn to a large family of flavonoids in citrus fruits, which may function as strong nutraceuticals in slowing down the development and progression of neuroinflammation. This review is aimed at elucidating and summarizing the effects of the flavonoid tangeretin (TAN) in the management of neuroinflammation-mediated neurodegenerative disorders. A literature survey was performed using various resources, including ScienceDirect, PubMed, Google Scholar, Springer, and Web of Science. The data revealed that TAN exhibited immense neuroprotective effects in addition to its anti-oxidant, anti-diabetic, and peroxisome proliferator-activated receptor-γ agonistic effects. The effects of TAN are mainly mediated through the inhibition of oxidative and inflammatory pathways via regulating multiple signaling pathways, including c-Jun N-terminal kinase, phosphoinositide 3-kinase, mitogen-activated protein kinase, nuclear factor erythroid-2-related factor 2, extracellular-signal-regulated kinase, and CRE-dependent transcription. In conclusion, the citrus flavonoid TAN has the potential to prevent neuronal death mediated by neuroinflammatory pathways and can be developed as an auxiliary therapeutic agent in the management of neurodegenerative disorders.

Cellular electrophysiological effects of the citrus flavonoid hesperetin in dog and rabbit cardiac ventricular preparations

Recent experimental data shows that hesperetin, a citrus flavonoid, affects potassium channels and can prolong the QTc interval in humans. Therefore, in the present study we investigated the effects of hesperetin on various transmembrane ionic currents and on ventricular action potentials. Transmembrane current measurements and action potential recordings were performed by patch-clamp and the conventional microelectrode techniques in dog and rabbit ventricular preparations. At 10 µM concentration hesperetin did not, however, at 30 µM significantly decreased the amplitude of the IK1, Ito, IKr potassium currents. Hesperetin at 3-30 µM significantly and in a concentration-dependent manner reduced the amplitude of the IKs current. The drug significantly decreased the amplitudes of the INaL and ICaL currents at 30 µM. Hesperetin (10 and 30 µM) did not change the action potential duration in normal preparations, however, in preparations where the repolarization reserve had been previously attenuated by 100 nM dofetilide and 1 µg/ml veratrine, caused a moderate but significant prolongation of repolarization. These results suggest that hesperetin at close to relevant concentrations inhibits the IKs outward potassium current and thereby reduces repolarization reserve. This effect in certain specific situations may prolong the QT interval and consequently may enhance proarrhythmic risk.

Interaction between dietary flavonoid intake and trouble sleeping on non-alcoholic fatty liver disease risk: a cross-sectional study

OBJECTIVE

The possible interaction of dietary flavonoid intake and sleep on non-alcoholic fatty liver disease (NAFLD) has not been well studied. This study investigated the interaction between dietary flavonoid intake and trouble sleeping on the risk of NAFLD.

METHODS

Three discrete National Health and Nutrition Examination Survey data cycles from 2007 to 2010 and 2017 to 2018 were used. NAFLD was diagnosed by a US Fatty Liver Index ≥30. A sleep questionnaire diagnosed trouble sleeping. Univariate and multivariate logistic regression, restricted cubic spline (RCS) and subgroup analyses were used to evaluate the association between dietary flavonoids, trouble sleeping and NAFLD. We employed the relative excess risk due to interaction, attributable proportion of interaction and synergy index to evaluate additive interactions.

RESULTS

Ultimately, 5056 participants were enrolled, and higher anthocyanidins and flavanones intake was negatively correlated with NAFLD. Conversely, trouble sleeping was positively associated with NAFLD. These correlations remained stable after adjusting for confounders, and there was a sex difference in this relationship. In the RCS model, anthocyanins were negatively non-linearly related to NAFLD, while flavanones showed a negative linear relationship. Moreover, there was a synergistic interplay between low dietary anthocyanin intake and trouble sleeping on the risk of NAFLD. A similar relationship existed for flavanone intake.

CONCLUSION

Anthocyanin and flavanone intake were negatively associated, whereas trouble sleeping was positively associated with NAFLD risk. There was a synergistic effect of low anthocyanin intake and trouble sleeping. The same relationship existed for low flavanone intake.

Optimized Sugar-Free Citrus Lemon Juice Fermentation Efficiency and the Lipid-Lowering Effects of the Fermented Juice

Aging and obesity make humans more prone to cardiovascular and metabolic syndrome diseases, leading to several serious health conditions, including hyperlipidemia, high blood pressure, and sleep disturbance. This study aimed to explore the hypolipidemic effect of fermented citrus lemon juice using a hyperlipidemic hamster model. The sugar-free lemon juice's fermentation was optimized, and the characteristics of fresh and fermented lemon juice (FLJ) were evaluated and compared, which contained polyphenols and superoxide dismutase-like activity. Results showed that the absorption and utilization efficiency of FLJ was higher compared with the unfermented lemon juice. This study's prefermentation efficiency evaluation found that 21-30 days of bacterial DMS32004 and DMS32005 fermentation of fresh lemon juice provided the best fermentation benefits, and 21-day FLJ was applied as a remedy after the efficiency compassion. After six weeks of feeding, the total cholesterol (TC) and triglyceride (TG) values in the blood and liver of the FLJ treatment groups were decreased compared with the high-fat diet (HFD) group. In addition, the blood low-density lipoprotein cholesterol (LDL-C) levels were significantly reduced in the FLJ treatment groups compared with the HFD group. In contrast, the blood high-density lipoprotein (HDL-C) to LDL-C ratio increased considerably in the FLJ treatment groups, and the total to HDL ratio was significantly lower than in the HFD group. Compared with the HFD group, the TC content in the FLJ treatment groups' feces increased significantly. This study demonstrated that the sugar-free fermentation method and fermentation cycle management provided FLJ with the potential to regulate blood lipids. Further research and verification will be carried out to isolate specific substances from the FLJ and identify their mechanisms of action.

Citrus flavonoids and adhesion molecules: Potential role in the management of atherosclerosis

Atherosclerosis as a chronic inflammatory disorder is accompanied with oxidative stress which causes a high morbidity and mortality. Adhesion molecules, including intercellular adhesion molecule-1 (ICAM-1), vascular cell adhesion molecule-1 (VCAM-1), P-selectin, and E-selectin, are amongst the most important contributors in atherosclerosis. In such cases, dietary interventions with functional foods containing natural antioxidant and anti-inflammatory constituents are of a great interest. Citrus fruits are rich sources of flavonoids as natural pigments with potent antioxidant and anti-inflammatory activities. This study aims to review current evidence regarding the role of citrus flavonoids in the management of atherosclerosis with a focus on their effect on adhesion molecules. Electronic databases including PubMed, Scopus, and Web of Science were searched with the names of adhesion molecules and flavonoids from inception until January 2023. The included articles highly support the beneficial effects of citrus flavonoids in preclinical models of atherosclerosis. Quercetin, naringin and naringenin, hesperidin and hesperetin, nobiletin, rutin, luteolin, apigenin, and kaempferol are the most common flavonoids in citrus fruits which could modulate adhesion molecules including ICAM-1, VCAM-1, E-selectin, and P-selectin. Additionally, markers of chronic inflammation such as interleukins, tumor necrosis factor-α, nuclear factor-κB, and nitric oxide signaling, as well as oxidative stress markers like superoxide dismutase and glutathione were all normalized upon administration of citrus flavonoids. Conclusively, this review confirms the modulatory role of flavonoids on adhesion molecules in atherosclerosis based on the preclinical evaluations. Thus, citrus fruits can be further studied in atherosclerotic patients regarding their activity in reducing adhesion molecules.

Dietary flavonoids prevent diabetes through epigenetic regulation: advance and challenge

The pathophysiology of diabetes has been studied extensively in various countries, but effective prevention and treatment methods are still insufficient. In recent years, epigenetics has received increasing attention from researchers in exploring the etiology and treatment of diabetes. DNA methylation, histone modifications, and non-coding RNAs play critical roles in the occurrence, maintenance, and progression of diabetes and its complications. Therefore, preventing or reversing the epigenetic alterations that occur during the development of diabetes may reduce the individual and societal burden of the disease. Dietary flavonoids serve as natural epigenetic modulators for the discovery of biomarkers for diabetes prevention and the development of alternative therapies. However, there is limited knowledge about the potential beneficial effects of flavonoids on the epigenetics of diabetes. In this review, the multidimensional epigenetic effects of different flavonoid subtypes in diabetes were summarized. Furthermore, it was discussed that parental flavonoid diets might reduce diabetes incidence in offspring, which represent a promising opportunity to prevent diabetes in the future. Future work will depend on exploring anti-diabetic effects of different flavonoids with different epigenetic regulation mechanisms and clinical trials.Highlights• "Epigenetic therapy" could reduce the burden of diabetic patients• "Epigenetic diet" ameliorates diabetes• Targeting epigenetic regulations by dietary flavonoids in the diabetes prevention• Dietary flavonoids prevent diabetes via transgenerational epigenetic inheritance.

A systematic review of the research progress of traditional Chinese medicine against pulmonary fibrosis: from a pharmacological perspective

Pulmonary fibrosis is a chronic progressive interstitial lung disease caused by a variety of etiologies. The disease can eventually lead to irreversible damage to the lung tissue structure, severely affecting respiratory function and posing a serious threat to human health. Currently, glucocorticoids and immunosuppressants are the main drugs used in the clinical treatment of pulmonary fibrosis, but their efficacy is limited and they can cause serious adverse effects. Traditional Chinese medicines have important research value and potential for clinical application in anti-pulmonary fibrosis. In recent years, more and more scientific researches have been conducted on the use of traditional Chinese medicine to improve or reduce pulmonary fibrosis, and some important breakthroughs have been made. This review paper systematically summarized the research progress of pharmacological mechanism of traditional Chinese medicines and their active compounds in improving or reducing pulmonary fibrosis. We conducted a systematic search in several main scientific databases, including PubMed, Web of Science, and Google Scholar, using keywords such as idiopathic pulmonary fibrosis, pulmonary fibrosis, interstitial pneumonia, natural products, herbal medicine, and therapeutic methods. Ultimately, 252 articles were included and systematically evaluated in this analysis. The anti-fibrotic mechanisms of these traditional Chinese medicine studies can be roughly categorized into 5 main aspects, including inhibition of epithelial-mesenchymal transition, anti-inflammatory and antioxidant effects, improvement of extracellular matrix deposition, mediation of apoptosis and autophagy, and inhibition of endoplasmic reticulum stress. The purpose of this article is to provide pharmaceutical researchers with information on the progress of scientific research on improving or reducing Pulmonary fibrosis with traditional Chinese medicine, and to provide reference for further pharmacological research.

Selected Flavonols in Breast and Gynecological Cancer: A Systematic Review

The consumption of foods that are rich in phenolic compounds has chemopreventive effects on many cancers, including breast cancer, ovarian cancer, and endometrial cancer. A wide spectrum of their health-promoting properties such as antioxidant, anti-inflammatory, and anticancer activities, has been demonstrated. This paper analyzes the mechanisms of the anticancer action of selected common flavonols, including kemferol, myricetin, quercetin, fisetin, galangin, isorhamnetin, and morin, in preclinical studies, with particular emphasis on in vitro studies in gynecological cancers and breast cancer. In the future, these compounds may find applications in the prevention and treatment of gynecological cancers and breast cancer, but this requires further, more advanced research.

Role of bZIP transcription factors in the regulation of plant secondary metabolism

MAIN CONCLUSION

This study provides an overview of the structure, classification, regulatory mechanisms, and biological functions of the basic (region) leucine zipper transcription factors and their molecular mechanisms in flavonoid, terpenoid, alkaloid, phenolic acid, and lignin biosynthesis. Basic (region) leucine zippers (bZIPs) are evolutionarily conserved transcription factors (TFs) in eukaryotic organisms. The bZIP TFs are widely distributed in plants and play important roles in plant growth and development, photomorphogenesis, signal transduction, resistance to pathogenic microbes, biotic and abiotic stress, and secondary metabolism. Moreover, the expression of bZIP TFs not only promotes or inhibits the accumulation of secondary metabolites in medicinal plants, but also affects the stress response of plants to the external adverse environment. This paper describes the structure, classification, biological function, and regulatory mechanisms of bZIP TFs. In addition, the molecular mechanism of bZIP TFs regulating the biosynthesis of flavonoids, terpenoids, alkaloids, phenolic acids, and lignin are also elaborated. This review provides a summary for in-depth study of the molecular mechanism of bZIP TFs regulating the synthesis pathway of secondary metabolites and plant molecular breeding, which is of significance for the generation of beneficial secondary metabolites and the improvement of plant varieties.

The protective roles of citrus flavonoids, naringenin, and naringin on endothelial cell dysfunction in diseases

The endothelial cells (ECs) make up the inner lining of blood vessels, acting as a barrier separating the blood and the tissues in several organs. ECs maintain endothelium integrity by controlling the constriction and relaxation of the vasculature, blood fluidity, adhesion, and migration. These actions of ECs are efficiently coordinated via an intricate signaling network connecting receptors, and a wide range of cellular macromolecules. ECs are naturally quiescent i.e.; they are not stimulated and do not proliferate. Upon infection or disease, ECs become activated, and this alteration is pivotal in the pathogenesis of a spectrum of human neurological, cardiovascular, diabetic, cancerous, and viral diseases. Considering the central position that ECs play in disease pathogenesis, therapeutic options have been targeted at improving ECs integrity, assembly, functioning, and health. The dietary intake of flavonoids present in citrus fruits has been associated with a reduced risk of endothelium dysfunction. Naringenin (NGN) and Naringin (NAR), major flavonoids in grapefruit, tomatoes, and oranges possess anti-inflammatory, antioxidant properties, and cell survival potentials, which improve the health of the vascular endothelium. In this review, we provide a comprehensive summary and present the advances in understanding of the mechanisms through which NGN and NAR modulate the biomarkers of vascular dysfunction and protect the endothelium against unresolved inflammation, oxidative stress, atherosclerosis, and angiogenesis. We also provide perspectives and suggest further studies that will help assess the efficacy of citrus flavonoids in the therapeutics of human vascular diseases.

Stachydrine, a Bioactive Equilibrist for Synephrine, Identified from Four Citrus Chinese Herbs

Four Chinese herbs from the Citrus genus, namely Aurantii Fructus Immaturus (Zhishi), Aurantii Fructus (Zhiqiao), Citri Reticulatae Pericarpium Viride (Qingpi) and Citri Reticulatae Pericarpium (Chenpi), are widely used for treating various cardiovascular and gastrointestinal diseases. Many ingredients have already been identified from these herbs, and their various bioactivities provide some interpretations for the pharmacological functions of these herbs. However, the complex functions of these herbs imply undisclosed cholinergic activity. To discover some ingredients with cholinergic activity and further clarify possible reasons for the complex pharmacological functions presented by these herbs, depending on the extended structure-activity relationships of cholinergic and anti-cholinergic agents, a simple method was established here for quickly discovering possible choline analogs using a specific TLC method, and then stachydrine and choline were first identified from these Citrus herb decoctions based on their NMR and HRMS data. After this, two TLC scanning (TLCS) methods were first established for the quantitative analyses of stachydrine and choline, and the contents of the two ingredients and synephrine in 39 samples were determined using the valid TLCS and HPLC methods, respectively. The results showed that the contents of stachydrine (3.04‱) were 2.4 times greater than those of synephrine (1.25‱) in Zhiqiao and about one-third to two-thirds of those of Zhishi, Qingpi and Chenpi. Simultaneously, the contents of stachydrine, choline and synephrine in these herbs present similar decreasing trends with the delay of harvest time; e.g., those of stachydrine decrease from 5.16‱ (Zhishi) to 3.04‱ (Zhike) and from 1.98‱ (Qingpi) to 1.68‱ (Chenpi). Differently, the contents of synephrine decrease the fastest, while those of stachydrine decrease the slowest. Based on these results, compared with the pharmacological activities and pharmacokinetics reported for stachydrine and synephrine, it is indicated that stachydrine can be considered as a bioactive equilibrist for synephrine, especially in the cardio-cerebrovascular protection from these citrus herbs. Additionally, the results confirmed that stachydrine plays an important role in the pharmacological functions of these citrus herbs, especially in dual-directionally regulating the uterus, and in various beneficial effects on the cardio-cerebrovascular system, kidneys and liver.

Effectiveness of targeting the NLRP3 inflammasome by using natural polyphenols: A systematic review of implications on health effects

Globally, inflammation and metabolic disorders pose serious public health problems and are major health concerns. It has been shown that natural polyphenols are effective in the treatment of metabolic diseases, including anti-inflammation, anti-diabetes, anti-obesity, neuron-protection, and cardio-protection. NLRP3 inflammasome, which are multiprotein complexes located within the cytosol, play an important role in the innate immune system. However, aberrant activation of the NLRP3 inflammasome were discovered as essential molecular mechanisms in triggering inflammatory processes as well as implicating it in several major metabolic diseases, such as type 2 diabetes mellitus, obesity, atherosclerosis or cardiovascular disease. Recent studies indicate that natural polyphenols can inhibit NLRP3 inflammasome activation. In this review, the progress of natural polyphenols preventing inflammation and metabolic disorders via targeting NLRP3 inflammasome is systemically summarized. From the viewpoint of interfering NLRP3 inflammasome activation, the health effects of natural polyphenols are explained. Recent advances in other beneficial effects, clinical trials, and nano-delivery systems for targeting NLRP3 inflammasome are also reviewed. NLRP3 inflammasome is targeted by natural polyphenols to exert multiple health effects, which broadens the understanding of polyphenol mechanisms and provides valuable guidance to new researchers in this field.

The Chemical Variability, Nutraceutical Value, and Food-Industry and Cosmetic Applications of Citrus Plants: A Critical Review

Citrus fruits occupy an important position in the context of the fruit trade, considering that both fresh fruits and processed products are produced on a large scale. Citrus fruits are recognized as an essential component of the human diet, thanks to their high content of beneficial nutrients such as vitamins, minerals, terpenes, flavonoids, coumarins and dietary fibers. Among these, a wide range of positive biological activities are attributed to terpenes and flavonoids derivatives. In this review, a list of bibliographic reports (from 2015 onwards) on the phytochemical composition, beneficial effects and potential applications of citrus fruits and their by-products is systematically summarized. In detail, information regarding the nutraceutical and medicinal value closely linked to the presence of numerous bioactive metabolites and their growing use in the food industry and food packaging, also considering any technological strategies such as encapsulation to guarantee their stability over time, were evaluated. In addition, since citrus fruit, as well as its by-products, are interesting alternatives for the reformulation of natural cosmetic products, the sector of the cosmetic industry is also explored. More in-depth knowledge of the latest information in this field will contribute to future conscious use of citrus fruits.

Health associations of liver enzymes and inflammatory scores with urinary citrus flavonoid metabolites

Background: Dietary flavonoid intake is associated with a reduced risk of some cardiometabolic disorders, attributed in part to their claimed anti-inflammatory activity. Our aim was to investigate the potential association between specific urine flavonoid metabolites, liver enzymes, and inflammatory status in individuals with metabolic syndrome (MetS). Methods: In this cross-sectional study, clinical and dietary data from 267 participants, aged 55 to 75 years, participating in the PREDIMED Plus study (PREvención con DIeta MEDiterránea) were analyzed. At the baseline, spot urine samples were collected and seven urinary flavonoid metabolites were quantified using ultra-performance liquid chromatography coupled to triple quadrupole mass spectrometry (UPLC-Q-q-Q MS). Liver enzymes, inflammatory scores, and urinary flavonoid concentrations were inverse normally transformed. Results: Adjusted linear regression models showed an inverse association between urinary citrus flavanone concentrations and gamma-glutamyl transferase (GGT) (all p-values <0.05). Naringenin 7'-GlcUA was significantly associated with a lower aggregate index of systemic inflammation (AISI) (B_{per 1SD} = -0.14; 95% CI: -0.27 to -0.02; p-value = 0.025) and systemic inflammation index (SII) (B_{per 1SD} = -0.14; 95% CI: -0.27 to -0.02; p-value = 0.028). To investigate the relationship between flavanone subclasses and GGT levels, we fitted a score of citrus-flavanones, and subjects were stratified into quartiles. The highest values of the citrus-flavanone score (per 1-SD increase) were associated with lower GGT levels (B_{per 1SD} = -0.41; 95% CI: -0.74 to -0.07), exhibiting a linear trend across quartiles (p-trend = 0.015). Conclusion: This cross-sectional study showed that higher urinary excretion of citrus-flavanone metabolites was associated with lower GGT levels in subjects diagnosed with MetS and obesity.

The Interaction between Flavonoids and Intestinal Microbes: A Review

In recent years, research on the interaction between flavonoids and intestinal microbes have prompted a rash of food science, nutriology and biomedicine, complying with future research trends. The gut microbiota plays an essential role in the maintenance of intestinal homeostasis and human health, but once the intestinal flora dysregulation occurs, it may contribute to various diseases. Flavonoids have shown a variety of physiological activities, and are metabolized or biotransformed by gut microbiota, thereby producing new metabolites that promote human health by modulating the composition and structure of intestinal flora. Herein, this review demonstrates the key notion of flavonoids as well as intestinal microbiota and dysbiosis, aiming to provide a comprehensive understanding about how flavonoids regulate the diseases by gut microbiota. Emphasis is placed on the microbiota-flavonoid bidirectional interaction that affects the metabolic fate of flavonoids and their metabolites, thereby influencing their metabolic mechanism, biotransformation, bioavailability and bioactivity. Potentially by focusing on the abundance and diversity of gut microbiota as well as their metabolites such as bile acids, we discuss the influence mechanism of flavonoids on intestinal microbiota by protecting the intestinal barrier function and immune system. Additionally, the microbiota-flavonoid bidirectional interaction plays a crucial role in regulating various diseases. We explain the underlying regulation mechanism of several typical diseases including gastrointestinal diseases, obesity, diabetes and cancer, aiming to provide a theoretical basis and guideline for the promotion of gastrointestinal health as well as the treatment of diseases.

The effects of citrus flavonoids and their metabolites on immune-mediated intestinal barrier disruption using an in vitro co-culture model

Hesperidin and naringin are citrus flavonoids with known anti-oxidative and anti-inflammatory properties. Evidence from previous studies indicates that both these compounds and the metabolites that are formed during intestinal metabolism are able to exert beneficial effects on intestinal barrier function and inflammation. However, so far, studies investigating the relative contributions of the various compounds are lacking. Therefore, we assessed the effect of citrus flavonoids and their intestinal metabolites on immune-mediated barrier disruption in an in vitro co-culture model. Caco-2 cell monolayers were placed in co-culture with phorbol 12-myristate 13-acetate-stimulated THP-1-Blue™ NF-κB cells for 30 h. At baseline, the citrus flavonoids and their metabolites were added to the apical compartment (50 or 100 µM per compound). After 24 h, THP-1 cells were incubated with lipopolysaccharide (LPS) in the basolateral compartment for 6 h. Incubation with citrus flavonoids and their metabolites did not induce changes in transepithelial electrical resistance, fluorescein isothiocyanate-dextran 4 kDa permeation or gene expression of barrier-related genes for any of the compounds tested. After LPS stimulation, NF-κB activity was significantly inhibited by all compounds (100 µM) except for one metabolite (all P ≤ 0·03). LPS-induced production of the cytokines IL-8, TNF-α and IL-6 was inhibited by most compounds (all P < 0·05). However, levels of IL-1β were increased, which may contribute to the lack of an improved barrier effect. Overall, these results suggest that citrus flavonoids may decrease intestinal inflammation via reduction of NF-κB activity and that the parent compounds and their metabolites formed during intestinal metabolism are able to exert comparable effects.

Fourteen-Day Evolution of COVID-19 Symptoms during the Third Wave in Nonvaccinated Subjects and Effects of Hesperidin Therapy: A Randomized, Double-Blinded, Placebo-Controlled Study

COVID-19 symptoms can cause substantial disability, yet no therapy can currently reduce their frequency or duration. We conducted a double-blind placebo-controlled trial of hesperidin 1000 mg once daily for 14 days in 216 symptomatic nonvaccinated COVID-19 subjects. Thirteen symptoms were recorded after 3, 7, 10, and 14 days. The primary endpoint was the proportion of subjects with any of four cardinal (group A) symptoms: fever, cough, shortness of breath, or anosmia. At the baseline, symptoms in decreasing frequency were as follows: cough (53.2%), weakness (44.9%), headache (42.6%), pain (35.2%), sore throat (28.7%), runny nose (26.9%), chills (22.7%), shortness of breath (22.2%), anosmia (18.5%), fever (16.2%), diarrhea (6.9%), nausea/vomiting (6.5%), and irritability/confusion (3.2%). Group A symptoms in the placebo vs. hesperidin group were 88.8% vs. 88.5% (day 1) and reduced to 58.5 vs. 49.4% at day 14 (OR 0.69, 95% CI 0.38–1.27, $p=0.23$ ). At day 14, 15 subjects in the placebo group and 28 in the hesperidin group failed to report their symptoms. In an attrition bias analysis imputing “no symptoms” to missing values, the hesperidin group showed reduction of 14.5% of group A symptoms from 50.9% to 36.4% (OR: 0.55, 0.32–0.96, $p=0.03$ ). Anosmia, the most frequent persisting symptom (29.3%), was lowered by 7.3% to 25.3% in the hesperidin group vs. 32.6% in the placebo group ( $p=0.29$ ). The mean number of symptoms in the placebo and hesperidin groups was 5.10 (SD 2.26) vs. 5.48 (SD 2.35) (day 1) and 1.40 (SD 1.65) vs. 1.38 (SD 1.76) (day 14) ( $p=0.92$ ). In conclusion, most nonvaccinated COVID-19 infected subjects remain symptomatic after 14 days with anosmia being the most frequently persisting symptom. Hesperidin 1 g daily may help reduce group A symptoms. Earlier treatment of longer duration and/or higher dosage should be tested.

Cardioprotective Effects of Grapefruit IntegroPectin Extracted via Hydrodynamic Cavitation from By-Products of Citrus Fruits Industry: Role of Mitochondrial Potassium Channels

Citrus flavonoids are well-known for their beneficial effects at the cardiovascular and cardio-metabolic level, but often the encouraging in vitro results are not confirmed by in vivo approaches; in addition, the clinical trials are also inconsistent. Their limited bioavailability can be, at least in part, the reason for these discrepancies. Therefore, many efforts have been made towards the improvement of their bioavailability. Hydrodynamic cavitation methods were successfully applied to the extraction of byproducts of the Citrus fruits industry, showing high process yields and affording stable phytocomplexes, known as IntegroPectin, endowed with great amounts of bioactive compounds and high water solubility. The cardioprotective effects of grapefruit IntegroPectin were evaluated by an ex vivo ischemia/reperfusion protocol. Further pharmacological characterization was carried out to assess the involvement of mitochondrial potassium channels. Grapefruit IntegroPectin, where naringin represented 98% of the flavonoids, showed anti-ischemic cardioprotective activity, which was better than pure naringenin (the bioactive aglycone of naringin). On cardiac-isolated mitochondria, this extract confirmed that naringenin/naringin were involved in the activation of mitochondrial potassium channels. The hydrodynamic cavitation-based extraction confirmed a valuable opportunity for the exploitation of Citrus fruits waste, with the end product presenting high levels of Citrus flavonoids and improved bioaccessibility that enhances its nutraceutical and economic value.

Recent Overview of Resveratrol's Beneficial Effects and Its Nano-Delivery Systems

Highlights

Abstract

Natural polyphenols have a wide variety of biological activities and are taken into account as healthcare materials. Resveratrol is one such natural polyphenol, belonging to a group known as stilbenoids (STBs). Resveratrol (3,5,4′-trihydroxy-trans-stilbene) is mainly found in grapes, wine, nuts, and berries. A wide range of biological activities has been demonstrated by resveratrol, including antimicrobial, antioxidant, antiviral, antifungal, and antiaging effects, and many more are still under research. However, as with many other plant-based polyphenol products, resveratrol suffers from low bioavailability once administered in vivo due to its susceptibility to rapid enzyme degradation by the body’s innate immune system before it can exercise its therapeutic influence. Therefore, it is of the utmost importance to ensure the best use of resveratrol by creating a proper resveratrol delivery system. Nanomedicine and nanodelivery systems utilize nanoscale materials as diagnostic tools or to deliver therapeutic agents in a controlled manner to specifically targeted locations. After a brief introduction about polyphenols, this review overviews the physicochemical characteristics of resveratrol, its beneficial effects, and recent advances on novel nanotechnological approaches for its delivery according to the type of nanocarrier utilized. Furthermore, the article summarizes the different potential applications of resveratrol as, for example, a therapeutic and disease-preventing anticancer and antiviral agent.

Process Optimization and Stability of Waste Orange Peel Polyphenols in Extracts Obtained with Organosolv Thermal Treatment Using Glycerol-Based Solvents

This study was focused on the simultaneous organosolv treatment/extraction of waste orange peels (WOP) for the effective recovery of polyphenolic antioxidants. The treatments were performed with aqueous glycerol mixtures, which were acidified either with citric acid or hydrochloric acid (HCl). Process optimization was carried out using response surface methodology and comparative appraisal of the different processes tested, based on both the extraction efficiency factor (FEE), severity factor (SF) or combined severity factor (CSF). Metabolite stability was also of major concern, and it was examined by deploying liquid chromatography-mass spectrometry. The results drawn suggested 90% (w/w) glycerol to be the highest-performing system, providing a yield in total polyphenols of 44.09 ± 5.46 mg GAE g−1 DM at 140 °C for 50 min, with a FEE of 2.20 and an SF of 2.88. Acidification with 1% citric acid was proven less efficient and equally severe, whereas acidification with 1% HCl was less severe but also less efficient. The major disadvantage associated with the use of HCl was its detrimental impact on the polyphenolic composition of WOP since major metabolites, such as narirutin, hesperidin and didymin, did not survive the process. By contrast, the formation of lower molecular weight compounds was observed. With regard to antioxidant properties, the extract obtained with aqueous glycerol displayed significantly higher antiradical activity and reducing power, which was in line with its higher concentration in total polyphenols. It was concluded that organosolv treatment with aqueous glycerol under the conditions employed may boost polyphenol recovery from WOP, thus giving extracts with powerful antioxidant characteristics.

A Narrative Review of the Effects of Citrus Peels and Extracts on Human Brain Health and Metabolism

As life expectancy increases, age-associated diseases such as Alzheimer's disease (AD) become a major health problem. The onset of AD involves neurological dysfunction due to amyloid-β accumulation, tau hyperphosphorylation, oxidative stress, and neuroinflammation in the brain. In addition, lifestyle-related diseases-such as dyslipidemia, diabetes, obesity, and vascular dysfunction-increase the risk of developing dementia. The world population ages, prompting the development of new strategies to maintain brain health and prevent the onset of dementia in older and preclinical patients. Citrus fruits are abundant polymethoxylated flavone and flavanone sources. Preclinical studies reported that these compounds have neuroprotective effects in models of dementia such as AD. Interestingly, clinical and epidemiological studies appear to support preclinical evidence and show improved cognitive function and reduced associated disease risk in healthy individuals and/or patients. This review summarizes the recent evidence of the beneficial effects of citrus peels and extracts on human cognition and related functions.

Influences of Solubility and Vehicle Carriers on Eriodictyol Pharmacokinetics in Rats

In this study, the pharmacokinetics of oral doses of eriodictyol in 1% sodium carboxymethylcellulose and in saline/PEG400/Tween80 (75/20/5, v/v/v) in rats were compared. The pharmacokinetics of eriocitrin administered as a dissolved solution in water were also characterized. Metabolites of eriodictyol and eriocitrin in whole blood consisted mainly of eriodictyol, homoeriodictyol, and hesperetin glucuronides and ring-fission metabolites. In whole blood, no free nonconjugated flavanone aglycones were detected. Significant differences were observed in the pharmacokinetics of eriodictyol administered as a suspension in 1% sodium carboxymethylcellulose versus administration as a dissolved solution in saline/PEG400/Tween80 (75/20/5, v/v/v). At a dose of 25 mg kg^-1 eriodictyol administered with 1% sodium carboxymethylcellulose, a biphasic pharmacokinetic curve was observed, while only a single concentration peak was observed following an administration of 25 mg kg^-1 eriodictyol dissolved in saline/PEG400/Tween80 (75/20/5, v/v/v). For all trials, the pharmacokinetics of eriodictyol differed from those of eriocitrin dissolved in water.

Comparative Analysis of the Chalcone-Flavanone Isomerase Genes in Six Citrus Species and Their Expression Analysis in Sweet Orange (Citrus sinensis)

Citrus fruit contains rich nutrients which is edible and of officinal value. Citrus flavanones are widely used in the treatment of cardiovascular and other diseases, and they are a foundational material of Chinese medicine. The chalcone-flavanone isomerase (CHI) plays a key role in flavanone synthesis. Therefore, we comprehensively analyzed CHI genes in Citrus species. Here, thirty CHI genes were identified for the first time in six Citrus species, which were divided into CHI and FAP groups. Evolutionary analysis showed that CHI gene members were highly conserved and were an ancient family. All CsCHI genes showed the highest expression level after the second physiological fruit-falling period in C. sinensis. CsCHI1 and CsCHI3 were highly expressed at 50 days after the flowering (DAF) stage in albedo. The expression of CsFAP2 and CsCHI3 genes at the 50 DAF stage was 16.5 and 24.3 times higher than that at the 220 DAF stage, respectively. The expression of CsCHI1, CsCHI3, and CsFAP2 genes in the peel was higher than that in the pulp, especially in common sweet orange. The CsCHI3 gene maintained a high expression level in the epicarp and juice sac at all periods. The members of CHIs interacted with chalcone synthase (CHS), flavonol synthase/flavanone 3-hydroxylase (FLS) and naringenin, and 2-oxoglutarate 3-dioxygenase (F3H) to form heterodimers, which might together play a regulatory role and participate in the flavonoid pathway. This study will provide the basis for the selection of flavonoids in plant tissues and periods and fundamental information for further functional studies.

Molecular Insights on the Therapeutic Effect of Selected Flavonoids on Diabetic Neuropathy

One of the common clinical complications of diabetes is diabetic neuropathy affecting the nervous system. Painful diabetic neuropathy is widespread and highly prevalent. At least 50% of diabetes patients develop diabetic neuropathy eventually. The four main types of diabetic neuropathy are peripheral neuropathy, autonomic neuropathy, proximal neuropathy (diabetic polyradiculopathy), and mononeuropathy (Focal neuropathy). Glucose control remains the common therapy for diabetic neuropathy due to limited knowledge on early biomarkers that are expressed during nerve damage, thereby limiting the cure through pharmacotherapy. Glucose control dramatically reduces the onset of neuropathy in type 1 diabetes but proves less effective in type 2 diabetes. Therefore, the focus is on various herbal remedies for prevention and treatment. There is numerous research on the use of anticonvulsants and antidepressants for the management of pain in diabetic neuropathy. Extensive research is being done on natural products including the isolation of pure compounds like flavonoids from plants and their effect on diabetic neuropathy. This review focuses on the use of an important of flavonoids such as flavanols (e.g., quercetin, rutin, kaempferol, and isorhamnetin), flavanones (e.g., hesperidin, naringenin and c,lass eriodictyol), and flavones (e.g., apigenin, luteolin, tangeretin, chrysin, and diosmin) for the prevention and treatment of diabetic neuropathy. The mechanisms of action of flavonoids against diabetic neuropathy by their antioxidant, anti-inflammation, anti-glycation properties, etc. are also covered in this review article.

Comprehensive Characterization and Quantification of Antioxidant Compounds in Finger Lime (Citrus australasica L.) by HPLC-QTof-MS and UPLC-MS/MS

Australian finger limes (Citrus australasica L.), an unusual citrus due to its unique pulp with a caviar-like appearance, has reached the global market as a promising source of bioactive compounds that promote health. This research was, therefore, performed to shed light on the bioactivity and composition of different parts of Citrus australasica L. (peel and pulp). Initial ultrasound-assisted extraction using MeOH:H2O (80:20, v/v) was carried out. After that, four fractions (hexane, ethyl acetate, butanol and water) were generated through liquid–liquid partitioning, and the total phenolic content (TPC) and antioxidant activity were evaluated using the Folin–Ciocalteu and the ferric reducing antioxidant power (FRAP) assays, respectively. The ethyl acetate fraction in the peel, which presented the highest values of TPC and antioxidant activity, was characterized using high-performance liquid chromatography coupled to quadrupole time-of-flight (HPLC-QTof) mass spectrometry. Fifteen compounds were identified, of which seven were characterized for the first time in this matrix. Moreover, ten phenolic compounds were quantified using ultra-performance liquid chromatography coupled with tandem mass spectrometry (UPLC-MS/MS). The major compounds in the sample were citric acid, pyrogallol, caffeic acid, coumarin, rutin, naringin, 2-coumaric acid, didymin, naringenin and isorhamnetin, which were found in a range from 2.7 to 8106.7 µg/g sample dry weight. Finally, the results presented in this novel work confirmed that the peel by-product of C. australasica L. is a potential source of bioactive compounds and could result in a positive outcome for the food, cosmetics and pharmaceutical industries.

Carotenoids and Carcinogenesis: Exploring the Antioxidant and Cell Signaling Roles of Carotenoids in the Prevention of Cancer

Carotenoids are lipid soluble pigments found in various fruits and vegetables and are naturally produced in photoautotrophic plants. Various studies have investigated the properties of carotenoids to determine how they are able to mitigate numerous diseases, including cancer. Carotenoids present in human serum, including β-carotene, α-carotene, lycopene, β-cryptoxanthin, zeaxanthin, and lutein have demonstrated the ability to act as anticarcinogenic agents. Prevention of disease is often described to be more effective than treatment; as cancer impacts millions of lives globally, the role of carotenoids in the prevention of oncogenesis for numerous types of cancers have been extensively researched. This review provides an in-depth analysis of the structure and properties of carotenoids, as well as the identified and potential mechanisms by which carotenoids can act as a chemopreventative agent.

Understanding the Functional Activity of Polyphenols Using Omics-Based Approaches

Plant polyphenols are the main category of natural active substances, and are distributed widely in vegetables, fruits, and plant-based processed foods. Polyphenols have a beneficial performance in preventing diseases and maintaining body health. However, its action mechanism has not been well understood. Foodomics is a novel method to sequence and widely used in nutrition, combining genomics, proteomics, transcriptomics, microbiome, and metabolomics. Based on multi-omics technologies, foodomics provides abundant data to study functional activities of polyphenols. In this paper, physiological functions of various polyphenols based on foodomics and microbiome was discussed, especially the anti-inflammatory and anti-tumor activities and gut microbe regulation. In conclusion, omics (including microbiomics) is a useful approach to explore the bioactive activities of polyphenols in the nutrition and health of human and animals.

Effects of flavonoids in experimental models of arterial hypertension

Flavonoids are a class of substances of a vegetal origin with many interesting actions from the point of view of human disease. Interest in flavonoids in the diet has increased in recent years due to the publication of basic, clinical and epidemiological studies that have shown a whole array of salutory effects related to intake of flavonols and flavones as well as a lower morbility and mortality of cardiovascular diseases. Since arterial hypertension is the most common modifiable risk factor for cardiovascular diseases, this review will focus mainly on the effects of flavonoids on the cardiovascular system with relation to the elevation of blood pressure. Its antihypertensive effects as well as the many investigations performed in experimental models of arterial hypertension are reviewed in this mini-review.

Naringenin alleviates myocardial ischemia/reperfusion injury by regulating the nuclear factor-erythroid factor 2-related factor 2 (Nrf2) /System xc-/ glutathione peroxidase 4 (GPX4) axis to inhibit ferroptosis

Ferroptosis is an important form of myocardial cell death in myocardial ischemia-reperfusion injury (MIRI). Naringenin (NAR), as a flavonoid, has a significant advantage in improving MIRI. But the regulatory effect and mechanism of NAR on ferroptosis in MIRI have not been reported. After the rats were given NAR and induced to form myocardial ischemia-reperfusion (MI/R) injury, Tetrazolium chloride (TTC) staining was used to detect the myocardial infarction area of rats, and Hematoxylin-eosin (H&E) staining was used to detect myocardial injury. The markers of tissue inflammation were detected by ELISA. Serum creatine kinase Serum creatin kinase (CPK), Lactate dehydrogenase (LDH), and lipid peroxide (LPO) and oxidative stress related levels were measured. In addition, iron detection kits were used to detect total iron and Fe²⁺ levels in cardiac tissues, and western blot was used to detect the expression of ferroptosis-related proteins and the expression of nuclear factor-erythroid factor 2-related factor 2 (Nrf2) and glutathione peroxidase 4 (GPX4). At the cellular level, H9C2 cardiomyocytes were induced by hypoxia/reoxygenation (H/R), and ferroptosis inducer Erastin was administered to detect cell viability, ferroptosis-related indicators, oxidative stress related indicators, and expressions of Nrf2 and GPX4, to explore the mechanisms involved. NAR alleviated MI/R-induced pathological damage, inflammation and lipid peroxidation in myocardial tissue of rats. NAR adjusted the NRF2 /System xc – /GPX4 axis and improved ferroptosis. At the cellular level, ferroptosis inducer Erastin reversed the protective effect of NAR on H/R-induced H9C2 cardiomyocytes. In conclusion, NAR can alleviate MIRI by regulating the Nrf2/System xc-/GPX4 axis to inhibit ferroptosis.

Two fungal flavonoid-specific glucosidases/rutinosidases for rutin hydrolysis and rutinoside synthesis under homogeneous and heterogeneous reaction conditions

The glycosidases within GH5-23 cleave the glycosidic bond of β-glucosylated or rutinosylated flavonoids. Moreover, by virtue of their transglycosylation activity, glycoconjugates with glucosyl and rutinosyl moieties are accessible. Here we report the biochemical characterization and biotechnological assessment of two heterologously expressed members of GH5-23—McGlc from Mucor circinelloides and PcGlc from Penicillium chrysogenum. Both enzymes exhibited the highest hydrolytic activities with quercetin-3-β-O-glucopyranoside, whereas lower specificity constants were determined with the rutinosides narcissin, rutin and hesperidin. High stabilities against thermal, ethanol and dimethyl sulfoxide-induced inactivation, a very limited secondary hydrolysis of the formed transglycosylation products, and no detectable product inhibition were additional features appropriate for biotechnological applications. The enzymes were compared in their efficiencies to hydrolyze rutin and to synthesize 2-phenylethyl rutinoside under homogeneous and heterogeneous reaction conditions using high rutin concentrations of 100 and 300 mM. Highest transglycosylation efficiencies were achieved with fully dissolved rutin in reaction mixtures containing 25% dimethyl sulfoxide. Molecular docking and multiple sequence alignments suggest that the hydrophobic environment of aromatic residues within the + 1 subsite of GH5-23 glycosidases is very important for the binding of flavonoid glucosides and rutinosides.

High Hydrostatic Pressure vs. Thermal Pasteurization: The Effect on the Bioactive Compound Profile of a Citrus Maqui Beverage

The effects of high hydrostatic pressure (HHP) compared to thermal pasteurization (TP) were studied in healthy citrus-maqui beverages. The impact of the processing technologies on the microbiological and phytochemical profile was assessed by applying two HHP treatments at 450 and 600 MPa for 180 s and TP at 85 °C for 15 s. The shelf life under refrigeration (4 °C) and room temperature (20 °C) was monitored for 90 days. All treatments ensured microbiological stability at both storage temperatures. Aside from that, the physicochemical parameters were not significantly different after processing or throughout the storage period. Regarding color parameters, an increase in the reddish coloration was observed during storage for those beverages treated by HHP. In general, phenolic compounds were little affected by the processing technique, even when treatment under HHP was more stable than by TP during storage. On the other hand, vitamin C showed great degradation after processing under any condition. It can be concluded that HHP is an effective alternative to thermal treatments, achieving effective microbial inactivation and extending the shelf life of the juices by contributing to a better preservation of color and bioactive compounds.

Vasorelaxant effect of 5,7,4'- Trihydroxyflavanone (Naringenin) via endothelium dependent, potassium and calcium channels in Sprague Dawley rats: Aortic ring model

Naringenin is a naturally occurring flavanone (flavonoid) known to have bioactive effects on human health. It has been reported to show cardiovascular effects. This study aimed to investigate the possible vasorelaxant effect of naringenin and the mechanism behind it by using a Sprague Dawley rat aortic ring assay model. Naringenin caused significant vasorelaxation of endothelium-intact aortic rings precontracted with phenylephrine (pD₂ = 4.27 ± 0.05; R_max = 121.70 ± 4.04%) or potassium chloride (pD₂ = 4.00 ± 0.04; R_max = 103.40 ± 3.82%). The vasorelaxant effect decreased in the absence of an endothelium (pD₂ = 3.34 ± 0.10; R_max = 62.29 ± 2.73%). The mechanisms of the vasorelaxant effect of naringenin in the presence of antagonists were also investigated. Indomethacin, 1H-[1,2,4]oxadiazolo[4,3-a]quinoxalin-1-one, atropine, 4-aminopyridine, Nω-nitro-l-arginine methyl ester, glibenclamide and propranolol significantly reduced the relaxation stimulated by naringenin in the presence of endothelium. Besides that, the effect of naringenin on the voltage-operated calcium channel (VOCC) in the endothelium-intact aortic ring was studied, as was intracellular Ca²⁺ release from the sarcoplasmic reticulum (SR) in the endothelium-denuded aortic ring. The results showed that naringenin also significantly blocked the entry of Ca²⁺ via the VOCC, SERCA/SOCC and suppressed the release of Ca²⁺ from the SR. Thus, the vasorelaxant effect shown by naringenin mostly involve the COX pathway, the endothelium-dependent pathway via NO/sGC/prostaglandin, calcium and potassium channels.

Hesperetin regulates transforming growth factor-β1/Smads pathway to suppress epithelial-mesenchymal transition -mediated invasion and migration in cervical cancer cell

Hesperetin is an abundant flavonoid in citrus fruits, and be confirmed to possess a chemo-preventive effect on cancer. Migration and invasion are the main causes of death of cervical cancer patients, in which epithelial-mesenchymal transition (EMT) can directly contribute to malignant phenotypes of tumor cells. The present study aims to investigate the inhibitory effect of hesperetin on EMT-mediated invasion and migration in cervical cancer cells through transforming growth factor-β1 (TGF-β1)/Smads pathway. Cell viability, cell migration and invasion ability, and cell morphology were evaluated and monitored using 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2-H-tetrazolium bromide assays, Transwell assays and optical microscope, respectively. The change of EMT marker protein E-cadherin and N-cadherin was assessed by immunofluorescence assay, whereas the protein expression of EMT bio-marker and TGF-β1/Smads pathway were detected through western blot analysis. In conclusion, hesperetin can suppress EMT-mediated invasion and migration of cervical cancer cells by inhibiting abnormal activation of TGF-β1/Smads pathway. The study provides an experimental basis for the prevention of the invasion and migration of cervical cancer.

Current developments in the synthesis of 4-chromanone-derived compounds

The chroman-4-one framework is a significant structural entity that belongs to the class of oxygen-containing heterocycles. It acts as a major building block in a large class of medicinal compounds, and synthetic compounds exhibit a broad variety of remarkable biological and pharmaceutical activities. Several studies have been performed to improve the methodologies of 4-chromanone-derived compounds. This review focuses on the major synthetic methods of preparation reported on chroman-4-one derivatives from 2016 to 2021.

Analytical Methods for Exploring Nutraceuticals Based on Phenolic Acids and Polyphenols

Phenolic compounds such as phenolic acids, flavonoids, and stilbenes comprise an enormous family of bioactive molecules with a range of positive properties, including antioxidant, antimicrobial, or anti-inflammatory effects. As a result, plant extracts are often purified to recover phenolic compound-enriched fractions to be used to develop nutraceutical products or dietary supplements. In this article, we review the properties of some remarkable plant-based nutraceuticals in which the active molecules are mainly polyphenols and related compounds. Methods for the characterization of these extracts, the chemical determination of the bioactivities of key molecules, and the principal applications of the resulting products are discussed in detail.

Natural Products with tandem Anti-inflammatory, Immunomodulatory and Anti-SARS-CoV/2 effects: A Drug Discovery Perspective against SARS-CoV-2

BACKGROUND

COVID-19 is still causing victims with long-term health consequences, mass deaths, and collapsing healthcare systems around the world. The disease has no efficient drugs. However, previous studies revealed that SARS-CoV-2 and SARS-CoV have 96% and 86.5% similarities in cysteine proteases (3CL^pro) and papain-like protease (PL^pro) sequences, respectively. This resemblance could be significant in the search for drug candidates with antiviral effects against SARS-CoV-2.

OBJECTIVE

This paper is a compilation of natural products that inhibit SARS-CoV 3CL^pro and PL^pro and, concomitantly, reduce inflammation and/or modulate the immune system as a perspective strategy for COVID-19 drug discovery. It also presents in silico studies performed on these selected natural products using SARS-CoV-2 3CL^pro and PL^pro as targets to propose a list of hit compounds.

METHOD

The plant metabolites were selected in the literature based on their biological activities on SARS-CoV proteins, inflammatory mediators, and immune response. The consensus docking analysis was performed using four different packages.

RESULTS

Seventy-nine compounds reported in the literature with inhibitory effects on SARS-CoV proteins were reported as anti-inflammatory agents. Fourteen of them showed in previous studies immunomodulatory effects. Five and six of these compounds showed significant in silico consensus as drug candidates that can inhibit PL^pro and 3CL^pro, respectively. Our findings corroborated recent results reported on anti-SARS-CoV-2 in the literature.

CONCLUSION

This study revealed that amentoflavone, rubranoside B, savinin, psoralidin, hirsutenone, and papyriflavonol A are good drug candidate for the search of antibiotics against COVID-19.

The Use of Bio-Active Compounds of Citrus Fruits as Chemopreventive Agents and Inhibitor of Cancer Cells Viability

Common therapy of cancer, such as chemotherapy, has various side effects for the patients. In recent studies, new therapeutic approaches in cancer treatment are adjuvant therapy, along with a reduction in side effects of chemotherapy drugs. Treatment by herbal medicines may have some advantages over treatment with single purified chemicals, also in terms of side effects, the use of plants in cancer treatment is a more secure method. Citrus fruits are one of the most consumed natural products in the world due to the presence of various metabolites and bioactive compounds, such as phenols, flavonoids and, carotenoids. Bioactive compounds of citrus modulate signaling pathways and interact with signaling molecules such as apoptotic and cell cycle (P53, P21, etc.) and thus have a wide range of pharmacological activities, including anti-inflammatory, anti-cancer and oxidative stress. The findings discussed in this review strongly support their potential as anti-cancer agents. Therefore, the purpose of this review was to examine the effects of active compounds in citrus as a therapy agent in cancer treatment.

Citrus flavanone metabolites protect pancreatic-β cells under oxidative stress induced by cholesterol

Cholesterol is one of the triggers of oxidative stress in the pancreatic-β cell, generating high levels of reactive oxygen species, which leads to impairment of insulin synthesis and secretion. Bioactive compounds, such as citrus flavanones, which possess anti-inflammatory and antioxidant activities, could reduce oxidative stress in β-cells and improve their function. We describe for the first time the protective effects of the phase-II flavanone metabolites [naringenin 7-O-glucuronide, hesperetin 3'-O-glucuronide, and hesperetin 7-O-glucuronide], and two flavanones-catabolites derived from gut microbiota metabolism [hippuric acid and 3-(4-hydroxyphenyl)propionic acid], on pancreatic β-cell line MIN6 under oxidative stress, at physiologically relevant concentration. Cholesterol reduced cell viability in a dose and time-dependent manner, with an improvement in the presence of the metabolites. Moreover, flavanone metabolites attenuated oxidative stress by reducing levels of lipid peroxides, superoxide anions, and hydrogen peroxide. In response to the reduction of reactive oxygen species, a decrease in superoxide dismutase and glutathione peroxidase activities was observed; these activities were elevated by cholesterol. Moreover, all the flavanone metabolites improved mitochondrial function and insulin secretion, and reduced apoptosis. Flavanone metabolites were found uptake by β-cells, and therefore could be responsible for the observed protective effects. These results demonstrated that circulating phase-II hesperetin and naringenin metabolites, and also phenolics derived from gut microbiota, protect pancreatic-β cells against oxidative stress, leading to an improvement in β-cell function and could be the bioactive molecules derived from the citrus consumption.

The role and mechanism of citrus flavonoids in cardiovascular diseases prevention and treatment

Cardiovascular diseases (CVDs) have been ranked as the leading cause of death in the world, whose global incidence is increasing year by year. Citrus, one of the most popular fruits in the world, is rich in flavonoids. Citrus flavonoids attract special attention due to a variety of biological activities, especially in the prevention and treatment of CVDs. The research progress of citrus flavonoids on CVDs have been constantly updated, but relatively fragmented, which needed to be systematically summarized. Hence, the recent research about citrus flavonoids and CVDs were reviewed, including the types and in vivo processes of citrus flavonoids, epidemiology study and mechanism on prevention and treatment of CVDs by citrus flavonoids. This review would provide a theoretical basis for the citrus flavonoids research and a new idea in the citrus industry development and application.

An Up-to-Date Review on Citrus Flavonoids: Chemistry and Benefits in Health and Diseases

Flavonoids, the main class of polyphenols, are characterized by the presence of 2-phenyl-benzo-pyrane nucleus. They are found in rich quantities in citrus fruits. Citrus flavonoids are classified into flavanones, flavones, flavonols, polymethoxyflavones and anthocyanins (found only in blood oranges). Flavanones are the most abundant flavonoids in citrus fruits. In many situations, there are structure-function relationships. Due to their especial structures and presence of many hydroxyls, polymethoxies and glycoside moiety, the flavonoids have an array of multiple biological and pharmacological activities. This article provides an updated overview of the differences in chemical structures of the classes and members of citrus flavonoids and their benefits in health and diseases. The review article also sheds light on the mechanisms of actions of citrus flavonoids in the treatment of different diseases, including arthritis, diabetes mellitus, cancer and neurodegenerative disorders as well as liver, kidney and heart diseases. The accumulated and updated knowledge in this review may provide useful information and ideas in the discovery of new strategies for the use of citrus flavonoids in the protection, prevention and therapy of diseases.

Novel Polymeric Biomaterial Based on Naringenin

Biomaterials prepared based on raw plant materials are becoming more and more popular due to their specific properties and environmental friendliness. Naringenin is a flavonoid naturally occurring in citrus fruit with antioxidant and pharmacological activity. Polymeric materials based on flavonoids may have favorable properties in comparison to monomeric polyphenols, such as stronger antioxidant and antimicrobial properties. One of the methods of obtaining the polymeric form of flavonoids is polymerization with a cross-linking compound. This method has already been used to obtain poly(quercetin) and poly(rutin) from a flavonol group as well as poly(catechin) from the flavan-3-ol group of flavonoids. However, to date, no polymeric forms of flavanones have been prepared in a cross-linking reaction; the aim of this study was to obtain poly(naringenin) by reaction with a cross-linking compound using glycerol diglycide ether GDE. The degree of conversion of naringenin to poly(naringenin) determined by FTIR spectroscopy was 85%. In addition, the thermal, antioxidant and antimicrobial properties of poly(naringenin) were analyzed. Poly(naringenin) was characterized by greater resistance to oxidation and better thermal stability than monomeric naringenin. Moreover, polymeric naringenin also had a better ability to scavenge ABTS and DPPH free-radicals. In contrast to monomeric form, poly(naringenin) had antimicrobial activity against Candida albicans. Polymeric biomaterial based on naringenin could potentially be used as a natural stabilizer and antimicrobial additive for polymer compositions, as well as pro-ecological materials.

Wnt/β-catenin Antagonists: Exploring New Avenues to Trigger Old Drugs in Alleviating Glioblastoma Multiforme

BACKGROUND

Glioblastoma multiforme is one of the most heterogenous primary brain tumor with high mortality. Nevertheless, of the current therapeutic approaches, survival rate remains poor with 12 to 15 months following preliminary diagnosis, this warrants the need for effective treatment modality. Wnt/β-catenin pathway is presumably the most noteworthy pathway up-regulated in almost 80% GBM cases contributing to tumor-initiation, progression and survival. Therefore, therapeutic strategies targeting key components of Wnt/β-catenin cascade using established genotoxic agents like temozolomide and pharmacological inhibitors would be an effective approach to modulate Wnt/β-catenin pathway. Recently, drug repurposing by means of effective combination therapy has gained importance in various solid tumors including GBM, by targeting two or more proteins in a single pathway, thereby possessing the ability to overcome the hurdle implicated by chemo-resistance in GBM.

OBJECTIVE

In this context, by employing computational tools, an attempt has been carried out to speculate the novel combinations against Wnt/β-catenin signaling pathway.

METHODS

We have explored the binding interactions of three conventional drugs namely temozolomide, metformin, chloroquine along with three natural compounds viz., epigallocatechin gallate, naringenin and phloroglucinol on the major receptors of Wnt/β-catenin signaling.

RESULTS

It was noted that all the experimental compounds possessed profound interaction with the two major receptors of Wnt/β-catenin pathway.

CONCLUSION

To the best of our knowledge, this study is the first of its kind to characterize the combined interactions of the afore-mentioned drugs on Wnt/β-catenin signaling in silico and this will putatively open up new avenues for combination therapies in GBM treatment.

Bergamottin and 5-Geranyloxy-7-methoxycoumarin Cooperate in the Cytotoxic Effect of Citrus bergamia (Bergamot) Essential Oil in Human Neuroblastoma SH-SY5Y Cell Line

The plant kingdom has always been a treasure trove for valuable bioactive compounds, and Citrus fruits stand out among the others. Bergamottin (BRG) and 5-geranyloxy-7-methoxycoumarin (5-G-7-MOC) are two coumarins found in different Citrus species with well-acknowledged pharmacological properties. Previously, they have been claimed to be relevant in the anti-proliferative effects exerted by bergamot essential oil (BEO) in the SH-SY5Y human neuroblastoma cells. This study was designed to verify this assumption and to assess the mechanisms underlying the anti-proliferative effect of both compounds. Our results demonstrate that BRG and 5-G-7-MOC are able to reduce the proliferation of SH-SY5Y cells, inducing apoptosis and increasing cell population in sub-G0/G1 phase. Moreover, we demonstrated the pro-oxidant activity of the two coumarins that increased reactive oxygen species and impaired mitochondrial membrane potential. From a molecular point of view, BRG and 5-G-7-MOC were able to modulate apoptosis related factors at both protein and gene levels. Lastly, we evaluated the synergistic effect of their combination, finding that the highest synergy was observed at a concentration ratio similar to that occurring in the BEO, supporting our initial hypothesis. Taken together, our results deepen the knowledge regarding the effect of BRG and 5-G-7-MOC in SH-SY5Y cells, emphasizing the relevance of their cooperation in achieving this effect.

New Insights into the Metabolism of the Flavanones Eriocitrin and Hesperidin: A Comparative Human Pharmacokinetic Study

The intake of hesperidin-rich sources, mostly found in orange juice, can decrease cardiometabolic risk, potentially linked to the gut microbial phase-II hesperetin derivatives. However, the low hesperidin solubility hampers its bioavailability and microbial metabolism, yielding a high inter-individual variability (high vs. low-producers) that prevents consistent health-related evidence. Contrarily, the human metabolism of (lemon) eriocitrin is hardly known. We hypothesize that the higher solubility of (lemon) eriocitrin vs. (orange) hesperidin might yield more bioavailable metabolites than hesperidin. A randomized-crossover human pharmacokinetic study (n = 16) compared the bioavailability and metabolism of flavanones from lemon and orange extracts and postprandial changes in oxidative, inflammatory, and metabolic markers after a high-fat-high-sugars meal. A total of 17 phase-II flavanone-derived metabolites were identified. No significant biomarker changes were observed. Plasma and urinary concentrations of all metabolites, including hesperetin metabolites, were higher after lemon extract intake. Total plasma metabolites showed significantly mean lower Tmax (6.0 ± 0.4 vs. 8.0 ± 0.5 h) and higher Cmax and AUC values after lemon extract intake. We provide new insights on hesperetin-eriodictyol interconversion and naringenin formation from hesperidin in humans. Our results suggest that regular consumption of a soluble and eco-friendly eriocitrin-rich lemon extract could provide a circulating concentration metabolites threshold to exert health benefits, even in the so-called low-producers.