Antiproliferative effect of plant sterols at colonic concentrations on Caco-2 cells

Phytosterols: Physiological Functions and Potential Application

Dietary intake of natural substances to regulate physiological functions is currently regarded as a potential way of promoting health. As one of the recommended dietary ingredients, phytosterols that are natural bioactive compounds distributed in plants have received increasing attention for their health effects. Phytosterols have attracted great attention from scientists because of many physiological functions, for example, cholesterol-lowering, anticancer, anti-inflammatory, and immunomodulatory effects. In addition, the physiological functions of phytosterols, the purification, structure analysis, synthesis, and food application of phytosterols have been widely studied. Nowadays, many bioactivities of phytosterols have been assessed in vivo and in vitro. However, the mechanisms of their pharmacological activities are not yet fully understood, and in-depth investigation of the relationship between structure and function is crucial. Therefore, a contemporaneous overview of the extraction, beneficial properties, and the mechanisms, as well as the current states of phytosterol application, in the food field of phytosterols is provided in this review.

Phytosterols and the Digestive System: A Review Study from Insights into Their Potential Health Benefits and Safety

Phytosterols are a large group of substances belonging to sterols-compounds naturally occurring in the tissues of plants, animals, and humans. The most well-known animal sterol is cholesterol. Among phytosterols, the most significant compounds are β-sitosterol, stigmasterol, and campesterol. At present, they are mainly employed in functional food products designed to counteract cardiovascular disorders by lowering levels of 'bad' cholesterol, which stands as their most extensively studied purpose. It is currently understood that phytosterols may also alleviate conditions associated with the gastrointestinal system. Their beneficial pharmacological properties in relation to gastrointestinal tract include anti-inflammatory and hepatoprotective activity. Also, the anti-cancer properties as well as the impact on the gut microbiome could be a very interesting area of research, which might potentially lead to the discovery of their new application. This article provides consolidated knowledge on a new potential use of phytosterols, namely the treatment or prevention of gastrointestinal diseases. The cited studies indicate high therapeutic efficacy in conditions such as peptic ulcer disease, IBD or liver failure caused by hepatotoxic xenobiotics, however, these are mainly in vitro or in vivo studies. Nevertheless, studies to date indicate their therapeutic potential as adjunctive treatments to conventional therapies, which often exhibit unsatisfactory efficacy or serious side effects. Unfortunately, at this point there is a lack of significant clinical study data to use phytosterols in clinical practice in this area.

Chemopreventive Effect of an In Vitro Digested and Fermented Plant Sterol-Enriched Wholemeal Rye Bread in Colon Cancer Cells

Diet is crucial for the prevention of colorectal cancer. Whole grains are the source of beneficial compounds for this, such as fiber. The enrichment of wholemeal rye bread with plant sterols (PSs) could increase its beneficial effects. This study aimed to assess the potential antiproliferative effect of this enriched food on colon adenocarcinoma cells (Caco-2) compared with a non-enriched one. After a human oral chewing, simulated semi-dynamic gastrointestinal digestion and colonic fermentation in a simgi® system, fermentation liquids (FLs) obtained were used as treatment for cells. Cytotoxicity assay showed that samples diluted 1/5 (v/v) with DMEM are not toxic for non-tumoral cells, whereas they damage tumoral cells. Samples with PS (FLPS) produced a higher chemopreventive effect (vs. blank) in MTT and apoptosis assays, as well as higher gene expression of TP53 and Casp8. Nevertheless, FL0 (without PS) produced a higher chemopreventive effect in a cell cycle and reduced glutathione and calcium assays, besides producing higher gene expression of Casp3 and lower CCND1. The distinct antiproliferative effect of both FLs is attributed to differences in PSs, short chain fatty acids (lower concentration in FLPS vs. FL0) and antioxidant compounds. These results may support wholemeal rye bread consumption as a way of reducing the risk of colorectal cancer development, although further research would be needed.

Ethylcoprostanol modulates colorectal cancer cell proliferation and mitigates cytotoxicity of cholesterol metabolites in non-tumor colon cells

Sterols can be metabolized by gut microbiota. The cholesterol metabolites have been proposed as promoters of colorectal cancer (CRC), while the effect of plant sterol metabolites is unknown. This study aimed to evaluate the cytotoxicity of metabolites from cholesterol (coprostanol, cholestanol, coprostanone and cholestenone) and β-sitosterol (ethylcoprostanol) on human colon tumor (Caco-2) and non-tumor (CCD-18Co) cells at physiological concentrations (9-300 μM) and exposure time (24 h). Ethylcoprostanol reduced the tumor cell proliferation (MTT), showing in flow cytometry assays induction of apoptosis via production of reactive oxygen species (ROS) and ceramide. Transcriptomic analysis (qPCR) showed activation of the intrinsic apoptosis pathway (BAX/BCL2 ratio and CASP9 increased), accompanied by downregulation of the p21 gene. Cholesterol metabolites, mainly the most hydrophobic, induced apoptosis and G0/G1 phase arrest in non-tumor cells through overproduction of ROS. Both the intrinsic and extrinsic (CASP8 increased) apoptosis pathways occurred. In turn, a reduction in the expression of the cyclin E1 gene confirmed the cell cycle arrest. In addition, ethylcoprostanol protected non-tumor cells from the most cytotoxic cholesterol metabolite (cholestenone). In conclusion, ethylcoprostanol is a promising candidate as a therapeutic adjuvant in CRC, while cholesterol metabolites could act as CRC promoters through their cytotoxicity.

Chemical composition and bioactive compounds of cashew (Anacardium occidentale) apple juice and bagasse from Colombian varieties

Cashew nut production generates large amounts of cashew apple as residue. In Colombia, cashew cultivation is increasing together with the concerns on residue management. The objective of this study was to provide the first chemical, physical and thermal decomposition characterization of cashew apple from Colombian varieties harvested in Vichada, Colombia. This characterization was focused to identify the important bioactive and natural compounds that can be further valorized in the formulation of food, nutraceuticals, and pharmacological products. The results obtained in this study are helpful to portray the cashew apple as a potential by-product due to its renewable nature and valuable composition, instead of seeing it just as an agricultural residue. For that, cashew apples of Regional 8315 and Mapiria varieties were studied. The natural juice (cashew apple juice) that was extracted from the cashew apples and the remanent solids (cashew apple bagasse) were separately analyzed. The HPLC analytical technique was used to determine the concentration of bioactive compounds, structural carbohydrates, and soluble sugars that constitute this biomass. Spectrophotometric techniques were used to determine the concentration of tannins, carotenoids, and total polyphenols. Mineral content and antioxidant activity (DPPH and ABTS assays) were determined in the biomass. Also, the thermal decomposition under an inert atmosphere or pyrolysis was performed on cashew apple bagasse. The varieties of cashew apple studied in this work showed similar content of bioactive compounds, total phenolic content, and structural carbohydrates. However, the Mapiria variety showed values slightly higher than the Regional 8315. Regarding cashew apple juice, it is rich in tannins and ascorbic acid with values of 191 mg/100 mL and 70 mg/100 mL, respectively, for Mapiria variety. Additionally, the principal reservoir of bioactive compounds and constitutive carbohydrates was the cashew apple bagasse. About 50 wt.% of it was composed of cellulose and hemicellulose. Also, in the bagasse, the ascorbic acid content was in a range of 180–200 mg/100 g, which is higher than other fruits and vegetables. Moreover, alkaloids were identified in cashew apples. The maximum value of antioxidant activity (DPPH assay: 405 TEs/g) was observed in the bagasse of Mapiria variety. The bagasse thermal decomposition started around 150 °C when the structural carbohydrates and other constitutive substances started to degrade. After thermogravimetric analysis, a remanent of 20% of the initial weight suggested the formation of a rich-carbon solid, which could correspond to biochar. Therefore, the cashew apple harvested in Vichada is a valuable reservoir of a wide range of biomolecules that potentially could be valorized into energy, foods, and pharmacologic applications. Nevertheless, future work is necessary to describe the complex compounds of this residual biomass that are still unknown.

Phytosterols: From Preclinical Evidence to Potential Clinical Applications

Phytosterols (PSs) are plant-originated steroids. Over 250 PSs have been isolated, and each plant species contains a characteristic phytosterol composition. A wide number of studies have reported remarkable pharmacological effects of PSs, acting as chemopreventive, anti-inflammatory, antioxidant, antidiabetic, and antiatherosclerotic agents. However, PS bioavailability is a key issue, as it can be influenced by several factors (type, source, processing, preparation, delivery method, food matrix, dose, time of administration into the body, and genetic factors), and the existence of a close relationship between their chemical structures (e.g., saturation degree and side-chain length) and low absorption rates has been stated. In this sense, the present review intends to provide in-depth data on PS therapeutic potential for human health, also emphasizing their preclinical effects and bioavailability-related issues.

Antiproliferative activity of green, black tea and olive leaves polyphenols subjected to biosorption and in vitro gastrointestinal digestion in Caco-2 cells

Olive (Olea europaea L.) leaves and tea (Camellia sinensis) are rich sources of bioactive compounds, especially polyphenols. Our previous studies have evidenced the potential use of Saccharomyces cerevisiae as a natural delivery system for these antioxidants and a means to improve their bioaccessibility in the human gut. In the present work, the antiproliferative effect of green tea (GT), black tea (BT) and olive leaves (OL) infusions and suspensions of S. cerevisiae were evaluated, for the first time, in human colon cancer cells (Caco-2) after biosorption and in vitro gastrointestinal digestion. The bioaccessible fractions (BF) were not overtly cytotoxic, not affecting cell viability. ROS and mitochondrial membrane potential changes (Δψm) values were reduced compared with control cells. Moreover, all the BF after biosorption induced a significant (p < 0.05) increase in cell proportions in S-phase. The arrest of the cell cycle was reversible without induction of apoptosis, suggesting that the biosorbed phenolics in both infusions and suspensions act as cytostatic agents.

Antiproliferative Effect of Bioaccessible Fractions of Four Brassicaceae Microgreens on Human Colon Cancer Cells Linked to Their Phytochemical Composition

The antiproliferative effect of the bioaccessible fractions (BFs) of four hydroponic Brassicaceae microgreens (broccoli, kale, mustard and radish) was evaluated on colon cancer Caco-2 cells vs. normal colon CCD18-Co cells after 24 h treatment with BFs diluted 1:10 v/v in cell culture medium. Their bioactivity was compared with the digestion blank, while the colon cancer chemotherapeutic drug 5-fluorouracil was used as a positive control. Cell viability (mitochondrial enzyme activity assay (MTT test) and Trypan blue test) and mechanisms related to antiproliferative activity (cell cycle, apoptosis/necrosis, mitochondrial membrane potential, reactive oxygen species (ROS) production, Ca2+ and glutathione (GSH) intracellular content) were studied. All microgreen BFs increased ROS and decreased GSH, altering the redox status and causing mitochondrial membrane dissipation followed by a general cell cycle arrest in G2/M and apoptotic cell death via a Ca2+-independent mechanism. As a result, the antioxidant bioactive compounds present in these microgreen species reduced the proliferation of tumoral cells (10 to 12.8% -MTT or 20 to 41.9% -Trypan blue), showing lesser effects with broccoli microgreens, in line with their lower ascorbic acid content and total antioxidant capacity. Therefore, the daily intake of microgreens within a balanced diet could be a preventive nutritional strategy to reduce the burden of chronic degenerative diseases such as colon cancer.

Apoptotic effect of a phytosterol-ingredient and its main phytosterol (β-sitosterol) in human cancer cell lines

Dietary interventions may effectively control cancer development, with phytosterols (PS) being a class of cancer chemopreventive dietary phytochemicals. The present study, for the first time, evaluates the antiproliferative effects of a PS-ingredient used for the enrichment of several foods and its main PS, β-sitosterol, at physiological serum levels, in the most prevalent cancer cells in women (breast (MCF-7), colon (HCT116) and cervical (HeLa)). In all three cell lines, these compounds induced significant cell viability reduction without a clear time- and dose-dependent response. Moreover, all treatments produced apoptotic cell death with the induction of DNA fragmentation through the appearance of a sub-G1 cell population. Thus, the use of PS as functional ingredients in the development of PS-enriched foods could exert a potential preventive effect against human breast, colon and cervical cancer, although further in vivo studies are required to confirm our preclinical findings.

A positive impact on the serum lipid profile and cytokines after the consumption of a plant sterol-enriched beverage with a milk fat globule membrane: a clinical study

Positive impact on serum lipids and cytokines after functional beverage's intake by postmenopausal women.