Use of Oleuropein and Hydroxytyrosol for Cancer Prevention and Treatment: Considerations about How Bioavailability and Metabolism Impact Their Adoption in Clinical Routine

Caffeic acid stimulates migration and invasion of human trophoblast HTR-8/SVneo cells

The placenta is a transient organ essential for development of the fetus. Adequate invasion of trophoblast cells, specialized cells of the placenta, is of utmost importance for the establishment and maintenance of healthy pregnancy. Caffeic acid (CA), one of the most abundantly present hydroxycynamic acids in everyday human diet, exhibits various physiological effects such as antioxidant, anti-inflammatory and anticancer activities including an inhibitory effect on migration and invasion of different cancer cell types. There are not many studies on CA safety in human pregnancy. Therefore, the aim of this research was to investigate the potential of CA to affect trophoblast cell function. We evaluated adhesion, migration and invasion of human trophoblast HTR-8/SVneo cells following CA treatment by functional assays. Furthermore, expression of molecular mediators of these processes such as integrin α1, α5 and β1 subunits and matrix metalloproteinase (MMP)-2 and MMP-9 was evaluated at the mRNA level by qPCR and the protein level by cell-based ELISA assay or zymography. Our results showed that 24 h treatment with 10 μM CA stimulated migration and invasion of HTR-8/SVneo cells as well as expression of the integrin α1 subunit. Furthermore, treatment with 100 μM CA stimulated expression of MMP2 and MMP9 mRNA in the treated HTR-8/SVneo cells as well as secretion of MMP-9. According to obtained results, we can conclude that CA could have the potential to affect processes important for placentation. However, further research is needed to elucidate all aspects of potential CA effects on placental function and pregnancy as a whole.

Dietary polyphenols for tumor therapy: bioactivities, nano-therapeutic systems and delivery strategies

Various dietary polyphenols have demonstrated potent anti-tumor properties and are being evaluated as potential adjuncts in cancer treatment. Although several reviews have offered extensive insights into the anti-tumor activities of dietary polyphenols, they frequently lack a detailed discussion on the design of therapeutic protocols and targeted delivery strategies of these compounds, which impedes the translation of their biological activity into clinical practice. This article aims to deliver a comprehensive review of the anti-tumor properties of dietary polyphenols, while also examining the design and implementation of nanotherapy systems based on these compounds. Additionally, given the challenges of low water solubility and stability of dietary polyphenols, this article outlines the current methodologies for the formulation and delivery of nano-preparations to enhance tumor targeting and therapeutic efficacy. This comprehensive review aspires to deepen our understanding of the operational mechanisms of dietary polyphenols and expand their clinical applications, thereby facilitating the development of polyphenol-based dietary supplements and food additives, and promoting the progress of dietary polyphenol-related nanomedicine.

Oleuropein: a viable therapeutic option for malaria and cancer

Oleuropein (OLP) holds promise as a therapeutic candidate for both Plasmodium falciparum infection and cancer. It modulates the phosphoinositide 3-kinase (PI3K)-Akt1 signaling pathway to regulate inflammation and restore immune homeostasis. Moreover, it influences the cell death/autophagy axis, along with increasing the antimalarial efficacy of artemisinin. Our findings indicate that the anti-breast-cancer effect of OLP could be mediated by regulating the balance of T helper 17 and regulatory T cells. Additionally, we discuss the use of hematopoietic-stem-cell-transplanted immunodeficient mice with a humanized immune system for validating the antimalarial activity, autophagy and anticancer activity of OLP.

3,4 Dihydroxyphenylethanol May Inhibit Metastasis in HepG2 Cells by Influencing the Expression of miR-21 and Genes Associated with Metastasis

Background

Hepatocellular carcinoma (HCC) is one of the lethal malignancies with a poor prognosis due to metastatic complications. Matrix metalloproteinases (MMPs) and their inhibitors, tissue inhibitors of metalloproteinases (TIMPs), have an important role in metastasis. MicroRNA-21 (miR-21) is significantly overexpressed in nearly all types of human cancers, including HCC. Targeting miR-21 pharmacologically could be a promising therapeutic approach for HCC. 3,4-dihydroxyphenylethanol (DHPE), a phenolic phytochemical compound found in olive, has potent antioxidant and anticancer properties. This study aimed to investigate the effect of DHPE on the expression of miR-21 with genes associated with metastasis (MMP-2, MMP-9, TIMP-1, and TIMP-2) and their correlation with miR-21 in HepG2 cells.

Methods

This experimental study had four groups, including a control, and three groups of treatment with different concentrations of DHPE (50, 100, and 150 µM) for 24 hours. The expression levels of genes were determined by RT-qPCR.

Results

The results showed that the treatment of cells with DHPE significantly reduced the expression of miR-21, MMP-2, MMP-9, and TIMP-1 but increased TIMP-2 compared to the control group; additionally, there was a negative correlation between miR-21 and TIMP-2 but a positive correlation between miR-21 with MMP-2, MMP-9, and TIMP-1.

Conclusions

The results showed that DHPE, likely by reducing the expression of miR-21, can increase TIMP-2 and reduce MMP-2, MMP-9, and TIMP-1 gene expression and may play a role in inhibiting cell migration in HepG2 cells.

Proton-Coupled Electron Transfer and Hydrogen Tunneling in Olive Oil Phenol Reactions

Olive oil phenols are recognized as molecules with numerous positive health effects, many of which rely on their antioxidative activity, i.e., the ability to transfer hydrogen to radicals. Proton-coupled electron transfer reactions and hydrogen tunneling are ubiquitous in biological systems. Reactions of olive oil phenols, hydroxytyrosol, tyrosol, oleuropein, oleacein, oleocanthal, homovanillyl alcohol, vanillin, and a few phenolic acids with a DPPH• (2,2-diphenyl-1-picrylhydrazyl) radical in a 1,4-dioxane:water = 95:5 or 99:1 v/v solvent mixture were studied through an experimental kinetic analysis and computational chemistry calculations. The highest rate constants corresponding to the highest antioxidative activity are obtained for the ortho-diphenols hydroxytyrosol, oleuropein, and oleacein. The experimentally determined kinetic isotope effects (KIEs) for hydroxytyrosol, homovanillyl alcohol, and caffeic acid reactions are 16.0, 15.4, and 16.7, respectively. Based on these KIEs, thermodynamic activation parameters, and an intrinsic bond orbital (IBO) analysis along the IRC path calculations, we propose a proton-coupled electron transfer mechanism. The average local ionization energy and electron donor Fukui function obtained for the phenolic compounds show that the most reactive electron-donating sites are associated with π electrons above and below the aromatic ring, in support of the IBO analysis and proposed PCET reaction mechanism. Large KIEs and isotopic values of Arrhenius pre-exponential factor AH/AD determined for the hydroxytyrosol, homovanillyl alcohol, and caffeic acid reactions of 0.6, 1.3, and 0.3, respectively, reveal the involvement of hydrogen tunneling in the process.