Flavonoids and mitochondrial pharmacology: A new paradigm for cardioprotection

Effects of natural products on angiogenesis in melanoma

Melanoma is the most aggressive form of skin cancer and originates from genetic mutations in melanocytes. The disease is multifactorial, but its main cause is overexposure to UV radiation. Currently, available chemotherapy expresses little to no results, which may justify the extensive use of natural products to treat this cancer. In this study, we reviewed the inhibition of melanoma angiogenesis by natural products and its potential mechanisms using literature from PubMed, EMBASE, Web of Science, Ovid, ScienceDirect and China National Knowledge Infrastructure databases. According to summarizes 27 natural products including alkaloids, polyphenols, terpenoids, flavonoids, and steroids that effectively inhibit angiogenesis in melanoma. In addition to these there are 15 crude extracts that can be used as promising agents to inhibit angiogenesis, but their core components still deserve further investigation. There are current studies on melanoma angiogenesis involving oxidative stress, immune-inflammatory response, cell proliferation and migration and capillary formation. The above natural products can be involved in melanoma angiogenesis through core targets such as VE-cadherin, COX-2, iNOS, VEGF, bFGF, FGF2,MMP2,MMP9,IL-1β,IL-6 play a role in inhibiting melanoma angiogenesis. Effective excavation of natural products can not only clarify the mechanism of drug action and key targets, but also help to promote the preclinical research of natural products for melanoma treatment and further promote the development of new clinical drugs, which will bring the gospel to the vast number of patients who are deeply afflicted by melanoma.

The Protective Effect of Flavonoids in the Diet on Autophagy-Related Cardiac Impairment

The compounds known as flavonoids, commonly found in fruits, vegetables, legumes, medicinal herbs, chocolate, and coffee and tea beverages, have been extensively researched for their impact on cardiovascular health. Flavonoids, with their demonstrated potential, have shown promising effects in regulating blood vessel function and apoptotic processes, as well as in improving lipid profiles. While their powerful antioxidant properties were initially thought to be the main reason behind these effects, recent studies have uncovered new insights into the positive effects of flavonoids on cardiovascular health, and researchers have now identified several signaling pathways and mechanisms that also play a role. Of particular interest are the studies that have highlighted the role of autophagy in maintaining the physiological functions of cardiomyocytes and protecting them from harm. Recent publications have linked the dysregulation of autophagic processes with the development of cardiomyopathies, heart failure, and other cardiovascular diseases. This review aims to present the latest, novel findings from preclinical research regarding the potential beneficial effects of flavonoids on various heart conditions associated with altered autophagy processes.

Roles of flavonoids in ischemic heart disease: Cardioprotective effects and mechanisms against myocardial ischemia and reperfusion injury

BACKGROUND

Flavonoids are extensively present in fruits, vegetables, grains, and medicinal plants. Myocardial ischemia and reperfusion (MI/R) comprise a sequence of detrimental incidents following myocardial ischemia. Research indicates that flavonoids have the potential to act as cardioprotective agents against MI/R injuries. Several specific flavonoids, e.g., luteolin, hesperidin, quercetin, kaempferol, and puerarin, have demonstrated cardioprotective activities in animal models.

PURPOSE

The objective of this review is to identify the cardioprotective flavonoids, investigate their mechanisms of action, and explore their application in myocardial ischemia.

METHODS

A search of PubMed database and Google Scholar was conducted using keywords "myocardial ischemia" and "flavonoids". Studies published within the last 10 years reporting on the cardioprotective effects of natural flavonoids on animal models were analyzed.

RESULTS

A total of 55 natural flavonoids were identified and discussed within this review. It can be summarized that flavonoids regulate the following main strategies: antioxidation, anti-inflammation, calcium modulation, mitochondrial protection, ER stress inhibition, anti-apoptosis, ferroptosis inhibition, autophagy modulation, and inhibition of adverse cardiac remodeling. Additionally, the number and position of OH, 3'4'-catechol, C2=C3, and C4=O may play a significant role in the cardioprotective activity of flavonoids.

CONCLUSION

This review serves as a reference for designing a daily diet to prevent or reduce damages following ischemia and screening of flavonoids for clinical application.

Association of flavonoid intake with coronary artery disease risk in the older population based on the National Health and Nutrition Examination Survey

We investigated the association between flavonoid intake and coronary artery disease (CAD) risk in older adults. Data were extracted from the National Health and Nutrition Examination Survey (age ≥ 70 years; 2007-2010 and 2017-2018; n = 2 417). The total flavonoid and flavonoid subclass intake was calculated using validated food frequency questionnaires. The association between flavonoid intake and CAD risk was examined using generalized linear models with restricted cubic spline models. After multivariate adjustment, anthocyanin intake was positively associated with CAD risk; no significant associations were observed between other flavonoid subcategories and endpoint outcomes. Anthocyanins exhibited a non-linear association with CAD risk, and threshold effect analysis showed an inflection point of 15.8 mg/day for anthocyanins. Per unit increase in anthocyanins, the odds of CAD on the left of the inflection point decreased by 2%, while the odds on the right increased by 35.8%. Excessive flavonoid intake may increase CAD risk in the older population.

The Protective Role of Dietary Polyphenols in Urolithiasis: Insights into Antioxidant Effects and Mechanisms of Action

Urolithiasis is a common urological disease with increasing prevalence and high recurrence rates around the world. Numerous studies have indicated reactive oxygen species (ROS) and oxidative stress (OS) were crucial pathogenic factors in stone formation. Dietary polyphenols are a large group of natural antioxidant compounds widely distributed in plant-based foods and beverages. Their diverse health benefits have attracted growing scientific attention in recent decades. Many literatures have reported the effectiveness of dietary polyphenols against stone formation. The antiurolithiatic mechanisms of polyphenols have been explained by their antioxidant potential to scavenge free radicals and ROS, modulate the expression and the activity of endogenous antioxidant and prooxidant enzymes, regulate signaling pathways associated with OS, and maintain cell morphology and function. In this review, we first describe OS and its pathogenic effects in urolithiasis and summarize the classification and sources of dietary polyphenols. Then, we focus on the current evidence defining their antioxidant potential against stone formation and put forward challenges and future perspectives of dietary polyphenols. To conclude, dietary polyphenols offer potential applications in the treatment and prevention of urolithiasis.

Exogenous spraying of 4-chlorophenoxyacetic acid sodium salt promotes growth and flavonoid biosynthesis of mulberry leaves (Morus alba L.)

Mulberry (Morus alba L.) leaves are known as an ideal vegetable with good antioxidant effect, which can bring delicious taste and multiple health benefits. In the present study, the effects of 4-Chlorophenoxyacetic acid sodium salt (4-CPANa) treatment on growth and content of flavonoid compounds in mulberry leaves were investigated. Moreover, the changes in the expression levels of genes involved in flavonoid biosynthetic pathways, and the accumulation of important secondary metabolites including rutin (Rut), chlorogenic acid (ChA), isoquercitrin (IQ) and astragalin (Ast), were investigated in mulberry leaves. The results showed that 4-CPANa treatment could significantly promote the differentiation and growth of mulberry, increased shoot number, bud number, leaf fresh weight and leaf area of mulberry compared with control. Besides, the contents of ChA, Rut, IQ and Ast were significantly increased after 4-CPANa (5 mg/L) treatment. Further analysis revealed that 5 mg/L 4-CPANa strongly induced the expression of flavonoid biosynthesis-related genes including flavonoid 3-O-glucosyltransferase (F3GT) gene, chalcone synthase (CHS) gene, 4-xoumarate-CoA ligase (4CL) and phenylalanine ammonia lyase (PAL) gene. In conclusion, exogenous spraying of 4-CPANa provides a new way to improve the medicinal quality and development of mulberry leaf food with high value.

Supplementary Information

The online version contains supplementary material available at 10.1007/s12298-023-01339-z.

Rhamnetin ameliorates non-alcoholic steatosis and hepatocellular carcinoma in vitro

Non-alcoholic fatty liver (NAFLD) is a widespread disease with various complications including Non-alcoholic steatohepatitis (NASH) that could lead to cirrhosis and ultimately hepatocellular carcinoma (HCC). Up till now there is no FDA approved drug for treatment of NAFLD. Flavonoids such as Rhamnetin (Rhm) have been ascribed effective anti-inflammatory and anti-oxidative properties. Thus, Rhm as a potent flavonoid could target multiple pathological cascades causing NAFLD to prevent its progression into HCC. NAFLD is a multifactorial disease and its pathophysiology is complex and is currently challenged by the ‘Multiple-hit hypothesis’ that includes wider range of comorbidities rather than previously established theory of ‘Two-hit hypothesis’. Herein, we aimed at establishing reliable in vitro NASH models using different mixtures of variable ratios and concentrations of oleic acid (OA) and palmitic acid (PA) combinations using HepG2 cell lines. Moreover, we compared those models in the context of oil red staining, triglyceride levels and their altered downstream molecular signatures for genes involved in de novo lipogenesis, inflammation, oxidative stress and apoptotic machineries as well. Lastly, the effect of Rhm on NASH and HCC models was deeply investigated. Over the 10 NASH models tested, PA 500 µM concentration was the best model to mimic the molecular events of steatosis induced NAFLD. Rhm successfully ameliorated the dysregulated molecular events caused by the PA-induced NASH. Additionally, Rhm regulated inflammatory and oxidative machinery in the HepG2 cancerous cell lines. In conclusion, PA 500 µM concentration is considered an effective in vitro model to mimic NASH. Rhm could be used as a promising therapeutic modality against both NASH and HCC pathogenesis.

Kaempferol: Antimicrobial Properties, Sources, Clinical, and Traditional Applications

Flavonoids are a category of plant-derived compounds which exhibit a large number of health-related effects. One of the most well-known and studied flavonoids is kaempferol, which can be found in a wide variety of herbs and plant families. Apart from their anticarcinogenic and anti-inflammatory effects, kaempferol and its associated compounds also exhibit antibacterial, antifungal, and antiprotozoal activities. The development of drugs and treatment schemes based on these compounds is becoming increasingly important in the face of emerging resistance of numerous pathogens as well as complex molecular interactions between various drug therapies. In addition, many of the kaempferol-containing plants are used in traditional systems all over the world for centuries to treat numerous conditions. Due to its variety of sources and associated compounds, some molecular mechanisms of kaempferol antimicrobial activity are well known while others are still under analysis. This paper thoroughly documents the vegetal and food sources of kaempferol as well as the most recent and significant studies regarding its antimicrobial applications.

Luteolin-Induced Activation of Mitochondrial BKCa Channels: Undisclosed Mechanism of Cytoprotection

Luteolin (LUT) is a well-known flavonoid that exhibits a number of beneficial properties. Among these, it shows cardioprotective effects, as confirmed by numerous studies. However, its effect on mitochondrial potassium channels, the activation of which is related to cytoprotection, as well as on heart ischemia/reperfusion (I/R) damage prevention, has not yet been investigated. The large conductance calcium-regulated potassium channel (mitoBKCa) has been identified in both the mitochondria of the vascular endothelial cells, which plays a significant role in the functioning of the cardiovascular system under oxidative stress-related conditions, and in the mitochondria of cardiomyocytes, where it is deeply involved in cardiac protection against I/R injury. Therefore, the aim of this study was to explore the role of the mitoBKCa channel in luteolin-induced cytoprotection. A number of in vitro, in vivo, ex vivo and in silico studies have confirmed that luteolin activates this channel in the mitochondria of cardiomyocytes and endothelial cells, which in turn leads to the protection of the endothelium and a significant reduction in the extent of damage resulting from myocardial infarction, where this effect was partially abolished by the mitoBKCa channel blocker paxilline. In conclusion, these results suggest that luteolin has cardioprotective effects, at least in part, through the activation of the mitoBKCa channel, shedding light on a new putative mechanism of action.

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.

Screening of bioactive ingredients of Tsantan Sumtang in ameliorating H9c2 cells injury

ETHNOPHARMACOLOGICAL RELEVANCE

Tsantan Sumtang (TS), a traditional Tibetan medicine, has been used in the clinic for the treatment of myocardial ischemia (MI) for ages, however, the bioactive ingredients that are responsible for improving MI remain unknown.

AIM OF THE STUDY

This study investigated the chemical components of TS and their medicinal efficacies at cell levels, in order to expound the bioactive ingredients in TS.

MATERIALS AND METHODS

First, a response-surface methodology was employed to determine the optimum ethanol reflux extraction process of polyphenols in TS (PTS) due to their close correlation with MI improvement. Second, a serum pharmacochemistry technique was used to analyze the compounds of PTS absorbed into the blood of rats. Third, hypoxia-, H₂O₂-, and adriamycin (ADM)-induced H9c2 cell injury models were used to investigate the cardioprotective effects of these compounds in vitro. Fourth, protective effects of isovitexin, quercitrin, and isoeugenol on mitochondrial function were further tested.

RESULTS

The optimum extraction conditions for obtaining PTS were an ethanol concentration of 78.22%, an extraction time of 67.4 min, and a material-liquid ratio of 1:72.60 mL/g. Serum pharmacochemistry analysis detected 21 compounds, of which 11 compounds were always present in the blood within 5 h. Cytotoxicity and the protective effect of 11 compounds in hypoxia-, H₂O₂-, and ADM-induced H9c2 cell injury models shown that isovitexin, quercitrin, and isoeugenol had almost no cytotoxicity, and they could elevate the survival rate in injured H9c2 cells. Furthermore, isovitexin, quercitrin, and isoeugenol could decrease mitochondrial reactive oxygen species (ROS) releasion, inhibite mitochondrial permeability transition pore (mPTP) opening, ameliorate the change of mitochondrial membrane potential (MMP) to exert mitochondrial protection effect.

CONCLUSION

Isovitexin, quercitrin, and isoeugenol exhibited cardioprotective effect at cell levles, these three compounds might be the bioactive ingredients in TS. These findings elucidate the pharmacodynamic substances and mechanisms of TS, guiding its clinical use.

Lycopene ameliorates skin aging by regulating the insulin resistance pathway and activating SIRT1

Lycopene could reverse insulin resistance through SIRT1 during skin aging and promotes microcirculation via the improvement of microvascular neovascularization to protect aging skin.

Dietary intake of cyanidin-3-glucoside induces a long-lasting cardioprotection from ischemia/reperfusion injury by altering the microbiota

The anthocyanin class of flavonoids, including cyanidin-3-glucoside (C3G) present in berries, blood oranges and pigmented cereal crops, are food bioactives with antioxidant and anti-inflammatory action, capable to reduce myocardial ischemia/reperfusion (I/R) injury by unclear mechanism. Assessing the value of sporadic beneficial diet is critical for practical application. We aimed to determine whether and how the cardioptotective effect of dietary intake of anthocyanins persists. Gene expression, histology and resistance to I/R were investigated ex vivo in hearts from mice after a month beyond the cease of the C3G-enriched diet. Cardiac injury, oxidative stress and mitochondrial damage following I/R was effectively reduced in mice fed C3G-enriched diet, even after a month of wash out with standard diet. Cardioprotection was observed also in immune-deficient mice lacking mature B and T cells indicating the anti-inflammatory activity of C3G was not involved. Moreover, the transcription reprogramming induced by the C3G-enriched diets was rescued by the wash out treatment. Instead, we found C3G-enriched diet changed the microbiome and the transplantation of the fecal microbiota transferred the cardioprotection from mice fed C3G-enriched diet to mice fed standard diet. These findings established the effect of C3G dietary intake on gut microbiota determines long lasting cardioprotection.

Xanthoceras sorbifolium Bunge: A Review on Botany, Phytochemistry, Pharmacology, and Applications

Xanthoceras sorbifolium Bunge (Sapindaceae) is a native Chinese plant with promising applications as a biofuel feedstock and a source of novel drugs. Historical records and documents from different periods have mentioned the use of X. sorbifolium and its botanical constituents in treating diseases, highlighting its central role in Chinese and Mongolian traditional medicinal therapies. Phytochemical research has focused on the husks, leaves, trunks, and branches of this herb. A total of 278 chemical compounds have been isolated and divided into 8 categories: triterpenoids, flavonoids, phenylpropanoids, steroids, phenols, fatty acids, alkaloids, and quinones. Modern pharmacological studies on X. sorbifolium have demonstrated positive effects on learning and memory, as well as anti-inflammatory, anti-tumor, and anti-oxidative properties. This review provides a comprehensive analysis of the available research on X. sorbifolium, focusing on the relationship between chemical constituents, traditional uses, and pharmacological effects. We also assess the potential for therapeutic and other applications of this plant in support of further research and development of X. sorbifolium.

Dietary Flavonoids: Cardioprotective Potential with Antioxidant Effects and Their Pharmacokinetic, Toxicological and Therapeutic Concerns

Flavonoids comprise a large group of structurally diverse polyphenolic compounds of plant origin and are abundantly found in human diet such as fruits, vegetables, grains, tea, dairy products, red wine, etc. Major classes of flavonoids include flavonols, flavones, flavanones, flavanols, anthocyanidins, isoflavones, and chalcones. Owing to their potential health benefits and medicinal significance, flavonoids are now considered as an indispensable component in a variety of medicinal, pharmaceutical, nutraceutical, and cosmetic preparations. Moreover, flavonoids play a significant role in preventing cardiovascular diseases (CVDs), which could be mainly due to their antioxidant, antiatherogenic, and antithrombotic effects. Epidemiological and in vitro/in vivo evidence of antioxidant effects supports the cardioprotective function of dietary flavonoids. Further, the inhibition of LDL oxidation and platelet aggregation following regular consumption of food containing flavonoids and moderate consumption of red wine might protect against atherosclerosis and thrombosis. One study suggests that daily intake of 100 mg of flavonoids through the diet may reduce the risk of developing morbidity and mortality due to coronary heart disease (CHD) by approximately 10%. This review summarizes dietary flavonoids with their sources and potential health implications in CVDs including various redox-active cardioprotective (molecular) mechanisms with antioxidant effects. Pharmacokinetic (oral bioavailability, drug metabolism), toxicological, and therapeutic aspects of dietary flavonoids are also addressed herein with future directions for the discovery and development of useful drug candidates/therapeutic molecules.

Poria cocos (Fuling) targets TGFβ/Smad7 associated collagen accumulation and enhances Nrf2-antioxidant mechanism to exert anti-skin aging effects in human dermal fibroblasts

Oxidative stress is a major cause of aging related skin injuries. Hydrogen peroxide related ROS accumulation triggers increase in matrix metalloproteinases and elevated collagen degradation, which is a characteristic of skin aging. In this study, we investigated the protective effect of Poria cocos, used widely in the treatment of inflammatory diseases, against H₂ O₂ induced oxidative stress. The aqueous extract of dried P. cocos was obtained by heating 10 g in 500 ml of distilled water. The mixture was evaporated up to 400 ml and the remaining 100 ml was filtered through muslin cloth repeatedly to obtain a clear aqueous extract of the P. cocos. Hs68 human dermal fibroblast cells were challenged with 100 μM of H₂ O₂ for 24 h. Following H₂ O₂ challenge, the cells were treated with increasing concentration of P. cocos extract (100-400 μg/ml) for 24 h. P. cocos extract hindered the H₂ O₂ induced cell death significantly that was correlated with reduction in ROS accumulation. Western blot analysis show that P. cocos extract suppressed the expression of metallomatrix proteinases, inflammatory markers and skin aging markers, but increased TGF-β1 levels and antioxidant related proteins. These data suggest that P. cocos is effective in attenuating oxidative stress associated skin aging effects and may be a potential agent in cosmetics products.

Luteolin attenuates Fipronil-induced neurotoxicity through reduction of the ROS-mediated oxidative stress in rat brain mitochondria

Luteolin (LUT) as a natural compound found in vegetables and fruits has various pharmacological effects. Fipronil (FPN), as a pesticide, has been considered for its effect on the antioxidant system and induction of oxidative stress. This study was designed to investigate the protective effects of LUT against the oxidative stress and mitochondrial toxicity induced by FPN on the rat brain. Several parameters such as mitochondrial reactive oxygen species (ROS) level, mitochondrial membrane potential (MMP) collapse, mitochondrial swelling, cytochrome c release, mitochondrial glutathione (GSH), lipid peroxidation (LPO) and Adenosine triphosphate (ATP) levels were assessed. Results indicated that the administration of LUT (25 μM) significantly improved oxidative stress and mitochondrial damages induced via FPN (6, 12 and 24 μM) in isolated mitochondria from the brain. These results show that LUT exerted protective effects against FPN-induced neurotoxicity in vitro through improving oxidative stress and mitochondrial damages.

A review on phytochemical and therapeutic potential of Iris germanica

Objectives

Iris germanica L. is a medicinal plant, which has a long history of uses, mainly in medieval Persia and many places worldwide for the management of a wide variety of diseases. In this study, we aimed to review ethnopharmacological applications in addition to phytochemical and pharmacological properties of I. germanica.

Key findings

Ethnomedical uses of I. germanica have been reported from many countries such as China, Pakistan, India, Iran and Turkey. The medicinal part of I. germanica is the rhizome and the roots. Based on phytochemical investigations, different bioactive compounds, including flavonoids, triterpenes, sterols, phenolics, ceramides and benzoquinones, have been identified in its medicinal parts. Current pharmacological studies represent that the plant possesses several biological and therapeutic effects, including neuroprotective, hypoglycaemic, hypolipidaemic, antimicrobial, antioxidant, antiproliferative, anti-inflammatory, antiplasmodial, antifungal, immunomodulatory, cytotoxic and antimutagenic effects.

Summary

Although the majority of preclinical studies reported various pharmacological activities of this plant, however, sufficient clinical trials are not currently available. Therefore, to draw a definitive conclusion about the efficacy and therapeutic activities of I. germanica and its bioactive compounds, further clinical and experimental studies are required. Moreover, it is necessary to focus on the pharmacokinetic and safety studies on the extracts of I. germanica.

Synthesis and pharmacological characterization of mitochondrial KATP channel openers with enhanced mitochondriotropic effects

Mitochondria play a key role for deciding fate of cells and thus are considered an attractive target for pharmacological interventions focused on containment of myocardial ischemia/reperfusion (I/R) injury. Notably, the activation of mitochondrial potassium (mitoK) channels produces a mild depolarization of mitochondrial membrane, that contributes to reduce the driving force to calcium uptake and prevents the formation of mitochondrial transition membrane pore (MPTP); these events underlie anti-ischemic cardioprotection. However, an ideal mitoK channel opener should possess the fundamental requirement to be delivered at mitochondrial level; therefore, to improve the mitochondrial delivery of a previously characterized spirocyclic benzopyrane F81, new compounds have been developed. The three original triphenylphosphonium (TPP⁺)-derivatives of F81 (1-3), were evaluated for their cardioprotective activity on both isolated cardiac mitochondria and cardiac H9c2 cell line. Compound 1 was further investigated in an in vivo infarct model. This work confirms that the TPP⁺ strategy applied to mitoKATP openers could foster mitochondrial delivery and enhance the cardioprotective effects of mitochondrial activators of potassium channels.

From Ethnomedicine to Plant Biotechnology and Machine Learning: The Valorization of the Medicinal Plant Bryophyllum sp

The subgenus Bryophyllum includes about 25 plant species native to Madagascar, and is widely used in traditional medicine worldwide. Different formulations from Bryophyllum have been employed for the treatment of several ailments, including infections, gynecological disorders, and chronic diseases, such as diabetes, neurological and neoplastic diseases. Two major families of secondary metabolites have been reported as responsible for these bioactivities: phenolic compounds and bufadienolides. These compounds are found in limited amounts in plants because they are biosynthesized in response to different biotic and abiotic stresses. Therefore, novel approaches should be undertaken with the aim of achieving the phytochemical valorization of Bryophyllum sp., allowing a sustainable production that prevents from a massive exploitation of wild plant resources. This review focuses on the study of phytoconstituents reported on Bryophyllum sp.; the application of plant tissue culture methodology as a reliable tool for the valorization of bioactive compounds; and the application of machine learning technology to model and optimize the full phytochemical potential of Bryophyllum sp. As a result, Bryophyllum species can be considered as a promising source of plant bioactive compounds, with enormous antioxidant and anticancer potential, which could be used for their large-scale biotechnological exploitation in cosmetic, food, and pharmaceutical industries.

Flavonoids Regulate Inflammation and Oxidative Stress in Cancer

Cancer is the second leading cause of death globally. Millions of persons die due to cancer each year. In the last two decades, the anticancer effects of natural flavonoids have become a hot topic in many laboratories. Meanwhile, flavonoids, of which over 8000 molecules are known to date, are potential candidates for the discovery of anticancer drugs. The current review summarizes the major flavonoid classes of anticancer efficacy and discusses the potential anti-cancer mechanisms through inflammation and oxidative stress action, which were based on database and clinical studies within the past years. The results showed that flavonoids could regulate the inflammatory response and oxidative stress of tumor through some anti-inflammatory mechanisms such as NF-κB, so as to realize the anti-tumor effect.

Cardioprotective Effects of Natural Products via the Nrf2 Signaling Pathway

Due to its poor regenerative capacity, the heart is specifically vulnerable to xenobiotic- induced cardiotoxicity, myocardial ischaemia/reperfusion injury and other pathologies. Nuclear factor erythroid-2-related factor 2 (Nrf2) is considered as an essential factor in protecting cardiomyocytes against oxidative stress resulting from free radicals and reactive oxygen species. It also serves as a key regulator of antioxidant enzyme expression via the antioxidant response element, a cis-regulatory element, which is found in the promoter region of several genes encoding detoxification enzymes and cytoprotective proteins. It has been reported that a variety of natural products are capable of activating Nrf2 expression, and in this way, increase the antioxidant potential of cardiomyocytes. In the present review, we consider the cardioprotective activities of natural products and their possible therapeutic potential.

Flavonoids and Mitochondria: Activation of Cytoprotective Pathways?

A large number of diverse mechanisms that lead to cytoprotection have been described to date. Perhaps, not surprisingly, the role of mitochondria in these phenomena is notable. In addition to being metabolic centers, due to their role in cell catabolism, ATP synthesis, and biosynthesis these organelles are triggers and/or end-effectors of a large number of signaling pathways. Their role in the regulation of the intrinsic apoptotic pathway, calcium homeostasis, and reactive oxygen species signaling is well documented. In this review, we aim to characterize the prospects of influencing cytoprotective mitochondrial signaling routes by natural substances of plant origin, namely, flavonoids (e.g., flavanones, flavones, flavonols, flavan-3-ols, anthocyanidins, and isoflavones). Flavonoids are a family of widely distributed plant secondary metabolites known for their beneficial effects on human health and are widely applied in traditional medicine. Their pharmacological characteristics include antioxidative, anticarcinogenic, anti-inflammatory, antibacterial, and antidiabetic properties. Here, we focus on presenting mitochondria-mediated cytoprotection against various insults. Thus, the role of flavonoids as antioxidants and modulators of antioxidant cellular response, apoptosis, mitochondrial biogenesis, autophagy, and fission and fusion is reported. Finally, an emerging field of flavonoid-mediated changes in the activity of mitochondrial ion channels and their role in cytoprotection is outlined.

Regulation of the Mitochondrial BKCa Channel by the Citrus Flavonoid Naringenin as a Potential Means of Preventing Cell Damage

Naringenin, a flavanone obtained from citrus fruits and present in many traditional Chinese herbal medicines, has been shown to have various beneficial effects on cells both in vitro and in vivo. Although the antioxidant activity of naringenin has long been believed to be crucial for its effects on cells, mitochondrial pathways (including mitochondrial ion channels) are emerging as potential targets for the specific pharmacological action of naringenin in cardioprotective strategies. In the present study, we describe interactions between the mitochondrial large-conductance calcium-regulated potassium channel (mitoBK_Ca channel) and naringenin. Using the patch-clamp method, we showed that 10 µM naringenin activated the mitoBK_Ca channel present in endothelial cells. In the presence of 30 µM Ca²⁺, the increase in the mitoBK_Ca channel probability of opening from approximately 0.25 to 0.50 at −40 mV was observed. In addition, regulation of the mitoBK_Ca channel by naringenin was dependent on the concentration of calcium ions. To confirm our data, physiological studies on the mitochondria were performed. An increase in oxygen consumption and a decrease in membrane potential was observed after naringenin treatment. In addition, contributions of the mitoBK_Ca channel to apoptosis and necrosis were investigated. Naringenin protected cells against damage induced by tumor necrosis factor α (TNF-α) in combination with cycloheximide. In this study, we demonstrated that the flavonoid naringenin can activate the mitoBK_Ca channel present in the inner mitochondrial membrane of endothelial cells. Our studies describing the regulation of the mitoBK_Ca channel by this natural, plant-derived substance may help to elucidate flavonoid-induced cytoprotective mechanisms.

Brain-derived neurotrophic factor mimetic, 7,8-dihydroxyflavone, protects against myocardial ischemia by rebalancing optic atrophy 1 processing

Brain-derived neurotrophic factor (BDNF)/tropomyosin-related kinase B (TrkB) pathway is associated with ischemic heart diseases (IHD). 7,8-dihydroxyflavone (7,8-DHF), BDNF mimetic, is a potent agonist of TrkB. We aimed to investigate the effects and the underlying mechanisms of 7,8-DHF on cardiac ischemia. Myocardial ischemic mouse model was induced by ligation of left anterior descending coronary artery. 7,8-DHF (5 mg/kg) was administered intraperitoneally two days after ischemia for four weeks. Echocardiography, HE staining and transmission electron microscope were used to examine the function, histology and ultrastructure of the heart. H9c2 cells were treated with hydrogen peroxide (H₂O₂), 7,8-DHF or TrkB inhibitor ANA-12. The effects of 7,8-DHF on cell viability, mitochondrial membrane potential (MMP) and mitochondrial superoxide generation were examined. Furthermore, mitochondrial fission and protein expression of mitochondrial dynamics (Mfn2 [mitofusin 2], OPA1 [optic atrophy 1], Drp1 [dynamin-related protein 1] and Fis-1 [fission 1]) was detected by mitotracker green staining and western blot, respectively. 7,8-DHF attenuated cardiac dysfunction and cardiomyocyte abnormality of myocardial ischemic mice. Moreover, 7,8-DHF increased cell viability and reduced cell death accompanied by improving MMP, inhibiting mitochondrial superoxide and preventing excessive mitochondrial fission of H₂O₂-treated H9c2 cells. The cytoprotective effects of 7,8-DHF were antagonized by ANA-12. Mechanistically, 7,8-DHF repressed OMA1-dependent conversion of L-OPA1 into S-OPA1, which was abolished by Akt inhibitor. In conclusion, 7,8-DHF protects against cardiac ischemic injury by inhibiting the proteolytic cleavage of OPA1. These findings provide a novel pharmacological effect of 7,8-DHF on mitochondrial dynamics and a new potential target for IHD.

Natural Bioactive Compounds As Protectors Of Mitochondrial Dysfunction In Cardiovascular Diseases And Aging

Diet, particularly the Mediterranean diet, has been considered as a protective factor against the development of cardiovascular diseases, the main cause of death in the world. Aging is one of the major risk factors for cardiovascular diseases, which have an oxidative pathophysiological component, being the mitochondria one of the key organelles in the regulation of oxidative stress. Certain natural bioactive compounds have the ability to regulate oxidative phosphorylation, the production of reactive oxygen species and the expression of mitochondrial proteins; but their efficacy within the mitochondrial physiopathology of cardiovascular diseases has not been clarified yet. The following review has the purpose of evaluating several natural compounds with evidence of mitochondrial effect in cardiovascular disease models, ascertaining the main cellular mechanisms and their potential use as functional foods for prevention of cardiovascular disease and healthy aging.

Naringenin as an opener of mitochondrial potassium channels in dermal fibroblasts

Flavonoids belong to a large group of polyphenolic compounds that are widely present in plants. Certain flavonoids, including naringenin, have cytoprotective properties. Although the antioxidant effect has long been thought to be a crucial factor accounting for the cellular effects of flavonoids, mitochondrial channels have emerged recently as targets for cytoprotective strategies. In the present study, we characterized interactions between naringenin and the mitochondrial potassium (mitoBK_{C a} and mitoK_ATP ) channels recently described in dermal fibroblasts. With the use of the patch-clamp technique and mitoplasts isolated from primary human dermal fibroblast cells, our study shows that naringenin in micromolar concentrations leads to an increase in mitoBK_{C a} channel activity. The opening probability of the channel decreased from 0.97 in the control conditions (200 μmol/L Ca²⁺ ) to 0.06 at a low Ca²⁺ level (1 μmol/L) and increased to 0.85 after the application of 10 μmol/L naringenin. Additionally, the activity of the mitoK_ATP channel increased following the application of 10 μmol/L naringenin. To investigate the effects of naringenin on mitochondrial function, the oxygen consumption of dermal fibroblast cells was measured in potassium-containing media. The addition of naringenin significantly and dose-dependently increased the respiratory rate from 5.8 ± 0.2 to 14.0 ± 0.6 nmol O₂  × min^-1  × mg protein^-1 . Additionally, a Raman spectroscopy analysis of skin penetration indicated that the naringenin was distributed in all skin layers, including the epidermis and dermis. In this study, we demonstrated that a flavonoid, naringenin, can activate two potassium channels present in the inner mitochondrial membrane of dermal fibroblasts.

Coupling Ultrasound with Heat-Reflux to Improve the Extraction of Quercetin, Kaempferol, Ginkgetin and Sciadopitysin from Mairei Yew Leaves

The coupling of ultrasound and heat–reflux extraction (UHRE) was developed for separation for quercetin (QU), kaempferol (KA), ginkgetin (GI) and sciadopitysin (SC) from Mairei Yew leaves. The Box–Behnken design was used to optimize the UHRE conditions for obtaining the maximum yield of flavonoids. The optimal extraction conditions were as follows: boiling 80% methanol (V/V) for extraction solvent, 20 min for the extraction time, 200 W for the ultrasonic power and 26 mL/g for the liquid–solid ratio. By UHRE, the yields of QU, KA, GI and SC were, respectively, 0.109, 0.406, 0.031 and 0.355 mg/g, and total yield of four flavonoids was 0.901 mg/g, which were, respectively, 1.25-fold and 1.23-fold higher than those by using ultrasonic-assisted extraction (UAE) and heating reflux extraction (HRE). Moreover, the extraction time for the equilibrium yields of flavonoids using UHRE was 83.3% and 27.8%, respectively, less than the corresponding time using UAE and HRE. Compared with HRE and UAE, UHRE showed the increase of cell disruption degree as observed by scanning electron microscopy, which may be the reason for high yield and rapid extraction of target compounds.

Cardiovascular Effects of Flavonoids

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Cardiovascular Disease (CVD) is the major cause of death worldwide, especially in Western society. Flavonoids are a large group of polyphenolic compounds widely distributed in plants, present in a considerable amount in fruit and vegetable. Several epidemiological studies found an inverse association between flavonoids intake and mortality by CVD. The antioxidant effect of flavonoids was considered the main mechanism of action of flavonoids and other polyphenols. In recent years, the role of modulation of signaling pathways by direct interaction of flavonoids with multiple protein targets, namely kinases, has been increasingly recognized and involved in their cardiovascular protective effect. There are strong evidence, in in vitro and animal experimental models, that some flavonoids induce vasodilator effects, improve endothelial dysfunction and insulin resistance, exert platelet antiaggregant and atheroprotective effects, and reduce blood pressure. Despite interacting with multiple targets, flavonoids are surprisingly safe. This article reviews the recent evidence about cardiovascular effects that support a beneficial role of flavonoids on CVD and the potential molecular targets involved.

Astragalin: A Bioactive Phytochemical with Potential Therapeutic Activities

Natural products, an infinite treasure of bioactive chemical entities, persist as an inexhaustible resource for discovery of drugs. This review article intends to emphasize on one of the naturally occurring flavonoids, astragalin (kaempferol 3-glucoside), which is a bioactive constituent of various traditional medicinal plants such as Cuscuta chinensis. This multifaceted compound is well known for its diversified pharmacological applications such as anti-inflammatory, antioxidant, neuroprotective, cardioprotective, antiobesity, antiosteoporotic, anticancer, antiulcer, and antidiabetic properties. It carries out the aforementioned activities by the regulation and modulation of various molecular targets such as transcription factors (NF-κB, TNF-α, and TGF-β1), enzymes (iNOS, COX-2, PGE2, MMP-1, MMP-3, MIP-1α, COX-2, PGE-2, HK2, AChe, SOD, DRP-1, DDH, PLCγ1, and GPX), kinases (JNK, MAPK, Akt, ERK, SAPK, IκBα, PI3K, and PKCβ2), cell adhesion proteins (E-cadherin, vimentin PAR-2, and NCam), apoptotic and antiapoptotic proteins (Beclin-1, Bcl-2, Bax, Bcl-xL, cytochrome c, LC3A/B, caspase-3, caspase-9, procaspase-3, procaspase-8, and IgE), and inflammatory cytokines (SOCS-3, SOCS-5, IL-1β, IL-4, IL-6, IL-8, IL-13, MCP-1, CXCL-1, CXCL-2, and IFN-γ). Although researchers have reported multiple pharmacological applications of astragalin in various diseased conditions, further experimental investigations are still mandatory to fully understand its mechanism of action. It is contemplated that astragalin could be subjected to structural optimization to ameliorate its chemical accessibility, to optimize its absorption profiles, and to synthesize its more effective analogues which will ultimately lead towards potent drug candidates.

Acacetin protects against cardiac remodeling after myocardial infarction by mediating MAPK and PI3K/Akt signal pathway

Since inhibiting cardiac remodeling is a critical treatment goal after myocardial infarction (MI), many drugs have been evaluated for this purpose. Acacetin is a flavonoid compound that has been shown to have anti-cancer, anti-mutagenic, anti-inflammatory and anti-peroxidative effects. In this study, we investigated whether acacetin is able to exert a protective effect against MI. One week after anterior wall standard MI surgeries or sham surgeries were performed in mice, acacetin was administered via gavage for two weeks. The results of echocardiographic and hemodynamic evaluation revealed that cardiac dysfunction significantly improved after acacetin treatment. H&E staining indicated that the ratio of the infarct size and the cardiomyocyte cross-sectional area was decreased by acacetin. Masson's staining detected that the fibrotic area ratio was evidently lower in the acacetin-treated MI group. TUNEL assays showed that acacetin ameliorated cardiomyocyte apoptosis after MI. RT-qPCR analysis showed that levels of hypertrophic and fibrotic markers were significantly decreased after acacetin treatment. Western blot analysis of various signaling pathway proteins showed that acacetin targets the MAPK and PI3K/Akt signaling pathways. Collectively, acacetin improves mouse left ventricular function and attenuates cardiac remodeling by inhibiting of the MAPK and PI3K/Akt signaling pathway.

Influence of Flavonoids on Mechanism of Modulation of Insulin Secretion

BACKGROUND

The development of alternatives for insulin secretion control in vivo or in vitro represents an important aspect to be investigated. In this direction, natural products have been progressively explored with this aim. In particular, flavonoids are potential candidates to act as insulin secretagogue.

OBJECTIVE

To study the influence of flavonoid on overall modulation mechanisms of insulin secretion.

METHODS

The research was conducted in the following databases and platforms: PubMed, Scopus, ISI Web of Knowledge, SciELO, LILACS, and ScienceDirect, and the MeSH terms used for the search were flavonoids, flavones, islets of Langerhans, and insulin-secreting cells.

RESULTS

Twelve articles were included and represent the basis of discussion on mechanisms of insulin secretion of flavonoids. Papers in ISI Web of Knowledge were in number of 1, Scopus 44, PubMed 264, ScienceDirect 511, and no papers from LILACS and SciELO databases.

CONCLUSION

According to the literature, the majority of flavonoid subclasses can modulate insulin secretion through several pathways, in an indication that corresponding molecule is a potential candidate for active materials to be applied in the treatment of diabetes.

SUMMARY

The action of natural products on insulin secretion represents an important investigation topic due to their importance in the diabetes controlIn addition to their typical antioxidant properties, flavonoids contribute to the insulin secretionThe modulation of insulin secretion is induced by flavonoids according to different mechanisms. Abbreviations used: KATP channels: ATP-sensitive K+ channels, GLUT4: Glucose transporter 4, ERK1/2: Extracellular signal-regulated protein kinases 1 and 2, L-VDCCs: L-type voltage-dependent Ca+2 channels, GLUT1: Glucose transporter 1, AMPK: Adenosine monophosphate-activated protein kinase, PTP1B: Protein tyrosine phosphatase 1B, GLUT2: Glucose transporter 2, cAMP: Cyclic adenosine monophosphate, PKA: Protein kinase A, PTK: Protein tyrosine kinase, CaMK II: Ca2+/calmodulin-dependent protein kinase II, GSIS: Glucose-stimulated insulin secretion, Insig-1: Insulin-induced gene 1, IRS-2: Insulin receptor substrate 2, PDX-1: Pancreatic and duodenal homeobox 1, SREBP-1c: Sterol regulatory element binding protein-1c, DMC: Dihydroxy-6'-methoxy-3',5'-dimethylchalcone, GLP-1: Glucagon-like peptide-1, GLP-1R: Glucagon-like peptide 1 receptor.

Mitochondriotropic and Cardioprotective Effects of Triphenylphosphonium-Conjugated Derivatives of the Diterpenoid Isosteviol

Mitochondria play a crucial role in the cell fate; in particular, reducing the accumulation of calcium in the mitochondrial matrix offers cardioprotection. This affect is achieved by a mild depolarization of the mitochondrial membrane potential, which prevents the assembly and opening of the mitochondrial permeability transition pore. For this reason, mitochondria are an attractive target for pharmacological interventions that prevent ischaemia/reperfusion injury. Isosteviol is a diterpenoid created from the acid hydrolysis of Stevia rebaudiana Bertoni (fam. Asteraceae) glycosides that has shown protective effects against ischaemia/reperfusion injury, which are likely mediated through the activation of mitochondrial adenosine tri-phosphate (ATP)-sensitive potassium (mitoKATP) channels. Some triphenylphosphonium (triPP)-conjugated derivatives of isosteviol have been developed, and to evaluate the possible pharmacological benefits that result from these synthetic modifications, in this study, the mitochondriotropic properties of isosteviol and several triPP-conjugates were investigated in rat cardiac mitochondria and in the rat heart cell line H9c2. This study’s main findings highlight the ability of isosteviol to depolarize the mitochondrial membrane potential and reduce calcium uptake by the mitochondria, which are typical functions of mitochondrial potassium channel openings. Moreover, triPP-conjugated derivatives showed a similar behavior to isosteviol but at lower concentrations, indicative of their improved uptake into the mitochondrial matrix. Finally, the cardioprotective property of a selected triPP-conjugated derivative was demonstrated in an in vivo model of acute myocardial infarct.

Decrease of the affinity of theophylline bind to serum proteins induced by flavonoids and their synergies on protein conformation

In this study, the single and simultaneous interactions of theophylline and flavonoids with human serum albumin (HSA) were studied by multi-spectroscopic and molecular docking approaches. The influences of flavonoids on the binding constant (K_b) and the binding distance (r) of theophylline bind to HSA were determined and the changes of HSA conformation caused by the synergies of theophylline and flavonoids were investigated. Because theophylline, rutin and baicalin are all bond to the same binding site, the competitive bind of theophylline and flavonoids to HSA leads to the reduction of the K_a value of theophylline binding to HSA. The addition of rutin and baicalin can increase the value of r of theophylline binding to HSA, which further confirm the existence of the competitive bind of theophylline and flavonoids to HSA. Additionally, the results of synchronous fluorescence, three-dimensional fluorescence and circular dichroism spectra indicate that the presence of rutin and baicalin can give rise to the further changes of HSA conformation. These results suggest that the intake of flavonoid-rich food and beverages can increase the serum concentrations of theophylline and induce a high incidence of toxic symptom in clinic.

Impacts of the serum containing total flavonoids of Ajuga on rat glomerular mesangial cells

The aim of the current study was to investigate the impacts and possible mechanisms of total flavonoids of Ajuga (TFA) on glomerular mesangial cells (GMC) through in vitro observations of the impacts of TFA‑containing serum on GMC proliferation and extracellular matrix (ECM) secretion in lipopolysaccharides (LPS)‑induced rats. Rat GMC was cultured in vitro, using LPS to stimulate the proliferation of GMC and the secretion of ECM; meanwhile, TFA‑containing serum (TFA‑S) was used for the intervention. Methyl thiazolyl tetrazolium (MTT) assay was performed to test the proliferation of GMC; enzyme‑linked immunosorbent assay (ELISA) was used to detect the expressions of fibronectin (FN) and collagen IV (Col‑IV) in cell supernatant, flow cytometry was performed to detect the cell cycle, and reverse transcription-polymerase chain reaction was performed to detect the expression levels of matrix metalloproteinase 9 (MMP‑9) mRNA and transforming growth factor β1 (TGF‑β1) mRNA. The GMC proliferation and the expressions of FN and Col‑IV in cell supernatant were significantly reduced after 24 and 48 h TFA‑S intervention (P<0.05 or 0.01). A total of 48 h subsequent to the intervention, the proportion of GMC in the G1 phase and the relative expression of MMP‑9 mRNA were significantly increased (P<0.05 or 0.01), however the proportion of GMC in S phase and the relative expression of TGF‑β1 mRNA were significantly reduced (P<0.05 or 0.01). TFA‑S can inhibit LPS‑induced GMC proliferation and ECM accumulation, and its roles are associated with regulating the cell cycle and the expression levels of TGF‑β1 and MMP‑9.

Nutraceutical Value of Citrus Flavanones and Their Implications in Cardiovascular Disease

Background- Cardiovascular diseases, including myocardial infarction, dyslipidaemia and coronary artery pathology, are a major cause of illness and death in Western countries. Therefore, identifying effective therapeutic approaches and their cellular signalling pathways is a challenging goal for medicine. In this regard, several epidemiological studies demonstrate a relationship between the intake of flavonoid-rich foods and the reduction of cardiovascular risk factors and mortality. In particular, flavonoids present in citrus fruits, such as oranges, bergamots, lemons and grapefruit (95% from flavanones), are emerging for their considerable nutraceutical value. Methods- In this review an examination of literature was performed while considering both epidemiological, clinical and pre-clinical evidence supporting the beneficial role of the flavanone class. We evaluated studies in which citrus fruit juices or single flavanone administration and cardiovascular risk factors were analysed; to identify these studies, an electronic search was conducted in PUBMED for papers fulfilling these criteria and written in English. Results- In addition to epidemiological evidence and clinical studies demonstrating that fruits in the Citrus genus significantly reduce the incidence of cardiovascular disease risk, pre-clinical investigations highlight cellular and subcellular targets that are responsible for these beneficial effects. There has been special attention on evaluating intracellular pathways involved in direct cardiovascular and cardiometabolic effects mediated by naringenin, hesperetin and eriodictyol or their glycosylated derivatives. Conclusions- Although some mechanisms of action remain unclear and bioavailability problems remain to be solved, the current evidence supports the use of a nutraceutical approach with citrus fruits to prevent and cure several aspects of cardiovascular disease.

The Citrus Flavanone Naringenin Produces Cardioprotective Effects in Hearts from 1 Year Old Rat, through Activation of mitoBK Channels

Background and Purpose: Incidence of cardiovascular disorders increases with age, because of a dramatic fall of endogenous self-defense mechanisms and increased vulnerability of myocardium. Conversely, the effectiveness of many cardioprotective drugs is blunted in hearts of 1 year old rat. The Citrus flavanone naringenin (NAR) was reported to promote cardioprotective effects against ischemia/reperfusion (I/R) injury, through the activation of mitochondrial large conductance calcium-activated potassium channel (mitoBK). These effects were observed in young adult rats, but no data are available about the possible cardioprotective effects of NAR in aged animals.

Experimental Approach: This study aimed at evaluating the potential cardioprotective effects of NAR against I/R damage in 1 year old rats, and the possible involvement of mitoBK.

Key Results: Naringenin protected the hearts of 1 year old rats in both ex vivo and in vivo I/R protocols. Noteworthy, these effects were antagonized by paxilline, a selective BK-blocker. The cardioprotective effects of NAR were also observed in senescent H9c2 cardiomyoblasts. In isolated mitochondria from hearts of 1 year old, NAR exhibited the typical profile of a mitoBK opener. Finally, Western Blot analysis confirmed a significant (albeit reduced) presence of BK-forming alpha and beta subunits, both in cardiac tissue of 1 year old rats and in senescent H9c2 cells.

Conclusion and Implications: This is the first work reporting cardioprotective effects of NAR in 1 year old rats. Although further studies are needed to better understand the whole pathway involved in the NAR-mediated cardioprotection, these preliminary data represent a promising perspective for a rational nutraceutical use of NAR in aging.

The surge of flavonoids as novel, fine regulators of cardiovascular Cav channels

Ion channels underlie a wide variety of physiological processes that involve rapid changes in cell dynamics, such as cardiac and vascular smooth muscle contraction. Overexpression or dysfunction of these membrane proteins are the basis of many cardiovascular diseases that represent the leading cause of morbidity and mortality for human beings. In the last few years, flavonoids, widely distributed in the plant kingdom, have attracted the interest of many laboratories as an emerging class of fine ion, in particular Ca_v, channels modulators. Pieces of in vitro evidence for direct as well as indirect effects exerted by various flavonoids on ion channel currents are now accumulating in the scientific literature. This activity may be responsible, at least in part, for the beneficial and protective effects of dietary flavonoids toward cardiovascular diseases highlighted in several epidemiological studies. Here we examine numerous studies aimed at analysing this feature of flavonoids, focusing on the mechanisms that promote their sometimes controversial activities at cardiovascular Ca_v channels. New methodological approaches, such as molecular modelling and docking to Ca_v1.2 channel α_1c subunit, used to elucidate flavonoids intrinsic mechanism of action, are introduced. Moreover, flavonoid-membrane interaction, bioavailability, and antioxidant activity are taken into account and discussed.

Melissa officinalis L. - A review of its traditional uses, phytochemistry and pharmacology

ETHNOPHARMACOLOGICAL RELEVANCE

Melissa officinalis L. is a medicinal plant that has long been used in different ethno-medical systems especially in the European Traditional Medicine and the Iranian Traditional Medicine for the treatment of several diseases. It is also widely used as a vegetable and to add flavor to dishes

AIM OF THE REVIEW

This review aimed to provide a summary on the botanical characterization, traditional uses, phytochemistry, pharmacological activities, pharmacokinetics and toxicity of M. officinalis, and discusses research gaps and future opportunities for investigations on this plant.

MATERIALS AND METHODS

We extensively reviewed major unpublished old texts, and published and electronic literature on traditional medicines of different regions of the world to find traditional uses of M. officinalis. Electronic databases including Web of Science, PubMed, ScienceDirect, Google Scholar and Scopus were searched to find articles (published between 1956 and 2015) on pharmacology and phytochemistry of M. officinalis.

RESULTS

Traditional uses of M. officinalis have been recorded mostly in European countries, Mediterranean region and Middle East countries. Phytochemical investigations revealed that this plant contains volatile compounds, triterpenoids, phenolic acids and flavonoids. Crude extracts and pure compounds isolated from M. officinalis exhibited numerous pharmacological effects, from which only anxiolytic, antiviral and antispasmodic activities of this plant as well as its effects on mood, cognition and memory have been shown in clinical trials. AChE inhibitory activity, stimulation of the acetylcholine and GABAA receptors, as well as inhibition of matrix metallo proteinase-2 are the main mechanisms proposed for the widely discussed neurological effects of this plant.

CONCLUSIONS

Modern pharmacological studies have now validated many traditional uses of M. officinalis. The data reviewed here revealed that M. officinalis is a potential source for the treatment of a wide range of diseases especially anxiety and some other CNS disorders, though confirmatory trials are warranted to substantiate these effects in the clinical setting. Data regarding many aspects of this plant such as mechanisms of actions, pharmacokinetics, adverse effects of the extracts, potential interactions with standard-of-care medications and active compounds is still limited which call for additional studies particularly in humans.

Studies on the interaction between promethazine and human serum albumin in the presence of flavonoids by spectroscopic and molecular modeling techniques

Fluorescence, absorption, time-correlated single photon counting (TCSPC), and circular dichroism (CD) spectroscopic techniques as well as molecular modeling methods were used to study the binding characterization of promethazine (PMT) to human serum albumin (HSA) and the influence of flavonoids, rutin and baicalin, on their affinity. The results indicated that the fluorescence quenching mechanism of HSA by PMT is a static quenching due to the formation of complex. The reaction was spontaneous and mainly mediated by hydrogen bonds and hydrophobic interactions. The binding distance between the tryptophan residue of HSA and PMT is less than 8nm, which indicated that the energy transfer from the tryptophan residue of HSA to PMT occurred. The binding site of PMT on HSA was located in sites I and the presence of PMT can cause the conformational changes of HSA. There was the competitive binding to HSA between PMT and flavonoids because of the overlap of binding sites in HSA. The flavonoids could decrease the association constant and increase the binding distance. In addition, their synergistic effect can further change the conformation of HSA. The decrease in the affinities of PMT binding to HSA in the presence of flavonoids may lead to the increase of free drug in blood, which would affect the transportation or disposition of drug and evoke an adverse or toxic effect. Hence, rationalising dosage and diet regimens should be taken into account in clinical application of PMT.