In Vitro Effects of Extracts of Extra Virgin Olive Oil on Human Colon Cancer Cells

Reviewing the cardiovascular and other health effects of olive oil: Limitations and future directions of current supplement formulations

AIMS

We reviewed the literature to date for high-level evidence on the cardiovascular and other health effects of olive oil with a focus on the amount, frequency of use and type of olive oil consumed in prior studies. A total of twelve prospective cohort studies with sample sizes of at least 4000 individuals and one meta-analysis were identified.

DATA SYNTHESIS

The majority of cohorts followed individuals aged ≥55 years old, free of cardiovascular disease (CVD) at baseline but at high risk, over periods of 4-10 years and with daily consumption amounts of 10-35 g/day. With the exception of the PREDIMED cohort that employed extra virgin olive oil, most remaining studies did not differentiate between different types of olive oil. Taken together, the data suggests an association between greater olive oil consumption and a lower CVD incidence/mortality and stroke risk. We use this information to evaluate the use of commercially available, capsule-based olive oil dietary supplements and suggest future directions. Notably, achieving minimum total daily doses described in the aforementioned studies would be challenging with current market formulations of olive oil supplements dosed at 1-1.25 g/capsule.

CONCLUSIONS

Outside of mechanistic studies, little progress has been made in determining the olive oil component(s) underlying the observed health effects given the lack of compositional reporting and consistency across large scale human studies. We propose the use of supplements of varying composition, such as varying total phenolic content, in pragmatic trial designs focused on low-cost methodologies to address this question.

Bio-phenols determination in olive oils: Recent mass spectrometry approaches

Extra virgin olive oil (EVOO) is largely used in Mediterranean diet, and it is also worldwide apprised not only for its organoleptic properties but also for its healthy effects mainly attributed to the presence of several naturally occurring phenolic and polyphenolic compounds (bio-phenols). These compounds are characterized by the presence of multiple phenolic groups in more or less complex structures. Their content is fundamental in defining the healthy qualities of EVOO and consequently the analytical methods for their characterization and quantification are of current interest. Traditionally their determination has been conducted using a colorimetric assay based on the reaction of Folin-Ciocalteu (FC) reagent with the functional hydroxy groups of phenolic compounds. Identification and quantification of the bio-phenols in olive oils requires certainly more performing analytical methods. Chromatographic separation is now commonly achieved by HPLC, coupled with spectrometric devices as UV, FID, and MS. This last approach constitutes an actual cutting-edge application for bio-phenol determination in complex matrices as olive oils, mostly on the light of the development of mass analyzers and the achievement of high resolution and accurate mass measurement in more affordable instrument configurations. After a short survey of some rugged techniques used for bio-phenols determination, in this review have been described the most recent mass spectrometry-based methods, adopted for the analysis of the bio-phenols in EVOOs. In particular, the sample handling and the results of HPLC coupled with low- and high-resolution MS and MS/MS analyzers, of ion mobility mass spectrometry and ambient mass spectrometry have been reported and discussed.

A Systematic Ex-Vivo Study of the Anti-Proliferative/Cytotoxic Bioactivity of Major Olive Secoiridoids' Double Combinations and of Total Olive Oil Phenolic Extracts on Multiple Cell-Culture Based Cancer Models Highlights Synergistic Effects

Several individual olive oil phenols (OOPs) and their secoiridoid derivatives have been shown to exert anti-proliferative and pro-apoptotic activity in treatments of human cancer cell lines originating from several tissues. This study evaluated the synergistic anti-proliferative/cytotoxic effects of five olive secoiridoid derivatives (oleocanthal, oleacein, oleuropein aglycone, ligstroside aglycone and oleomissional) in all possible double combinations and of total phenolic extracts (TPEs) on eleven human cancer cell lines representing eight cell-culture-based cancer models. Individual OOPs were used to treat cells for 72 h in half of their EC₅₀ values for each cell line and their synergistic, additive or antagonistic interactions were evaluated by calculating the coefficient for drug interactions (CDI) for each double combination of OOPs. Olive oil TPEs of determined OOPs' content, originating from three different harvests of autochthonous olive cultivars in Greece, were evaluated as an attempt to investigate the efficacy of OOPs to reduce cancer cell numbers as part of olive oil consumption. Most combinations of OOPs showed strong synergistic effect (CDIs < 0.9) in their efficacy, whereas TPEs strongly impaired cancer cell viability, better than most individual OOPs tested herein, including the most resistant cancer cell lines evaluated.

Hydroxytyrosol decreases EDNRA expression through epigenetic modification in colorectal cancer cells

The Mediterranean diet (MD) is one of the healthiest ones and is associated with a lower incidence of cardiovascular and cerebrovascular diseases as well as cancer. Extra virgin olive oil (EVOO) is probably the most idiosyncratic component of this diet. EVOO has been attributed with many healthful effects, which may be due to its phenolic components, e.g. including hydroxytyrosol (HT). Recent studies suggest that EVOO and HT have molecular targets in human tissues and modulate epigenetic mechanisms. DNA methylation is one of the most studied epigenetic mechanisms and consists of the addition of a methyl group to the cytosines of the DNA chain. Given the purported health effects of EVOO (poly)phenols, we analyzed the changes induced by HT in DNA methylation, in a colorectal cancer cell line. Caco-2 cells were treated with HT for one week or with the demethylating agent 5'-azacytidine for 48 h. Global DNA methylation was assessed by ELISA. DNA bisulfitation was performed and Infinium Methylation EPIC BeadChips were used to analyze the specific methylation of CpG sites. We show an increase in global DNA methylation in Caco-2 cells after HT treatment, with a total of 32,141 differentially methylated (CpGs DMCpGs). Interestingly, our analyses revealed the endothelin receptor type A gene (EDNRA) as a possible molecular target of HT. In summary, we demonstrate that cellular supplementation with HT results in a specific methylome map and propose a potential gene target for HT.

Functional nanoemulsion and nanocomposite microparticles as an anticolorectal cancer and antimicrobial agent: applied in yogurt

Great concern for human health has led the food industry to focus on functional products. Microparticles based on nanoemulsions (M1) and nanocomposites (M2) were developed to deliver vital agents against colorectal cancer and microbial infection. The functional microparticles were prepared by coating extra virgin olive oil (EVOO), probiotics, and fig leaves extract with sodium alginate (SA) and whey protein concentrate (WPC) using the freeze drying technique. The antimicrobial, cytotoxic, apoptotic, encapsulation efficiency (EE %), release rate, and antioxidant activity were investigated. The yogurt was loaded with microparticles and evaluated microbiology, chemically, and sensory during storage. The results showed that the size of nanoemulsion and nanocomposite was between 476.1 and 517.7 nm, while the zeta potentials were −30.1 and −34.5 mV, respectively. M2 microparticles recorded the lowest IC50 values against human colorectal cancerous Caco-2 and HCT 116 cell lines: 1.10 μg/mL and 15.34 μg/mL, respectively. The inhibition zones were between 11 to 20 and 9 to 18 mm for M1 and M2, respectively. The highest EE% was 89.20% for EVOO and 91.34% for probiotics in M2 microparticles. The induction period of the EVOO from M1 and M2 microparticles was 15.37 h and 13.09 h, respectively. The antioxidant activity was between 78 and 65.8% for M1 and M2 microparticles, respectively. The probiotics in yogurt with microparticles were more than un-coated cells, and the taste of these samples was acceptable during storage. This study suggests that microencapsulation could be considered an interesting therapeutic tool when EVOO and probiotics are used in functional food.

Antimicrobial and cytotoxic activity to human colon adenocarcinoma cell lines (HT-29) potential of olive oil extraction residue

In the Olive drupe (Olea europaea L.) oil extraction process, 80% of the volume generated is waste (bagasse). Advancing the expansion of the olive oil market, it is necessary to develop alternatives that, in addition to adding value to industrial waste, also reduce possible environmental damage. Our study aimed to understand the antimicrobial and Cytotoxic activity potential of the residues from the extraction of olive oil from the blend of the varieties Arbequina and Arbosana. The extract shows cytotoxic activity, inhibiting about 75% of cancer cells in the human colon at a concentration of 0.15 mg of Gallic Acid equivalent (GAE)/mL. The effectiveness of the extract against microorganisms often associated with foodborne diseases and food decomposition has also been discovered, without compromising the microorganisms responsible for fermentation. Thus, this study provides future perspectives for the use of active ingredients extracted from the residue from the extraction of olive oil.

Potential of olive oil and its phenolic compounds as therapeutic intervention against colorectal cancer: a comprehensive review

Colorectal cancer (CRC) is one of the major causes of death across the world and incidence rate of CRC increasing alarmingly each passing year. Diet, genomic anomalies, inflammation and deregulated signalling pathways are among the major causes of CRC. Because of numerous side effects of CRC therapies available now, researchers all over the world looking for alternative treatment/preventive strategy with lesser/no side effects. Olive oil which is part of Mediterranean diet contains numerous phenolic compounds that fight against free radicals and inflammation and also well-known for protective role against CRC. The current review focused on the recent evidences where olive oil and its phenolic compounds such as hydroxytyrosol, oleuropein and oleocanthal showed activities against CRC as well to analyse the cellular and molecular signalling mechanism through which these compounds act on. These compounds shown to combat CRC by reducing proliferation, migration, invasion and angiogenesis through regulation of numerous signalling pathways including MAPK pathway, PI3K-Akt pathway and Wnt/β-catenin pathway and at the same time, induce apoptosis in different CRC model. However, further research is an absolute necessity to establish these compounds as nutritional supplements and develop therapeutic strategy in CRC.

A Comparison of the Anti-Cancer Effects of Free and PLGA-PAA Encapsulated Hydroxytyrosol on the HT-29 Colorectal Cancer Cell Line

BACKGROUND

Hydroxytyrosol is one of the phenolic compounds of olive oil and can induce anti-cancer effects on the colorectal cancer cells.

OBJECTIVE

The aim of the present study was to evaluate the free hydroxytyrosol and nano-capsulated hydroxytyrosol effects on the cell cycle arrest in HT-29 colorectal cancer cell line.

METHODS

The nano-capsulated hydroxytyrosol was synthesized in poly lactide-co-glycolide-co-polyacrylic acid (PLGA-PAA) copolymer. MTT assay was performed to evaluate the anti- proliferative and anti-tumor effects of the free hydroxytyrosol and nano-capsulated hydroxytyrosol. Finally, the relative expression of CDKN1A, CDKN1B and CCND1 genes was evaluated in the control and treated colorectal cancer cells by using Real-Time PCR.

RESULTS

The obtained results from the MTT assay showed that the cytotoxic effects of the nano-capsulated hydroxytyrosol on the colorectal cancer cell line (IC50= 6PPM) was significantly more than free hydroxytyrosol (IC50= 12PPM) after 72h. Also, nano-capsulated hydroxytyrosol showed more significant effects on the up-regulation of CDKN1A and CDKN1B genes, and down-regulation of the CCND1 gene in the colorectal cancer cells.

CONCLUSION

In conclusion, the present study showed that the hydroxytyrosol led to die the colorectal cancer cell through the cell cycle arrest. Also, the PLGA-PAA copolymer dramatically caused to increase the cytotoxic effects of the hydroxytyrosol on the colorectal cancer cells.

Antique Traditional Practice: Phenolic Profile of Virgin Olive Oil Obtained from Fruits Stored in Seawater

Virgin olive oil (VOO) is a functional food specific to the Mediterranean diet and related to human health, especially as a protector of cardiovascular health, in the prevention of several types of cancers, and in modification of immune and inflammatory response. Phenolic compounds have central importance for these extraordinary health benefits. In the production of high-quality olive oils, it is very important to process freshly picked olives and avoid any storage of fruits. However, in Croatia there is a very traditional and environmentally friendly method of olive oil production, where olive fruits are stored in seawater for some time prior to processing. This practice is also notable nowadays since there are people who prefer the characteristic flavor of the “seawater olive oil”, although some people argue against its quality and biomedical relevance. In this study, the phenolic contents of VOO prepared from the immediately processed fresh olives and olives processed after storage in seawater were compared with the use of high-performance liquid chromatography-mass spectrometry (HPLC-MS) and spectrophotometric analysis. The results suggest that “seawater olive oil” should be considered as a safe food of biomedical relevance, as it still contains a significant proportion of important phenolics like hydroxytyrosol, tyrosol and oleacein (e.g., 63.2% of total phenols in comparison to VOO).

An Industrial and Sustainable Platform for the Production of Bioactive Micronized Powders and Extracts Enriched in Polyphenols From Olea europaea L. and Vitis vinifera L. Wastes

In the last few years, literature data have reported that health status is related to the consumption of foods rich in polyphenols, bioactive compounds found in the plant world, in particular in vegetables and fruit. These pieces of scientific evidence have led to an increase in the demand for functional foods and drinks enriched in polyphenols, so that plant materials are more and more requested. The availability of food and agricultural wastes has adverse effects on the economy, environment, and human health. On the other hand, these materials are a precious source of bioactive compounds as polyphenols. Their recovery and reuse from wastes are according to the circular economy strategy, which has introduced the “zero waste concept.” However, the process is convenient from an economic and environmental point of view only if the final products are standardized and obtained using sustainable and industrial technologies. In this panorama, this paper describes an industrial and sustainable platform for the production of micronized powders and extracts enriched in polyphenols from Olea europaea L. and Vitis vinifera L. wastes that are useful for food, cosmetics, and pharmaceuticals sectors. The platform is based on drying plant materials, extraction of polyphenols through membrane technologies with water, and, when necessary, the concentration of the final fractions under vacuum evaporation. All powders and extracts were characterized by high-performance liquid chromatography–diode array detector–mass spectrometry analysis to define the qualitative and quantitative content of bioactive compounds and insure their standardization and reproducibility. The chromatographic profiles evidenced the presence of secoiridoids, flavones, flavonols, anthocyanins, hydroxycinnamic acids, catechins, and condensed tannins. An overview of the biological activities of the main polyphenols present in Olea europaea L. and Vitis vinifera L. powders and extracts is reported because of biomedical applications.

Biological Activity of Phenolic Compounds in Extra Virgin Olive Oils through Their Phenolic Profile and Their Combination with Anticancer Drugs Observed in Human Cervical Carcinoma and Colon Adenocarcinoma Cells

The roles of phenolics from olive oils as effective anticancer agents have been documented in various in vitro studies of different cancer cells lines, but the relationship between the phenolic profile of olive oil and its biological activity needs more elucidation. In this study, we analysed phenolic profiles of extra virgin olive oils (EVOOs) from different autochthonous cultivars from Croatia (Oblica, Bjelica, Buža, Žižolera) and investigated the biological effect of EVOO phenolic extracts (EVOO-PEs) on human cervical (HeLa) and human colon (SW48) cancer cell lines alone and in combination with cisplatin (cDDP), carboplatin (CBP), 5-fluorouracil (5-FU) and irinotecan. The quantitative evaluation of olive oil polyphenols was performed by HPLC-DAD and spectrophotometric analysis. The biological effect of EVOO-PEs alone and in combination with anticancer drugs was measured by MTT assay. Analysed EVOO-PEs differ in phenolic profile and inhibited HeLa and SW48 cells in a dose-dependent manner. Further, it is shown that EVOO-PEs (Oblica-Sea, Buža and Žižolera), in combination with anticancer drugs, increase the metabolic activity of HeLa and SW48 cells and have a protective role. These data imply careful consummation of olive oil during chemotherapy of cancer patients.

Anticancer effects of olive oil polyphenols and their combinations with anticancer drugs

Cancer presents one of the leading causes of death in the world. Current treatment includes the administration of one or more anticancer drugs, commonly known as chemotherapy. The biggest issue concerning the chemotherapeutics is their toxicity on normal cells and persisting side effects. One approach to the issue is chemoprevention and the other one is the discovery of more effective drugs or drug combinations, including combinations with polyphenols. Olive oil polyphenols (OOPs), especially hydroxytyrosol (HTyr), tyrosol (Tyr) and their derivatives oleuropein (Ole), oleacein and oleocanthal (Oc) express anticancer activity on different cancer models. Recent studies report that phenolic extract of virgin olive oil may be more effective than the individual phenolic compounds. Also, there is a growing body of evidence about the combined treatment of OOPs with various anticancer drugs, such as cisplatin, tamoxifen, doxorubicin and others. These novel approaches may present an advanced strategy in the prevention and treatment of cancer.

Virgin Olive Oil and Health: Summary of the III International Conference on Virgin Olive Oil and Health Consensus Report, JAEN (Spain) 2018

The Mediterranean diet is considered as the foremost dietary regimen and its adoption is associated with the prevention of degenerative diseases and an extended longevity. The preeminent features of the Mediterranean diet have been agreed upon and the consumption of olive oil stands out as the most peculiar one. Indeed, the use of olive oil as the nearly exclusive dietary fat is what mostly characterizes the Mediterranean area. Plenty of epidemiological studies have correlated that the consumption of olive oil was associated with better overall health. Indeed, extra virgin olive oil contains (poly)phenolic compounds that are being actively investigated for their purported biological and pharma-nutritional properties. On 18 and 19 May 2018, several experts convened in Jaen (Spain) to discuss the most recent research on the benefits of olive oil and its components. We reported a summary of that meeting (reviewing several topics related to olive oil, not limited to health) and concluded that substantial evidence is accruing to support the widespread opinion that extra virgin olive oil should, indeed, be the fat of choice when it comes to human health and sustainable agronomy.

A whole-food approach to the in vitro assessment of the antitumor activity of gazpacho

Gazpacho is a traditional cold soup of the Mediterranean diet consisting of a main base of fresh pureed tomato and other vegetables. Tomato and tomato products have demonstrated chemopreventive activity against several types of cancer through in vitro studies, and in animal and clinical research. Here we have applied a whole-food approach for the preclinical assessment of the antitumor potential of gazpacho. Colon cancer cells (HT-29) were exposed to growing concentrations of gazpacho previously digested in vitro to simulate the delivery of bioactive molecules to colon cells after food consumption. The cytotoxicity of gazpacho ingredients was also tested in independent experiments. Programmed cell death by apoptosis was detected by using a multiparametric analysis that combines image-based bright-field and fluorescence cytometry, intracellular ATP level determination and enzymatic activity of caspase-3/7. Modulation of gene expression of key regulatory genes (p53, Bcl-2, BAX, and cyclin D1) was also investigated. Our cytotoxicity data showed that in vitro digestion of samples allowed the delivery of bioactive levels of antitumor phytochemicals to cultured cells. Controlled experiments showed significant repetitive dose and time-response cytotoxicity of gazpacho. Gazpacho digestates caused net cell death of cultures suggesting synergic activity among phytochemicals from its vegetable ingredients. Multiparametric and genetic analyses showed that gazpacho digestates can trigger colon cancer cells death by apoptosis through the activation of caspase cascade. Our results show that coupled in vitro methodology employed can be applied to investigate the antitumor potential of complex food matrixes or combinations of foods in the diet.

Pharma-Nutritional Properties of Olive Oil Phenols. Transfer of New Findings to Human Nutrition

The Mediterranean diet has been long associated with improved cardiovascular prognosis, chemoprevention, and lower incidence of neurodegeneration. Of the multiple components of this diet, olive oil stands out because its use has historically been limited to the Mediterranean basin. The health benefits of olive oil and some of its components are being rapidly decoded. In this paper we review the most recent pharma-nutritional investigations on olive oil biophenols and their health effects, chiefly focusing on recent findings that elucidate their molecular mechanisms of action.

Characterization of phenolic extracts from Brava extra virgin olive oils and their cytotoxic effects on MCF-7 breast cancer cells

The aim of the present work was to evaluate the phenolic profile of the 'Brava' extra virgin olive oil and assess its potential as a "natural adjuvant" in combination with chemotherapy treatment. The total phenol content of the phenolic extracts was 764 mg gallic acid equivalents/kg and the total antioxidant capacity was 2309, 1881 and 2088 μM trolox equivalents/kg determined by Diphenyl-1-picrylhydrazyl free radical method, Ferric Reducing Antioxidant Power and Trolox Equivalent Antioxidant Capacity assay, respectively. Secoiridoids comprised 83% of the total phenolic compounds. The main secoiridoid from oleuropein was the main isomer of oleuropein aglycone (74 mg/kg). The main secoiridoid from ligstroside was the main isomer of ligstroside aglycone (214 mg/kg). These phenolic extracts showed a significant decrease in cell viability on MCF-7 breast cancer cells in a dose and time dependent manner. 48 h-treatments with different concentrations of the extracts induced intracellular ROS generation and cell death.

Lipophilization of Hydroxytyrosol-Enriched Fractions from Olea europaea L. Byproducts and Evaluation of the in Vitro Effects on a Model of Colorectal Cancer Cells

A hydroxytyrosol (HTyr)-enriched fraction containing HTyr 6% w/w, derived from Olea europaea L. byproducts and obtained using an environmentally and economically sustainable technology, was lipophilized under green chemistry conditions. The effects of three fractions containing hydroxytyrosyl butanoate, octanoate, and oleate, named, respectively, lipophilic fractions 5, 6, and 7, and unreacted HTyr on the human colon cancer cell line HCT8-β8 engineered to overexpress estrogen receptor β (ERβ) were evaluated and compared to those of pure HTyr. The experimental data demonstrated that HTyr and all fractions showed an antiproliferative effect, as had been observed by the evaluation of the cellular doubling time under these different conditions (mean control, 32 ± 4 h; HTyr 1, 65 ± 9 h; fraction 5, 64 ± 11 h; fraction 6, 62 ± 14 h; fraction 7, 133 ± 30 h). As evidenced, fraction 7 containing hydroxytyrosyl oleate showed the highest activity. These results were related to the link with ER-β, which was assessed through simultaneous treatment with an inhibitor of ERβ.

Transcriptomics and the Mediterranean Diet: A Systematic Review

The Mediterranean diet has been proven to be highly effective in the prevention of cardiovascular diseases and cancer and in decreasing overall mortality. Nowadays, transcriptomics is gaining particular relevance due to the existence of non-coding RNAs capable of regulating many biological processes. The present work describes a systematic review of current evidence supporting the influence of the Mediterranean diet on transcriptomes of different tissues in various experimental models. While information on regulatory RNA is very limited, they seem to contribute to the effect. Special attention has been given to the oily matrix of virgin olive oil. In this regard, monounsaturated fatty acid-rich diets prevented the expression of inflammatory genes in different tissues, an action also observed after the administration of olive oil phenolic compounds. Among these, tyrosol, hydroxytyrosol, and secoiridoids have been found to be particularly effective in cell cycle expression. Less explored terpenes, such as oleanolic acid, are important modulators of circadian clock genes. The wide range of studied tissues and organisms indicate that response to these compounds is universal and poses an important level of complexity considering the different genes expressed in each tissue and the number of different tissues in an organism.