In Vitro Effect of 8-Prenylnaringenin and Naringenin on Fibroblasts and Glioblastoma Cells-Cellular Accumulation and Cytotoxicity

A review of natural products and small-molecule therapeutics acting on central nervous system malignancies: Approaches for drug development, targeting pathways, clinical trials, and challenges

In 2021, the World Health Organization released the fifth edition of the central nervous system (CNS) tumor classification. This classification uses histopathology and molecular pathogenesis to group tumors into more biologically and molecularly defined entities. The prognosis of brain cancer, particularly malignant tumors, has remained poor worldwide, approximately 308,102 new cases of brain and other CNS tumors were diagnosed in the year 2020, with an estimated 251,329 deaths. The cost and time-consuming nature of studies to find new anticancer agents makes it necessary to have well-designed studies. In the present study, the pathways that can be targeted for drug development are discussed in detail. Some of the important cellular origins, signaling, and pathways involved in the efficacy of bioactive molecules against CNS tumorigenesis or progression, as well as prognosis and common approaches for treatment of different types of brain tumors, are reviewed. Moreover, different study tools, including cell lines, in vitro, in vivo, and clinical trial challenges, are discussed. In addition, in this article, natural products as one of the most important sources for finding new chemotherapeutics were reviewed and over 700 reported molecules with efficacy against CNS cancer cells are gathered and classified according to their structure. Based on the clinical trials that have been registered, very few of these natural or semi-synthetic derivatives have been studied in humans. The review can help researchers understand the involved mechanisms and design new goal-oriented studies for drug development against CNS malignancies.

A comprehensive review of the benefits of drinking craft beer: Role of phenolic content in health and possible potential of the alcoholic fraction

Currently, there is greater production and consumption of craft beer due to its appreciated sensory characteristics. Unlike conventional beer, craft beers provide better health benefits due to their varied and high content of phenolic compounds (PCs) and also due to their alcohol content, but the latter is controversial. The purpose of this paper was to report on the alcoholic fraction and PCs present in craft beers and their influence on health. Despite the craft beer boom, there are few studies on the topic; there is a lot of field to explore. The countries with the most research are the United States > Italy > Brazil > United Kingdom > Spain. The type and amount of PCs in craft beers depends on the ingredients and strains used, as well as the brewing process. It was determined that it is healthier to be a moderate consumer of alcohol than to be a teetotaler or heavy drinker. Thus, studies in vitro, with animal models and clinical trials on cardiovascular and neurodegenerative diseases, cancer, diabetes and obesity, osteoporosis and even the immune system suggest the consumption of craft beer. However, more studies with more robust designs are required to obtain more generalizable and conclusive results. Finally, some challenges in the production of craft beer were detailed and some alternative solutions were mentioned.

The Spectrum of Pharmacological Actions of Syringetin and Its Natural Derivatives-A Summary Review

Mono- and poly-O-methylated flavonols and their glycoside derivatives belong to the group of natural plant polyphenols with a wide spectrum of pharmacological activities. These compounds are known for their antioxidant, antimutagenic, hepatoprotective, antidiabetic, and antilipogenic properties. Additionally, they inhibit carcinogenesis and cancer development. Having in mind the multidirectional biological activity of methylated flavonols, we would like to support further study on their health-promoting activities; in this review we summarized the most recent reports on syringetin and some of its structural analogues: laricitrin, ayanin, and isorhamnetin. Natural sources and biological potential of these substances were described based on the latest research papers.

Naringenin and Its Derivatives-Health-Promoting Phytobiotic against Resistant Bacteria and Fungi in Humans

Naringenin is a trihydroxyflavanone present in large amount in different citrus fruits, e.g., oranges, pomelos, grapefruits, but also in tomatoes, fenugreek and coffee. It has a wide range of pharmacological and biological effects beneficial to human health. Its antioxidant, anti-cancer, anti-inflammatory, antifungal and antimicrobial activity is frequently reported in scientific literature. In this review we presented the current state of knowledge on the antimicrobial activity of naringenin and its natural and synthetic derivatives as a phytobiotic against resistant Gram-positive and Gram-negative bacteria as well as fungi in humans. Most of the data reported here have been obtained from in vitro or in vivo studies. Over the past few years, due to the overuse of antibiotics, the occurrence of bacteria resistant to all available antibiotics has been growing. Therefore, the main focus here is on antibiotic resistant strains, which are a significant, worldwide problem in the treatment of infectious diseases. The situation is so alarming that the WHO has listed microbial resistance to drugs on the list of the 10 most important health problems facing humanity. In addition, based on scientific reports from recent years, we described the potential molecular mechanism of action of these bioflavonoids against pathogenic strains of microorganisms. As plant-derived substances have been pushed out of use with the beginning of the antibiotic era, we hope that this review will contribute to their return as alternative methods of preventing and treating infections in the epoch of drug resistance.

Naringenin and Phytoestrogen 8-Prenylnaringenin Protect against Islet Dysfunction and Inhibit Apoptotic Signaling in Insulin-Deficient Diabetic Mice

It has been shown that citrus flavanone naringenin and its prenyl derivative 8-prenylnaringenin (8-PN) possess various pharmacological activities in in vitro and in vivo models. Interestingly, it has been proposed that prenylation can enhance biological potentials, including the estrogen-like activities of flavonoids. The objective of this study was to investigate the anti-diabetic potential and molecular mechanism of 8-PN in streptozotocin (STZ)-induced insulin-deficient diabetic mice in comparison with naringenin reported to exhibit hypoglycemic effects. The oral administration of naringenin and 8-PN ameliorated impaired glucose homeostasis and islet dysfunction induced by STZ treatment. These protective effects were associated with the suppression of pancreatic β-cell apoptosis and inflammatory responses in mice. Moreover, both naringenin and 8-PN normalized STZ-induced insulin-signaling defects in skeletal muscles and apoptotic protein expression in the liver. Importantly, 8-PN increased the protein expression levels of estrogen receptor-α (ERα) in the pancreas and liver and of fibroblast growth factor 21 in the liver, suggesting that 8-PN could act as an ERα agonist in the regulation of glucose homeostasis. This study provides novel insights into the mechanisms underlying preventive effects of naringenin and 8-PN on the impairment of glucose homeostasis in insulin-deficient diabetic mice.

Naringenin: A potential flavonoid phytochemical for cancer therapy

Naringenin is an important phytochemical which belongs to the flavanone group of polyphenols, and is found mainly in citrus fruits like grapefruits and others such as tomatoes and cherries plus medicinal plants derived food. Available evidence demonstrates that naringenin, as herbal medicine, has important pharmacological properties, including anti-inflammatory, antioxidant, neuroprotective, hepatoprotective, and anti-cancer activities. Collected data from in vitro and in vivo studies show the inactivation of carcinogens after treatment with pure naringenin, naringenin-loaded nanoparticles, and also naringenin in combination with anti-cancer agents in various malignancies, such as colon cancer, lung neoplasms, breast cancer, leukemia and lymphoma, pancreatic cancer, prostate tumors, oral squamous cell carcinoma, liver cancer, brain tumors, skin cancer, cervical and ovarian cancer, bladder neoplasms, gastric cancer, and osteosarcoma. Naringenin inhibits cancer progression through multiple mechanisms, like apoptosis induction, cell cycle arrest, angiogenesis hindrance, and modification of various signaling pathways including Wnt/β-catenin, PI3K/Akt, NF-ĸB, and TGF-β pathways. In this review, we demonstrate that naringenin is a natural product with potential for the treatment of different types of cancer, whether it is used alone, in combination with other agents, or in the form of the naringenin-loaded nanocarrier, after proper technological encapsulation.

Antioxidant and Antiproliferation Activities of Lemon Verbena (Aloysia citrodora): An In Vitro and In Vivo Study

Aloysia citrodora (Verbenaceae) is traditionally used to treat various diseases, including bronchitis, insomnia, anxiety, digestive, and heart problems. In this study, this plant’s antioxidant and anti-proliferation effects were evaluated. In addition to volatiles extraction, different solvent extracts were prepared. The GC-MS, LC-MS analysis and the Foline-Ciocalteu (F-C) method were used to investigate the phytochemical components of the plant. MTT assay was used to measure the antiproliferative ability for each extract. Antioxidant activity was determined using the 2,2-diphenylpicrylhydrazyl (DPPH) assay. In in vivo anti-proliferation experiments, Balb/C mice were inoculated with tumor cells and IP-injected with ethyl acetate extract of A. citrodora. After treatment, a significant reduction in tumor size (57.97%) and undetected tumors (44.44%) were obtained in treated mice, demonstrating the antiproliferative efficacy of the ethyl acetate extract. Besides, ethanol extract revealed the most potent radical scavenging effect. The findings of this study displayed that A. citrodora has promising cytotoxic and antioxidant activities. Still, further testing is required to investigate the extract’s chemical composition to understand its mechanisms of action.

The Potent Phytoestrogen 8-Prenylnaringenin: A Friend or a Foe?

8-prenylnaringenin (8-PN) is a prenylated flavonoid, occurring, in particular, in hop, but also in other plants. It has proven to be one of the most potent phytoestrogens in vitro known to date, and in the past 20 years, research has unveiled new effects triggered by it in biological systems. These findings have aroused the hopes, expectations, and enthusiasm of a “wonder-drug” for a host of human diseases. However, the majority of 8-PN effects require such high concentrations that they cannot be reached by normal dietary exposure, only pharmacologically; thus, adverse impacts may also emerge. Here, we provide a comprehensive and up-to-date review on this fascinating compound, with special reference to the range of beneficial and untoward health consequences that may ensue from exposure to it.

Targeting the two-pore channel 2 in cancer progression and metastasis

The importance of Ca²⁺ signaling, and particularly Ca²⁺ channels, in key events of cancer cell function such as proliferation, metastasis, autophagy and angiogenesis, has recently begun to be appreciated. Of particular note are two-pore channels (TPCs), a group of recently identified Ca²⁺-channels, located within the endolysosomal system. TPC2 has recently emerged as an intracellular ion channel of significant pathophysiological relevance, specifically in cancer, and interest in its role as an anti-cancer drug target has begun to be explored. Herein, an overview of the cancer-related functions of TPC2 and a discussion of its potential as a target for therapeutic intervention, including a summary of clinical trials examining the TPC2 inhibitors, naringenin, tetrandrine, and verapamil for the treatment of various cancers is provided.

Neuroimmunomodulatory Properties of Flavonoids and Derivates: A Potential Action as Adjuvants for the Treatment of Glioblastoma

Glioblastomas (GBMs) are tumors that have a high ability to migrate, invade and proliferate in the healthy tissue, what greatly impairs their treatment. These characteristics are associated with the complex microenvironment, formed by the perivascular niche, which is also composed of several stromal cells including astrocytes, microglia, fibroblasts, pericytes and endothelial cells, supporting tumor progression. Further microglia and macrophages associated with GBMs infiltrate the tumor. These innate immune cells are meant to participate in tumor surveillance and eradication, but they become compromised by GBM cells and exploited in the process. In this review we discuss the context of the GBM microenvironment together with the actions of flavonoids, which have attracted scientific attention due to their pharmacological properties as possible anti-tumor agents. Flavonoids act on a variety of signaling pathways, counteracting the invasion process. Luteolin and rutin inhibit NFκB activation, reducing IL-6 production. Fisetin promotes tumor apoptosis, while inhibiting ADAM expression, reducing invasion. Naringenin reduces tumor invasion by down-regulating metalloproteinases expression. Apigenin and rutin induce apoptosis in C6 cells increasing TNFα, while decreasing IL-10 production, denoting a shift from the immunosuppressive Th2 to the Th1 profile. Overall, flavonoids should be further exploited for glioma therapy.

Naringenin attenuates cell viability and migration of C6 glioblastoma cell line: a possible role of hedgehog signaling pathway

OBJECTIVE

Gliomas are the most prevalent type of malignant primary brain tumors. Despite the availability of several treatment modalities, these tumors have poor prognostic features. Aberrant Hedgehog (Hh) signaling has been found to be implicated in the development of numerous malignancies including gliomas. Naringenin appears to have anti-proliferative and anti-cancer properties. However, there is no report describing its effects via the Hh signaling pathway on the C6 glioblastoma cell line. The current study was set to examine the anti-cancer effects of naringenin on C6 cells in order to determine the effect of this compound on the Hh signaling pathway.

METHODS

The anti-proliferative and apoptotic effects of naringenin against C6 and 3T3 fibroblast cells were measured by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay and annexin-V/PI dual staining assay, respectively. The effect of naringenin on the migration of C6 cells was evaluated by the migration scratch assay. To assess the anti-cancer effect of naringenin on the Hh signaling pathway, the expression of Gli-1, Smo, and Sufu at protein levels in C6 cells was analyzed using western blotting.

RESULTS

The obtained data indicated that naringenin exerted higher cytotoxicity against C6 cells (IC50 value of 114 ± 3.4 µg/mL) than normal 3T3 fibroblasts (IC50 value of 290 ± 7 µg/mL). Naringenin (114 µg/mL) also induced stronger apoptotic effects on C6 cells than 3T3 cells after 24 h of incubation. Furthermore, naringenin at a concentration of 114 µg/mL and a lower concentration of 60 µg/mL inhibited the migration of the C6 cell line. In addition, naringenin at a concentration of 114 µg/mL significantly decreased the expression of Gli-1 and Smo and elevated the expression of Sufu at the protein level in the C6 cell line.

CONCLUSION

These data represent that naringenin may have a potential effect on the management of the proliferation and metastasis of malignant gliomas by inhibiting the Hh signaling pathway.

Chrysin: Perspectives on Contemporary Status and Future Possibilities as Pro-Health Agent

Chrysin belongs to the group of natural polyphenols. It can be found, among others, in honey, propolis and fruits and has a wide range of biological activities, including the prevention of oxidative stress, inflammation, neurodegeneration and carcinogenesis. Being a part of the human diet, chrysin is considered to be a promising compound to be used in the prevention of many diseases, including cancers, diabetes and neurodegenerative diseases such as Alzheimer's or Parkinson's. Nevertheless, due to the low solubility of chrysin in water and under physiological conditions, its bioavailability is low. For this reason, attempts at its functionalization have been undertaken, aiming to increase its absorption and thus augment its in vivo therapeutic efficacy. The aim of this review is to summarize the most recent research on chrysin, including its sources, metabolism, pro-health effects and the effects of its functionalization on biological activity and pharmacological efficacy, evaluated both in vitro and in vivo.

Prenylated Flavonoids with Potential Antimicrobial Activity: Synthesis, Biological Activity, and In Silico Study

Prenylated flavonoids are an important class of naturally occurring flavonoids with important biological activity, but their low abundance in nature limits their application in medicines. Here, we showed the hemisynthesis and the determination of various biological activities of seven prenylated flavonoids, named 7–13, with an emphasis on antimicrobial ones. Compounds 9, 11, and 12 showed inhibitory activity against human pathogenic fungi. Compounds 11, 12 (flavanones) and 13 (isoflavone) were the most active against clinical isolated Staphylococcus aureus MRSA, showing that structural requirements as prenylation at position C-6 or C-8 and OH at positions C-5, 7, and 4′ are key to the antibacterial activity. The combination of 11 or 12 with commercial antibiotics synergistically enhanced the antibacterial activity of vancomycin, ciprofloxacin, and methicillin in a factor of 10 to 100 times against drug-resistant bacteria. Compound 11 combined with ciprofloxacin was able to decrease the levels of ROS generated by ciprofloxacin. According to docking results of S enantiomer of 11 with ATP-binding cassette transporter showed the most favorable binding energy; however, more studies are needed to support this result.

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

BACKGROUND

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

OBJECTIVE

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

METHODS

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

RESULTS

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

CONCLUSION

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

Current methodologies to refine bioavailability, delivery, and therapeutic efficacy of plant flavonoids in cancer treatment

Over the last two decades, several advancements have been made to improve the therapeutic efficacy of plant flavonoids, especially in cancer treatment. Factors such as low bioavailability, poor flavonoid stability and solubility, ineffective targeted delivery, and chemo-resistance hinder the application of flavonoids in anti-cancer therapy. Many anti-cancer compounds failed in the clinical trials because of unexpected altered clearance of flavonoids, poor absorption after administration, low efficacy, and/or adverse effects. Hence, the current research strategies are focused on improving the therapeutic efficacy of plant flavonoids, especially by enhancing their bioavailability through combination therapy, engineering gut microbiota, regulating flavonoids interaction with adenosine triphosphate binding cassette efflux transporters, and efficient delivery using nanocrystal and encapsulation technologies. This review aims to discuss different methodologies with examples from reported dietary flavonoids that showed an enhanced anti-cancer efficacy in both in vitro and in vivo models. Further, the review discusses the recent progress in biochemical modifications of flavonoids to improve bioavailability, solubility, and therapeutic efficacy.

Alcoholic and Non-Alcoholic Beer Modulate Plasma and Macrophage microRNAs Differently in a Pilot Intervention in Humans with Cardiovascular Risk

Beer is a popular beverage and some beneficial effects have been attributed to its moderate consumption. We carried out a pilot study to test if beer and non-alcoholic beer consumption modify the levels of a panel of 53 cardiometabolic microRNAs in plasma and macrophages. Seven non-smoker men aged 30–65 with high cardiovascular risk were recruited for a non-randomised cross-over intervention consisting of the ingestion of 500 mL/day of beer or non-alcoholic beer for 14 days with a 7-day washout period between interventions. Plasma and urine isoxanthohumol were measured to assess compliance with interventions. Monocytes were isolated and differentiated into macrophages, and plasma and macrophage microRNAs were analysed by quantitative real-time PCR. Anthropometric, biochemistry and dietary parameters were also measured. We found an increase in plasma miR-155-5p, miR-328-3p, and miR-92a-3p after beer and a decrease after non-alcoholic beer consumption. Plasma miR-320a-3p levels decreased with both beers. Circulating miR-320a-3p levels correlated with LDL-cholesterol. We found that miR-17-5p, miR-20a-5p, miR-145-5p, miR-26b-5p, and miR-223-3p macrophage levels increased after beer and decreased after non-alcoholic beer consumption. Functional analyses suggested that modulated microRNAs were involved in catabolism, nutrient sensing, Toll-like receptors signalling and inflammation. We concluded that beer and non-alcoholic beer intake modulated differentially plasma and macrophage microRNAs. Specifically, microRNAs related to inflammation increased after beer consumption and decreased after non-alcoholic beer consumption.

Disentangling the therapeutic tactics in GBM: From bench to bedside and beyond

Glioblastoma multiforme (GBM) is one of the most common and malignant form of adult brain tumor with a high mortality rate and dismal prognosis. The present standard treatment comprising surgical resection followed by radiation and chemotherapy using temozolomide can broaden patient's survival to some extent. However, the advantages are not palliative due to the development of resistance to the drug and tumor recurrence following the multimodal treatment approaches due to both intra- and intertumoral heterogeneity of GBM. One of the major contributors to temozolomide resistance is O⁶ -methylguanine-DNA methyltransferase. Furthermore, deficiency of mismatch repair, base excision repair, and cytoprotective autophagy adds to temozolomide obstruction. Rising proof additionally showed that a small population of cells displaying certain stem cell markers, known as glioma stem cells, adds on to the resistance and tumor progression. Collectively, these findings necessitate the discovery of novel therapeutic avenues for treating glioblastoma. As of late, after understanding the pathophysiology and biology of GBM, some novel therapeutic discoveries, such as drug repurposing, targeted molecules, immunotherapies, antimitotic therapies, and microRNAs, have been developed as new potential treatments for glioblastoma. To help illustrate, "what are the mechanisms of resistance to temozolomide" and "what kind of alternative therapeutics can be suggested" with this fatal disease, a detailed history of these has been discussed in this review article, all with a hope to develop an effective treatment strategy for GBM.

Celecoxib substituted biotinylated poly(amidoamine) G3 dendrimer as potential treatment for temozolomide resistant glioma therapy and anti-nematode agent

Glioblastoma multiforme (GBM) is a one of the most widely diagnosed and difficult to treat type of central nervous system tumors. Resection combined with radiotherapy and temozolomide (TMZ) chemotherapy prolongs patients' survival only for 12 - 15 months after diagnosis. Moreover, many patients develop TMZ resistance, thus important is search for a new therapy regimes including targeted drug delivery. Most types of GBM reveal increased expression of cyclooxygenase-2 (COX-2) and production of prostaglandin E2 (PGE₂), that are considered as valuable therapeutic target. In these studies, the anti-tumor properties of the selective COX-2 inhibitor celecoxib (CXB) and biotinylated third generation of the poly(amidoamine) dendrimer substituted with 31 CXB residues (G3BC31) on TMZ -resistant U-118 MG glioma cell line were examined and compared with the effect of TMZ alone including viability, proliferation, migration and apoptosis, as well as the cellular expression of COX-2, ATP level, and PGE₂ production. Confocal microscopy analysis with the fluorescently labeled G3BC31 analogue has shown that the compound was effectively accumulated in U-118 MG cells in time-dependent manner and its localization was confirmed in lysosomes but not nuclei. G3BC31 reveal much higher cytotoxicity for U-118 MG cells at relatively low concentrations in the range of 2-4 µM with compared to CBX alone, active at 50-100 µM. This was due to induction of apoptosis and inhibition of proliferation and migration. Observed effects were concomitant with reduction of PGE₂ production but independent of COX-2 expression. We suggest that investigated conjugate may be a promising candidate for therapy of TMZ-resistant glioblastoma multiforme, although applicable in local treatment, since our previous study of G3BC31 did not demonstrate selectivity against glioma cells compared to normal human fibroblasts. However, it has to be pointed that in our in vivo studies conducted with model organism, Caenorhabditis elegans indicated high anti-nematode activity of G3BC31 in comparison with CXB alone that confirms of usefulness of that organism for estimation of anti-cancer drug toxicity.

The Modulation of Phase II Drug-Metabolizing Enzymes in Proliferating and Differentiated CaCo-2 Cells by Hop-Derived Prenylflavonoids

Prenylflavonoids in the human organism exhibit various health-beneficial activities, although they may interfere with drugs via the modulation of the expression and/or activity of drug-metabolizing enzymes. As intestinal cells are exposed to the highest concentrations of prenylflavonoids, we decided to study the cytotoxicity and modulatory effects of the four main hop-derived prenylflavonoids on the activities and mRNA expression of the main drug-conjugating enzymes in human CaCo-2 cells. Proliferating CaCo-2 cells were used for these purposes as a model of colorectal cancer cells, and differentiated CaCo-2 cells were used as an enterocyte-like model. All the tested prenylflavonoids inhibited the CaCo-2 cells proliferation, with xanthohumol proving the most effective (IC₅₀ 8.5 µM). The prenylflavonoids modulated the activities and expressions of the studied enzymes to a greater extent in the differentiated, as opposed to the proliferating, CaCo-2 cells. In the differentiated cells, all the prenylflavonoids caused a marked increase in glutathione S-transferase and catechol-O-methyltransferase activities, while the activity of sulfotransferase was significantly inhibited. Moreover, the prenylflavonoids upregulated the mRNA expression of uridine diphosphate (UDP)-glucuronosyl transferase 1A6 and downregulated that of glutathione S-transferase 1A1/2.

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.

Improving Anticancer Therapy with Naringenin-Loaded Silk Fibroin Nanoparticles

Naringenin (NAR), a flavonoid present in a variety of fruits, vegetables and herbs, exhibits a wide range of pharmacological effects, including anticancer activity. Nevertheless, its application in cancer therapy is limited due to its low bioavailability at the tumour site because of its poor solubility in water and slow dissolution rate. To improve the therapeutic efficacy of NAR, emergent research is looking into using nanocarriers. Silk fibroin (SF), from the Bombyx mori silkworm, is a biocompatible and biodegradable polymer with excellent mechanical properties and an amphiphilic chemistry that make it a promising candidate as a controlled release drug system. The aim of this work is to synthesize naringenin-loaded silk fibroin nanoparticles (NAR-SFNs) by dissolving the SF in the ionic liquid 1-ethyl-3-methylimidazolium acetate, using high-power ultrasounds and rapid desolvation in methanol followed by the adsorption of NAR. The NAR-SFNs were characterized by dynamic light scattering, Fourier transform infrared spectroscopy and thermogravimetric analysis. The drug loading content and encapsulation efficiency were calculated. The drug release profile best fitted a first order equation. The cytotoxicity effects of free NAR, bare silk fibroin nanoparticles (SFNs) and NAR-SFNs were assessed on HeLa and EA.hy926 cells via 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. The results demonstrated the higher in vitro anticancer potential of synthesized NAR-SFNs than that of free NAR in HeLa cancer cells.

A Review on Sources and Pharmacological Aspects of Sakuranetin

Sakuranetin belongs to the group of methoxylated flavanones. It is widely distributed in Polyomnia fruticosa and rice, where it acts as a phytoalexin. Other natural sources of this compound are, among others, grass trees, shrubs, flowering plants, cheery, and some herbal drugs, where it has been found in the form of glycosides (mainly sakuranin). Sakuranetin has antiproliferative activity against human cell lines typical for B16BL6 melanoma, esophageal squamous cell carcinoma (ESCC) and colon cancer (Colo 320). Moreover, sakuranetin shows antiviral activity towards human rhinovirus 3 and influenza B virus and was reported to have antioxidant, antimicrobial, antiinflammatory, antiparasitic, antimutagenic, and antiallergic properties. The aim of this review is to present the current status of knowledge of pro-health properties of sakuranetin.

Naringenin potentiated β-sitosterol healing effect on the scratch wound assay

In the present investigation scratch wound assay was used to study the ability of several combinations of each flavonoid (chrysin, naringenin or resveratrol) with β-sitosterol to heal wounds in vitro. MTT test was performed to determine if the combination of flavonoid with β-sitosterol was toxic to fibroblasts or not. Also, superoxide dismutase (SOD) activity and interleukin-1β (IL-1β) concentrations were measured. The best closure rates were obtained with β-sitosterol combined with naringenin and β-sitosterol combined with resveratrol. The combination that produced the best closure rate namely β-sitosterol with naringenin increased SOD activity significantly. However, this combination was not better than naringenin or β-sitosterol alone in reducing IL-β concentration. The results of MTT test indicated that the combination as well as β-sitosterol alone or naringenin alone has no toxic effect on fibroblasts. In conclusion, the combination of β-sitosterol and naringenin exerted a synergistic effect on wound closure without decreasing the viability of fibroblasts, increased antioxidant defense mechanism and decreased IL-β.

The citrus flavonoid naringenin impairs the in vitro infection of human cells by Zika virus

The Zika virus (ZIKV) is an arthropod-borne virus that belongs to the Flaviviridae family. The ZIKV infection is usually asymptomatic or is associated with mild clinical manifestations; however, increased numbers of cases of microcephaly and birth defects have been recently reported. To date, neither a vaccine nor an antiviral treatment has become available to control ZIKV replication. Among the natural compounds recognized for their medical properties, flavonoids, which can be found in fruits and vegetables, have been found to possess biological activity against a variety of viruses. Here, we demonstrate that the citrus flavanone naringenin (NAR) prevented ZIKV infection in human A549 cells in a concentration-dependent and ZIKV-lineage independent manner. NAR antiviral activity was also observed when primary human monocyte-derived dendritic cells were infected by ZIKV. NAR displayed its antiviral activity when the cells were treated after infection, suggesting that NAR acts on the viral replication or assembly of viral particles. Moreover, a molecular docking analysis suggests a potential interaction between NAR and the protease domain of the NS2B-NS3 protein of ZIKV which could explain the anti-ZIKV activity of NAR. Finally, the results support the potential of NAR as a suitable candidate molecule for developing anti-ZIKV treatments.

Synthesis and Different Effects of Biotinylated PAMAM G3 Dendrimer Substituted with Nimesulide in Human Normal Fibroblasts and Squamous Carcinoma Cells

Squamous cell carcinoma (SCC) remains a main cause of mortality in patients with neck and head cancers, with poor prognosis and increased prevalence despite of available therapies. Recent studies have identified a role of cyclooxygenases, particularly inducible isoform cyclooxygenase-2 (COX-2) and its metabolite prostaglandin E2 (PGE₂) in cancer cell proliferation, and its inhibition become a target for control of cancer development, particularly in the view of recognized additive or synergic action of COX-2 inhibitors with other forms of therapy. Nimesulide (N), the selective COX-2 inhibitor, inhibits growth and proliferation of various types of cancer cells by COX-2 dependent and independent mechanisms. In the presented study, the conjugates of biotinylated third generation poly(amidoamine) dendrimer (PAMAM) with covalently linked 18 (G3^B18N) and 31 (G3^B31N) nimesulide residues were synthesized and characterized by NMR spectroscopy. Biological properties of conjugates were evaluated, including cytotoxicity, proliferation, and caspase 3/7 activities in relation to COX-2/PGE₂ axis signaling in human normal fibroblast (BJ) and squamous cell carcinoma (SCC-15). Both conjugates exerted a selective cytotoxicity against SCC-15 as compared with BJ cells at low 1.25-10 µM concentration range and their action in cancer cells was over 250-fold stronger than nimesulide alone. Conjugates overcome apoptosis resistance and sensitized SCC-15 cells to the apoptotic death independently of COX-2/PGE₂ axis. In normal human fibroblasts the same concentrations of G3^B31N conjugate were less effective in inhibition of proliferation and induction of apoptosis, as measured by caspase 3/7 activity in a manner depending on increase of PGE₂ production by either COX-1/COX-2.

Prospect of natural products in glioma: A novel avenue in glioma management

Glioma is one of the most perplexing cancers because of its infiltrating nature, molecular signaling, and location in central nervous system. Blood-brain barrier acts as a natural barrier to the glioma making it difficult to access by conventional chemotherapy. Clinicians are using natural compounds or their derivatives for several diseases including different cancers. However, the feasibility of using natural compounds in glioma is not explored in details. Natural compounds can act over a wide variety of signaling pathways such as survival and metabolic pathways and induce cell death. Some of the natural agents have additional benefits of crossing biological barriers such as blood-brain barrier with ease having few or no impact on the surrounding healthy cells. All of these benefits make natural compounds a prospective candidate for the glioma management. This article evaluates the benefits of using natural compounds for glioma therapy and their possible mechanism of actions. We have discussed the natural compounds assessed currently for glioma therapy and proposed a few novel natural compounds with potential antiglioma effect based on their mechanism of action.

Reversal of Multidrug Resistance in Cancer by Multi-Functional Flavonoids

Multidrug resistance (MDR) resulting from different defensive mechanisms in cancer is one of the major obstacles of clinical treatment. To circumvent MDR many reversal agents have been developed, but most of them fail in clinical trials due to severely adverse effects. Recently, certain natural products have been reported to overcome MDR, including flavonoids which are abundant in plants, foods, and herbs. The structure of flavonoids can be abbreviated as C6-C3-C6 (C for carbon), and further categorized into flavonoids, iso-flavonoids and neo-flavonoids, according to their structural backbones. Flavonoids possess multiple bioactivities, and a growing body of research has indicated that both flavonoids and iso-flavonoids can either kill or re-sensitize conventional chemotherapeutics to resistant cancer cells. Here, we summarize the research and discuss the underlying mechanisms, concluding that these flavonoids do not function as specific regulators of target proteins, but rather as multi-functional agents that negatively regulate the key factors contributing to MDR.

Antiproliferative Effects of Hop-derived Prenylflavonoids and Their Influence on the Efficacy of Oxaliplatine, 5-fluorouracil and Irinotecan in Human ColorectalC Cells

Beer, the most popular beverage containing hops, is also frequently consumed by cancer patients. Moreover, non-alcoholic beer, owing to its nutritional value and high content of biological active compounds, is sometimes recommended to patients by oncologists. However, the potential benefits and negatives have to date not been sufficiently evaluated. The present study was designed to examine the effects of four main hop-derived prenylflavonoids on the viability, reactive oxygen species (ROS) formation, activity of caspases, and efficiency of the chemotherapeutics 5-fluorouracil (5-FU), oxaliplatin (OxPt) and irinotecan (IRI) in colorectal cancer cell lines SW480, SW620 and CaCo-2. All the prenylflavonoids exerted substantial antiproliferative effects in all cell lines, with xanthohumol being the most effective (IC₅₀ ranging from 3.6 to 7.3 µM). Isoxanthohumol increased ROS formation and the activity of caspases-3/7, but 6-prenylnaringenin and 8-prenylnaringenin exerted antioxidant properties. As 6-prenylnaringenin acted synergistically with IRI, its potential in combination therapy deserves further study. However, other prenylflavonoids acted antagonistically with all chemotherapeutics at least in one cell line. Therefore, consumption of beer during chemotherapy with 5-FU, OxPt and IRI should be avoided, as the prenylflavonoids in beer could decrease the efficacy of the treatment.

Naringenin inhibited migration and invasion of glioblastoma cells through multiple mechanisms

Glioblastoma (GBM) is the most mortality brain cancer in the world. Due to high invasion and drug resistance cause the poor prognosis of GBM. Naringenin, an ingredient of citrus, exhibits many cellular functions such as antioxidant, anti-inflammation, and anticancer. Naringenin inhibits the migration of bladder and lung cancer via modulation of MMP-2 and/or MMP-9 activities, Naringenin inhibits migration and trigger apoptosis in gastric cancer cells through downregulation of AKT pathway. However, the effects of naringenin in GBM still remain to be elucidated. In this study, we reveal the molecular mechanisms of naringenin in the inhibition of migration and invasion in GBM. No overt alternation of cell proliferation was found in of GBM 8901 cells treated with different concentration of naringenin. Slight decreased cell viability was found in GBM 8401 cell treated with 200 and 300 μM naringenin. Significant reduction of migration and invasion as assayed by Boyden chamber analysis was found in of GBM cells treated with 100, 200, and 300 μM naringenin. Zymography analysis also revealed that the activities of MMP-2 and MMP-9 of GBM cells were significantly inhibited in response to 100, 200, or 300 μM naringenin treatment. Proteins of MMP-2 and MMP-9 were downregulated in naringenin treated GBM cells. In addition, naringenin also attenuated the activities of ERK and p38. Naringenin decreased mesenchymal markers (snail and slug) expression as revealed by Western blot analysis. Taken together, our findings indicated that naringenin eliminated the migration and invasion of GBM cells through multiple mechanisms including inhibition of MMPs, ERK, and p38 activities and modulation of EMT markers. Our results also suggested that naringenin may be a potential agent to prevent metastasis of GBM.

Positive allosteric modulation of native and recombinant GABAA receptors by hops prenylflavonoids

Hops are a major component of beer that is added during brewing. In addition to its wide range of bioactivity, it exhibits neuroactive properties as a sedative and sleeping aid. The compounds responsible for this activity are yet to be revealed and understood in terms of their pharmacological properties. Here we evaluated the potential of several hops flavonoids in modulating the GABAergic activity and assessed their selectivity to GABA_A receptors subtypes. GABA-potentiating effects were measured using [³H]ethynylbicycloorthobenzoate (EBOB) radioligand binding assay in native and recombinant α1β3γ2, α2β3γ2 and α6β3δ receptors expressed in HEK293 cells. Flumazenil sensitivity of GABA-potentiating effects and [³H]Ro 15-4513 binding assay were used to examine the flavonoids binding to benzodiazepine site. The prenylflavonoids xanthohumol (XN), isoxanthohumol (IXN) and 8-prenylnaringenin (8PN) potentiated GABA-induced displacement of [³H]EBOB binding in a concentration-dependent manner. The IC₅₀ for this potentiation in native GABA_A receptors were 29.7 µM, 11.6 µM, 7.3 µM, respectively. In recombinant receptors, the sensitivity to prenylflavonoid potentiation of GABA-induced displacement of [³H]EBOB binding followed the order α6β3δ > α2β3γ2 > α1β3γ2 with the strongest inhibition observed by 8PN in α6β3δ (IC₅₀ = 3.6 μM). Flumazenil had no significant effect on the prenylflavonoid-induced displacement of [³H]EBOB binding and [³H]Ro 15-4513 displacement from native GABA_A receptors was only detected at high micromolar concentrations (100 µM). We identified potent prenylflavonoids in hops that positively modulate GABA-induced responses in native and αβγ/δ recombinant GABA_A receptors at low micromolar concentrations. These GABAergic modulatory effects were not mediated via the high-affinity benzodiazepine binding site.

The Therapeutic Potential of Naringenin: A Review of Clinical Trials

Naringenin is a flavonoid belonging to flavanones subclass. It is widely distributed in several Citrus fruits, bergamot, tomatoes and other fruits, being also found in its glycosides form (mainly naringin). Several biological activities have been ascribed to this phytochemical, among them antioxidant, antitumor, antiviral, antibacterial, anti-inflammatory, antiadipogenic and cardioprotective effects. Nonetheless, most of the data reported have been obtained from in vitro or in vivo studies. Although some clinical studies have also been performed, the main focus is on naringenin bioavailability and cardioprotective action. In addition, these studies were done in compromised patients (i.e., hypercholesterolemic and overweight), with a dosage ranging between 600 and 800 μM/day, whereas the effect on healthy volunteers is still debatable. In fact, naringenin ability to improve endothelial function has been well-established. Indeed, the currently available data are very promising, but further research on pharmacokinetic and pharmacodynamic aspects is encouraged to improve both available production and delivery methods and to achieve feasible naringenin-based clinical formulations.

Highly Cancer Selective Antiproliferative Activity of Natural Prenylated Flavonoids

Xanthohumol (XN) and four minor hops prenylflavonoids: α,β-dihydroxanthohumol (2HXN), isoxanthohumol (IXN), 8-prenylnaringenin (8PN), and 6-prenylnaringenin (6PN), were tested for antiproliferative activity towards human cancer and normal cell lines. Nonprenylated naringenin (NG) was used as a model compound. Xanthohumol, α,β-dihydroxanthohumol and 6-prenylnaringenin were the most active compounds. Xanthohumol exhibited higher antiproliferative activity than cisplatin (CP) against five cancer cell lines: ovarian resistant to cisplatin A2780cis, breast MDA-MB-231 and T-47D, prostate PC-3, and colon HT-29. Isoxanthohumol was more potent than cisplatin against breast cancer cell lines MDA-MB-231 and T-47D whereas 6-prenylnaringenin was stronger than cisplatin against breast cancer cell line T-47D. It was found that tested chalcones possessed highly selective antiproliferative activity towards all tested breast cancer lines compared to the normal breast MCF 10A cell line (the calculated selectivity index ranged from 5 to 10). Low antiproliferative activity of naringenin indicates the importance of the prenyl group with respect to antiproliferative activity.

Biotinylated PAMAM G3 dendrimer conjugated with celecoxib and/or Fmoc-l-Leucine and its cytotoxicity for normal and cancer human cell lines

Tumors still remain one of the main causes of mortality due to the lack of effective anti-cancer therapy. Recently it has been shown, that overexpression of inducible cyclooxygenase-2 (COX-2) and decrease of peroxisome proliferator-activated receptor γ (PPARγ) expression accompany many malignances, therefore, it has been proposed, that COX-2 inhibitors and PPARγ agonists are potential candidates for anticancer therapy and their synergistic, antineoplastic action has been described. In the present study a COX-2 inhibitor (celecoxib) and/or PPARγ agonist (Fmoc-l-Leucine) were conjugated with the biotinylated G3 PAMAM dendrimer to form a three different constructs targeted to cells with increased biotin uptake. All conjugates were characterized by the NMR spectroscopy. Investigation of three types of human cells: normal skin fibroblasts (BJ), immortalized keratinocytes (HaCaT) and cancer lines: glioblastoma (U-118 MG) and squamous cell carcinoma (SCC-15) revealed similar biotin labeled ATTO590 accumulation (after 24 h), except for SCC-15 with significantly lower loading. Constitutive expression of COX-2 protein was confirmed in all tested cells with significantly higher levels (2-2.5 times) in both cancer lines. Comparison of cytotoxicity of the new synthetized dendrimers clearly documented the highest cytotoxicity of the G3^1B16C15L dendrimer conjugated with both drugs (1: 1) as compared with drugs alone and single conjugates. Additive effects of construct with both compounds were shown for fibroblasts and both cancer cell lines in the order BJ > U-118 MG > SCC-15 with IC₅₀ in the range: 0.69, 1.44 and 2.22 μM, respectively and lowest cytotoxicity in HaCaT cells (IC₅₀ = 2.88). Our results showed, that biotinylated G3 PAMAM dendrimers substituted with COX-2 inhibitor, celecoxib, and PPARγ agonist, Fmoc-l-Leucine (1:1) may be a good candidate for local therapy of glioblastoma but not a skin cancer. Since the effect of PPARγ agonists on COX-2 expression vary depending upon the cell type, specificity of used agonist and the presence of other environmental factors, it is necessary to carefully evaluate the response of chosen drugs on the target cells.

Therapeutic Perspectives of 8-Prenylnaringenin, a Potent Phytoestrogen from Hops

Hop (Humulus lupulus L.), as a key ingredient for beer brewing, is also a source of many biologically active molecules. A notable compound, 8-prenylnaringenin (8-PN), structurally belonging to the group of prenylated flavonoids, was shown to be a potent phytoestrogen, and thus, became the topic of active research. Here, we overview the pharmacological properties of 8-PN and its therapeutic opportunities. Due to its estrogenic effects, administration of 8-PN represents a novel therapeutic approach to the treatment of menopausal and post-menopausal symptoms that occur as a consequence of a progressive decline in hormone levels in women. Application of 8-PN in the treatment of menopause has been clinically examined with promising results. Other activities that have already been assessed include the potential to prevent bone-resorption or inhibition of tumor growth. On the other hand, the use of phytoestrogens is frequently questioned regarding possible adverse effects associated with long-term consumption. In conclusion, we emphasize the implications of using 8-PN in future treatments of menopausal and post-menopausal symptoms, including the need for precise evidence and further investigations to define the safety risks related to its therapeutic use.

Inhibitory effect of naringenin via IL-13 level regulation on thymic stromal lymphopoietin-induced inflammatory reactions

Naringenin (NG) has various beneficial properties, such as anti-cancer and anti-inflammatory effects. Thymic stromal lymphopoietin (TSLP) induces mast cell proliferation and inflammatory reactions. The aim of this study was to investigate the regulatory effect of NG on TSLP-induced mast cell proliferation and inflammatory reactions using human mast cell line (HMC-1) cells. HMC-1 cells were pre-treated with NG and then treated with TSLP. HMC-1 cells proliferation was determined by quantifying bromodeoxyuridine incorporation. Levels of anti-apoptotic and pro-apoptotic factors were analyzed by western blot analysis. The productions and mRNA expressions of interleukin (IL)-13 and tumour necrosis factor-α (TNF-α) were analyzed by ELISA and quantitative real-time PCR. We found that NG significantly attenuated HMC-1 cells proliferation and Ki-67 mRNA expression promoted by TSLP. NG significantly suppressed mRNA expression of TSLP receptor and IL-7 receptor α in TSLP-treated HMC-1 cells. NG significantly down-regulated levels of phosphorylated-signal transducer and activation of transcription 6 and murine double-minute 2 in TSLP-treated HMC-1 cells, up-regulated levels of cleaved poly ADP-ribose polymerase and p53 in TSLP-treated HMC-1 cells. Furthermore, NG significantly decreased the productions and mRNA expressions of IL-13 and TNF-α in TSLP-treated HMC-1 cells. These results suggest NG has an inhibitory effect on mast cell-mediated allergic inflammatory reactions.