Beneficial effects of flavonoids on animal models of atherosclerosis: A systematic review and meta-analysis

Flavonoids and their role in oxidative stress, inflammation, and human diseases

Oxidative stress and chronic inflammation are important drivers in the pathogenesis and progression of many chronic diseases, such as cancers of the breast, kidney, lung, and others, autoimmune diseases (rheumatoid arthritis), cardiovascular diseases (hypertension, atherosclerosis, arrhythmia), neurodegenerative diseases (Alzheimer's disease, Parkinson's disease, Huntington's disease), mental disorders (depression, schizophrenia, bipolar disorder), gastrointestinal disorders (inflammatory bowel disease, colorectal cancer), and other disorders. With the increasing demand for less toxic and more tolerable therapies, flavonoids have the potential to effectively modulate the responsiveness to conventional therapy and radiotherapy. Flavonoids are polyphenolic compounds found in fruits, vegetables, grains, and plant-derived beverages. Six of the twelve structurally different flavonoid subgroups are of dietary significance and include anthocyanidins (e.g. pelargonidin, cyanidin), flavan-3-ols (e.g. epicatechin, epigallocatechin), flavonols (e.g. quercetin, kaempferol), flavones (e.g. luteolin, baicalein), flavanones (e.g. hesperetin, naringenin), and isoflavones (daidzein, genistein). The health benefits of flavonoids are related to their structural characteristics, such as the number and position of hydroxyl groups and the presence of C2C3 double bonds, which predetermine their ability to chelate metal ions, terminate ROS (e.g. hydroxyl radicals formed by the Fenton reaction), and interact with biological targets to trigger a biological response. Based on these structural characteristics, flavonoids can exert both antioxidant or prooxidant properties, modulate the activity of ROS-scavenging enzymes and the expression and activation of proinflammatory cytokines (e.g., interleukin-1beta (IL-1β), interleukin-6 (IL-6), and tumor necrosis factor-alpha (TNF-α)), induce apoptosis and autophagy, and target key signaling pathways, such as the nuclear factor erythroid 2-related factor 2 (Nrf2) and Bcl-2 family of proteins. This review aims to briefly discuss the mutually interconnected aspects of oxidative and inflammatory mechanisms, such as lipid peroxidation, protein oxidation, DNA damage, and the mechanism and resolution of inflammation. The major part of this article discusses the role of flavonoids in alleviating oxidative stress and inflammation, two common components of many human diseases. The results of epidemiological studies on flavonoids are also presented.

Taoren Honghua Decoction alleviates atherosclerosis by inducing autophagy and inhibiting the PI3K-AKT signaling pathway to regulate cholesterol efflux and inflammatory responses

BACKGROUND

Taoren Honghua Decoction (THD) is a traditional Chinese formula known for enhancing blood circulation and demonstrating clinical efficacy in the treatment of cardiovascular and cerebrovascular diseases. However, the primary active components and the underlying mechanisms by which THD exerts its therapeutic effects on atherosclerosis (AS) remain insufficiently characterized.

OBJECTIVE

This study aims to systematically validate the protective effects of THD on AS and elucidate its potential molecular mechanisms through an integrative approach involving network pharmacology, in vivo, and in vitro experiments.

METHODS

The main active ingredients and corresponding targets of all traditional Chinese medicines in THD were collected from the TCSMP and BATMAN-TCM databases. Potential targets of AS were identified using the OMIM, DrugBank, DisGeNET, and CTD databases, and AS microarray gene data were obtained from the GEO database. A drug active ingredient-target relationship network and a PPI network were constructed using Cytoscape 3.9.2 software. The molecular functions of the core targets were annotated through GO and KEGG enrichment analyses to further elucidate the potential molecular mechanisms of THD's anti-AS effects. The ApoE-/-mouse AS model was constructed through a high-fat diet (HFD), and RAW264.7 macrophage model was induced with ox-LDL to further validate the results of network pharmacology.

RESULTS

Network pharmacology analysis revealed that the main five active ingredients of THD include quercetin, apigenin, luteolin, kaempferol, and tanshinone IIA. Subsequently, by analyzing the intersection genes of the main active ingredient targets of THD and the AS targets, a total of ten core targets were identified: TP53, PPARG, JUN, AKT1, INS, IL6, SIRT1, TNF, ESR1, and STAT3. These are considered the core targets of THD in the treatment of AS. The GO and KEGG enrichment analysis results indicate that THD may exert anti-AS effects by regulating lipid metabolism and the PI3K-AKT signaling pathway. In vivo and in vitro experiments showed that THD reduced circulating lipid levels, decreased intraplaque lipid accumulation, and increased intraplaque collagen fiber content in HFD-induced ApoE-/- mice. Additionally, THD reduced ox-LDL-induced macrophage-derived foam cell formation, inhibited the expression of inflammatory factors IL-6 and TNF-α, and promoted the expression of cholesterol efflux regulatory proteins PPARγ, ABCA1, and ABCG1. Notably, the autophagy inhibitor 3-MA reversed these effects, confirming that THD's action involves autophagy activation, evidenced by increased LC3II/I and decreased p62 levels.

CONCLUSION

This study demonstrates that THD exerts significant anti-AS effects through the inhibition of the PI3K/AKT signaling pathway and the activation of autophagy, thereby promoting cholesterol efflux and mitigating inflammation. By integrating network pharmacology with experimental validation, these findings provide a comprehensive understanding of THD's mechanisms in treating AS and offer a solid theoretical basis for its potential clinical application.

Scavenging of Methylglyoxal by the Total Flavonoids of Apocyni Veneti Folium in Mice

Scavenging MGO has been considered as an effective strategy for preventing atherosclerosis. A previous study showed that the total flavonoids of Apocyni Veneti Folium (TFAVF) had a significant antiatherosclerotic effect. However, there are no studies that have investigated the MGO scavenging capacities of TFAVF in mice. We found that TFAVF consisted mainly of quercetin glycosides and kaempferol glycosides using ultrahigh performance liquid chromatography coupled to quadrupole time-of-flight tandem mass spectrometry (UHPLC-QTOF-MS/MS). TFAVF was first demonstrated to effectively scavenge MGO in mice based on the formation of mono-MGO-quercetin, mono-MGO-dehydroquercetin, mono-MGO-isorhamnetin, mono-MGO-dehydroisorhamnetin, mono-MGO-kaempferol, and mono-MGO-dehydrokaempferol. In addition, one mono-MGO-quercetin was separated and purified, and its structure was elucidated as 8-MGO-quercetin based on UHPLC-QTOF-MS/MS and NMR data. Quantification studies have demonstrated that kaempferol, dehydrokaempferol, quercetin, dehydroquercetin, isorhamnetin, and dehydroisorhamnetin can dose dependently scavenge MGO in mice. Taken together, these results indicated that TFAVF showed a significant antiatherosclerotic effect, which might be based on MGO detoxification.

Flavonoids regulate LDLR through different mechanisms tied to their specific structures

Flavonoids, polyphenolic compounds found in plant-based diets, are associated with reduced risk of cardiovascular disease and longevity. These components are reported to reduce plasma levels of low-density lipoprotein (LDL) through an upregulation of the LDL receptor (LDLR), but the mechanism is still largely unknown. In this study, we have systematically screened the effect of 12 flavonoids from six different flavonoid subclasses on the effect on LDLR. This paper provides an in-depth analysis on how these flavonoids affect LDLR regulation and functionality. We found that most but not all of the tested flavonoids increased LDLR mRNA levels. Surprisingly, this increase was attributed to different regulatory mechanisms, such as enhanced LDLR promoter activity, LDLR mRNA stabilization, or LDLR protein stabilization, of which specific effectual parts of the flavonoid molecular structure could be assigned. These types of comparative analysis of various flavonoids enhance clarity and deepen the understanding of how the different structures of flavonoids affect LDLR regulation. Our data offer useful insights that may guide future research in developing therapeutic approaches for cardiovascular health.