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

The Citrus flavanone naringenin prolongs the lifespan in C. elegans and slows signs of brain aging in mice

Aging is one of the main risk factors for neurodegenerative disorders, which represent a global burden on healthcare systems. Therefore, identifying new strategies to slow the progression of brain aging is a compelling challenge. In this article, we first assessed the potential anti-aging effects of the Citrus flavanone naringenin (NAR), an activator of the enzyme sirtuin-1 (SIRT1), in a 3R-compliant and short-lived aging model (i.e., the nematode C. elegans). Then, we investigated the preventive effects of a 6-month treatment with NAR (100 mg/kg, orally) against brain aging and studied its mechanism of action in middle-aged mice. We demonstrated that NAR (100 μM) extends lifespan and improves healthspan in C. elegans. In the brain of middle-aged mice, NAR promotes the activity of metabolic enzymes (citrate synthase, cytochrome C oxidase) and increases the expression of the SIRT1 enzyme. Consistently, NAR up-regulates the expression of downstream antioxidant (Foxo3, Nrf2, Ho-1), anti-senescence (p16), and anti-inflammatory (Il-6, Il-18) markers. Our findings support NAR supplementation to slow the signs of brain aging.

Role of mitochondrial potassium channels in ageing

Ageing is described as an inevitable decline in body functions over time and an increase in susceptibility to age-related diseases. Therefore, the increase of life expectancy is also viewed as a condition in which many elderly will develop age-related diseases and disabilities, such as cardiovascular, metabolic, neurological and oncological ones. Currently, several recognized cellular hallmarks of senescence are taken in consideration to evaluate the level of biological ageing and are the topic to plan preventive/curative anti-ageing interventions, including genomic instability, epigenetic alterations, and mitochondrial dysfunction. In this scenario, alterations in the function/expression of mitochondrial ion channels have been found in ageing and associated to an impairment of calcium cycling and a reduced mitochondrial membrane potential. Although several ion channels have been described at mitochondrial level, undoubtedly the mitochondrial potassium (mitoK) channels are the most investigated. Therefore, this review summarized the evidence that sheds to light a correlation between age-related diseases and alteration of mitoK channels, focusing the attention of the main age-related diseases, i.e. cardiovascular, neurological and oncological ones.

Bioactive Compounds from Kinnow Processing Waste and their Associated Benefits: A Review

We have explored the expansive possibilities of kinnow peel, a frequently ignored by-product of the fruit processing industry, in this thorough analysis. The production of kinnow generates a significant amount of waste, including peel, seeds, and pulp. The disposal of this waste is a major environmental issue, as it can lead to pollution and greenhouse gas emissions. Due to the presence of bioactive substances that may be used in a variety of sectors, kinnow processing waste has the potential to provide a number of advantages. In the culinary, pharmaceutical, and cosmetic industries, the peel, seeds, and pulp from kinnow can be used as natural sources of antioxidants, aromatics, pectin, and dietary fibre. Utilizing kinnow waste promotes eco-innovation, increases sustainability, and aids in waste reduction. The development of a circular economy can be sped up with more study and commercialization of kinnow waste products. This analysis emphasises how important it is to understand and utilise the unrealized potential of agricultural byproducts, like kinnow peel.

Role of Flavonoids in Modulation of Mitochondria Dynamics during Oxidative Stress

BACKGROUND

Flavonoids are a widespread category of naturally occurring polyphenols distinguished by the flavan nucleus in plant-based foods and beverages, known for their various health benefits. Studies have suggested that consuming 150-500 mg of flavonoids daily is beneficial for health. Recent studies suggest that flavonoids are involved in maintaining mitochondrial activity and preventing impairment of mitochondrial dynamics by oxidative stress.

OBJECTIVE

This review emphasized the significance of studying the impact of flavonoids on mitochondrial dynamics, oxidative stress, and inflammatory response.

METHODS

This review analysed and summarised the findings related to the impact of flavonoids on mitochondria from publicly available search engines namely Pubmed, Scopus, and Web of Science.

DESCRIPTION

Any disruption in mitochondrial dynamics can contribute to cellular dysfunction and diseases, including cancer, cardiac conditions, and neurodegeneration. Flavonoids have been shown to modulate mitochondrial dynamics by regulating protein expression involved in fission and fusion events. Furthermore, flavonoids exhibit potent antioxidant properties by lowering the production of ROS and boosting the performance of antioxidant enzymes. Persistent inflammation is a characteristic of many different disorders. This is because flavonoids also alter the inflammatory response by controlling the expression of numerous cytokines and chemokines involved in the inflammatory process. Flavonoids exhibit an impressive array of significant health effects, making them an effective therapeutic agent for managing various disorders. Further this review summarised available mechanisms underlying flavonoids' actions on mitochondrial dynamics and oxidative stress to recognize the optimal dose and duration of flavonoid intake for therapeutic purposes.

CONCLUSION

This review may provide a solid foundation for developing targeted therapeutic interventions utilizing flavonoids, ultimately benefiting individuals afflicted with various disorders.

Lack of activity of the mitochondrial large-conductance calcium-regulated potassium channels in senescent vascular smooth muscle cells

A limited number of studies have shown functional changes in mitochondrial ion channels in aging and senescent cells. We have identified, for the first time, mitochondrial large-conductance calcium-regulated potassium channels in human smooth muscle mitochondria. This channel, with a conductance of 273 pS, was regulated by calcium ions and membrane potential. Additionally, it was activated by the potassium channel opener NS11021 and blocked by paxilline. Importantly, we have shown that senescence of these cells induced by hydrogen peroxide treatment leads to the disappearance of potassium channel protein levels and channel activity measured by the single channel patch-clamp technique. Our data suggest that disturbances in the expression of mitochondrial large conductance calcium-regulated potassium channels may be hallmarks of cellular senescence and contribute to the misregulation of mitochondrial function in senescent cells.

The cross-correlation-based analysis to digest the conformational dynamics of the mitoBK channels in terms of their modulation by flavonoids

The activity of mitochondrial large-conductance voltage- and [Formula: see text]-activated [Formula: see text] channels (mitoBK) is regulated by a number of biochemical factors, including flavonoids. In particular, naringenin (Nar) and quercetin (Que) reached reasonable scientific attention due to their well-pronounced channel-activating effects. The open-reinforcing outcomes of Nar and Que on the mitoBK channel gating have been already reported. Nevertheless, the molecular picture of the corresponding channel-ligand interactions remains still to be revealed. In this work, we investigate the effects of the Nar and Que on the conformational dynamics of the mitoBK channel. In this aim, the cross-correlation-based analysis of the single-channel signals recorded by the patch-clamp method is performed. The obtained results in the form of phase space diagrams enable us to visually monitor the effects exerted by the considered flavonoids at the level of temporal characteristics of repetitive sequences of channel conformations. It turns out that the mitoBK channel activation by naringenin and quercetin does not lead to the change in the number of clusters within the phase space diagrams, which can be related to the constant number of available channel macroconformations regardless of the flavonoid administration. The localization and occupancy of the clusters of cross-correlated sequences suggest that mitoBK channel stimulation by flavonoids affects the relative stability of channel conformations and the kinetics of switching between them. For most clusters, greater net effects are observed in terms of quercetin administration in comparison with naringenin. It indicates stronger channel interaction with Que than Nar.

Beneficial effects of flavonoids on cardiovascular diseases by influencing NLRP3 inflammasome

Cardiovascular diseases (CVDs) are a leading cause of global mortality and have a high incidence rate worldwide. The function of inflammasomes in CVDs has received a lot of attention recently, and the nucleotide-binding domain and leucine-rich repeat protein 3 (NLRP3) inflammasome may be a new target for the prevention and treatment of CVDs. Flavonoids, which are found in food and plant extracts, inhibited inflammation in CVDs by regulating the NLRP3 inflammasome. CB-Dock was used to investigate whether 34 flavonoids from natural products acted on NLRP3 inflammasome. In brief, the PDB format of NLRP3 was selected as a protein file, and 34 flavonoids in SDF format were selected as the ligand file, and then input to CB-Dock for molecular docking. The docking results showed that epigallocatechin-3-gallate (EGCG), amentoflavone, baicalin, scutellarin, vitexin, silibinin, and puerarin had good binding affinities to NLRP3, which could be used as NLRP3 inhibitors, and aid in the discovery of lead compounds for the design and development of CVDs.

Role of organellar Ca2+-activated K+ channels in disease development

The organellar Ca2+-activated K+ channels share a similar ability to transfer the alteration of Ca2+ concentration to membrane conductance of potassium. Multiple effects of Ca2+-activated K+ channels on cell metabolism and complex signaling pathways during organ development have been explored. The organellar Ca2+-activated K+ channels are able to control the ionic equilibrium and are always associated with oxidative stress in different organelles and the whole cells. Some drugs targeting Ca2+-activated K+ channels have been tested for various diseases in clinical trials. In this review, the known roles of organellar Ca2+-activated K+ channels were described, and their effects on different diseases, particularly on diabetes, cardiovascular diseases, and neurological diseases were discussed. It was attempted to summarize the currently known operational modes with the involvement of organellar Ca2+-activated K+ channels. This review may assist scholars to more comprehensively understand organellar Ca2+-activated K+ channels and related diseases.

Endoplasmic reticulum as a target in cardiovascular diseases: Is there a role for flavonoids?

Flavonoids are found in natural health products and plant-based foods. The flavonoid molecules contain a 15-carbon skeleton with the particular structural construction of subclasses. The most flavonoid's critical subclasses with improved health properties are the catechins or flavonols (e.g., epigallocatechin 3-gallate from green tea), the flavones (e.g., apigenin from celery), the flavanones (e.g., naringenin from citrus), the flavanols (e.g., quercetin glycosides from berries, onion, and apples), the isoflavones (e.g., genistein from soya beans) and the anthocyanins (e.g., cyanidin-3-O-glucoside from berries). Scientific data conclusively demonstrates that frequent intake of efficient amounts of dietary flavonoids decreases chronic inflammation and the chance of oxidative stress expressing the pathogenesis of human diseases like cardiovascular diseases (CVDs). The endoplasmic reticulum (ER) is a critical organelle that plays a role in protein folding, post-transcriptional conversion, and transportation, which plays a critical part in maintaining cell homeostasis. Various stimuli can lead to the creation of unfolded or misfolded proteins in the endoplasmic reticulum and then arise in endoplasmic reticulum stress. Constant endoplasmic reticulum stress triggers unfolded protein response (UPR), which ultimately causes apoptosis. Research has shown that endoplasmic reticulum stress plays a critical part in the pathogenesis of several cardiovascular diseases, including diabetic cardiomyopathy, ischemic heart disease, heart failure, aortic aneurysm, and hypertension. Endoplasmic reticulum stress could be one of the crucial points in treating multiple cardiovascular diseases. In this review, we summarized findings on flavonoids' effects on the endoplasmic reticulum and their role in the prevention and treatment of cardiovascular diseases.

Flavonoids as Modulators of Potassium Channels

Potassium channels are widely distributed integral proteins responsible for the effective and selective transport of K+ ions through the biological membranes. According to the existing structural and mechanistic differences, they are divided into several groups. All of them are considered important molecular drug targets due to their physiological roles, including the regulation of membrane potential or cell signaling. One of the recent trends in molecular pharmacology is the evaluation of the therapeutic potential of natural compounds and their derivatives, which can exhibit high specificity and effectiveness. Among the pharmaceuticals of plant origin, which are potassium channel modulators, flavonoids appear as a powerful group of biologically active substances. It is caused by their well-documented anti-oxidative, anti-inflammatory, anti-mutagenic, anti-carcinogenic, and antidiabetic effects on human health. Here, we focus on presenting the current state of knowledge about the possibilities of modulation of particular types of potassium channels by different flavonoids. Additionally, the biological meaning of the flavonoid-mediated changes in the activity of K+ channels will be outlined. Finally, novel promising directions for further research in this area will be proposed.

Natural flavonoids derived from herbal medicines are potential anti-atherogenic agents by inhibiting oxidative stress in endothelial cells

As the common pathological basis of various cardiovascular diseases, the morbidity and mortality of atherosclerosis (AS) have increased in recent years. Unfortunately, there are still many problems in the treatment of AS, and the prevention and treatment of the disease is not ideal. Up to now, the occurrence and development of AS can roughly include endothelial cell dysfunction, vascular smooth muscle cell proliferation, inflammation, foam cell production, and neoangiogenesis. Among them, endothelial dysfunction, as an early event of AS, plays a particularly important role in promoting the development of AS. In addition, oxidative stress occurs throughout the causes of endothelial dysfunction. Some previous studies have shown that flavonoids derived from herbal medicines are typical secondary metabolites. Due to its structural presence of multiple active hydroxyl groups, it is able to exert antioxidant activity in diseases. Therefore, in this review, we will search PubMed, Web of Science, Elesvier, Wliey, Springer for relevant literature, focusing on flavonoids extracted from herbal medicines, and summarizing how they can prevent endothelial dysfunction by inhibiting oxidative stress. Meanwhile, in our study, we found that flavonoid represented by quercetin and naringenin showed superior protective effects both in vivo and in vitro, suggesting the potential of flavonoid compounds in the treatment of AS.

Flavonoids as new regulators of mitochondrial potassium channels: contribution to cardioprotection

Objectives

Acute myocardial ischemia is one of the major causes of illness in western society. Reduced coronary blood supply leads to cell death and loss of cardiomyocyte population, resulting in serious and often irreversible consequences on myocardial function. Mitochondrial potassium (mitoK) channels have been identified as fine regulators of mitochondrial function and, consequently, in the metabolism of the whole cell, and in the mechanisms underlying the cardioprotection. Interestingly, mitoK channels represent a novel putative target for treating cardiovascular diseases, particularly myocardial infarction, and their modulators represent an interesting tool for pharmacological intervention. In this review, we took up the challenge of selecting flavonoids that show cardioprotective properties through the activation of mitoK channels.

Key findings

A brief overview of the main information on mitoK channels and their participation in the induction of cytoprotective processes was provided. Then, naringenin, quercetin, morin, theaflavin, baicalein, epigallocatechin gallate, genistein, puerarin, luteolin and proanthocyanidins demonstrated to be effective modulators of mitoK channels activity, mediating many beneficial effects.

Summary

The pathophysiological role of mitoK channels has been investigated as well as the impact of flavonoids on this target with particular attention to their potential role in the prevention of cardiovascular disorders.

Naringenin: A prospective therapeutic agent for Alzheimer's and Parkinson's disease

Neurodegenerative disorders (NDs) are a cluster of progressive, severe, and disabling disorders that affect millions of people worldwide and are on the surge. These disorders are characterized by the gradual loss of a selectively vulnerable group of neurons. Due to the complex pathophysiological mechanisms behind neurodegeneration and despite enormous efforts and understanding of the occurrence and progression of NDs, there is still a lack of an effective treatment for such diseases. Therefore, the development of a new therapeutic strategy for NDs is an unmet clinical need. Various natural compounds extracted from medicinal plants or fruits have shown promising activities in treating different types of NDs by targeting multiple signaling pathways. Among natural entities, flavonoids have incited a rise in public and scientific interest in recent years because of their purported health-promoting effects. Dietary supplementation of flavonoids has been shown to mitigate the severity of NDs such as Parkinson's disease (PD), Alzheimer's disease (AD), and dementia by their antioxidant effects. Naringenin is a citrus flavonoid that is known to possess numerous biological activities like antioxidant, anti-proliferative, and anti-inflammatory activities. Therefore, naringenin has emerged as a potential therapeutic agent that exerts preventive and curative effects on several neurological disorders. Increasing evidence has attained special attention on the variety of therapeutic targets along with complex signaling pathways of naringenin, which suggest its possible therapeutic applications in several NDs. Derived from the results of several pre-clinical research and considering the therapeutic effects of this compound, this review focuses on the potential role of naringenin as a pharmacological agent for the treatment and management of Alzheimer's and Parkinson's disease. The overall neuroprotective effects and different possible underlying mechanisms related to naringenin are discussed. In the light of substantial evidence for naringenin's neuroprotective efficacy in several experimental paradigms, this review suggests that this molecule should be investigated further as a viable candidate for the management of Alzheimer's and Parkinson's disease, with an emphasis on mechanistic and clinical trials to determine its efficacy. PRACTICAL APPLICATIONS: Naringenin is a flavanone, aglycone of Naringin, predominantly found in citrus fruits with a variety of pharmacological actions. Naringenin has been shown to exhibit remarkable therapeutic efficacy and has emerged as a potential therapeutic agent for the management of a variety of diseases such as various heart, liver, and metabolic disorders. Similarly, it has shown efficacy in neurodegenerative illnesses. Therefore, this review enables us to better understand the neuroprotective effects and different possible underlying mechanisms of naringenin. Also, this review provides a new indication to manage the symptoms of NDs like AD and PD. Furthermore, naringenin will be useful in the field of medicine as a new active ingredient for the treatment of neurodegenerative disorders like AD and PD.

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.

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.

The cardioprotective effects and mechanisms of naringenin in myocardial ischemia based on network pharmacology and experiment verification

Naringenin (Nar) is a natural flavonoid extracted from citrus fruits with abundant pharmacological properties against cardiac diseases, but existing studies are unsystematic and scattered. The present research systematically investigates the mechanism of action of Nar in the treatment of myocardial ischemia (MI). Network pharmacology was used to analyze the relevant targets of Nar against MI as well as the biological mechanisms. The protective effect of Nar was initially assessed in H9c2 cells induced by CoCl₂. In acutely isolated rat cardiomyocytes, Nar was further explored for effects on L-type Ca²⁺ currents, cell contractility and Ca²⁺ transients by using patch-clamp technique and Ion Optix system. Network pharmacology analysis indicated that Nar improved apoptosis, mitochondrial energy metabolism, inflammation and oxidative stress. Experimental validation demonstrated that Nar decreased ROS and MDA levels and increased antioxidant activity (e.g., GSH-P_X, SOD, and CAT), mitochondrial membrane potential, ATP and Ca²⁺-ATPase contents. Nar also markedly reduced inflammatory factor levels, apoptosis, and intracellular Ca²⁺ concentrations in H9c2 cells. Based on the experimental results, it is speculated that Ca²⁺ signals play an essential role in the process of Nar against MI. Thus, we further confirmed that Nar significantly inhibited the L-type Ca²⁺ currents, contractility and Ca²⁺ transients in acutely isolated cardiomyocytes. The inhibition of Ca²⁺ overload by Nar may be a novel cardioprotective mechanism. The present study may serve as a basis for future clinical research, and Nar as a Ca²⁺ channel inhibitor may provide new perspectives for the treatment of myocardial ischemic diseases.

To what extent naringenin binding and membrane depolarization shape mitoBK channel gating—A machine learning approach

The large conductance voltage- and Ca2+-activated K+ channels from the inner mitochondrial membrane (mitoBK) are modulated by a number of factors. Among them flavanones, including naringenin (Nar), arise as a promising group of mitoBK channel regulators from a pharmacological point of view. It is well known that in the presence of Nar the open state probability (pop) of mitoBK channels significantly increases. Nevertheless, the molecular mechanism of the mitoBK-Nar interactions remains still unrevealed. It is also not known whether the effects of naringenin administration on conformational dynamics can resemble those which are exerted by the other channel-activating stimuli. In aim to answer this question, we examine whether the dwell-time series of mitoBK channels which were obtained at different voltages and Nar concentrations (yet allowing to reach comparable pops) are discernible by means of artificial intelligence methods, including k-NN and shapelet learning. The obtained results suggest that the structural complexity of the gating dynamics is shaped both by the interaction of channel gate with the voltage sensor (VSD) and the Nar-binding site. For a majority of data one can observe stimulus-specific patterns of channel gating. Shapelet algorithm allows to obtain better prediction accuracy in most cases. Probably, because it takes into account the complexity of local features of a given signal. About 30% of the analyzed time series do not sufficiently differ to unambiguously distinguish them from each other, which can be interpreted in terms of the existence of the common features of mitoBK channel gating regardless of the type of activating stimulus. There exist long-range mutual interactions between VSD and the Nar-coordination site that are responsible for higher levels of Nar-activation (Δpop) at deeply depolarized membranes. These intra-sensor interactions are anticipated to have an allosteric nature.

The Systems of Naringenin with Solubilizers Expand Its Capability to Prevent Neurodegenerative Diseases

BACKGROUND

Naringenin (NAR) is a flavonoid with excellent antioxidant and neuroprotective potential that is limited by its low solubility. Thus, solid dispersions with β-cyclodextrin (β-CD), hydroxypropyl-β-cyclodextrin (HP-β-CD), hydroxypropylmethylcellulose (HPMC), and microenvironmental pH modifiers were prepared.

METHODS

The systems formation analysis was performed by X-Ray Powder Diffraction (XRPD) and Fourier-transform infrared spectroscopy (FT-IR). Water solubility and dissolution rates were studied with a pH of 1.2 and 6.8. In vitro permeability through the gastrointestinal tract (GIT) and the blood-brain barrier (BBB) was assessed with the parallel artificial membrane permeability assay (PAMPA) assay. The antioxidant activity was studied with the 2,2'-azinobis-(3-ethylbenzothiazoline-6-sulfonic acid (ABTS) and cupric ion reducing antioxidant capacity (CUPRAC) assays, while in vitro enzymes studies involved the inhibition of acetylcholinesterase, butyrylcholinesterase, and tyrosinase. For the most promising system, in silico studies were conducted.

RESULTS

NAR solubility was increased 458-fold by the solid dispersion NAR:HP-β-CD:NaHCO₃ in a mass ratio of 1:3:1. The dissolution rate was elevated from 8.216% to 88.712% in a pH of 1.2 and from 11.644% to 88.843% in a pH of 6.8 (within 3 h). NAR GIT permeability, described as the apparent permeability coefficient, was increased from 2.789 × 10^-6 cm s^-1 to 2.909 × 10^-5 cm s^-1 in an acidic pH and from 1.197 × 10^-6 cm s^-1 to 2.145 × 10^-5 cm s^-1 in a basic pH. NAR BBB permeability was established as 4.275 × 10^-6 cm s^-1. The antioxidant activity and enzyme inhibition were also increased. Computational studies confirmed NAR:HP-β-CD inclusion complex formation.

CONCLUSIONS

A significant improvement in NAR solubility was associated with an increase in its biological activity.

Alternative Targets for Modulators of Mitochondrial Potassium Channels

Mitochondrial potassium channels control potassium influx into the mitochondrial matrix and thus regulate mitochondrial membrane potential, volume, respiration, and synthesis of reactive oxygen species (ROS). It has been found that pharmacological activation of mitochondrial potassium channels during ischemia/reperfusion (I/R) injury activates cytoprotective mechanisms resulting in increased cell survival. In cancer cells, the inhibition of these channels leads to increased cell death. Therefore, mitochondrial potassium channels are intriguing targets for the development of new pharmacological strategies. In most cases, however, the substances that modulate the mitochondrial potassium channels have a few alternative targets in the cell. This may result in unexpected or unwanted effects induced by these compounds. In our review, we briefly present the various classes of mitochondrial potassium (mitoK) channels and describe the chemical compounds that modulate their activity. We also describe examples of the multidirectional activity of the activators and inhibitors of mitochondrial potassium channels.

Naringenin ameliorates homocysteine induced endothelial damage via the AMPKα/Sirt1 pathway

Introduction

Endothelial damage (ED) has been implicated in accelerating the development of atherosclerosis. The latter condition is a risk factor for developing several cardiovascular diseases (CVDs) associated with high morbidity and mortality rates worldwide.

Objectives

In our previous studies, we found naringenin (Nar), a bioactive flavanone compound, to protect against mitochondrial damage and oxidative stress. Though the pleiotropic effects of Nar have been well described, precise cytoprotective mechanisms of Nar against homocysteine (Hcy) induced ED remains elusive. Understanding these events may give an insight in to prevention and treatment of CVDs.

Methods

After ruling out the NMDA-R1 mediated pathway, RNA-Seq, a novel transcriptomic technique uncovered AMPK signaling pathway was identified as the mechanism with which Nar corrects ED. Further in vivo and in vitro tests validated the role of Nar against ED.

Results

In particular, Nar activates AMPKα/Sirt1 signaling pathway, which restores mitochondrial Ca2+ balance and ultimately lowered production of reactive oxygen species (ROS). Activated AMPKα/Sirt1 signaling pathway also up-regulates endothelial nitric oxide synthase (eNOS) activity, and then increasing the production of nitric oxide (NO), ultimately ameliorating ED.

Conclusion

Nar could increase the ROS elimination and decrease eNOS uncoupling, subsequently upregulate the NO bioavailability and endothelial function by activating AMPKα/Sirt1 signaling pathway.

BK in Double-Membrane Organelles: A Biophysical, Pharmacological, and Functional Survey

In the 1970s, calcium-activated potassium currents were recorded for the first time. In 10years, this Ca²⁺-activated potassium channel was identified in rat skeletal muscle, chromaffin cells and characterized in skeletal muscle membranes reconstituted in lipid bilayers. This calcium- and voltage-activated potassium channel, dubbed BK for “Big K” due to its large ionic conductance between 130 and 300 pS in symmetric K⁺. The BK channel is a tetramer where the pore-forming α subunit contains seven transmembrane segments. It has a modular architecture containing a pore domain with a highly potassium-selective filter, a voltage-sensor domain and two intracellular Ca²⁺ binding sites in the C-terminus. BK is found in the plasma membrane of different cell types, the inner mitochondrial membrane (mitoBK) and the nuclear envelope’s outer membrane (nBK). Like BK channels in the plasma membrane (pmBK), the open probability of mitoBK and nBK channels are regulated by Ca²⁺ and voltage and modulated by auxiliary subunits. BK channels share common pharmacology to toxins such as iberiotoxin, charybdotoxin, paxilline, and agonists of the benzimidazole family. However, the precise role of mitoBK and nBK remains largely unknown. To date, mitoBK has been reported to play a role in protecting the heart from ischemic injury. At the same time, pharmacology suggests that nBK has a role in regulating nuclear Ca²⁺, membrane potential and expression of eNOS. Here, we will discuss at the biophysical level the properties and differences of mitoBK and nBK compared to those of pmBK and their pharmacology and function.

3,5-Diiodothyronine protects against cardiac ischaemia-reperfusion injury in male rats

NEW FINDINGS

What is the central question of this study? 3,5-Diiodothyronine (3,5-T2) administration increases resting metabolic rate, prevents or treats liver steatosis in rodent models, and ameliorates insulin resistance: what are its effects on cardiac electrical and contractile properties and autonomic regulation? What is the main finding and its importance? Chronic 3,5-T2 administration has no adverse effects on cardiac function. Remarkably, 3,5-T2 improves the autonomous control of the rat heart and protects against ischaemia-reperfusion injury.

ABSTRACT

The use of 3,5,3'-triiodothyronine (T3) and thyroxine (T4) to treat metabolic diseases has been hindered by potential adverse effects on liver, lipid metabolism and cardiac electrical properties. It is recognized that 3,5-diiodothyronine (3,5-T2) administration increases resting metabolic rate, prevents or treats liver steatosis in rodent models and ameliorates insulin resistance, suggesting 3,5-T2 as a potential therapeutic tool. However, a comprehensive assessment of cardiac electrical and contractile properties has not been made so far. Three-month-old Wistar rats were daily administered vehicle, 3,5-T2 or 3,5-T2+T4 and no signs of atrial or ventricular arrhythmia were detected in non-anaesthetized rats during 90 days. Cardiac function was preserved as heart rate, left ventricle diameter and shortening fraction in 3,5-T2-treated rats compared to vehicle and 3,5-T2+T4 groups. Power spectral analysis indicated an amelioration of the heart rate variability only in 3,5-T2-treated rats. An increased baroreflex sensitivity at rest was observed in both 3,5-T2-treated groups. Finally, 3,5-T2 Langendorff-perfused hearts presented a significant recovery of left ventricular function and remarkably smaller infarction area after ischaemia-reperfusion injury. In conclusion, chronic 3,5-T2 administration ameliorates tonic cardiac autonomic control and confers cardioprotection against ischaemia-reperfusion injury in healthy male rats.

Identification of novel SIRT1 activators endowed with cardioprotective profile

Drugs targeting epigenetic mechanisms are attracting the attention of scientists since it was observed that the modulation of this post-translational apparatus, could help to identify innovative therapeutic strategies. Among the epigenetic druggable targets, the positive modulation of SIRT1 has also been related to significant cardioprotective effects. Unfortunately, actual SIRT1 activators (natural products and synthetic molecules) suffer from several drawbacks, particularly poor pharmacokinetic profiles. Accordingly, in this article we present the development of an integrated screening platform aimed at identifying novel SIRT1 activators with favorable drug-like features as cardioprotective agents. Encompassing several competencies (in silico, medicinal chemistry, and pharmacology), we describe a multidisciplinary approach for rapidly identifying SIRT1 activators and their preliminary pharmacological characterization. In the first step, we virtually screened an in-house chemical library comprising synthetic molecules inspired by nature, against SIRT1 enzyme. To this end, we combined molecular docking-based approach with the estimation of relative ligand binding energy, using the crystal structure of SIRT1 enzyme in complex with resveratrol. Eleven computational hits were identified, synthesized and tested against the isolated enzyme for validating the in silico strategy. Among the tested molecules, five of them behave as SIRT1 enzyme activators. Due to the superior response in activating the enzyme and its favorable calculated physico-chemical properties, compound 8 was further characterized in ex vivo studies on isolated and perfused rat hearts submitted to ischemia/reperfusion (I/R) period. The pharmacological profile of compound 8, suggests that this molecule represents a prototypic SIRT1 activator with satisfactory drug-like profile, paving the way for developing novel epigenetic cardioprotective agents.

Multidimensional Regulation of Cardiac Mitochondrial Potassium Channels

Mitochondria play a fundamental role in the energetics of cardiac cells. Moreover, mitochondria are involved in cardiac ischemia/reperfusion injury by opening the mitochondrial permeability transition pore which is the major cause of cell death. The preservation of mitochondrial function is an essential component of the cardioprotective mechanism. The involvement of mitochondrial K+ transport in this complex phenomenon seems to be well established. Several mitochondrial K+ channels in the inner mitochondrial membrane, such as ATP-sensitive, voltage-regulated, calcium-activated and Na+-activated channels, have been discovered. This obliges us to ask the following question: why is the simple potassium ion influx process carried out by several different mitochondrial potassium channels? In this review, we summarize the current knowledge of both the properties of mitochondrial potassium channels in cardiac mitochondria and the current understanding of their multidimensional functional role. We also critically summarize the pharmacological modulation of these proteins within the context of cardiac ischemia/reperfusion injury and cardioprotection.

Naringenin alleviates myocardial ischemia reperfusion injury by enhancing the myocardial miR-126-PI3K/AKT axis in streptozotocin-induced diabetic rats

Ischemic heart disease (IHD) is a leading cause of death in patients with type 1 diabetes. The key to treating IHD is to restore blood supply to the ischemic myocardium, which inevitably causes myocardial ischemia reperfusion (MI/R) injury. Although naringenin (Nar) prevents MI/R injury, the role of Nar in diabetic MI/R (D-MI/R) injury remains to be elucidated. The PI3K/AKT signaling pathway and microRNA (miR)-126 have previously been shown to serve anti-MI/R injury roles. The present study aimed to investigate the protection of Nar against D-MI/R injury and the role of the miR-126-PI3K/AKT axis. Diabetic rats were treated distilled water or Nar (25 or 50 mg/kg, orally) for 30 days and then exposed to MI/R. The present results revealed that Nar alleviated MI/R injury in streptozotocin (STZ)-induced diabetic rats, as shown below: the reduction myocardial enzymes levels was measured using spectrophotometry, the increase of cardiac viability was detected by MTT assay, the inhibition of myocardial oxidative stress was measured using spectrophotometry and the enhancement of cardiac function were recorded using a hemodynamic monitoring system. Furthermore, Nar upregulated the myocardial miR-126-PI3K/AKT axis in D-MI/R rats. These results indicated that Nar alleviated MI/R injury through upregulating the myocardial miR-126-PI3K/AKT axis in STZ-induced diabetic rats. The current findings revealed that Nar, as an effective agent against D-MI/R injury, may provide an effective approach in the management of diabetic IHD.

Retinal Neurodegeneration: Correlation between Nutraceutical Treatment and Animal Model

Retinal diseases can be induced by a variety of factors, including gene mutations, environmental stresses and dysmetabolic processes. The result is a progressive deterioration of visual function, which sometimes leads to blindness. Many treatments are under investigation, though results are still mostly unsatisfactory and restricted to specific pathologies, particularly in the case of gene therapy. The majority of treatments have been tested in animal models, but very few have progressed to human clinical trials. A relevant approach is to study the relation between the type of treatments and the degenerative characteristics of the animal model to better understand the effectiveness of each therapy. Here we compare the results obtained from different animal models treated with natural compounds (saffron and naringenin) to anticipate the potentiality of a single treatment in different pathologies.

Citrus Polyphenols in Brain Health and Disease: Current Perspectives

In addition to essential micronutrients such as vitamin C, citrus fruits represent a considerably rich source of non-essential bioactive compounds, in particular flavanones which form a sub-set of the flavonoid group. Preclinical studies have demonstrated the neuroprotective potential of citrus flavonoids and have highlighted both the well-established (anti-inflammatory and anti-oxidative properties), and newly emerging (influence upon blood-brain barrier function/integrity) mechanistic actions by which these neurological effects are mediated. Encouragingly, results from human studies, although limited in number, appear to support this preclinical basis, with improvements in cognitive performance and disease risk observed across healthy and disease states. Therefore, citrus fruits - both as whole fruit and 100% juices - should be encouraged within the diet for their potential neurological benefit. In addition, there should be further exploration of citrus polyphenols to establish therapeutic efficacy, particularly in the context of well-designed human interventions.

Mitochondrial Potassium Channels as Druggable Targets

Mitochondrial potassium channels have been described as important factors in cell pro-life and death phenomena. The activation of mitochondrial potassium channels, such as ATP-regulated or calcium-activated large conductance potassium channels, may have cytoprotective effects in cardiac or neuronal tissue. It has also been shown that inhibition of the mitochondrial Kv1.3 channel may lead to cancer cell death. Hence, in this paper, we examine the concept of the druggability of mitochondrial potassium channels. To what extent are mitochondrial potassium channels an important, novel, and promising drug target in various organs and tissues? The druggability of mitochondrial potassium channels will be discussed within the context of channel molecular identity, the specificity of potassium channel openers and inhibitors, and the unique regulatory properties of mitochondrial potassium channels. Future prospects of the druggability concept of mitochondrial potassium channels will be evaluated in this paper.

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.

Development of Fortified Citrus Olive Oils: From Their Production to Their Nutraceutical Properties on the Cardiovascular System

: Recently the use of food by-products as natural sources of biologically active substances has been extensively investigated especially for the development of functional foods fortified with natural antioxidants. Due to their content of bioactive compounds, such as carotenoids, flavonoids and limonoids, citrus peels could be suitable to formulate enriched olive oils able to boost healthy nutrition. The aim of this study was: (i) to determine the compositional and sensory profiles of citrus olive oil; and (ii) to evaluate its nutraceutical properties in rats with high fat diet-induced metabolic syndrome and oxidative stress. The results obtained show the potential of using citrus peels as a source of bioactive compounds to improve the sensory profile as well as the phytochemical composition of olive oil. We demonstrated that the production system of Citrus x aurantium olive oil and Citrus limon olive oil improves its organoleptic properties without altering its beneficial effects, which, like control extra virgin olive oil, showed protective effects relating to glucose and serum lipid levels, metabolic activity of adipocytes, myocardial tissue functionality, oxidative stress markers and endothelial function at blood vessel level.

Transient receptor potential channels in the context of nociception and pain - recent insights into TRPM3 properties and function

Potential harmful stimuli like heat, mechanical pressure or chemicals are detected by specialized cutaneous nerve fiber endings of nociceptor neurons in a process called nociception. Acute stimulation results in immediate protective reflexes and pain sensation as a normal, physiological behavior. However, ongoing (chronic) pain is a severe pathophysiological condition with diverse pathogeneses that is clinically challenging because of limited therapeutic options. Therefore, an urgent need exists for new potent and specific analgesics without afflicting adverse effects. Recently, TRPM3, a member of the superfamily of transient receptor potential (TRP) ion channels, has been shown to be expressed in nociceptors and to be involved in the detection of noxious heat (acute pain) as well as inflammatory hyperalgesia (acute and chronic pain). Current results in TRPM3 research indicate that this ion channel might not only be part of yet unraveled mechanisms underlying chronic pain but also has the potential to become a clinically relevant pharmacological target of future analgesic strategies. The aim of this review is to summarize and present the basic features of TRPM3 proteins and channels, to highlight recent findings and developments and to provide an outlook on emerging directions of TRPM3 research in the field of chronic pain.

The Citrus Flavonoid Naringenin Protects the Myocardium from Ageing-Dependent Dysfunction: Potential Role of SIRT1

Sirtuin 1 (SIRT1) enzyme plays a pivotal role in the regulation of many physiological functions. In particular, it is implicated in ageing-related diseases, such as cardiac hypertrophy, myocardial infarct, and endothelial dysfunction; moreover, its expression decreases with age. Therefore, an effective strategy to extend the lifespan and improve cardiovascular function is the enhancement of the expression/activity of SIRT1 with exogenous agents. The Citrus flavonoid naringenin (NAR) presents structural similarity with the natural SIRT1 activator resveratrol. In this study, we demonstrate through in vitro assays that NAR significantly activates SIRT1 enzyme and shows antisenescence effects. The binding mode of NAR into SIRT1 was detailed investigated through in silico studies. Moreover, chronic administration (for six months) of NAR (100 mg/kg/day) to 6-month-old mice leads to an enhancement of SIRT1 expression and a marked reduction of reactive oxygen species production in myocardial tissue. Furthermore, at the end of the treatment, the plasma levels of two well-known markers of cardiovascular inflammation, TNF-α and IL6, are significantly reduced in 12-month-old mice treated with NAR, as well as the cardiovascular risk (total cholesterol/HDL ratio) compared to control mice. Finally, the age-associated fibrotic remodeling, which is well detected through a Mallory trichrome staining in the vehicle-treated 12-month-old mice, is significantly reduced by the chronic treatment with NAR. Moreover, an improvement of myocardium functionality is highlighted by the enhancement of citrate synthase activity and stabilization of the mitochondrial membrane potential after NAR treatment. Taken together, these results suggest that a nutraceutical approach with NAR may have positive impacts on many critical hallmarks of myocardial senescence, contributing to improve the cardiac performance in aged subjects.

Hydroxypropyl-β-cyclodextrin-complexed naringenin by solvent change precipitation for improving anti-inflammatory effect in vivo

The flavonoid naringenin (NAR) exhibits an outstanding anti-inflammatory potential; however, stability problems and reduced solubility hinder its commercial insertion. This work aimed to obtain solid-state hydroxypropyl-β-cyclodextrin (CD) inclusion complexes with NAR using, for the first time, the solvent change precipitation method. For this, molecular modeling and physicochemical characterizations were conducted, followed by in vitro and in vivo assays. The complexation method showed thermal and spectroscopic evidence of NAR inclusion complexes formation, suggesting an improvement of its stability. Additionally, 30 min-dissolution efficiency of the complex was 57.2 %, whereas NAR, as supplied, showed only 14.3 %, a four-fold enhancement. In vitro and in vivo performance attested the potent anti-inflammatory and antinociceptive profile of NAR with significant suppression of TNF-α production. Moreover, NAR complexation with CD improved its therapeutic effect, which showed similar activity to that achieved with NAR as supplied but employing only 1/5 of its dose.

Specific BK Channel Activator NS11021 Protects Rat Renal Proximal Tubular Cells from Cold Storage-Induced Mitochondrial Injury In Vitro

Kidneys from deceased donors used for transplantation are placed in cold storage (CS) solution during the search for a matched recipient. However, CS causes mitochondrial injury, which may exacerbate renal graft dysfunction. Here, we explored whether adding NS11021, an activator of the mitochondrial big-conductance calcium-activated K⁺ (mitoBK) channel, to CS solution can mitigate CS-induced mitochondrial injury. We used normal rat kidney proximal tubular epithelial (NRK) cells as an in vitro model of renal cold storage (18 h) and rewarming (2 h) (CS + RW). Western blots detected the pore-forming α subunit of the BK channel in mitochondrial fractions from NRK cells. The fluorescent K⁺-binding probe, PBFI-AM, revealed that isolated mitochondria from NRK cells exhibited mitoBK-mediated K⁺ uptake, which was impaired ~70% in NRK cells subjected to CS + RW compared to control NRK cells maintained at 37 °C. Importantly, the addition of 1 μM NS11021 to CS solution prevented CS + RW-induced impairment of mitoBK-mediated K⁺ uptake. The NS11021–treated NRK cells also exhibited less cell death and mitochondrial injury after CS + RW, including mitigated mitochondrial respiratory dysfunction, depolarization, and superoxide production. In summary, these new data show for the first time that mitoBK channels may represent a therapeutic target to prevent renal CS-induced injury.

Naringenin improves mitochondrial function and reduces cardiac damage following ischemia-reperfusion injury: the role of the AMPK-SIRT3 signaling pathway

Mitochondrial dysfunction contributed greatly to myocardial ischemia-reperfusion (MI/R)-induced cardiomyocyte apoptosis. Naringenin is a flavonoid exhibiting potential protective effects on myocardial mitochondria under stress conditions. However, the detailed down-stream signaling pathway involved remains uncovered. This study was designed to elucidate naringenin's mitochondrial protective actions during MI/R with a focus on AMPK-SIRT3 signaling. Sprague-Dawley rats were administered with naringenin (50 mg kg-1 d-1) and subjected to MI/R surgery in the presence or absence of compound C (0.25 mg kg-1, Com.C, an AMPK inhibitor) co-treatment. An in vitro study was performed on H9c2 cardiomyoblasts subjected to simulated ischemia-reperfusion treatment. Before the treatment, the cells were administered with naringenin (80 μmol L-1) with or without SIRT3 siRNA/AMPK1α siRNA transfection. Naringenin improved post-reperfusion left ventricular systolic pressure and the instantaneous first derivative of left ventricular pressure, and reduced the infarction size and myocardial apoptosis index by suppressing mitochondrial oxidative stress damage (as evidenced by decreased mitochondrial cytochrome c release and oxidative markers) and enhancing mitochondrial biogenesis [as evidenced by increased NRF1, TFAM and oxidative phosphorylation subunit complexes (II, III and IV)]. These protective actions were abolished by Com.C (in vivo) or SIRT3 siRNA (in vitro) administration. Further investigation revealed that Com.C (in vivo) or AMPK1α siRNA (in vitro) markedly suppressed PGC-1α and SIRT3 levels while SIRT3 siRNA (in vitro) inhibited SIRT3 expression without significantly changing AMPK phosphorylation and PGC-1α levels. Taken together, we found that naringenin directly inhibits mitochondrial oxidative stress damage and preserves mitochondrial biogenesis, thus attenuating MI/R injury. Importantly, AMPK-SIRT3 signaling played a key role in this process.

Synthesis and In Vitro Antitumor Activity of Naringenin Oxime and Oxime Ether Derivatives

Naringenin is one of the most abundant dietary flavonoids exerting several beneficial biological activities. Synthetic modification of naringenin is of continuous interest. During this study our aim was to synthesize a compound library of oxime and oxime ether derivatives of naringenin, and to investigate their biological activities. Two oximes and five oxime ether derivatives were prepared; their structure has been elucidated by NMR and high-resolution mass spectroscopy. The antiproliferative activity of the prepared compounds was evaluated by MTT assay against human leukemia (HL-60) and gynecological cancer cell lines isolated from cervical (HeLa, Siha) and breast (MCF-7, MDA-MB-231) cancers. Tert-butyl oxime ether derivative exerted the most potent cell growth inhibitory activity. Moreover, cell cycle analysis suggested that this derivative caused a significant increase in the hypodiploid (subG1) phase and induced apoptosis in Hela and Siha cells, and induced cell cycle arrest at G2/M phase in MCF-7 cells. The proapoptotic potential of the selected compound was confirmed by the activation of caspase-3. Antioxidant activities of the prepared molecules were also evaluated with xanthine oxidase, DPPH and ORAC assays, and the methyl substituted oxime ether exerted the most promising activity.

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.