Exploring the Role of Apigenin in Neuroinflammation: Insights and Implications.

Neuroinflammation, a hallmark of various central nervous system disorders, is often associated with oxidative stress and neuronal or oligodendrocyte cell death. It is therefore very interesting to target neuroinflammation pharmacologically. One therapeutic option is the use of nutraceuticals, particularly apigenin. Apigenin is present in plants: vegetables (parsley, celery, onions), fruits (oranges), herbs (chamomile, thyme, oregano, basil), and some beverages (tea, beer, and wine). This review explores the potential of apigenin as an anti-inflammatory agent across diverse neurological conditions (multiple sclerosis, Parkinson's disease, Alzheimer's disease), cancer, cardiovascular diseases, cognitive and memory disorders, and toxicity related to trace metals and other chemicals. Drawing upon major studies, we summarize apigenin's multifaceted effects and underlying mechanisms in neuroinflammation. Our review underscores apigenin's therapeutic promise and calls for further investigation into its clinical applications.

Antiplatelet Effects of Flavonoid Aglycones Are Mediated by Activation of Cyclic Nucleotide-Dependent Protein Kinases.

Flavonoid aglycones are secondary plant metabolites that exhibit a broad spectrum of pharmacological activities, including anti-inflammatory, antioxidant, anticancer, and antiplatelet effects. However, the precise molecular mechanisms underlying their inhibitory effect on platelet activation remain poorly understood. In this study, we applied flow cytometry to analyze the effects of six flavonoid aglycones (luteolin, myricetin, quercetin, eriodictyol, kaempferol, and apigenin) on platelet activation, phosphatidylserine externalization, formation of reactive oxygen species, and intracellular esterase activity. We found that these compounds significantly inhibit thrombin-induced platelet activation and decrease formation of reactive oxygen species in activated platelets. The tested aglycones did not affect platelet viability, apoptosis induction, or procoagulant platelet formation. Notably, luteolin, myricetin, quercetin, and apigenin increased thrombin-induced thromboxane synthase activity, which was analyzed by a spectrofluorimetric method. Our results obtained from Western blot analysis and liquid chromatography-tandem mass spectrometry demonstrated that the antiplatelet properties of the studied phytochemicals are mediated by activation of cyclic nucleotide-dependent signaling pathways. Specifically, we established by using Förster resonance energy transfer that the molecular mechanisms are, at least partly, associated with the inhibition of phosphodiesterases 2 and/or 5. These findings underscore the therapeutic potential of flavonoid aglycones for clinical application as antiplatelet agents.

Apigenin and Rutaecarpine reduce the burden of cellular senescence in bone marrow stromal stem cells.

Introduction: Osteoporosis is a systemic age-related disease characterized by reduced bone mass and microstructure deterioration, leading to increased risk of bone fragility fractures. Osteoporosis is a worldwide major health care problem and there is a need for preventive approaches. Methods and results: Apigenin and Rutaecarpine are plant-derived antioxidants identified through functional screen of a natural product library (143 compounds) as enhancers of osteoblastic differentiation of human bone marrow stromal stem cells (hBMSCs). Global gene expression profiling and Western blot analysis revealed activation of several intra-cellular signaling pathways including focal adhesion kinase (FAK) and TGFß. Pharmacological inhibition of FAK using PF-573228 (5 µM) and TGFß using SB505124 (1µM), diminished Apigenin- and Rutaecarpine-induced osteoblast differentiation. In vitro treatment with Apigenin and Rutaecarpine, of primary hBMSCs obtained from elderly female patients enhanced osteoblast differentiation compared with primary hBMSCs obtained from young female donors. Ex-vivo treatment with Apigenin and Rutaecarpine of organotypic embryonic chick-femur culture significantly increased bone volume and cortical thickness compared to control as estimated by µCT-scanning. Discussion: Our data revealed that Apigenin and Rutaecarpine enhance osteoblastic differentiation, bone formation, and reduce the age-related effects of hBMSCs. Therefore, Apigenin and Rutaecarpine cellular treatment represent a potential strategy for maintaining hBMSCs health during aging and osteoporosis.

Apigenin and its combination with Vorinostat induces apoptotic-mediated cell death in TNBC by modulating the epigenetic and apoptotic regulators and related miRNAs.

Triple-negative breast cancer (TNBC) is a metastatic disease and a formidable treatment challenge as it does not respond to existing therapies. Epigenetic regulators play a crucial role in the progression and metastasis by modulating the expression of anti-apoptotic, pro-apoptotic markers and related miRNAs in TNBC cells. We have investigated the anti-TNBC potential of dietary flavonoid 'Apigenin' and its combination with Vorinostat on MDA-MB-231 cells. At Apigenin generated ROS, inhibited cell migration, arrested the cell cycle at subG0/G1 phases, and induced apoptotic-mediated cell death. Apigenin reduced the expression of the class-I HDACs at the transcriptomic and proteomic levels. In the immunoblotting study, Apigenin has upregulated pro-apoptotic markers and downregulated anti-apoptotic proteins. Apigenin inhibited the enzymatic activity of HDAC/DNMT and increased HAT activity. Apigenin has manifested its effect on miRNA expression by upregulating the tumor-suppressor miR-200b and downregulation oncomiR-21. Combination study reduced the growth of TNBC cells synergistically by modulating the expression of epigenetic and apoptotic regulators. Molecular docking and MD simulations explored the mechanism of catalytic inhibition of HDAC1 and HDAC3 and supported the in-vitro studies. The overall studies demonstrated an anti-TNBC potential of Apigenin and may help to design an effective strategy to treat metastatic phenotype of TNBC.

Scutellarin activates IDH1 to exert antitumor effects in hepatocellular carcinoma progression.

Isochlorate dehydrogenase 1 (IDH1) is an important metabolic enzyme for the production of α-ketoglutarate (α-KG), which has antitumor effects and is considered to have potential antitumor effects. The activation of IDH1 as a pathway for the development of anticancer drugs has not been attempted. We demonstrated that IDH1 can limit glycolysis in hepatocellular carcinoma (HCC) cells to activate the tumor immune microenvironment. In addition, through proteomic microarray analysis, we identified a natural small molecule, scutellarin (Scu), which activates IDH1 and inhibits the growth of HCC cells. By selectively modifying Cys297, Scu promotes IDH1 active dimer formation and increases α-KG production, leading to ubiquitination and degradation of HIF1a. The loss of HIF1a further leads to the inhibition of glycolysis in HCC cells. The activation of IDH1 by Scu can significantly increase the level of α-KG in tumor tissue, downregulate the HIF1a signaling pathway, and activate the tumor immune microenvironment in vivo. This study demonstrated the inhibitory effect of IDH1-α-KG-HIF1a on the growth of HCC cells and evaluated the inhibitory effect of Scu, the first IDH1 small molecule agonist, which provides a reference for cancer immunotherapy involving activated IDH1.

In vitro biological evaluation and in silico insights into the antiviral activity of standardized olive leaves extract against SARS-CoV-2.

There is still a great global need for efficient treatments for the management of SARS-CoV-2 illness notwithstanding the availability and efficacy of COVID-19 vaccinations. Olive leaf is an herbal remedy with a potential antiviral activity that could improve the recovery of COVID-19 patients. In this work, the olive leaves major metabolites were screened in silico for their activity against SARS-CoV-2 by molecular docking on several viral targets such as methyl transferase, helicase, Plpro, Mpro, and RdRp. The results of in silico docking study showed that olive leaves phytoconstituents exhibited strong potential antiviral activity against SARS-CoV-2 selected targets. Verbacoside demonstrated a strong inhibition against methyl transferase, helicase, Plpro, Mpro, and RdRp (docking scores = -17.2, -20, -18.2, -19.8, and -21.7 kcal/mol.) respectively. Oleuropein inhibited 5rmm, Mpro, and RdRp (docking scores = -15, -16.6 and -18.6 kcal/mol., respectively) respectively. Apigenin-7-O-glucoside exhibited activity against methyl transferase and RdRp (docking score = -16.1 and -19.4 kcal/mol., respectively) while Luteolin-7-O-glucoside inhibited Plpro and RdRp (docking score = -15.2 and -20 kcal/mol., respectively). The in vitro antiviral assay was carried out on standardized olive leaf extract (SOLE) containing 20% oleuropein and IC50 was calculated. The results revealed that 20% SOLE demonstrated a moderate antiviral activity against SARS-CoV-2 with IC50 of 118.3 µg /mL. Accordingly, olive leaf could be a potential herbal therapy against SARS-CoV-2 but more in vivo and clinical investigations are recommended.

Apigenin Suppresses Innate Immune Responses and Ameliorates Lipopolysaccharide-Induced Inflammation via Inhibition of STING/IRF3 Pathway.

The stimulator of interferon genes (STING) signaling pathway is crucial for the pathogenesis of autoimmune and inflammatory disorders, including acute lung injury (ALI). Apigenin (4[Formula: see text],5,7-trihydroxyflavone) is a natural flavonoid widely found in fruits, vegetables, and Chinese medicinal herbs that exhibits a range of pharmacological effects, such as antibacterial and anti-inflammatory activities. However, the efficacy of apigenin in STING pathway-mediated diseases remains unclear. Accordingly, this study screened Chinese medicines to identify potent agents that reduced the synthesis of type I interferons (IFNs). The results revealed apigenin as a potent compound with low cytotoxicity that markedly reduced the synthesis of type I IFNs in response to STING pathway agonists. Besides, apigenin markedly suppressed innate immune responses triggered by the STING agonist SR-717. Mechanistically, apigenin downregulated IFN beta 1 (IFNB1) expression mediated by the STING pathway via dose-dependent inhibition of STING expression, reduction of dimerization, nuclear translocation of phosphorylated IRF3, and disruption of the association between STING and IRF3. Moreover, apigenin effectively mitigated pathological pulmonary inflammation and lung edema in lipopolysaccharide (LPS)-induced ALI in mice. Apigenin further strongly attenuated the hallmarks of immoderate inflammation (interleukin (IL)-6, IL-1[Formula: see text], and tumor necrosis factor [Formula: see text]) and innate immune responses (IFNB1, C-X-C motif chemokine ligand 10, and IFN-stimulated gene 15) by preventing the activation of the STING/IRF3 pathway both in vitro and in vivo. Importantly, SR-717 significantly reversed the inhibitory effects of apigenin in LPS-induced THP1-BlueTM ISG macrophages. Collectively, apigenin effectively alleviated innate immune responses and mitigated inflammation in LPS-induced ALI via inhibition of the STING/IRF3 pathway. These findings suggest the potential of apigenin as a prophylactic and therapeutic candidate for managing STING-mediated diseases.

Food therapy of scutellarein ameliorates pirarubicin­induced cardiotoxicity in rats by inhibiting apoptosis and ferroptosis through regulation of NOX2­induced oxidative stress.

Pirarubicin (THP) is one of the most commonly used antineoplastic drugs in clinical practice. However, its clinical application is limited due to its toxic and heart­related side effects. It has been reported that oxidative stress, inflammation and apoptosis are closely associated with cardiotoxicity caused by pirarubicin (CTP). Additionally, it has also been reported that scutellarein (Sc) exerts anti­inflammatory, antioxidant, cardio­cerebral vascular protective and anti­apoptotic properties. Therefore, the present study aimed to investigate the effect of food therapy with Sc on CTP and its underlying molecular mechanism using echocardiography, immunofluorescence, western blot, ROS staining, and TUNEL staining. The in vivo results demonstrated that THP was associated with cardiotoxicity. Additionally, abnormal changes in the expression of indicators associated with oxidative stress, ferroptosis and apoptosis were observed, which were restored by Sc. Therefore, it was hypothesized that CTP could be associated with oxidative stress, ferroptosis and apoptosis. Furthermore, the in vitro experiments showed that Sc and the NADPH oxidase 2 (NOX2) inhibitor, GSK2795039 (GSK), upregulated glutathione peroxidase 4 (GPX4) and inhibited THP­induced oxidative stress, apoptosis and ferroptosis. However, cell treatment with the ferroptosis inhibitor, ferrostatin­1, or inducer, erastin, could not significantly reduce or promote, respectively, the expression of NOX2. However, GSK significantly affected ferroptosis and GPX4 expression. Overall, the results of the present study indicated that food therapy with Sc ameliorated CTP via inhibition of apoptosis and ferroptosis through regulation of NOX2­induced oxidative stress, thus suggesting that Sc may be a potential therapeutic drug against CTP.

Scutellarin, a flavonoid compound from Scutellaria barbata, suppresses growth of breast cancer stem cells in vitro and in tumor-bearing mice.

BACKGROUND: Scutellaria barbata D. Don (SB), commonly known as Ban Zhi Lian and firstly documented by Shigong Chen, is a dried whole plant that has been studied for its therapeutic effects on breast cancer, colon cancer, and prostate cancer. Among its various compounds, scutellarin (SCU) has been demonstrated with anti-tumor effects. PURPOSE: This study aimed to evaluate the effects of SB water extract (SBW) and scutellarin on breast cancer stem cells (BCSCs), and to investigate their potential therapeutic effects on breast tumors in mice. METHODS: BCSCs were enriched from human breast cancer cells (MDA-MB-231 and MDA-MB-361) and their characteristics were analyzed. The effects of varying concentrations of SBW and scutellarin on cell viability, proliferation, self-renewal, and migration abilities were studied, along with the underlying mechanisms. The in vivo anti-tumor effects of scutellarin were further evaluated in SCID/NOD mice. Firstly, mice were inoculated with naïve BCSCs and subjected to treatment with scutellarin or vehicle. Secondly, BCSCs were pre-treated with scutellarin or vehicle prior to inoculation into mice. RESULTS: The derived BCSCs expressed CD44, CD133 and ALDH1, but not CD24, indicating that BCSCs have been successfully induced from both MDA-MB-231 and MDA-MB-361 cells. Both SBW and scutellarin reduced the viability, proliferation, sphere and colony formation, and migration of BCSCs. In mice with tumors derived from naïve BCSCs, scutellarin significantly reduced tumor growth, expression of proliferative (Ki67) and stem cell markers (CD44), and lung metastasis. In addition, pre-treatment with scutellarin also slowed tumor growth. Western blot results suggested the involvement of Wnt/ß-catenin, NF-κB, and PTEN/Akt/mTOR signaling pathways underlying the inhibitory effects of scutellarin. CONCLUSION: Our study demonstrated for the first time that both SB water extract and scutellarin could reduce the proliferation and migration of BCSCs in vitro. Scutellarin was shown to possess novel inhibitory activities in BCSCs progression. These findings suggest that Scutellaria barbata water extract, in particular, scutellarin, may have potential to be further developed as an adjuvant therapy for reducing breast cancer recurrence.

Apigenin delays postovulatory oocyte aging by reducing oxidative stress through SIRT1 upregulation.

After ovulation, senescent oocytes inevitably experience reduced quality and defects in embryonic development. Apigenin (API) is a flavonoid with a wide range of pharmacological effects. Therefore, this study examined the protective effects of API on the quality of porcine oocytes during in-vitro ageing and the underlying mechanisms. The results showed that API treatment could reduce the activation rate after aging for 48 h. In addition, API significantly reduced reactive oxygen species, abnormal distribution of mitochondria, early apoptosis in ageing oocytes, increased glutathione, and mitochondrial adenosine triphosphate levels in ageing oocytes. Importantly, API increased the embryonic development rate in aged oocytes. We also examined molecular changes, finding decreased sirtuin 1 expression in in-vitro postovulatory oocytes, but API reversed this effect. Our results suggest that API attenuates the deterioration of oocyte quality during in-vitro ageing, possibly by reducing oxidative stress through the upregulation of sirtuin 1.

Rational design of mitochondria-targeted fluorescent biosensors for in vivo elucidation of the interaction between breast cancer metastasis and mitochondrial autophagy.

Breast cancer lung metastases (BCLM) are a major cause of high mortality in patients. The shortage of therapeutic targets and rapid drug screening tools for BCLM is a major challenge at present. Mitochondrial autophagy, which involves the degradation of proteins associated with cancer cell aggressiveness, represents a possible therapeutic approach for the treatment of BCLM. Herein, four fluorescent biosensors with different alkyl chains were designed and synthesized to monitor mitochondrial autophagy. Among them, PMV-12 demonstrated the highest sensitivity to viscosity variance, the least impact on polarity, and the longest imaging time. The introduction of the C12-chain made PMV-12 anchored in the mitochondrial membrane without being disturbed by changes of the mitochondrial membrane potential (MMP), thereby achieving the long-term monitor in situ for mitochondrial autophagy. Mitochondria stained with PMV-12 induced swelling and viscosity increase after treating with apigenin, which indicated that apigenin is a potential mitochondrial autophagy inducer. Apigenin was subsequently verified to inhibit cancer cell invasion by 92%. Furthermore, PMV-12 could monitor the process of BCLM in vivo and evaluate the therapeutic effects of apigenin. This work provides a fluorescent tool for elucidating the role of mitochondrial autophagy in the BCLM process and for anti-metastatic drug development.

Effects of apigenin on gastric cancer cells.

Gastric Cancer (GC) is one of the most prevalent cancers worldwide. As the currently available therapeutic options are invasive, new and more benign options are being explored. One of which is Apigenin (Api), a natural flavonoid found in fruits and vegetables, such as celery, parsley, garlic, bell pepper and chamomile tea. Api has known anti-inflammatory, -oxidant, and -proliferative proprieties in several diseases and its potential as an anticancer compound has been explored. Here we systematize the available data regarding the effects of Api on GC cells, in terms of cell proliferation, apoptosis, Helicobacter pylori (H. pylori) infection, and molecular targets. From the literature it is possible to conclude that Api inhibits cell growth in a dose- and time-dependent manner, which is accompanied by the reduction of clone formation and induction of apoptosis. This occurs through the Akt/Bad/Bcl2/Bax axis that activates the mitochondrial pathway of apoptosis, resulting in restriction of cell proliferation. Additionally, it seems that the anti-proliferative potential of Api on GC cells is particularly relevant in a more aggressive GC phenotype but can also affect normal gastric cells. This indicate that this flavonoid must be used in low-to-moderate doses to avoid side-effects induced by disturbance of the normal epithelium. In H. Pylori-infected cells, the literature demonstrates that Api reduces inflammation by diminishing the levels of H. pylori colonization, by preventing NF-kB activation and by diminishing the production of reactive oxygen specimens (ROS). Accordingly, in GC Api seems to regulate different hallmarks of cancer, such as cell proliferation, apoptosis, cell migration, inflammation and oxidative stress, demonstrating its potential has an anti-GC compound.

Novel Prognostic Model Construction of Tongue Squamous Cell Carcinoma Based on Apigenin-Associated Genes.

BACKGROUND: Clinical indexes are often selected as relevant factors for constructing prognostic models of tongue squamous cell carcinoma (TSCC) patients, while factors related to therapeutic targets are less frequently included. As Apigenin (API) shows anti-tumor properties in many tumors, in this study, we construct a novel prognostic model for TSCC patients based on Apigenin-associated genes through transcriptomic analysis. METHODS: The effect of Apigenin (API) on the cell characteristics of TSCC cells was measured by several phenotype experiments. RNA-seq was executed to ensure differentially expressed genes (DEGs) in squamous cell carcinoma-9 (SCC-9) cells after API treatment. Furthermore, reverse transcription quantitative polymerase chain reaction (RT-qPCR) and immunohistochemistry were performed to verify the expression of API-related genes. Then, combined with the gene expression data and relevant individual information of TSCC samples acquired from The Cancer Genome Atlas (TCGA), an API-related model was built through Lasso regression and multivariate Cox regression. A receiver operating characteristic (ROC) curve and a nomogram and calibration curve were created to forecast patient outcomes to improve the clinical suitability of the API-related signature. The relationships between the two risk groups and function enrichment, immune infiltration characteristics, and drug susceptibility were analyzed. RESULTS: We demonstrated that API could inhibit the malignant behavior of TSCC cells. Among API-related genes, TSCC cells treated with API, compared to the control group, have higher levels of transmembrane protein 213 (TMEM213) and G protein-coupled receptor 158 (GPR158), and lower levels of caspase 14 (CASP14) and integrin subunit alpha 5 (ITGA5). An 7 API-associated gene model was built through Lasso regression and multivariate Cox regression that could direct TSCC prognostic status and tumor immune cell infiltration. In addition, we acquired 6 potential therapeutic agents for TSCC based on the prognostic model. CONCLUSIONS: Our research suggested the inhibition effect of API on TSCC cells and provided a novel prognostic model combined with therapeutic factors that can guide the prognosis of TSCC and clinical decision-making in TSCC.

Evaluation of the anti-inflammatory activity of Acacia polyphylla and identification of a new apigenin-3-C- glycosylated type flavonoid.

Owing to the potentially harmful adverse effects of current anti-inflammatory drugs, there is a need to identify new alternative substances. Thus, this study aimed to perform a phytochemical analysis of A. polyphylla to identify compounds responsible for its anti-inflammatory activity. Several fractions of the A. polyphylla extract were obtained and evaluated in an ex vivo anti-inflammatory assay using fresh human blood. Among the evaluated fractions, the BH fraction displayed the highest percentage of PGE2 inhibition (74.8%) compared to the reference drugs dexamethasone and indomethacin, demonstrating its excellent potential for anti-inflammatory activity. Astragalin (P1), a known 3-O-glucoside of kaempferol, was isolated from the A. polyphylla extract for the first time. In addition, a new compound (P2) was isolated and identified as the apigenin-3-C-glycosylated flavonoid. Astragalin showed moderate PGE2 activity (48.3%), whereas P2 was not anti-inflammatory. This study contributes to the phytochemical studies of A. polyphylla and confirms its anti-inflammatory potential.

Polyphenol-enriched Penthorum chinense Pursh ameliorates alcohol-related liver injury through Ras/Raf/MEK/ERK pathway: Integrating network pharmacology and experiment validation.

ETHNOPHARMACOLOGICAL RELEVANCE: Penthorum chinense Pursh (PCP) has acknowledged as an edible herbal medicinal plant for the prevention and treatment of alcoholic liver injury (ALI). However, only few of researches focus on the chemical material basis and potential mechanisms of PCP against ALI. AIM OF THE STUDY: Herein, we explored the therapeutic effects of PCP extract against ALI based on the integration of network pharmacology, molecular docking, and experiment validation. METHODS: Based on the standard quality control of PCP herbs by UPLC fingerprint and quantitative determination, 80% ethanol extract fraction of PCP containing more polyphenols, compared to aqueous extract fraction of PCP, were chosen for further experiments. After oral administration of PCP ethanol extract, serum pharmacochemistry based on UPLC-Q-Exactive-MS analysis was implemented to evaluate the potential effective compounds. These absorbed prototypes in PCP were used to construct network pharmacology and predict the potential mechanisms of PCP extract against ALI. Then, the predicted targets and biological mechanisms of PCP extract were validated using animal experiments and molecular docking analysis. RESULTS: Although totally 19 polyphenol compounds were identified in PCP ethanol extract by UPLC-MS analysis, only 18 absorbed prototypes were found in the serum collected from mice at 1 h post-administration with PCP extract. These candidate active compounds were further screened into 13 compounds to construct network pharmacology and 433 targets were identified as PCP targets. GO and KEGG pathway enrichment analyses indicated that the effects of PCP extract would involve in Ras signaling pathway. The animal experiments on chronic ALI model mice shown that the oral administration of PCP can alleviate ALI by attenuating hepatic oxidative stress, inflammation and down-regulating the target proteins in Ras/Raf/MEK/ERK pathway. Molecular docking analysis revealed the good binding ability between the three polyphenols (i.e. quercetin, apigenin, thonningianin B) in PCP with the top contribution in network pharmacology, and these target proteins (Ras, Raf, MEK1/2, and ERK1/2). CONCLUSION: Our results clarified that PCP ethanol extract could effectively alleviate ALI by down-regulating Ras/Raf/MEK/ERK signaling pathway promisingly. Quercetin, apigenin, and thonningianin B may be the active compounds of PCP, attributing to the intervention benefits of PCP against ALI.

The strong anti-hyaluronidase effect of ellagic acid markedly decreases polyspermy during in vitro fertilization, resulting in sustainment of the developmental potency in porcine oocytes.

The present study investigated the effects of ellagic acid, a type of polyphenol that does not have a glycan and is composed of four hydroxyl groups and two lactone functional groups, on porcine in vitro fertilization (IVF) by focusing on its anti-hyaluronidase activity. A comparative analysis of ellagic acid and apigenin, which is commonly used as a hyaluronidase inhibitor, was performed. It compared the effects of ellagic acid and apigenin on hyaluronidase activity at different concentrations. The results showed that 10, 20, and 40 µM ellagic acid strongly reduced hyaluronidase activity (P < 0.05). The addition of 20 µM ellagic acid, but not apigenin, to porcine IVF medium effectively reduced polyspermy without decreasing sperm penetration or the formation rates of male pronuclei in cumulus-free oocytes. However, neither ellagic acid nor apigenin affected the number of sperm that bound to zona pellucida (ZP) or the induction of zona hardening and protease resistance. The percentage of acrosome-reacting sperm that bound to the ZP was markedly lower in the presence of 20 µM ellagic acid than in the untreated and apigenin-treated groups, even though the antioxidant capacity of ellagic acid was weaker than that of apigenin. Furthermore, a markedly higher percentage of embryos developed to the blastocyst stage in the ellagic acid-treated group, and the apoptotic indexes of expanded blastocysts produced by the ellagic acid treatment during IVF were significantly low. Therefore, the anti-hyaluronidase effect of ellagic acid markedly suppressed the induction of the acrosome reaction in sperm that bound to the ZP, resulting in a marked decrease in polyspermy under conditions that maintained high sperm penetrability during IVF and sustainment of the developmental potency in porcine oocytes.

Roles of Apigenin and Nepetin in the Assembly Behavior and Cytotoxicity of Prion Neuropeptide PrP106-126.

Development of potential inhibitors to prevent prion protein (PrP) fibrillation is a therapeutic strategy for prion diseases. The prion neuropeptide PrP106-126, a research model of abnormal PrP (PrPSc), presents similar physicochemical and biochemical characters to PrPSc, which is also a target of potential inhibitors against prion deposition. Many flavones have antioxidant, anti-inflammatory, and antibacterial properties, and they are applied in treating prion disorder and other amyloidosis as well. However, the inhibition mechanism of flavones on PrP106-126 fibrillation is still unclear. In the current work, apigenin and nepetin were used to suppress the aggregation of PrP106-126 and to alleviate the peptide-induced cytotoxicity. The results showed that apigenin and nepetin impeded the fibril formation of PrP106-126 and depolymerized the preformed fibrils. They were bound to PrP106-126 predominantly by hydrophobic and hydrogen bonding interactions. In addition, both flavones upregulated cell viability and decreased membrane leakage through reducing peptide oligomerization. The differences in inhibition and cell protection between the two small molecules were presumably attributed to the substitution of hydroxyl and methoxy groups in nepetin, which demonstrated the significant structure-function relationship of flavones with prion neuropeptide and the prospect of flavonoids as drug candidates against prion diseases.

Transcriptome reprogramming through alternative splicing triggered by apigenin drives cell death in triple-negative breast cancer.

Triple-negative breast cancer (TNBC) is characterized by its aggressiveness and resistance to cancer-specific transcriptome alterations. Alternative splicing (AS) is a major contributor to the diversification of cancer-specific transcriptomes. The TNBC transcriptome landscape is characterized by aberrantly spliced isoforms that promote tumor growth and resistance, underscoring the need to identify approaches that reprogram AS circuitry towards transcriptomes, favoring a delay in tumorigenesis or responsiveness to therapy. We have previously shown that flavonoid apigenin is associated with splicing factors, including heterogeneous nuclear ribonucleoprotein A2 (hnRNPA2). Here, we showed that apigenin reprograms TNBC-associated AS transcriptome-wide. The AS events affected by apigenin were statistically enriched in hnRNPA2 substrates. Comparative transcriptomic analyses of human TNBC tumors and non-tumor tissues showed that apigenin can switch cancer-associated alternative spliced isoforms (ASI) to those found in non-tumor tissues. Apigenin preferentially affects the splicing of anti-apoptotic and proliferation factors, which are uniquely observed in cancer cells, but not in non-tumor cells. Apigenin switches cancer-associated aberrant ASI in vivo in TNBC xenograft mice by diminishing proliferation and increasing pro-apoptotic ASI. In accordance with these findings, apigenin increased apoptosis and reduced tumor proliferation, thereby halting TNBC growth in vivo. Our results revealed that apigenin reprograms transcriptome-wide TNBC-specific AS, thereby inducing apoptosis and hindering tumor growth. These findings underscore the impactful effects of nutraceuticals in altering cancer transcriptomes, offering new options to influence outcomes in TNBC treatments.

HA-Coated PLGA Nanoparticles Loaded with Apigenin for Colon Cancer with High Expression of CD44.

Apigenin (API) possesses excellent antitumor properties but its limited water solubility and low bioavailability restrict its therapeutic impact. Thus, a suitable delivery system is needed to overcome these limitations and improve the therapeutic efficiency. Poly (lactic-co-glycolic acid) (PLGA) is a copolymer extensively utilized in drug delivery. Hyaluronic acid (HA) is a major extracellular matrix component and can specifically bind to CD44 on colon cancer cells. Herein, we aimed to prepare receptor-selective HA-coated PLGA nanoparticles (HA-PLGA-API-NPs) for colon cancers with high expression of CD44; chitosan (CS) was introduced into the system as an intermediate, simultaneously binding HA and PLGA through electrostatic interaction to facilitate a tighter connection between them. API was encapsulated in PLGA to obtain PLGA-API-NPs, which were then sequentially coated with CS and HA to form HA-PLGA-API-NPs. HA-PLGA-API-NPs had a stronger sustained-release capability. The cellular uptake of HA-PLGA-API-NPs was enhanced in HT-29 cells with high expression of CD44. In vivo, HA-PLGA-API-NPs showed enhanced targeting specificity towards the HT-29 ectopic tumor model in nude mice in comparison with PLGA-API-NPs. Overall, HA-PLGA-API-NPs were an effective drug delivery platform for API in the treatment of colon cancers with high expression of CD44.

The flavonoids fisetin, apigenin, kaempferol, naringenin, naringin regulate respiratory activity and membrane potential of rat liver mitochondria and inhibit oxidative processes in erythrocytes.

Flavonoids, secondary plant metabolites, represent the most abundant heterogeneous group of phytochemicals. The aim of this study to compare antioxidant activity and regulatory properties of several representatives of different classes of flavonoids, fisetin, apigenin, kaempferol, naringenin, naringin, using liver mitochondria and erythrocytes as research objects. In the concentration range of 2.5-25 µM fisetin, apigenin, kaempferol, naringenin, and naringin dose-dependently prevented oxidative damage of erythrocytes induced by 700 µM tert-butyl hydroperoxide: accumulation of lipid peroxidation (LPO) products and oxidation of glutathione GSH. The IC50 values corresponding to the flavonoid concentration inhibiting the LPO process in erythrocyte membranes by 50%, were 3.9±0.8 µM in the case of fisetin, 6.5±1.6 µM in the case of kaempferol, 8.1±2.1 µM in the case of apigenin, 37.8±4.4 µM in the case of naringenin, and 64.7±8.6 µM in the case of naringin. The antioxidant effect of flavonoids was significantly higher in the membrane structures compared to the cytoplasm of cells. All flavonoids studied (10-50 µM) effectively inhibited the respiratory activity of isolated rat liver mitochondria and, with the exception of kaempferol, stimulated Ca²âº-induced dissipation of the mitochondrial membrane potential. Cyclosporine A and ruthenium red inhibited flavonoid-stimulated Ca²âº-dependent membrane depolarization, thus indicating that the mitochondrial calcium uniporter and the mitochondrial permeability transition pore opening were involved in the flavonoid effects. Flavonoids, as the redox-active compounds with antioxidant properties, are able to regulate mitochondrial potential and respiratory activity, and prevent mitochondrial oxidative stress. They can be considered as effective pharmacological agents or nutraceuticals.