Apigenin: a promising molecule for cancer prevention

Pouteria ramiflora (Mart.) Radlk. extract: Flavonoids quantification and chemopreventive effect on HepG2 cells

Pouteria ramiflora (Mart.) Radlk., popularly known as curriola, is commonly used in Brazil as medicinal plant to treat worm infections, dysentery, pain, inflammation, hyperlipidemia, and obesity. At present the safety of this extract when used therapeutically in human remains to be determined. Thus, the aim of this study was to examine cytotoxicity, antiproliferative, and antimutagenic actions of this extract. The hydroalcoholic extract from P. ramiflora leaves consisted of flavonoids identified and quantified as myricetin-3-O-β-D-galactopyranoside (13.55 mg/g) and myricetin-3-O-α-L-rhamnopyranoside (9.61 mg/g). The extract exhibited cytotoxicity at concentrations higher than 1.5 µg/ml in human hepatocarcinoma (HepG2)and 2.5 µg/ml in non-tumoral primary gastric (GAS) cells using the MTT assay, and at concentrations higher than 3 µg/ml in HepG2 and 3.5 µg/ml in GAS cells by the neutral red assay. The extract did not show antiproliferative effect as evidenced by the nuclear division index (NDI). However, in the presence of benzo[a]pyrene (BaP) (positive control), an enhanced cytostatic effect in the NDI and flow cytometry was noted. It is of interest that when the extract was co-incubated with BaP a significant decrease in DNA damage was observed indicating an antimutagenic action. This protective effect might be attributed to myricetin and gallic acid found in P. ramiflora extract. The low cytotoxicity action and protective effect observed in the present study encourage further studies regarding other biological effects of P. ramiflora, as well as its potential use as a chemopreventive agent.

Antioxidative and Protective Actions of Apigenin in a Paracetamol-Induced Hepatotoxicity Rat Model

BACKGROUND AND OBJECTIVES

Apigenin is known to have various pharmacological properties without causing significant toxicity; however, hepatoprotective effect of apigenin is not often reported. The aim of our study was to investigate if the alterations in lipid peroxidation and antioxidant status are in favor to prove the efficacy of apigenin against paracetamol-induced hepatotoxicity.

METHODS

The effect of apigenin on paracetamol-induced hepatotoxicity in rats was examined by determining biochemical parameters, histological assessment and oxidative status in liver homogenates.

RESULTS

The treatment of animals with both apigenin and paracetamol attenuates the parameters of hepatotoxicity, especially for ALT and ALP activity which was significantly lower compared to groups of animals treated with saline and paracetamol. Hepatotoxicity induced by toxic dose of paracetamol was revealed also by notable histopathological alterations, which were not observed in the group treated with paracetamol together with apigenin. Apigenin also prevented paracetamol-induced increase in malondialdehyde (MDA) level. The activities of both CAT (catalase) and GR (glutathione reductase) enzymes after the toxic dose of paracetamol were significantly increased in the liver homogenates, compared to control group. Apigenin reversed these parameters near to values of control group.

CONCLUSIONS

The result of our study indicates that apigenin inhibits the level of lipid peroxidation and significantly increases the enzyme antioxidant defense mechanisms in paracetamol-induced hepatotoxicity in rats.

Apigenin suppresses the apoptosis of H9C2 rat cardiomyocytes subjected to myocardial ischemia‑reperfusion injury via upregulation of the PI3K/Akt pathway

Apigenin, a flavonoid with multiple physiological and pharmacological activities, is associated with the prevention of cardiovascular diseases. The present study aimed to examine the roles and mechanisms of apigenin in the apoptosis of H9C2 rat cardiomyocytes, which were subjected to myocardial ischemia-reperfusion (MI/R) injury. Cell viability, reactive oxygen species (ROS), mitochondrial membrane potential (MMP) and cellular apoptosis were evaluated using cell counting kit-8 assays and flow cytometry. The content/activity of oxidative stress markers was determined using commercial kits. Western blot analysis and reverse transcription-quantitative polymerase chain reaction assays were used to measure protein and mRNA expression, respectively. The results demonstrated that apigenin had limited cytotoxicity on the viability of H9C2 rat cardiomyocytes. Apigenin reduced the oxidative stress, ROS production and cellular apoptotic capacity of MI/R-induced H9C2 cells. Apigenin additionally increased the MMP level of MI/R-induced H9C2 cells. Furthermore, apigenin modulated apoptosis-associated protein expression and phosphatidylinositol 3′-kinase (PI3K)/RAC-α serine/threonine-protein kinase (Akt) signaling in MI/R-induced H9C2 cells. Treatment with LY294002 reversed the anti-apoptotic effect of apigenin. In conclusion, apigenin suppressed the apoptosis of H9C2 cells that were subjected to MI/R injury by activating the PI3K/Akt pathway. It was suggested that apigenin may be effective as an MI/R therapy.

Apigenin loaded nanoparticle delayed development of hepatocellular carcinoma in rats

Hepatocellular carcinoma (HCC) is one of the major causes of cancer related death globally. Apigenin, a dietary flavonoid, possesses anti-tumor activity against HCC cells in-vitro. Development, physicochemical characterization of apigenin loaded nanoparticles (ApNp), biodistribution pattern and pharmacokinetic parameters of apigenin upon intravenous administration of ApNp, and effect of ApNp treatment in rats with HCC were investigated. Apigenin loaded nanoparticles had a sustained drug release pattern and successfully reached the hepatic cancer cells in-vitro as well as in liver of carcinogenic animals. ApNp predominantly delayed the progress of HCC in chemical induced hepatocarcinogenesis in rats. Quantification of apigenin by liquid chromatography-mass spectroscopy (LC-MS/MS) showed that apigenin availability significantly increased in blood and liver upon ApNp treatment. Apigenin loaded nanoparticle delivery substantially controlled the severity of hepatocellular carcinoma and could be a future hope for lingering the survival in hepatic cancer patients.

Apigenin inhibits growth of the Plasmodium berghei and disrupts some metabolic pathways in mice

Due to the challenges in the control, prevention, and eradication of parasitic diseases like malaria, there is an urgent need to discover new therapeutic agents. Plant-derived medicines may open new ways in the field of antiplasmodial therapy. This study is aimed to investigate the toxicity and in vivo antiplasmodial activity of apigenin, a dietary flavonoid. Apigenin cytotoxicity was investigated on Huh7 cell line, brine shrimp (Artemia salina) larva, and human red blood cells. In vivo toxicity of apigenin was assessed by metabolomics approaches. Apigenin exhibited significant suppression of parasitemia in a dose-dependent manner; it suppressed Plasmodium berghei growth by 69.74%, 50.3%, and 49.23% at concentrations of 70, 35, and 15 mg/kg/day, respectively. The IC₅₀ value for apigenin after 24 hr exposure to Huh7 cells was 225 μg/ml. Apigenin did not show noticeable toxicity on A. salina and also on the membrane integrity of red blood cells. After 24 hr exposure of mice to apigenin, alterations were seen in the metabolism of glucocorticoids and mineralocorticoids, bile acid metabolism (alternative pathway), sulfur metabolism, bile acid metabolism, metabolism of estrogens and androgens, cholesterol catabolism, and biosynthesis of cholesterol. These findings indicate that apigenin has potential in vivo antiplasmodial activity against P. berghei infected mice with high selectivity against malaria, but it can disrupt some metabolic pathways in mice.

The Flavonoid Apigenin Is a Progesterone Receptor Modulator with In Vivo Activity in the Uterus

Apigenin is a flavonoid with well-documented anti-cancer properties; however, its mechanisms of action are still unclear. We previously identified apigenin as a potential phytoprogestin, a natural product with a chemical scaffold that interacts with the progesterone receptor (PR). Our objective was to characterize the ability of apigenin to interact with PR through molecular docking studies, in vitro activity assays, and the ability of apigenin to elicit progestin-like effects in vivo. Molecular docking confirmed that apigenin could interact with PR, though with lower affinity than progesterone due to fewer van der Waals interactions. In Ishikawa cells stably expressing PR-B, apigenin significantly increased progesterone response element/luciferase (PRE/Luc) activity at 5 and 10 μM, but not in the parental Ishikawa cells that lack PR expression. In the presence of 100 nM of progesterone, 10 μM apigenin reduced PRE/Luc activity, indicative of mixed agonist activity. Apigenin also triggered degradation of PR in Ishikawa PR-B cells as measured by western blot. Apigenin reduced proliferation of Ishikawa cells, but through a PR-independent mechanism. In contrast, apigenin and progesterone both stimulated proliferation of T47D cells, an effect blocked by RU486. Apigenin activated other nuclear receptors evidenced by increased luciferase activity in MDA-MB-231 cells, which are PR negative. In vivo, apigenin blocked the genistein-stimulated increase in uterine epithelial cell height; stimulated endometrial expression of Hand2, a transcription factor stimulated by PR, and significantly reduced genistein-induced proliferation. In summary, apigenin is a phytoprogestin, with mixed agonist activity that demonstrates activity in vivo by hindering estrogen receptor-mediated uterine proliferation.

Apigenin induces apoptosis by suppressing Bcl-xl and Mcl-1 simultaneously via signal transducer and activator of transcription 3 signaling in colon cancer

Apigenin is a natural flavonoid that exhibits anti-proliferative activity and induces apoptosis in various types of cancer, including colon cancer. The aim of the present study was to determine the mechanism underlying the apoptosis-inducing effect of apigenin in colon cancer. Apigenin reduced the proliferation of colon cancer cell lines, stimulated the cleavage of PARP and induced apoptosis in a dose-dependent manner. Apigenin treatment also suppressed the expression of the anti-apoptotic proteins Bcl-xL and Mcl-1. Small interfering RNA was used to knockdown Bcl-xL and Mcl-1 expression alone and in concert, and the proliferation and apoptosis of cancer cells were subsequently measured. The knockdown of Bcl-xL and Mcl-1 expression together markedly suppressed cell proliferation and induced apoptosis. Apigenin treatment also inhibited the phosphorylation of signal transducer and activator of transcription 3 (STAT3), which targets Bcl-xL and Mcl-1. The results of the current study therefore determined that apigenin induces the apoptosis of colon cancer cells by inhibiting the phosphorylation of STAT3 and consequently downregulates the anti-apoptotic proteins Bcl-xL and Mcl-1.

Combined effect of apigenin and ferulic acid on frozen-thawed boar sperm quality

The main aim of the present study was to evaluate the cryoprotective effect of apigenin (AP) and ferulic acid (FA) on boar sperm during cryopreservation. AP and FA were both demonstrated to be high-efficiency antioxidants and had not previously been used to protect sperm from cryodamage. As boar sperm is sensitive to oxidative stress, suitable antioxidants are still needed for improving frozen-thawed sperm quality. With this purpose, semen samples coming from five boars were used in this study. Ejaculates of five boars were mixed and split into 16 aliquots, in which different doses of AP and FA were added separately or together. The motility, the plasma membrane integrity, the mitochondrial activity, the acrosomal integrity, the antioxidase activities and the malondialdehyde concentration of the frozen-thawed boar sperm were assessed. The results suggested that both AP and FA significantly improved the frozen-thawed boar sperm quality in all these aspects when they were added to the freezing extender separately, while the highest improvement was recorded when the extender was supplemented with 0.1 mmol/L AP plus 0.15 mmol/L FA. These findings demonstrated that supplementation of freezing extender with both AP and FA had a combined, beneficial effect on frozen-thawed boar sperm.

Bioinformatics and in vitro experimental analyses identify the selective therapeutic potential of interferon gamma and apigenin against cervical squamous cell carcinoma and adenocarcinoma

The clinical management and treatment of cervical cancer, one of the most commonly diagnosed cancers and a leading cause of cancer-related female death, remains a huge challenge for researchers and health professionals. Cervical cancer can be categorized into two major subtypes: common squamous cell carcinoma (SCC) and adenocarcinoma (AC). Although it is a relatively rare histological subtype of cervical cancer, there has been a steady increase in the incidences of AC. Therefore, new strategies to treat cervical cancer are urgently needed. In this study, the potential uses of IFNγ-based therapy for cervical cancer were evaluated using bioinformatics approaches. Gene expression profiling identified that cell cycle dysregulation was a major hallmark of cervical cancer including SCC and AC subtypes, and was associated with poor clinical outcomes for cervical cancer patients. In silico and in vitro experimental analyses demonstrated that IFNγ treatment could reverse the cervical cancer hallmark and induce cell cycle arrest and apoptosis. Furthermore, we demonstrated that apigenin could enhance the anticancer activity of IFNγ in a HeLa cervical AC cell line by targeting cyclin-dependent kinase 1. Taken together, the present study suggests the selective therapeutic potential of IFNγ alone or in combination with apigenin for managing cervical SCC and AC.

Isolation, identification and characterization of apigenin from Justicia gendarussa and its anti-inflammatory activity

Inflammatory responses during chronic diseases such as atherosclerosis, cancer etc., are harmful to host organisms. Generally NSAIDs are used to treat against these severe conditions but due to its adverse effects studies are going on with medicinal plants, since they are rich in bioactive compounds. Justicia gendarussa is one such plant which has been used as a remedial measure for treating inflammatory diseases since ancient time. Thus the present study involved in the isolation, characterization and identification of apigenin (flavonoid) from this plant and to elucidate its molecular mechanism against inflammation via TLR-NF-κB signaling pathway using ox-LDL induced hPBMCs in in vitro model. Methanolic extract was used for the isolation process and results showed that the F6 fraction collected from ethyl acetate through column chromatography showed 89% paw edema inhibition at a dose of 10 mg/kg in carrageenan induced rats. Purification of F6 by TLC with toluene: chloroform: acetone (8:5:7) and further characterization by ¹HNMR indicated the presence of bioactive compound, apigenin. In vitro studies revealed that pretreatment of ox-LDL induced hPBMCs with apigenin (25 μM) significantly (P < 0.05) reduced the levels of TLR4, MyD88, TRIF, TRAF6, NF-κB, COX-2, PGE2, IL-1β and TNF-α responsible for generating inflammation and elevated the level of anti-inflammatory cytokine, IL-10. These results indicate the therapeutic efficacy of bioflavonoid apigenin which was isolated from Justicia gendarussa against ox-LDL induced inflammation. Therefore apigenin can be treated as a suitable therapeutic agent against inflammatory diseases.

Role of Plant-Derived Flavonoids and Their Mechanism in Attenuation of Alzheimer's and Parkinson's Diseases: An Update of Recent Data

Neurodegeneration is a progressive loss of neuronal cells in certain regions of the brain. Most of the neurodegenerative disorders (NDDs) share the communal characteristic such as damage or reduction of various cell types typically including astrocytes and microglial activity. Several compounds are being trialed to treat NDDs but they possess solitary symptomatic advantages along with copious side effects. The finding of more enthralling and captivating compounds to suspend and standstill the pathology of NDDs will be considered as a hallmark of present times. Phytochemicals possess the potential to alternate the synthetic line of therapy against NDDs. The present review explores the potential efficacy of plant-derived flavonoids against most common NDDs including Alzheimer's disease (AD) and Parkinson's disease (PD). Flavonoids are biologically active phytochemicals which possess potential pharmacological effects, including antiviral, anti-allergic, antiplatelet, anti-inflammatory, anti-tumor, anti-apoptotic and anti-oxidant effects and are able to attenuate the pathology of various NDDs through down-regulating the nitric oxide (NO) production, by reducing the tumor necrosis factor-α (TNF-α), by reducing the excitotoxicity of superoxide as well as acting as tyrosine kinase (TK) and monoamine oxidase (MAO) inhibiting enzyme.

Beneficial Effect of Jojoba Seed Extracts on Hyperglycemia-Induced Oxidative Stress in RINm5f Beta Cells

Hyperglycemia occurs during diabetes and insulin resistance. It causes oxidative stress by increasing reactive oxygen species (ROS) levels, leading to cellular damage. Polyphenols play a central role in defense against oxidative stress. In our study, we investigated the antioxidant properties of simmondsin, a pure molecule present in jojoba seeds, and of the aqueous extract of jojoba seeds on fructose-induced oxidative stress in RINm5f beta cells. The exposure of RINm5f beta cells to fructose triggered the loss of cell viability (-48%, p < 0.001) and disruption of insulin secretion (p < 0.001) associated with of reactive oxygen species (ROS) production and a modulation of pro-oxidant and antioxidant signaling pathway. Cell pre-treatments with extracts considerably increased cell viability (+86% p < 0.001) for simmondsin and +74% (p < 0.001) for aqueous extract and insulin secretion. The extracts also markedly decreased ROS (-69% (p < 0.001) for simmondsin and -59% (p < 0.001) for aqueous extract) and caspase-3 activation and improved antioxidant defense, inhibiting p22phox and increasing nuclear factor (erythroid-derived 2)-like 2 (Nrf2) levels (+70%, p < 0.001) for aqueous extract. Simmondsin had no impact on Nrf2 levels. The richness and diversity of molecules present in jojoba seed extract makes jojoba a powerful agent to prevent the destruction of RINm5f beta cells induced by hyperglycemia.

Apigenin, a dietary flavonoid, induces apoptosis, DNA damage, and oxidative stress in human breast cancer MCF-7 and MDA MB-231 cells

Apigenin is found in several dietary plant foods such as vegetables and fruits. To investigate potential anticancer properties of apigenin on human breast cancer, ER-positive MCF-7 and triple-negative MDA MB-231 cells were used. Moreover, toxicological safety of apigenin towards normal cells was evaluated in human lymphocytes. Cytotoxicity of apigenin towards cancer cells was evaluated by MTT assay whereas further genotoxic and oxidative stress parameters were measured by comet and lipid peroxidation assays, respectively. In order to examine the type of cell death induced by apigenin, several biomarkers were used. Toxicological safety towards normal cells was evaluated by cell viability and comet assays. After the treatment with apigenin, we observed changes in cell morphology in a dose- (10 to 100 μM) and time-dependent manner. Moreover, apigenin caused cell death in both cell lines leading to significant toxicity and dominantly to apoptosis. Furthermore, apigenin proved to be genotoxic towards the selected cancer cells with a potential to induce oxidative damage to lipids. Of great importance is that no significant cytogenotoxic effects were detected in normal cells. The observed cytogenotoxic and pro-cell death activities of apigenin coupled with its low toxicity towards normal cells indicate that this natural product could be used as a future anticancer modality. Therefore, further analysis to determine the exact mechanism of action and in vivo studies on animal models are warranted.

Tannic Acid Induces Endoplasmic Reticulum Stress-Mediated Apoptosis in Prostate Cancer

Endoplasmic reticulum (ER) stress is an intriguing target with significant clinical importance in chemotherapy. Interference with ER functions can lead to the accumulation of unfolded proteins, as detected by transmembrane sensors that instigate the unfolded protein response (UPR). Therefore, controlling induced UPR via ER stress with natural compounds could be a novel therapeutic strategy for the management of prostate cancer. Tannic acid (a naturally occurring polyphenol) was used to examine the ER stress mediated UPR pathway in prostate cancer cells. Tannic acid treatment inhibited the growth, clonogenic, invasive, and migratory potential of prostate cancer cells. Tannic acid demonstrated activation of ER stress response (Protein kinase R-like endoplasmic reticulum kinase (PERK) and inositol requiring enzyme 1 (IRE1)) and altered its regulatory proteins (ATF4, Bip, and PDI) expression. Tannic acid treatment affirmed upregulation of apoptosis-associated markers (Bak, Bim, cleaved caspase 3, and cleaved PARP), while downregulation of pro-survival proteins (Bcl-2 and Bcl-xL). Tannic acid exhibited elevated G₁ population, due to increase in p18INK4C and p21WAF1/CIP1 expression, while cyclin D1 expression was inhibited. Reduction of MMP2 and MMP9, and reinstated E-cadherin signifies the anti-metastatic potential of this compound. Altogether, these results demonstrate that tannic acid can promote apoptosis via the ER stress mediated UPR pathway, indicating a potential candidate for cancer treatment.

Modeling Ramp-hold Indentation Measurements based on Kelvin-Voigt Fractional Derivative Model

Interpretation of experimental data from micro- and nano-scale indentation testing is highly dependent on the constitutive model selected to relate measurements to mechanical properties. The Kelvin-Voigt Fractional Derivative model (KVFD) offers a compact set of viscoelastic features appropriate for characterizing soft biological materials. This paper provides a set of KVFD solutions for converting indentation testing data acquired for different geometries and scales into viscoelastic properties of soft materials. These solutions, which are mostly in closed-form, apply to ramp-hold relaxation, load-unload and ramp-load creep-testing protocols. We report on applications of these model solutions to macro- and nano-indentation testing of hydrogels, gastric cancer cells and ex vivo breast tissue samples using an Atomic Force Microscope (AFM). We also applied KVFD models to clinical ultrasonic breast data using a compression plate as required for elasticity imaging. Together the results show that KVFD models fit a broad range of experimental data with a correlation coefficient typically R2 > 0.99. For hydrogel samples, estimation of KVFD model parameters from test data using spherical indentation versus plate compression as well as ramp relaxation versus load-unload compression all agree within one standard deviation. Results from measurements made using macro- and nano-scale indentation agree in trend. For gastric cell and ex vivo breast tissue measurements, KVFD moduli are, respectively, 1/3 - 1/2 and 1/6 of the elasticity modulus found from the Sneddon model. In vivo breast tissue measurements yield model parameters consistent with literature results. The consistency of results found for a broad range of experimental parameters suggest the KVFD model is a reliable tool for exploring intrinsic features of the cell/tissue microenvironments.

Phytochemicals as potent modulators of autophagy for cancer therapy

The dysregulation of autophagy is involved in the pathogenesis of a broad range of diseases, and accordingly universal research efforts have focused on exploring novel compounds with autophagy-modulating properties. While a number of synthetic autophagy modulators have been identified as promising cancer therapy candidates, autophagy-modulating phytochemicals have also attracted attention as potential treatments with minimal side effects. In this review, we firstly highlight the importance of autophagy and its relevance in the pathogenesis and treatment of cancer. Subsequently, we present the data on common phytochemicals and their mechanism of action as autophagy modulators. Finally, we discuss the challenges associated with harnessing the autophagic potential of phytochemicals for cancer therapy.

A comparative study of biotechnological approaches for producing valuable flavonoids in Prosopis farcta

The callus and hairy root cultures of Prosopis farcta were established to develop effective strategies to enhance its valuable and medicinally important flavonoid compounds. For callus induction, the hypocotyl, cotyledon and shoot explants were subjected to different plant hormones, naphthalene acetic acid (NAA), benzylaminopurine (BAP), kinetin and dichlorophenoxyacetic acid (2,4-D). Greater callus induction was obtained from hypocotyl explants on MS medium containing 3.0 mg L^-1 NAA + 2.0 mg L^-1 BAP. With the addition of 0.5 mg L^-1 asparagine to this medium, the maximum callus growth was achieved. Hairy root culture of P. farcta was performed using transformation of different explants with strains of Agrobacterium rhizogenes LBA9404, A4, AR15834. The AR15834 strain was more effective for hairy root induction where it caused hairy root formation on 59% of the infected cotyledon explants. We compared profiles of flavonoids isolated from seedling roots, hairy roots, and callus cultures of P. farcta. The colorimetric analysis showed that the content of total flavonoids of hairy roots was 1.54 and 2.52 times higher than in seedling roots and callus, respectively. The presence of flavonoids was verified by LC/MS in positive ion mode. The results showed that flavonoid composition was different in the roots and callus. Naringenin was the major constituent in callus, whereas resveratrol, quercetin and myricetin were the most abundant compounds found in hairy roots. The main objective of this research was to establish hairy roots in P. farcta to synthesize flavonoids at levels comparable to in vitro-grown roots. The present study also opens up a way to further improve the production of pharmaceutically valuable flavonoids and to produce desired metabolites using the hairy root culture system.

Apigenin's anticancer properties and molecular mechanisms of action: Recent advances and future prospectives

Cancer is a major health concern and leading burden on economy worldwide. An increasing effort is devoted to isolation and development of plant-derived dietary components as effective chemo-preventive products. Phytochemical compounds from natural resources such as fruits and vegetables are responsible for decreasing the risk of certain cancers among the consuming populations. Apigenin, a flavonoid phytochemical found in many kinds of fruits and vegetables, has been shown to exert significant biological effects, such as anti-oxidant, anti-inflammatory and most particularly anti-neoplastic properties. This review is intended to summarize the most recent advances in the anti-proliferative and chemo-preventive effects of apigenin in different cancer models. Analysis of the data from the studied cancer models has revealed that apigenin exerts its anti-proliferative effects through multiple and complex pathways. This guided us to discover some controversial results about the exact role of certain molecular pathways such as autophagy in the anticancer effects of apigenin. Further, there were cumulative positive evidences supporting the involvement of certain pathways such as apoptosis, ROS and DNA damage and repair. Apigenin possesses a high potential to be used as a chemosensitizing agent through the up-regulation of DR5 pathway. According to these preclinical findings we recommend that further robust unbiased studies should consider the possible interactions between different molecular pathways.

Apigenin promotes TRAIL-mediated apoptosis regardless of ROS generation

Apigenin is a bioactive flavone in several herbs including parsley, thyme, and peppermint. Apigenin possesses anti-cancer and anti-inflammatory properties; however, whether apigenin enhances TRAIL-mediated apoptosis in cancer cells is unknown. In the current study, we found that apigenin enhanced TRAIL-induced apoptosis by promoting caspase activation and death receptor 5 (DR5) expression and a chimeric antibody against DR5 completely blocked the apoptosis. Apigenin also upregulated reactive oxygen species (ROS) generation; however, intriguingly, ROS inhibitors, glutathione (GSH) or N-acetyl-l-cysteine (NAC), moderately increased apigenin/TRAIL-induced apoptosis. Additional results showed that an autophagy inducer, rapamycin, enhanced apigenin/TRAIL-mediated apoptosis by a slight increase of ROS generation. Accordingly, NAC and GSH rather decreased apigenin-induced autophagy formation, suggesting that apigenin-induced ROS generation increased autophagy formation. However, autophagy inhibitors, bafilomycin (BAF) and 3-methyladenine (3-MA), showed different result in apigenin/TRAIL-mediated apoptosis without ROS generation. 3-MA upregulated the apoptosis but remained ROS levels; however, no changes on apoptosis and ROS generation were observed by BAF treatment. Taken together, these findings reveal that apigenin enhances TRAIL-induced apoptosis by activating apoptotic caspases by upregulating DR5 expression regardless of ROS generation, which may be a promising strategy for an adjuvant of TRAIL.

Epigenetic actions of environmental factors and promising drugs for cancer therapy

Carcinogenesis is known to be primarily associated with gene mutations. Recently, increasing evidence has suggested that epigenetic events also serve crucial roles in tumor etiology. Environmental factors, including nutrition, toxicants and ethanol, are involved in carcinogenesis through inducing epigenetic modifications, such as DNA methylation, histone deacetylase and miRNA regulation. Studying epigenetic mechanisms has facilitated the development of early diagnostic strategies and potential therapeutic avenues. Modulation at the epigenetic level, including reversing epigenetic modifications using targeted drugs, has demonstrated promise in cancer therapy. Therefore, identifying novel epigenetic biomarkers and therapeutic targets has potential for the future of cancer therapy. The present review discusses the environmental factors involved in epigenetic modifications and potential drug candidates for cancer therapy.

Relationship between Antioxidant and Anticancer Activity of Trihydroxyflavones

Plant polyphenols have been highlighted not only as chemopreventive, but also as potential anticancer substances. Flavones are a subclass of natural flavonoids reported to have an antioxidant and anticancer activity. The aim of our study was to evaluate antioxidant and anticancer activity of seventeen trihydroxyflavone derivatives, including apigenin (API) and baicalein (BCL). Also, we wanted to find out if there is a correlation between those two effects. Cell growth inhibition testing was carried out using MTT assay in three different human cancer cell lines: lung (A549), breast (MCF-7) and brain epithelial (U87). Antioxidant activity was determined by the DPPH radical scavenging method. Thirteen trihydroxyflavones possessed anticancer activity against at least one tested cancer cell line. They were more active against the MCF-7 cell line, and the lowest activity was determined against the U87 cell line. The majority of compounds inhibited cancer cell growth at EC₅₀ values between 10-50 µM. The most active compound was 3',4',5-trihydroxyflavone 7, especially against A549 and MCF-7 cell lines. The correlation between anti-proliferative and antioxidant activity was only moderate, and it was determined for A549 and U87 cancer cell lines. The most important fragment for those two effects is the ortho-dihydroxy group in ring B.

CONCLUSIONS

Trihydroxyflavones demonstrated anticancer activity. Further and more detailed studies should to be carried out to estimate the structure-activity relationship of these compounds.

The Role of Secondary Metabolites on Gynecologic Cancer Therapy: Some Pathways and Mechanisms

Gynecologic cancers are among the most common cancers in humans and animals. Treatment success depends on several factors including stage at diagnosis, tumor type, origin and metastasis. Currently, surgery, chemotherapy, and radiotherapy are preferred in the treatment of these cancers. However, many anticarcinogenic drugs can cause severe adverse effects and also the expected response to treatment may not be obtained. In recent studies, the importance of the relationship between cancer and inflammation has been emphasized. Therefore, several phytochemicals that exhibit beneficial bioactive effects towards inflammatory pathways were proven to have anticarcinogenic potential for gynecologic cancer therapy. This review summarizes the role of inflammatory pathways in gynecologic cancers and effective secondary metabolites for cancer therapy.

Ethnobotanical survey of medicinal plants in northeastern of Algeria

BACKGROUND

In order to document medicinal uses of plants in the northeastern of Algeria, preserve traditional heritage and highlighted the risks of excessive human exploitation on flora and biodiversity of the region, an inventory of medicinal species existed in the traditional pharmacopoeia in Skikda region (north-east of Algeria) was made. The survey was carried out during the year (2015-2016), through face to face interviews, using pre-prepared questionnaire. The form contains: sociodemorgaphic profile of each respondent (sex, age, educational level and monthly income), local name of medicinal species used, uses, used parts and methods of preparations.

RESULTS

A total of 90 species belonging to 42 botanical families, were listed. The analysis of the obtained results showed that the frequency of use of medicinal plants is related to the age, sex, educational level and monthly income of our respondents. It was recorded that the majority of remedies are prepared in the form of a decoctate from the leaves of the different species, in order to treat a wide range of diseases especially those of the digestive tract.

CONCLUSION

Local population has a rich indigenous knowledge, but is always stays not adequately documented. It should be noted that some listed species are suffering from surexploitation which can subjects to the disappearance of the most vulnerable species. It will be urgent and essential to adopt a sustainable management strategy to avoid the degradation of biodiversity of the region.

Plant flavone apigenin: An emerging anticancer agent

Research in cancer chemoprevention provides convincing evidence that increased intake of vegetables and fruits may reduce the risk of several human malignancies. Phytochemicals present therein provide beneficial anti-inflammatory and antioxidant properties that serve to improve the cellular microenvironment. Compounds known as flavonoids categorized anthocyanidins, flavonols, flavanones, flavonols, flavones, and isoflavones have shown considerable promise as chemopreventive agents. Apigenin (4', 5, 7-trihydroxyflavone), a major plant flavone, possessing antioxidant, anti-inflammatory, and anticancer properties affecting several molecular and cellular targets used to treat various human diseases. Epidemiologic and case-control studies have suggested apigenin reduces the risk of certain cancers. Studies demonstrate that apigenin retain potent therapeutic properties alone and/or increases the efficacy of several chemotherapeutic drugs in combination on a variety of human cancers. Apigenin's anticancer effects could also be due to its differential effects in causing minimal toxicity to normal cells with delayed plasma clearance and slow decomposition in liver increasing the systemic bioavailability in pharmacokinetic studies. Here we discuss the anticancer role of apigenin highlighting its potential activity as a chemopreventive and therapeutic agent. We also highlight the current caveats that preclude apigenin for its use in the human trials.

Natural agents mediated autophagic signal networks in cancer

Recent studies suggested that natural compounds are important in finding targets for cancer treatments. Autophagy (“self-eating”) plays important roles in multiple diseases and acts as a tumor suppressor in cancer. Here, we examined the molecular mechanism by which natural agents regulate autophagic signals. Understanding the relationship between natural agents and cellular autophagy may provide more information for cancer diagnosis and chemoprevention.

Antitumor and radiosensitizing synergistic effects of apigenin and cryptotanshinone against solid Ehrlich carcinoma in female mice

Considerable attention has been paid to the introduction of novel naturally occurring plant-derived radiosensitizer compounds in order to augment the radiation efficacy and improve the treatment outcome of different tumors. This study was therefore undertaken to evaluate the antitumor, antiangiogeneic, and synergistic radiosensitizing effects of apigenin, a dietary flavonoid, and/or cryptotanshinone, a terpenoid isolated from the roots of Salvia miltiorrhiza, against the growth of solid Ehrlich carcinoma in female mice. Apigenin (50 mg/kg body weight) and/or cryptotanshinone (40 mg/kg body weight) was intraperitoneally (i.p.) injected into non-irradiated or γ-irradiated (6.5 Gy whole-body γ-irradiation) solid Ehrlich carcinoma-bearing mice for 30 consecutive days. Investigations included molecular targets involved in proliferation, inflammation, angiogenesis, and tumor invasiveness. Treatment with apigenin and/or cryptotanshinone significantly suppressed the growth of solid Ehrlich carcinoma tumors and demonstrated a synergistic radiosensitizing efficacy together with γ-irradiation. These effects were achieved through downregulating the expression of angiogenic and lymphangiogenic regulators, including signal transducer and activator of transcription 3, vascular endothelial growth factor C, and tumor necrosis factor alpha, suppressing matrix metalloproteinase-2 and -9 activities, which play a key role in tumor invasion and metastasis, and enhancing apoptosis via inducing cleaved caspase-3 and granzyme B levels. Histological findings of solid Ehrlich carcinoma tumors verified the recorded data. In conclusion, a synergistic radiosensitizing efficacy for apigenin and cryptotanshinone was demonstrated against Ehrlich carcinoma in the current in vivo murine model, representing therefore a potential therapeutic strategy for increasing the radiation response of solid tumors.

AgFNS overexpression increase apigenin and decrease anthocyanins in petioles of transgenic celery

Apigenin and anthocyanin biosyntheses share common precursors in plants. Flavone synthase (FNS) converts naringenin into apigenin in higher plants. Celery is an important edible and medical vegetable crop that contains apigenin in its tissues. However, the effect of high AgFNS gene expression on the apigenin and anthocyanins contents of purple celery remains to be elucidated. In this study, the AgFNS gene was cloned from purple celery ('Nanxuan liuhe purple celery') and overexpressed in this purple celery to determine its influence on anthocyanins and apigenin contents. Results showed that the AgFNS gene was 1068bp, which encodes 355 amino acid residues. Evolution analysis showed that the AgFNS protein belongs to the FSN I type. In AgFNS transgenic celery, the anthocyanins content in petioles was lower than that wild-type celery plants. Apigenin content increased in the petioles of AgFNS transgenic celery. The transcript levels of the AgPAL, AgC4H, AgCHS, and AgCHI genes were up-regulated, whereas those of the AgF3H, AgF3'H, AgDFR, AgANS, and Ag3GT genes were down-regulated in the petioles of AgFNS transgenic plants compared with wild-type celery plants. This work provides basic knowledge about the function of the AgFNS gene in the anthocyanin and apigenin biosyntheses of celery.

Modulation of oncogenic transcription factors by bioactive natural products in breast cancer

Carcinogenesis, a multi-step phenomenon, characterized by alterations at genetic level and affecting the main intracellular pathways controlling cell growth and development. There are growing number of evidences linking oncogenes to the induction of malignancies, especially breast cancer. Modulations of oncogenes lead to gain-of-function signals in the cells and contribute to the tumorigenic phenotype. These signals yield a large number of proteins that cause cell growth and inhibit apoptosis. Transcription factors such as STAT, p53, NF-κB, c-JUN and FOXM1, are proteins that are conserved among species, accumulate in the nucleus, bind to DNA and regulate the specific genes targets. Oncogenic transcription factors resulting from the mutation or overexpression following aberrant gene expression relay the signals in the nucleus and disrupt the transcription pattern. Activation of oncogenic transcription factors is associated with control of cell cycle, apoptosis, migration and cell differentiation. Among different cancer types, breast cancer is one of top ten cancers worldwide. There are different subtypes of breast cancer cell-lines such as non-aggressive MCF-7 and aggressive and metastatic MDA-MB-231 cells, which are identified with distinct molecular profile and different levels of oncogenic transcription factor. For instance, MDA-MB-231 carries mutated and overexpressed p53 with its abnormal, uncontrolled downstream signalling pathway that account for resistance to several anticancer drugs compared to MCF-7 cells with wild-type p53. Appropriate enough, inhibition of oncogenic transcription factors has become a potential target in discovery and development of anti-tumour drugs against breast cancer. Plants produce diverse amount of organic metabolites. Universally, these metabolites with biological activities are known as "natural products". The chemical structure and function of natural products have been studied since 1850s. Investigating these properties leaded to recognition of their molecular effects as anticancer drugs. Numerous natural products extracted from plants, fruits, mushrooms and mycelia, show potential inhibitory effects against several oncogenic transcription factors in breast cancer. Natural compounds that target oncogenic transcription factors have increased the number of candidate therapeutic agents. This review summarizes the current findings of natural products in targeting specific oncogenic transcription factors in breast cancer.

Programmed cell death in Acanthamoeba castellanii Neff induced by several molecules present in olive leaf extracts

Therapy against Acanthamoeba infections such as Granulomatous Amoebic Encephalitis (GAE) and Acanthamoeba Keratitis (AK), remains as an issue to be solved due to the existence of a cyst stage which is highly resistant to most chemical and physical agents. Recently, the activity of Olive Leaf Extracts (OLE) was demonstrated against Acanthamoeba species. However, the molecules involved in this activity were not identified and/or evaluated. Therefore, the aim of this study was to evaluate the activity of the main molecules which are present in OLE and secondly to study their mechanism of action in Acanthamoeba. Among the tested molecules, the observed activities ranged from an IC50 of 6.59 in the case of apigenine to an IC50 > 100 μg/ml for other molecules. After that, elucidation of the mechanism of action of these molecules was evaluated by the detection of changes in the phosphatidylserine (PS) exposure, the permeability of the plasma membrane, the mitochondrial membrane potential and the ATP levels in the treated cells. Vanillic, syringic and ursolic acids induced the higher permeabilization of the plasma membrane. Nevertheless, the mitochondrial membrane was altered by all tested molecules which were also able to decrease the ATP levels to less than 50% in IC90 treated cells after 24 h. Therefore, all the molecules tested in this study could be considered as a future therapeutic alternative against Acanthamoeba spp. Further studies are needed in order to establish the true potential of these molecules against these emerging opportunistic pathogenic protozoa.

Apigenin Impacts the Growth of the Gut Microbiota and Alters the Gene Expression of Enterococcus

Apigenin is a major dietary flavonoid with many bioactivities, widely distributed in plants. Apigenin reaches the colon region intact and interacts there with the human gut microbiota, however there is little research on how apigenin affects the gut bacteria. This study investigated the effect of pure apigenin on human gut bacteria, at both the single strain and community levels. The effect of apigenin on the single gut bacteria strains Bacteroides galacturonicus, Bifidobacterium catenulatum, Lactobacillus rhamnosus GG, and Enterococcus caccae, was examined by measuring their anaerobic growth profiles. The effect of apigenin on a gut microbiota community was studied by culturing a fecal inoculum under in vitro conditions simulating the human ascending colon. 16S rRNA gene sequencing and GC-MS analysis quantified changes in the community structure. Single molecule RNA sequencing was used to reveal the response of Enterococcus caccae to apigenin. Enterococcus caccae was effectively inhibited by apigenin when cultured alone, however, the genus Enterococcus was enhanced when tested in a community setting. Single molecule RNA sequencing found that Enterococcus caccae responded to apigenin by up-regulating genes involved in DNA repair, stress response, cell wall synthesis, and protein folding. Taken together, these results demonstrate that apigenin affects both the growth and gene expression of Enterococcus caccae.

Apigenin inhibits growth and induces apoptosis in human cholangiocarcinoma cells

A promising nutraceutical, apigenin, was recently revealed to exhibit biological activity in inhibiting several types of cancer. The effects of apigenin on the growth inhibition and apoptosis of the cholangiocarcinoma HuCCA-1 cell line were investigated. Protein alterations subsequent to apigenin treatment were studied using a proteomic approach. The values of 20, 50 and 90% inhibition of cell growth (IC₂₀, IC₅₀ and IC₉₀) were determined by MTT cell viability assay. Apoptotic cell death was detected using two different methods, a flow cytometric analysis (Muse Cell Analyzer) and DNA fragmentation assay. A number of conditions including attached and detached cells were selected to perform two-dimensional gel electrophoresis (2-DE) to study the alterations in the expression levels of treated and untreated proteins and identified by liquid chromatography (LC)/tandem mass spectrometry (MS/MS). The IC₂₀, IC₅₀ and IC₉₀ values of apigenin after 48 h treatment in HuCCA-1 cells were 25, 75 and 200 µM, respectively, indicating the cytotoxicity of this compound. Apigenin induced cell death in HuCCA-1 cells via apoptosis as detected by flow cytometric analysis and exhibited, as confirmed with DNA fragmentation, characteristics of apoptotic cells. A total of 67 proteins with altered expression were identified from the 2-DE analysis and LC/MS/MS. The cleavage of proteins involved in cytoskeletal, cytokeratin 8, 18 and 19, and high expression of S100-A6 and S100-A11 suggested that apoptosis was induced by apigenin via the caspase-dependent pathway. Notably, two proteins, heterogeneous nuclear ribonucleoprotein H and A2/B1, disappeared completely subsequent to treatment, suggesting the role of apigenin in inducing cell death. The present study indicated that apigenin demonstrates an induction of growth inhibition and apoptosis in cholangiocarcinoma cells and the apoptosis pathway was confirmed by proteomic analysis.