Despite several decades of research, the beneficial effect of flavonoids on health is still enigmatic. Here, we focus on the antioxidant effect of flavonoids, which is elementary to their biological activity. A relatively new strategy for obtaining a more accurate understanding of this effect is to leverage computational chemistry. This review systematically presents various computational chemistry indicators employed over the past five years to investigate the antioxidant activity of flavonoids. We categorize these strategies into five aspects: electronic structure analysis, thermodynamic analysis, kinetic analysis, interaction analysis, and bioavailability analysis. The principles, characteristics, and limitations of these methods are discussed, along with current trends.

Quercetin, a dietary flavonoid, has demonstrated antioxidant, anti-inflammatory, and anti-tumor activities. Increasing evidence highlights that its metabolites contribute to these health benefits. This review summarizes current knowledge on the molecular mechanisms and therapeutic potential of quercetin and its metabolites in non-alcoholic fatty liver disease (NAFLD) and hepatocellular carcinoma (HCC), with a focus on redox modulation and microbiota interactions. Substantial preclinical evidence supports the protective effects of quercetin and its metabolites in NAFLD and HCC. However, clinical translation is hampered by poor bioavailability, potential redox–drug interactions, and incomplete understanding of the precise molecular mechanisms involved. Future research should prioritize further elucidating the molecular mechanisms, as they represent the foundation for the rational use of quercetin and metabolite-based derivatives in the prevention and treatment of liver-related diseases. In particular, strategies that direct the activity of these bioactive compounds to their desired sites of action—by exploiting differences between normal and cancer cells—warrant more in-depth investigation.

It has been reported that in an oxidative environment, the flavonoid 2R,3R-dihydroquercetin (2R,3R-DHQ) oxidizes into a product that rearranges to form quercetin. As quercetin is a very potent antioxidant, much better than 2R,3R-DHQ, this would be an intriguing form of targeting the antioxidant quercetin. The aim of the present study is to further elaborate on this targeting. We can confirm the previous observation that 2R,3R-DHQ is oxidized by horseradish peroxidase (HRP), with H₂O₂ as the oxidant. However, HPLC analysis revealed that no quercetin was formed, but instead an unstable oxidation product. The inclusion of glutathione (GSH) during the oxidation process resulted in the formation of a 2R,3R-DHQ-GSH adduct, as was identified using HPLC with IT-TOF/MS detection. GSH adducts appeared on the B-ring of the 2R,3R-DHQ quinone, indicating that during oxidation, the B-ring is oxidized from a catechol to form a quinone group. Ascorbate could reduce the quinone back to 2R,3R-DHQ. No 2S,3R-DHQ was detected after the reduction by ascorbate, indicating that a possible epimerization of 2R,3R-DHQ quinone to 2S,3R-DHQ quinone does not occur. The fact that no epimerization of the oxidized product of 2R,3R-DHQ is observed, and that GSH adducts the oxidized product of 2R,3R-DHQ on the B-ring, led us to conclude that the redox-modulating activity of 2R,3R-DHQ quinone resides in its B-ring. This could be confirmed by chemical calculation. Apparently, the administration of 2R,3R-DHQ in an oxidative environment does not result in ‘biotargeting’ quercetin.

Background: Quercetin, a dietary flavonoid and a widely used supplement, has hepatoprotective properties. Given its urate-lowering effects and epidemiological evidence linking elevated serum urate levels to liver cancer risk, we tested whether quercetin reduces liver cancer risk via modulation of urate levels by bioinformatics methods. Methods: We employed drug-target Mendelian randomization using genome-wide association study summary statistics from public databases (e.g., MRC-IEU) to assess genetic associations, and integrated these findings with GEO datasets (such as GSE138709 and GSE179443) and immune infiltration analyses using tools like xCell, TIMER. Results: Our analyses identified ABCG2-mediated urate elevation as a causal risk factor for hepatocellular carcinoma (OR = 1.001, p < 0.01), cholangiocarcinoma (OR = 3.424, p < 0.01), and liver fibrosis (OR = 2.528, p < 0.01). Single-cell transcriptomics revealed elevated ABCG2 expression in cholangiocarcinoma endothelial cells, while immune infiltration analysis showed significant associations between ABCG2 expression and both endothelial cell and macrophage infiltration. Survival analysis further indicated that ABCG2 was not associated with poor prognosis in cholangiocarcinoma or hepatocellular carcinoma. Conclusions: Considering quercetin’s multifaceted interactions with BCRP/ABCG2, our findings support its potential use as a preventive dietary supplement for hepatic diseases rather than as an adjunctive therapy for established liver cancer.

Background/Aim: Flavonoids are a group of polyphenols, abundantly present in our diet. Although, based on their chemoprotective effects, intake of flavonoids is associated with a high anticancer potential as evidenced in in vitro and in vivo models, the molecular mechanism is still elusive. This study explores the antiproliferative and cytotoxic effects of the semi-synthetic flavonoid MonoHER (7-mono-O-(β-hydroxyethyl)-rutoside) in vitro on cancer cells. Materials and Methods: HepG2 liver, MCF7 breast, and H1299 lung cancer cells were grown under ambient conditions with or without MonoHER exposure. CCK8 assay was used to assess cell viability. Apoptosis, JC-1, and mitochondrial mass were determined using flow cytometry and confocal analysis. The effects of monoHER on apoptosis proteins were detected by confocal microscopy analysis and Western blot. Results: It was found that MonoHER can reduce HepG2 cells’ and MCF7 cells’ viability, but not H1299 cells’, and induced apoptosis only in HepG2 cells. MonoHER has the potential to enhance the expression of caspase-9 and caspase-3, to damage mitochondria, and to provoke the release of cytochrome C from the mitochondria. Conclusion: MonoHER can inhibit cell growth and induce apoptosis especially in HepG2 human liver cancer cells by triggering the mitochondrial signal transduction pathway, leading to the release of cytochrome C in the cytoplasm and the subsequent activation of caspase-9 and caspase-3. Future research should further explore MonoHER’s mechanism of action, efficacy, and potential for clinical translation.

Background/Objectives: Ulcerative colitis (UC) is a chronic inflammatory bowel disease (IBD) with a relapsing nature and complex etiology. Bioinformatics analysis has been widely applied to investigate various diseases. This study aimed to identify crucial differentially expressed genes (DEGs) and explore potential therapeutic agents for UC. Methods: The GSE47908 and GSE55306 colon tissue transcriptome gene datasets were downloaded from the Gene Expression Omnibus-NCBI (GEO) database. GEO2R and Gene Set Enrichment Analysis (GSEA) were used to screen for DEGs in patients with UC compared to the normal population based on weighted gene co-expression network analysis (WGCNA). GO-BP analysis and KEGG enrichment analysis were performed on the intersecting differential genes via the Metascape website, while hub genes were analyzed by STRING11.0 and Cytoscape3.7.1. The expression of hub genes was verified in the dataset GSE38713 colon tissue specimens. Finally, the gene expression profiles of the validation set were analyzed by immuno-infiltration through the ImmuCellAI online tool, and the CMap database was used to screen for negatively correlated small molecule compounds. Results: A total of 595 and 926 genes were screened by analysis of GSE47908 and GSE55306 datasets, respectively. Combined WGCNA hub module intersection yielded 12 hub genes (CXCL8, IL1β, CXCL1, CCL20, CXCL2, CXCR2, LCN2, SELL, AGT, LILRB3, MMP3, IDO1) associated with the pathogenesis of UC. GSEA analysis yielded intersecting pathways for both datasets (colorectal cancer pathway, base excision repair, cell cycle, apoptosis). GO-BP and KEGG enrichment analyses were performed to obtain key biological processes (inflammatory response, response to bacteria, leukocyte activation involved in the immune response, leukocyte–cell adhesion, apoptosis, positive regulation of immune effector processes) and key signaling pathways (cytokine–cytokine receptor interactions, IBD, NOD-like receptor signaling pathways). The immune cell infiltration analysis suggested that the incidence of UC was mainly related to the increase in CD4+T cells, depletion of T cells, T follicular helper cells, natural killer cells, γδ T cells and the decrease in CD8 naive T cells, helper T cells 17 and effector T cells. The CMap database results showed that small molecule compounds such as vorinostat, roxarsone, and wortmannin may be therapeutic candidates for UC. Conclusions: This study not only aids in early prediction and prevention but also provides novel insights into the pathogenesis and treatment of UC.