Differential metabolomic analysis of the potential antiproliferative mechanism of olive leaf extract on the JIMT-1 breast cancer cell line

Olive Leaves as a Source of Anticancer Compounds: In Vitro Evidence and Mechanisms

Olive trees not only produce olives but also generate a substantial amount of waste and by-products, including leaves, pomace (the solid remains after pressing olives for oil), and wastewater from the olive oil-making process. The waste products, particularly the leaves, contain bioactive compounds, especially phenolic compounds, known for their health benefits, such as high antioxidant potential and the ability to reduce inflammation. These compounds have shown promise in preventing and treating cancer. This review, based on in vitro evidence, provides a detailed description and discussion of the mechanisms through which these compounds from olive leaves can prevent development, the ways they might act against cancer cells, and their potential to increase the sensitivity of tumor cells to conventional anticancer therapy. The possible synergistic effects of these compounds suggest that olive leaf extracts may offer a promising approach for cancer treatment, compared with isolated compounds, thus providing novel possibilities for cancer therapy.

Diosmetin: A dietary flavone as modulator of signaling pathways in cancer progression

Flavonoids, constituting the most extensive category of polyphenols, founds in a variety of plants and comprise over 9000 compounds. Diosmetin, O-methylated flavone (3',5,7-trihydroxy-4'-methoxyflavone) of flavonoid aglycone diosmin have witnessed a significant surge in recent years. Many studies showed that flavonoids induced cytotoxicity in different organ specific cancer types. Thus, current review evaluates the anticancer potential of diosmetin and shed light on its mechanism of action such as cell cycle regulation, apoptosis via both intrinsic and extrinsic pathway, autophagy and tumour progression and metastasis. It also provides comprehensive analysis of different cancer targets and their role in breast, colon, hepatic, gliomas, leukemia, lung, prostate and skin cancer. Combination studies of diosmetin to improve drug sensitivity and reduce toxicity towards normal cells has been also discussed. Besides, in vitro studies, present review also discuss the anticancer potential of diosmetin on xenograft mice model. Different natural sources of diosmetin, limitations, pharmacokinetic analysis and toxicity study also summarized in current review. The emphasis on enhancing solubility and permeability for clinical utility has been thoroughly highlighted with particular attention given to the utilization of nano formulations to overcome existing barriers. At last, in-depth analysis of current challenges and a forward-looking perspective deliberated to address the existing gaps and position it as a promising lead compound for clinical applications in cancer treatment. This discussion is boosted by diosmetin's potential anticancer properties on different cancers, makes valuable candidates in the ongoing quest for effective therapeutic interventions against cancer.

Luteolin: A promising multifunctional natural flavonoid for human diseases

Natural products are closely associated with human health. Luteolin (LUT), a flavonoid polyphenolic compound, is widely found in fruits, vegetables, flowers, and herbs. It is noteworthy that LUT exhibits a variety of beneficial pharmacological properties and holds significant potential for clinical applications, particularly in antitumor, anti-convulsion, diabetes control, anti-inflammatory, neuroprotection, anti-oxidation, anti-cardiovascular, and other aspects. The potential mechanism of action has been partially elucidated, including the mediation of NF-κB, toll-like receptor, MAPK, Wnt/β-catenin, PI3K/Akt, AMPK/mTOR, and Nrf-2, among others. The review that aimed to comprehensively consolidate essential information on natural sources, pharmacological effects, therapeutic and preventive potential, as well as potential mechanisms of LUT. The objective is to establish a theoretical basis for the continued development and application of LUT.

Therapeutic potential of natural products in inflammation: underlying molecular mechanisms, clinical outcomes, technological advances, and future perspectives

Chronic inflammation is a common underlying factor in many major diseases, including heart disease, diabetes, cancer, and autoimmune disorders, and is responsible for up to 60% of all deaths worldwide. Metformin, statins, and corticosteroids, and NSAIDs (non-steroidal anti-inflammatory drugs) are often given as anti-inflammatory pharmaceuticals, however, often have even more debilitating side effects than the illness itself. The natural product-based therapy of inflammation-related diseases has no adverse effects and good beneficial results compared to substitute conventional anti-inflammatory medications. In this review article, we provide a concise overview of present pharmacological treatments, the pathophysiology of inflammation, and the signaling pathways that underlie it. In addition, we focus on the most promising natural products identified as potential anti-inflammatory therapeutic agents. Moreover, preclinical studies and clinical trials evaluating the efficacy of natural products as anti-inflammatory therapeutic agents and their pragmatic applications with promising outcomes are reviewed. In addition, the safety, side effects and technical barriers of natural products are discussed. Furthermore, we also summarized the latest technological advances in the discovery and scientific development of natural products-based medicine.

Plant-derived compounds for treating autosomal dominant polycystic kidney disease

Autosomal dominant polycystic kidney disease (ADPKD), the most common monogenic hereditary kidney disease, is the fourth leading cause of end-stage kidney disease worldwide. In recent years, significant progress has been made in delaying ADPKD progression with different kinds of chemical drugs, such as tolvaptan, rapamycin, and somatostatin. Meanwhile, numerous plant-derived compounds have been investigated for their beneficial effects on slowing ADPKD progression. Among them, saikosaponin-d, Ganoderma triterpenes, curcumin, ginkgolide B, steviol, resveratrol, Sparganum stoloniferum Buch.-Ham, Cordyceps sinensis, triptolide, quercitrin, naringin, cardamonin, gambogic acid, and olive leaf extract have been found to retard renal cyst development by inhibiting cell proliferation or promoting cell apoptosis in renal cyst-lining epithelial cells. Metformin, a synthesized compound derived from French lilac or goat's rue (Galega officinalis), has been proven to retard the progression of ADPKD. This review focuses on the roles and mechanisms of plant-derived compounds in treating ADPKD, which may constitute promising new therapeutics in the future.

Influence of Drying Temperature and Harvesting Season on Phenolic Content and Antioxidant and Antiproliferative Activities of Olive (Olea europaea) Leaf Extracts

Interest in plant compounds has increased, given recent evidence regarding their role in human health due to their pleiotropic effects. For example, plant bioactive compounds present in food products, including polyphenols, are associated with preventive effects in various diseases, such as cancer or inflammation. Breast and colorectal cancers are among the most commonly diagnosed cancers globally. Although appreciable advances have been made in treatments, new therapeutic approaches are still needed. Thus, in this study, up to 28 olive leaf extracts were obtained during different seasons and using different drying temperatures. The influence of these conditions on total polyphenolic content (measured using Folin-Ciocalteu assays), antioxidant activity (using Trolox Equivalent Antioxidant Capacity and Ferric Reducing Ability of Plasma assays) and antiproliferative capacity (using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide, MTT assays) was tested in breast and colorectal cancer cells. Increased phenolic composition and antioxidant and antiproliferative capacity are noted in the extracts obtained from leaves harvested in autumn, followed by summer, spring and winter. Regarding drying conditions, although there is not a general trend, conditions using the highest temperatures lead to the optimal phenolic content and antioxidant and antiproliferative activities in most cases. These results confirm previously published studies and provide evidence in support of the influence of both harvesting and drying conditions on the biological activity of olive leaf extracts.

Olive Fruit and Leaf Wastes as Bioactive Ingredients for Cosmetics-A Preliminary Study

Olea europaea cultivar, native in the Mediterranean basin, has expanded worldwide, mainly due to the olive oil industry. This expansion is attributed to the benefits of olive oil consumption, since this product is rich in nutritional and bioactive compounds. However, the olive industry generates high amounts of wastes, which could be related to polluting effects on soil and water. To minimize the environmental impact, different strategies of revalorization have been proposed. In this sense, the aim of this work was to develop high cosmetic value added oleuropein-enriched extracts (O20 and O30), a bioactive compound from olive byproducts, performing a comprehensive characterization using high performance liquid chromatography coupled to mass spectrometry and evaluate their bioactivity by in vitro assays. A total of 49 compounds were detected, with oleuropein and its derivatives widely found in O30 extract, whereas iridoids were mainly detected in O20 extract. Moreover, 10 compounds were detected for the first time in olive leaves. Both extracts demonstrated strong antioxidant and antiradical activities, although O30 showed higher values. In addition, radical oxygen and nitrogen species scavenging and enzyme inhibition values were higher in O30, with the exception of HOCl and hyaluronidase inhibition assays. Regarding cell viability, olive byproduct extracts did not lead to a decrease in keratinocytes viability until 100 µg/mL. All data reported by the present study reflect the potential of industrial byproducts as cosmetic ingredients.

Olive leaf extract impairs mitochondria by pro-oxidant activity in MDA-MB-231 and OVCAR-3 cancer cells

Breast and ovarian cancers are the leading and fifth reason for tumor death among females, respectively. Recently, many studies demonstrated antiproliferative activities of natural aliments in cancer. In this study, we investigated the antitumor potential of Olive Leaf Extract (OLE) in triple-negative breast and ovarian cancer cells. A HPLC/DAD analysis on OLE has been performed to assess the total polyphenolics and other secondary metabolites content. HCEpiC, MDA-MB-231, and OVCAR-3 cell lines were used. MTS, Cytofluorimetric, Western Blot analysis were performed to analyze cell viability, cell proliferation, apoptosis, and oxidative stress. Fluorimetric and IncuCyte® analyses were carried out to evaluate apoptosis and mitochondrial function. We confirmed that OLE, containing a quantity of oleuropein of 87 % of the total extract, shows anti-proliferative and pro-apoptotic activity on MDA-MB-231 cells. For the first time, our results indicate that OLE inhibits OVCAR-3 cell viability inducing cell cycle arrest, and it also increases apoptotic cell death up-regulating the protein level of cleaved-PARP and caspase 9. Moreover, our data show that OLE treatment causes a significant decrease in mitochondrial functionality, paralleled by a reduction of mitochondrial membrane potential. Interestingly, OLE increased the level of intracellular and mitochondrial reactive oxygen species (ROS) together with a decreased activity of ROS scavenging enzymes, confirming oxidative stress in both models. Our data demonstrate that mitochondrial ROS generation represented the primary mechanism of OLE antitumor activity, as pretreatment with antioxidant N-acetylcysteine prevented OLE-induced cell cycle arrest and apoptosis.

Oleuropein Aglycone Peracetylated (3,4-DHPEA-EA(P)) Attenuates H2O2-Mediated Cytotoxicity in C2C12 Myocytes via Inactivation of p-JNK/p-c-Jun Signaling Pathway

Oleuropein, a glycosylated secoiridoid present in olive leaves, is known to be an important antioxidant phenolic compound. We studied the antioxidant effect of low doses of oleuropein aglycone (3,4-DHPEA-EA) and oleuropein aglycone peracetylated (3,4-DHPEA-EA(P)) in murine C2C12 myocytes treated with hydrogen peroxide (H2O2). Both compounds were used at a concentration of 10 μM and were able to inhibit cell death induced by the H2O2 treatment, with 3,4-DHPEA-EA(P) being more. Under our experimental conditions, H2O2 efficiently induced the phosphorylated-active form of JNK and of its downstream target c-Jun. We demonstrated, by Western blot analysis, that 3,4-DHPEA-EA(P) was efficient in inhibiting the phospho-active form of JNK. This data suggests that the growth arrest and cell death of C2C12 proceeds via the JNK/c-Jun pathway. Moreover, we demonstrated that 3,4-DHPEA-EA(P) affects the myogenesis of C2C12 cells; because MyoD mRNA levels and the differentiation process are restored with 3,4-DHPEA-EA(P) after treatment. Overall, the results indicate that 3,4-DHPEA-EA(P) prevents ROS-mediated degenerative process by functioning as an efficient antioxidant.

Industrial-Scale Study of the Chemical Composition of Olive Oil Process-Derived Matrices

The effect of the industrial process and collecting period on produced olive oil and by-products was evaluated. Obtained results showed significant variations for the majority of quality indices before and after vertical centrifugation between all samples from the three collecting periods. All samples were rich in monounsaturated fatty acid: Oleic acid (C18:1) with a maximum of 69.95%. The total polyphenols and individual phenolic compounds varied significantly through the extraction process, with a significant variation between olive oil and by-products. Notably, the percentage of secoiridoids and their derivatives was significant in paste and olive oil, highlighting the activity of many enzymes released during the different extraction steps. Regarding antioxidant capacity, the most remarkable result was detected in olive oil and olive mill wastewater samples.

Seasonal Variations in the Chemical Composition of Liangshan Olive Leaves and Their Antioxidant and Anticancer Activities

The seasonal changes in the chemical composition of Olea europaea leaves from January to December at Liangshan (China) have been investigated. The highest total phenolic content (TPC), total flavonoid content (TFC), and free amino acid content (FAAC) levels were found in May and December, while the lowest levels were detected in April and September. The soluble protein content (SPC) and the soluble sugar content (SSC) were highest in spring but lowest in summer and winter. The levels of major phenolic compounds, including oleuropein, and luteolin-4’-O-glucoside, followed by apigenin-7-O-glucoside, quercetin, rutin, luteolin, and apigenin, increased during spring and winter but decreased during summer and autumn. In addition, phenolic extracts (PEs) showed dose-dependent antioxidant activity using 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical and superoxide radical scavenging activity assays; the reducing power was tested. The anticancer activities of PE at various concentrations were assessed by a cell counting kit-8 (CCK-8), and the IC₅₀ (50% effective concentration) to HEK293, HeLa, and S180 cells were 841.48, 7139, and 457.69 μg/mL, respectively. PE-treated S180 cells inhibited proliferation through activation of caspase-3/9 and disruption of the mitochondrial membrane potential. Thus, PE in Liangshan olive leaves possessed strong antioxidant and anticancer potential, and spring and winter were determined as optimal harvesting seasons.

Oleuropein modulates glioblastoma miRNA pattern different from Olea europaea leaf extract

Glioblastoma (GBM) is the most prevalent and deadliest subtype of glioma. Despite current innovations in existing therapeutic modalities, GBM remains incurable, and alternative therapies are required. Previously, we demonstrated that Olea europaea leaf extract (OLE) kills GBM cells by modulating miR-181b, miR-137, miR-153 and Let-7d expression. However, although oleuropein (OL) is the main compound in OLE, its role in the antitumour effect of OLE remains unknown. This study determined the effect of OL on GBM cell line T98G and compared the results with our previous findings regarding the effect of OLE on the same cell line. The antiproliferative activity of OL and its effect on temozolomide (TMZ) response were tested inT98G cells using WST-1 assay. OL inhibition was evaluated using one-way analysis of variance with Tukey's post hoc test. The effect of OL on miR-181b, miR-137, miR-153 and Let-7d expression was assessed using quantitative reverse transcription polymerase chain reaction. Fold differences in expression between untreated, OL or OL + TMZ-treated samples were calculated using 2^-ΔCt method. Significance was evaluated using an independent sample t-test. Treatment with 277.5 and 555 µM OL resulted in 39.51% and 75.40% reductions in T98G cells within 24 h. Coadministration of 325 µM TMZ and 277.5 or 555 µM, OL caused 2.08- and 2.83-fold increases, respectively, in the therapeutic effect of TMZ. OL + TMZ significantly increased microRNA expression, particularly Let-7d, than OLE. In conclusion, OL has an antitumour effect on GBM cells mainly via regulation of Let-7d expression. The present results also indicate other minor compounds in OLE play important anticancer roles.

Phytochemical screening, antioxidant activity and inhibitory potential of Ficus carica and Olea europaea leaves

It is our interest to screen Oela europaea L and Ficus carica L leaf extract for total phenolic, flavonoid contents and to evaluate their free radical scavenging and Ferric reducing power (FRAP) using 1,1-diphenyl-2-picrylhydrazyl (DPPH). Data shows that Olea europaea and Ficus carica have strong antioxidant potency to scavenge free radical at an optimal phenolic and flavonoid concentration. Results further suggest a strong correlation between antioxidant activities, phenolic and flavonoid contents. Thus, the screening of Ficus carica and Olea europaea leaf extracts for potential antioxidants as source of drugs for several diseases especially oxidative stress and cancers is illustrated.

Monitoring the Bioactive Compounds Status in Olea europaea According to Collecting Period and Drying Conditions

Polyphenols and triterpenoids in olive have relevant importance both in the physiology of the plant and the nutritional and biological value of its products. Olive leaf extracts are of special interest for their numerous health-promoting properties. The present research is investigating the occurrence of phytochemicals in supercritical fluid extracts from leaves with regard to collection time and drying temperature. The phytochemical profiles of the olive leaf extracts were determined by reversed-phase high-performance liquid chromatography (HPLC) coupled to electrospray ionization time-of-flight mass spectrometry (ESI-TOF-MS) detection. The main extracted phytochemicals were phenols and terpenoids. A significant variation in the amounts of the different components was observed as a function of the different drying temperature and collecting time (p < 0.05). Among samples, the maximal contents of polyphenols and secoiridoid derivatives were found in the extracts from olive leaves collected in November and dried at 120 °C, whereas triterpenoids showed the highest content in fresh leaves collected in August.

Olive leaf extract counteracts cell proliferation and cyst growth in an in vitro model of autosomal dominant polycystic kidney disease

Autosomal dominant polycystic kidney disease (ADPKD) is characterized by progressive enlargement of kidney cysts, leading to chronic kidney disease. Since the available treatment for ADPKD is limited, there is emerging interest for natural compounds as potential therapeutic candidates. The aim of our study was to investigate whether an olive leaf extract may be able to counteract the cyst growth in an in vitro model of ADPKD. We treated WT9-12 cells with an olive leaf extract (OLE). In monolayer culture we evaluated cell viability by the MTT assay, protein expression by western-blot analysis and apoptosis by DNA laddering and TUNEL assays. For functional studies we used transient transfection and ChIP assays. Intracellular calcium measurement was performed with a spectrofluorimeter using a fluorescent probe. 3D-cell-culture was used for cyst growth studies. OLE reduced the WT9-12 cell growth rate and affected intracellular signaling due to high c-AMP levels, as OLE reduced PKA levels, enhanced p-AKT, restored B-Raf-inactivation and down-regulated p-ERK. We elucidated the molecular mechanism by which OLE, via Sp1, transactivates the p21WAF1/Cip1 promoter, whose levels are down-regulated by mutated PKD1. We demonstrated that p-AKT up-regulation also played a crucial role in the OLE-induced anti-apoptotic effect and that OLE ameliorated intracellular calcium levels, the primary cause of ADPKD. Finally, using a 3D-cell-culture model we observed that OLE reduced the cyst size. Therefore, multifaceted OLE may be considered a new therapeutic approach for ADPKD treatment.

Oleuropein inhibits migration ability through suppression of epithelial-mesenchymal transition and synergistically enhances doxorubicin-mediated apoptosis in MCF-7 cells

Distinct metastasis is one of the main causes of breast cancer (BC)-related mortality and epithelial-mesenchymal transition (EMT) is a primary step in metastasis dissemination. On the other hand, doxorubicin (DOX) is an effective chemotherapeutic agent against BC; unfortunately, its clinical use is limited by dose-dependent side effects. Therefore, extensive efforts have been dedicated to suppressing metastasis of BC and also to overcome DOX side effects together with keeping its antitumor efficacy. Studies supported the role of oleuropein (OLEU) in reducing DOX-induced side effects besides its antitumor actions. In this study, the antimigratory effect of OLEU was assessed and real-time PCR (RT-PCR) was used to detect OLEU effect on the expression level of EMT markers, in MCF-7 cells. The cytotoxic effect of OLEU and DOX was assessed by MTT assay, whereas the ratio of apoptosis was investigated by flow cytometry. The results showed that migration ability of MCF-7 cells remarkably decreased in OLEU treated group and RT-PCR results showed that OLEU may exert its antimigratory action by suppressing EMT through downregulation of sirtuin1 (SIRT1). Also, the results indicated that both OLEU and DOX were cytotoxic to MCF-7 cells, whereas DOX-OLEU cotreatment led to additive cytotoxicity and apoptosis rate. This study provides evidence regarding the suppressive role of OLEU on MCF-7 cells migration ability through suppression of EMT, and for the first time, it was proposed that SIRT1 downregulation can be involved in the OLEU antimigratory effect. Also, the findings demonstrated that OLEU can reduce DOX-induced side effects by reducing its effective dose.

A specific QSAR model for proteasome inhibitors from Oleaeuropaea and Ficuscarica

Oleaeuropaea and Ficuscarica are widely used in traditional medicine for the treatment of cancer. Therefore, it is of interest to develop a QSAR model for screening proteasome inhibitors from plant source. Hence, a QSAR model was developed using multiple linear regressions; partial least squares regression and principal component regression methods. Results of QSAR modeling and docking demonstrate that compounds derived from both plants have great potentiality to be proteasome inhibitors. The developed QSAR model highlights a strong structure-effect relationship. The predicted correlation of comparative molecular field analysis, and comparative molecular similarity indexes are 0.963 and 0.919, respectively. Computed absorption, distribution, metabolism, excretion and toxicity studies on these derivatives showed encouraging results with very low toxicity, distribution and absorption.

Diosmetin suppresses human prostate cancer cell proliferation through the induction of apoptosis and cell cycle arrest

Diosmetin, a plant flavonoid, has been shown to exert promising effects on prostate cancer cells as an anti‑proliferative and anticancer agent. In this study, using western blot analysis for protein expression and flow cytometry for cell cycle analysis, we determined that the treatment of the LNCaP and PC‑3 prostate cancer cells with diosmetin resulted in a marked decrease in cyclin D1, Cdk2 and Cdk4 expression levels (these proteins remain active in the G0‑G1 phases of the cell cycle). These changes were accompanied by a decrease in c-Myc and Bcl-2 expression, and by an increase in Bax, p27Kip1 and FOXO3a protein expression, which suggests the potential modulatory effects of diosmetin on protein transcription. The treatment of prostate cancer cells with diosmetin set in motion an apoptotic machinery by inhibiting X-linked inhibitor of apoptosis (XIAP) and increasing cleaved PARP and cleaved caspase-3 expression levels. On the whole, the findings of this study provide an in-depth analysis of the molecular mechanisms responsible for the regulatory effects of diosmetin on key molecules that perturb the cell cycle to inhibit cell growth, and suggest that diosmetin may prove to be an effective anticancer agent for use in the treatment of prostate cancer in the future.

Characterization by liquid chromatography-mass spectrometry and antioxidant activity of an ethanolic extract of Inula viscosa leaves

Inula viscosa (I. viscosa) is a common Mediterranean plant, well known for its content on bioactive molecules. The chemical composition of an ethanolic extract from I. viscosa leaves, growing in Algeria, was analysed by liquid chromatography coupled to photodiode array detection and electrospray ionization mass spectrometry (LC-DAD-ESI-MS/MS) operating in negative and positive mode. The methodology used revealed the presence of 51 compounds from which 47 were putatively identified, including 11 phenolic acids, 23flavonoids, one lignan and 12 terpenoids. Twenty-six of these compounds are described for the first time in I. viscosa. Antioxidant activity was measured using three different and complementary chemical assays: DPPH radical scavenging activity, oxygen radical absorbance capacity (ORAC) and hydroxyl radical scavenging capacity (HOSC). Results demonstrate that ethanolic leaf extract exhibit a high scavenging ability against DPPH (157.72 ± 6.45 μM TE/g DW), peroxyl (4471.42 ± 113.16 μM TE/g DW) and hydroxyl (630.10 ± 17.81 μM TE/g DW) radicals, indicating that I. viscosa can be a promising source of bioactive compounds.

Geographical Characterization of Tunisian Olive Tree Leaves (cv. Chemlali) Using HPLC-ESI-TOF and IT/MS Fingerprinting with Hierarchical Cluster Analysis

The olive plant has been extensively studied for its nutritional value, whereas its leaves have been specifically recognized as a processing by-product. Leaves are considered by-products of olive farming, representing a significant material arriving to the olive mill. They have been considered for centuries as an important herbal remedy in Mediterranean countries. Their beneficial properties are generally attributed to the presence of a range of phytochemicals such as secoiridoids, triterpenes, lignans, and flavonoids. With the aim to study the impact of geographical location on the phenolic compounds, Olea europaea leaves were handpicked from the Tunisian cultivar "Chemlali" from nine regions in the north, center, and south of Tunisia. The ground leaves were then extracted with methanol : water 80% (v/v) and analyzed by using high-performance liquid chromatography coupled to electrospray time of flight and ion trap mass spectrometry analyzers. A total of 38 compounds could be identified. Their contents showed significant variation among samples from different regions. Hierarchical cluster analysis was applied to highlight similarities in the phytochemical composition observed between the samples of different regions.

Polyphenols as Promising Drugs against Main Breast Cancer Signatures

Breast cancer is one of the most common neoplasms worldwide, and in spite of clinical and pharmacological advances, it is still a clinical problem, causing morbidity and mortality. On the one hand, breast cancer shares with other neoplasms some molecular signatures such as an imbalanced redox state, cell cycle alterations, increased proliferation and an inflammatory status. On the other hand, breast cancer shows differential molecular subtypes that determine its prognosis and treatment. These are characterized mainly by hormone receptors especially estrogen receptors (ERs) and epidermal growth factor receptor 2 (HER2). Tumors with none of these receptors are classified as triple negative breast cancer (TNBC) and are associated with a worse prognosis. The success of treatments partially depends on their specificity and the adequate molecular classification of tumors. New advances in anticancer drug discovery using natural compounds have been made in the last few decades, and polyphenols have emerged as promising molecules. They may act on various molecular targets because of their promiscuous behavior, presenting several physiological effects, some of which confer antitumor activity. This review analyzes the accumulated evidence of the antitumor effects of plant polyphenols on breast cancer, with special attention to their activity on ERs and HER2 targets and also covering different aspects such as redox balance, uncontrolled proliferation and chronic inflammation.

A review of Tunisian medicinal plants with anticancer activity

Cancer is a major public health problem in the world. The use of the medicinal plants in cancer prevention and management is frequent in Africa, especially in Tunisia, and it is transmitted from generation to generation within cultures. Many previous studies showed that a wide range of Tunisian medicinal plants exerted cytotoxic and anticancer activity. A comprehensive review was conducted to collect information from scientific journal articles, including indigenous knowledge researches, about Tunisian medicinal plants used for the prevention and management of cancer. The aim of this review article is to provide the reader with information concerning the importance of Tunisian medicinal plants in the prevention and management of cancer and to open the door for the health professionals and scientists working in the field of pharmacology and therapeutics to produce new drug formulations to treat different types of cancer.

Applications of Metabolomics in Cancer Studies

Since the start of metabolomics as a field of research, the number of studies related to cancer has grown to such an extent that cancer metabolomics now represents its own discipline. In this chapter, the applications of metabolomics in cancer studies are explored. Different approaches and analytical platforms can be employed for the analysis of samples depending on the goal of the study and the aspects of the cancer metabolome being investigated. Analyses have concerned a range of cancers including lung, colorectal, bladder, breast, gastric, oesophageal and thyroid, amongst others. Developments in these strategies and methodologies that have been applied are discussed, in addition to exemplifying the use of cancer metabolomics in the discovery of biomarkers and in the assessment of therapy (both pharmaceutical and nutraceutical). Finally, the application of cancer metabolomics in personalised medicine is presented.

The Val158Met polymorphism in COMT gene and cancer risk: role of endogenous and exogenous catechols

Catechol-O-methyltransferase, COMT, is an important phase II enzyme catalyzing the transfer of a methyl-group from S-adenosylmethionine to a catechol-containing substrate molecule. A genetic variant Val158Met in the COMT gene leads to a several-fold decrease in the enzymatic activity giving rise to the accumulation of potentially carcinogenic endogenous catechol estrogens and their reactive intermediates and increasing thus the risk of tumorigenesis. However, numerous association studies between the COMT genotype and susceptibility to various malignancies have shown inconsistent and controversial findings indicating that additional gene-gene and gene-environment interactions might be crucial in modulating the physiological role of the COMT. In this review article, the important contribution of dietary catechol-containing flavonoids to modification of the relationships between the COMT genotype and cancer risk is discussed. Whereas, the diverse anticancer activities of common phytochemicals, such as green tea polyphenols, quercetin, fisetin or luteolin, can be markedly changed (both decreased or increased) by the COMT-mediated O-methylation of these exogenous substrates, flavonoids can also behave as potent inhibitors of the COMT enzyme slowing detoxification of endogenous catechol estrogens. Such a many-featured functioning of the COMT and its complex regulation by several different genetic and environmental factors, including plant-based food ingredients, emphasizes the necessity to further stratify the association studies between the COMT genotype and tumor risk by consumption of catechol-containing dietary flavonoids. Currently, it can be only speculated that some of the possible associations might be masked by the regular intake of specific food polyphenols, taking effect in certain communities or populations.

Evidence to Support the Anti-Cancer Effect of Olive Leaf Extract and Future Directions

The traditional Mediterranean diet (MD) is associated with long life and lower prevalence of cardiovascular disease and cancers. The main components of this diet include high intake of fruit, vegetables, red wine, extra virgin olive oil (EVOO) and fish, low intake of dairy and red meat. Olive oil has gained support as a key effector of health benefits and there is evidence that this relates to the polyphenol content. Olive leaf extract (OLE) contains a higher quantity and variety of polyphenols than those found in EVOO. There are also important structural differences between polyphenols from olive leaf and those from olive fruit that may improve the capacity of OLE to enhance health outcomes. Olive polyphenols have been claimed to play an important protective role in cancer and other inflammation-related diseases. Both inflammatory and cancer cell models have shown that olive leaf polyphenols are anti-inflammatory and protect against DNA damage initiated by free radicals. The various bioactive properties of olive leaf polyphenols are a plausible explanation for the inhibition of progression and development of cancers. The pathways and signaling cascades manipulated include the NF-κB inflammatory response and the oxidative stress response, but the effects of these bioactive components may also result from their action as a phytoestrogen. Due to the similar structure of the olive polyphenols to oestrogens, these have been hypothesized to interact with oestrogen receptors, thereby reducing the prevalence and progression of hormone related cancers. Evidence for the protective effect of olive polyphenols for cancer in humans remains anecdotal and clinical trials are required to substantiate these claims idea. This review aims to amalgamate the current literature regarding bioavailability and mechanisms involved in the potential anti-cancer action of olive leaf polyphenols.