Flavonoids play an important role in preventive and therapeutic research due to their significant antioxidant properties. However, their application is limited by several pharmacokinetic drawbacks, such as poor water solubility and low bioavailability. Cyclodextrin-based delivery systems offer an opportunity to overcome these disadvantages. Cyclodextrins are able to form stable, water-soluble inclusion complexes with flavonoids, thereby improving their solubility, chemical stability, and antioxidant activity. This review summarizes the structural characteristics and complexation mechanisms of various flavonoid–cyclodextrin complexes and examines how these interactions influence biological activity. Special attention is given to nanotechnological formulations—such as liposomes, nanofibers, and nanosponges—that enable targeted drug delivery and enhanced therapeutic efficacy. The aim of this review is to provide a comprehensive overview of the role of cyclodextrin-based carriers in the formulation of flavonoids and to highlight the future potential of these systems in modern therapeutics and functional product development.

Background: MicroRNAs (miRNAs) play a regulatory role in various human cancers. The roles of hsa-miR-15a-5p, hsa-miR-99b-5p, and hsa-miR-181a-5p have not been fully explored in the angiogenesis of renal cell carcinoma (RCC). Aims: The present study aimed to evaluate the expression of these miRNAs in tumorous and adjacent healthy tissues of RCC. Methods: Paired tumorous and adjacent normal kidney tissues from 20 patients were studied. The expression levels of hsa-miR-15b-5p, hsa-miR-99b-5p, and hsa-miR-181a-5p were quantified by TaqMan miRNA Assays. Putative targets were analyzed by qRT-PCR. Results: Significant downregulation of all three miRNAs investigated was observed in tumorous samples compared to adjacent normal kidney tissues. Spearman analysis showed a negative correlation between the expression levels of miRNAs and the pathological grades of the patients. Increased expression of vascular endothelial growth factor-A (VEGF-A) and hypoxia-inducible factor-1α (HIF-1α), a tissue inhibitor of metalloproteinases-1 (TIMP-1), was observed in tumorous samples compared to adjacent normal tissues. Depletion of tissue inhibitors of metalloproteinase-2 (TIMP-2) and metalloproteinase-2 (MMP-2) was detected compared to normal adjacent tissues. The examined miRNAs might function as contributing factors to renal carcinogenesis. However, more prospective studies are warranted to evaluate the potential role of miRNAs in RCC angiogenesis.

Photodamage-induced and viral keratitis could benefit from treatment with novel nonsteroid anti-inflammatory agents. Therefore, we determined whether human corneal epithelial cells (HCECs) express members of the endocannabinoid system (ECS), and examined how the endocannabinoid anandamide (AEA, N-arachidonoyl ethanolamine) influences the Toll-like receptor 3 (TLR3) agonism- or UVB irradiation-induced inflammatory response of these cells. Other than confirming the presence of cannabinoid receptors, we show that endocannabinoid synthesizing and catabolizing enzymes are also expressed in HCECs in vitro, as well as in the epithelial layer of the human cornea in situ, proving that they are one possible source of endocannabinoids. p(I:C) and UVB irradiation was effective in promoting the transcription and secretion of inflammatory cytokines. Surprisingly, when applied alone in 100 nM and 10 μM, AEA also resulted in increased pro-inflammatory cytokine production. Importantly, AEA further increased levels of these cytokines in the UVB model, whereas its lower concentration partially prevented the transcriptional effect of p(I:C), while not decreasing the p(I:C)-induced cytokine release. HCECs express the enzymatic machinery required to produce endocannabinoids both in vitro and in situ. Moreover, our data show that, despite earlier reports about the anti-inflammatory potential of AEA in murine cornea, its effects on the immune phenotype of human corneal epithelium may be more complex and context dependent.

Background: Uveal melanoma (UM) is the most common intraocular cancer of the eye, with high metastatic potential in adults. In 50% of patients, UM spreads to other tissues, causing a fatal outcome. Flavonoids are bioactive phenolic compounds found in fruits and plants, thus commonly present in the natural diet. Quercetin is the most remarkable agent among flavonols proved to have an anticancer effect. Thus, we aimed to investigate the effect of quercetin on a metastatic UM cell line MM28. Methods: MM28 cells were treated with increasing concentrations of quercetin (0.1–10 µM). The changes of proliferation and migration markers were studied both in gene and protein expression level by qPCR, Western blotting, and Proteome Profiler Human XL Oncology Array. Results: Quercetin had only a slight anti-proliferative effect on MM28 cells. However, 1 µM of quercetin significantly elevated the mRNA expression of the Maspin gene and downregulated MMP2 gene expression. In addition, the protein expression levels of pAKT, NF-κB, and MMP8 were significantly decreased by the treatment. Conclusions: Our findings indicate that low-dose (1 µM) quercetin treatment is able to suppress the expression of certain migration markers, and therefore, it might be a useful adjuvant compound to reduce metastasis formation of UM.

Immunotherapy has become one of the primary forms of cancer treatment. The inhibition of immune checkpoint molecules, including indoleamine 2,3-dioxygenase (IDO), is a promising approach for immunotherapy. Phosphatase and tensin homolog (PTEN) is well known as a tumor suppressor that antagonizes oncogenic signaling molecules/pathways and plays a key role in the prognosis and (immuno)therapy of the disease. In this study, twenty healthy and tumorous renal tissue pairs were investigated, and the mRNA (RT-qPCR) and protein (Western blot) expression of IDO and PTEN were analyzed. In two cancer cell lines (CAKI-2; A-498), the protein of IDO and PTEN was measured followed by IDO induction with interferon alpha-2 (IFN-α2). According to our results, a significantly higher mRNA expression of IDO and PTEN was found in tumorous tissues compared to the adjacent healthy kidney specimens. The mRNA expression of IDO and PTEN showed a positive correlation in 80% of the sample pairs. Western blot results confirmed the protein expression of both IDO and PTEN. In the cell lines, immunocytochemistry showed that IDO is inducible with IFN-α2. In summary, our results suggest that IDO expression may play a role in the development of renal cancer, and IDO as well as PTEN might be potential biomarkers for patients with RCC.

Background: Uveal melanoma is the most common intraocular malignancy in adults with a poor prognosis. Although local therapies are effective, treatment options for advanced disease remain limited. Combination strategies using chemotherapeutic agents and natural compounds, such as quercetin, are in focus for their potential to enhance antitumor efficiency and overcome resistance. Methods: The effects of doxorubicin, quercetin, and their combination were investigated in uveal melanoma cell lines. Cell viability was determined by an MTT assay, and apoptosis and cell cycle distribution by flow cytometry. Invasion assays were performed to evaluate metastatic potential, while modifications in signaling pathways were analyzed by Western blotting and qPCR. Results: Both doxorubicin and quercetin significantly reduced cell viability and induced apoptotic and necrotic cell death. The combination treatment demonstrated additional inhibitory effects in both cell lines, shown by increased SubG1 populations, reduced invasive capacity, and modulation of signaling pathways. Cell cycle analysis indicated treatment-induced growth inhibition. Notably, pathway modifications varied between cell lines, suggesting heterogeneous responses. Conclusions: Quercetin may potentiate certain antitumor effects of doxorubicin in uveal melanoma, particularly by reducing post-treatment invasiveness and modulating certain PI3K/AKT pathway-related proteins. These results support the possibility of quercetin-based combination therapies, although further molecular and in vivo studies are required.