Phytochemical compounds targeting on Nrf2 for chemoprevention in colorectal cancer

Targeting ferroptosis regulators by natural products in colorectal cancer

Colorectal cancer (CRC) poses a significant global health challenge, ranking as the third most diagnosed cancer and the second leading cause of cancer-related deaths. Despite advancements in treatment, challenges such as delayed diagnosis, multidrug resistance, and limited therapeutic effectiveness persist, emphasizing the need for innovative approaches. This review explores the potential of natural products, nutraceuticals, and phytochemicals for targeting ferroptosis-related regulators as a novel strategy in CRC. Ferroptosis, a form of regulated cell death characterized by iron-dependent lethal lipid peroxide accumulation, holds substantial importance in CRC progression and therapy resistance. Natural products, known for their diverse bioactive effects and favorable safety profiles, emerge as promising candidates to induce ferroptosis in CRC cells. Exploring amino acid, iron, lipid metabolism regulators, and oxidative stress regulators reveals promising avenues for inducing cell death in CRC. This comprehensive review provides insights into the multifaceted effects of natural products on proteins integral to ferroptosis regulation, including GPX4, SLC7A11, ACSL4, NCOA4, and HO-1. By elucidating the intricate mechanisms through which natural products modulate these proteins, this review lays the foundation for a promising therapeutic strategy in CRC.

Insights into the anti-Candida albicans properties of natural phytochemicals: An in vitro and in vivo investigation

Invasive candidiasis, attributed to Candida albicans, has long been a formidable threat to human health. Despite the advent of effective therapeutics in recent decades, the mortality rate in affected patient populations remains discouraging. This is exacerbated by the emergence of multidrug resistance, significantly limiting the utility of conventional antifungals. Consequently, researchers are compelled to continuously explore novel solutions. Natural phytochemicals present a potential adjunct to the existing arsenal of agents. Previous studies have substantiated the efficacy of phytochemicals against C. albicans. Emerging evidence also underscores the promising application of phytochemicals in the realm of antifungal treatment. This review systematically delineates the inhibitory activity of phytochemicals, both in monotherapy and combination therapy, against C. albicans in both in vivo and in vitro settings. Moreover, it elucidates the mechanisms underpinning the antifungal properties, encompassing (i) cell wall and plasma membrane damage, (ii) inhibition of efflux pumps, (iii) induction of mitochondrial dysfunction, and (iv) inhibition of virulence factors. Subsequently, the review introduces the substantial potential of nanotechnology and photodynamic technology in enhancing the bioavailability of phytochemicals. Lastly, it discusses current limitations and outlines future research priorities, emphasizing the need for high-quality research to comprehensively establish the clinical efficacy and safety of phytochemicals in treating fungal infections. This review aims to inspire further contemplation and recommendations for the effective integration of natural phytochemicals in the development of new medicines for patients afflicted with C. albicans.

Chemopreventive effect and induction of DNA repair by oenothein B ellagitannin isolated from leaves of Eugenia uniflora in Swiss Webster treated mice

Oenothein B (OeB) is a dimeric ellagitannin with potent antioxidative, antitumor, immunomodulatory, and anti-inflammatory properties. Despite the promising activities of OeB, studies examining the genotoxic or protective effects of this ellagitannin on DNA are scarce. Therefore, to further comprehensively elucidate the chemopreventive profile of OeB, the aim of this study was to evaluate the mutagenic and antimutagenic actions of OeB using Salmonella typhimurium strains with the Ames test. The micronucleus (MN) test and comet assay were used to assess the anticytotoxic and antigenotoxic effects of OeB on mouse bone marrow cells following differing treatments (pre-, co-, and post-treatment) in response to cyclophosphamide (CPA)-induced DNA damage. In addition, histopathological analyses were performed to assess liver and kidney tissues of Swiss Webster treated mice. Our results did not detect mutagenic or antimutagenic activity attributed to OeB at any concentration in the Ames test. Regarding the MN test, data showed that this ellagitannin exerted antigenotoxic and anticytotoxic effects against CPA-induced DNA damage under all treatment conditions. However, no anticytotoxic action was observed in MN test after pre-treatment with the highest doses of OeB. In addition, OeB demonstrated antigenotoxic effects in the comet assay for all treatments. Histopathological analyses indicated that OeB attenuated the toxic effects of CPA in mouse liver and kidneys. These findings suggest that OeB exerted a chemoprotective effect following pre- and co-treatments and a DNA repair action in post-treatment experiments. Our findings indicate that OeB protects DNA against CPA-induced damaging agents and induces post-damage DNA repair.

Targeting beta-catenin signaling for prevention of colorectal cancer - Nutraceutical, drug, and dietary options

Progressive up-regulation of β-catenin signaling is very common in the transformation of colorectal epithelium to colorectal cancer (CRC). Practical measures for opposing such signaling hence have potential for preventing or slowing such transformation. cAMP/PKA activity in colon epithelium, as stimulated by COX-2-generated prostaglandins and β2-adrenergic signaling, boosts β-catenin activity, whereas cGMP/PKG signaling has the opposite effect. Bacterial generation of short-chain fatty acids (as supported by unrefined high-carbohydrate diets, berberine, and probiotics), dietary calcium, daily aspirin, antioxidants opposing cox-2 induction, and nicotine avoidance, can suppress cAMP production in colonic epithelium, whereas cGMP can be boosted via linaclotides, PDE5 inhibitors such as sildenafil or icariin, and likely high-dose biotin. Selective activation of estrogen receptor-β by soy isoflavones, support of adequate vitamin D receptor activity with UV exposure or supplemental vitamin D, and inhibition of CK2 activity with flavanols such as quercetin, can also oppose β-catenin signaling in colorectal epithelium. Secondary bile acids, the colonic production of which can be diminished by low-fat diets and berberine, can up-regulate β-catenin activity by down-regulating farnesoid X receptor expression. Stimulation of PI3K/Akt via insulin, IGF-I, TLR4, and EGFR receptors boosts β-catenin levels via inhibition of glycogen synthase-3β; plant-based diets can down-regulate insulin and IGF-I levels, exercise training and leanness can keep insulin low, anthocyanins and their key metabolite ferulic acid have potential for opposing TLR4 signaling, and silibinin is a direct antagonist for EGFR. Partially hydrolyzed phytate can oppose growth factor-mediated down-regulation of β-catenin by inhibiting Akt activation. Multifactorial strategies for safely opposing β-catenin signaling can be complemented with measures that diminish colonic mutagenesis and DNA hypomethylation - such as avoidance of heme-rich meat and charred or processed meats, consumption of phase II-inductive foods and nutraceuticals (e.g., Crucifera), and assurance of adequate folate status.

Pharmacological Potential of Betulin as a Multitarget Compound

Betulin is a natural triterpene, usually from birch bark, known for its potential wound-healing properties. Despite having a wide range of pharmacological targets, no studies have proposed betulin as a multitarget compound. Betulin has protective effects against cardiovascular and liver diseases, cancer, diabetes, oxidative stress, and inflammation. It reduces postprandial hyperglycemia by inhibiting α-amylase and α-glucosidase activity, combats tumor cells by inducing apoptosis and inhibiting metastatic proteins, and modulates chronic inflammation by blocking the expression of proinflammatory cytokines via modulation of the NFκB and MAPKs pathways. Given its potential to influence diverse biological networks with high target specificity, it can be hypothesized that betulin may eventually become a new lead for drug development because it can modify a variety of pharmacological targets. The summarized research revealed that the diverse beneficial effects of betulin in various diseases can be attributed, at least in part, to its multitarget anti-inflammatory activity. This review focuses on the natural sources, pharmacokinetics, pharmacological activity of betulin, and the multi-target effects of betulin on signaling pathways such as MAPK, NF-κB, and Nrf2, which are important regulators of the response to oxidative stress and inflammation in the body.

Mechanisms of Action of Fruit and Vegetable Phytochemicals in Colorectal Cancer Prevention

Colorectal cancer (CRC) is the third most common cancer worldwide and its incidence is expected to increase by almost 80% by 2030. CRC apparition is related to poor diet, mainly due to low consumption of phytochemicals present in fruits and vegetables. Hence, this paper reviews the most promising phytochemicals in the literature, presenting scientific evidence regarding potential CRC chemopreventive effects. Moreover, this paper reveals the structure and action of CRC mechanisms that these phytochemicals are involved in. The review reveals that vegetables rich in phytochemicals such as carrots and green leafy vegetables, as well as some fruits such as pineapple, citrus fruits, papaya, mango, and Cape gooseberry, that have antioxidant, anti-inflammatory, and chemopreventive properties can promote a healthy colonic environment. Fruits and vegetables in the daily diet promote antitumor mechanisms by regulating cell signaling and/or proliferation pathways. Hence, daily consumption of these plant products is recommended to reduce the risk of CRC.

Pathogenic mechanisms and regulatory factors involved in alcoholic liver disease

Alcoholism is a widespread and damaging behaviour of people throughout the world. Long-term alcohol consumption has resulted in alcoholic liver disease (ALD) being the leading cause of chronic liver disease. Many metabolic enzymes, including alcohol dehydrogenases such as ADH, CYP2E1, and CATacetaldehyde dehydrogenases ALDHsand nonoxidative metabolizing enzymes such as SULT, UGT, and FAEES, are involved in the metabolism of ethanol, the main component in alcoholic beverages. Ethanol consumption changes the functional or expression profiles of various regulatory factors, such as kinases, transcription factors, and microRNAs. Therefore, the underlying mechanisms of ALD are complex, involving inflammation, mitochondrial damage, endoplasmic reticulum stress, nitrification, and oxidative stress. Moreover, recent evidence has demonstrated that the gut-liver axis plays a critical role in ALD pathogenesis. For example, ethanol damages the intestinal barrier, resulting in the release of endotoxins and alterations in intestinal flora content and bile acid metabolism. However, ALD therapies show low effectiveness. Therefore, this review summarizes ethanol metabolism pathways and highly influential pathogenic mechanisms and regulatory factors involved in ALD pathology with the aim of new therapeutic insights.

The Potential of Flavonoids and Flavonoid Metabolites in the Treatment of Neurodegenerative Pathology in Disorders of Cognitive Decline

Flavonoids are a biodiverse family of dietary compounds that have antioxidant, anti-inflammatory, antiviral, and antibacterial cell protective profiles. They have received considerable attention as potential therapeutic agents in biomedicine and have been widely used in traditional complimentary medicine for generations. Such complimentary medical herbal formulations are extremely complex mixtures of many pharmacologically active compounds that provide a therapeutic outcome through a network pharmacological effects of considerable complexity. Methods are emerging to determine the active components used in complimentary medicine and their therapeutic targets and to decipher the complexities of how network pharmacology provides such therapeutic effects. The gut microbiome has important roles to play in the generation of bioactive flavonoid metabolites retaining or exceeding the antioxidative and anti-inflammatory properties of the intact flavonoid and, in some cases, new antitumor and antineurodegenerative bioactivities. Certain food items have been identified with high prebiotic profiles suggesting that neutraceutical supplementation may be beneficially employed to preserve a healthy population of bacterial symbiont species and minimize the establishment of harmful pathogenic organisms. Gut health is an important consideration effecting the overall health and wellbeing of linked organ systems. Bioconversion of dietary flavonoid components in the gut generates therapeutic metabolites that can also be transported by the vagus nerve and systemic circulation to brain cell populations to exert a beneficial effect. This is particularly important in a number of neurological disorders (autism, bipolar disorder, AD, PD) characterized by effects on moods, resulting in depression and anxiety, impaired motor function, and long-term cognitive decline. Native flavonoids have many beneficial properties in the alleviation of inflammation in tissues, however, concerns have been raised that therapeutic levels of flavonoids may not be achieved, thus allowing them to display optimal therapeutic effects. Dietary manipulation and vagal stimulation have both yielded beneficial responses in the treatment of autism spectrum disorders, depression, and anxiety, establishing the vagal nerve as a route of communication in the gut-brain axis with established roles in disease intervention. While a number of native flavonoids are beneficial in the treatment of neurological disorders and are known to penetrate the blood–brain barrier, microbiome-generated flavonoid metabolites (e.g., protocatechuic acid, urolithins, γ-valerolactones), which retain the antioxidant and anti-inflammatory potency of the native flavonoid in addition to bioactive properties that promote mitochondrial health and cerebrovascular microcapillary function, should also be considered as potential biotherapeutic agents. Studies are warranted to experimentally examine the efficacy of flavonoid metabolites directly, as they emerge as novel therapeutic options.

Role of Oxidative Stress in Liver Disorders

Oxygen is vital for life as it is required for many different enzymatic reactions involved in intermediate metabolism and xenobiotic biotransformation. Moreover, oxygen consumption in the electron transport chain of mitochondria is used to drive the synthesis of ATP to meet the energetic demands of cells. However, toxic free radicals are generated as byproducts of molecular oxygen consumption. Oxidative stress ensues not only when the production of reactive oxygen species (ROS) exceeds the endogenous antioxidant defense mechanism of cells, but it can also occur as a consequence of an unbalance between antioxidant strategies. Given the important role of hepatocytes in the biotransformation and metabolism of xenobiotics, ROS production represents a critical event in liver physiology, and increasing evidence suggests that oxidative stress contributes to the development of many liver diseases. The present review, which is part of the special issue “Oxidant stress in Liver Diseases”, aims to provide an overview of the sources and targets of ROS in different liver diseases and highlights the pivotal role of oxidative stress in cell death. In addition, current antioxidant therapies as treatment options for such disorders and their limitations for future trial design are discussed.

Cucurbitacin B alleviates cerebral ischemia/reperfusion injury by inhibiting NLRP3 inflammasome-mediated inflammation and reducing oxidative stress

Cucurbitacin B (CuB) has been demonstrated to possess anti-inflammatory and antioxidative properties. However, the effect of CuB on cerebral ischemia/reperfusion (I/R) injury was unclear. In this work, we found that CuB significantly elevated cell viability, decreased lactate dehydrogenase (LDH) release, reactive oxygen species (ROS) production, and proinflammatory factor levels in oxygen-glucose deprivation/reoxygenation-exposed PC12 cells, reduced cerebral infarction volume and neuronal apoptosis, inhibited oxidative stress and inflammation, and improved neurological function in mice with middle cerebral artery occlusion-induced cerebral I/R injury. Meanwhile, CuB decreased levels of NLRP3, cleaved caspase-1, and cleaved interleukin-1β, which were upregulated by I/R injury. Moreover, upregulation of NLRP3 dramatically reversed the effects of CuB on NLRP3 inflammasome activation, cell viability, and levels of proinflammatory factors in vitro. In conclusion, this study demonstrated that CuB attenuated cerebral I/R injury by inhibiting NLRP3 inflammasome-mediated inflammation and reducing oxidative stress.

The potential roles of Nrf2/Keap1 signaling in anticancer drug interactions

Nuclear factor (erythroid-derived 2)-related factor 2 (Nrf2), together with its suppressive binding partner Kelch-like ECH-associated protein 1 (Keap1), regulates cellular antioxidant response and drug metabolism. The roles of Nrf2/Keap1 signaling in the pathology of many diseases have been extensively investigated, and small molecules targeting Nrf2/Keap1 signaling have been developed to prevent or treat diseases such as multiple sclerosis, chronic kidney disease and cancer. Notably, Nrf2 plays dual roles in cancer development and treatment. Activation of Nrf2/Keap1 signaling in cancer cells has been reported to promote cancer progression and result in therapy resistance. Since cancer patients are often suffering comorbidities of other chronic diseases, anticancer drugs could be co-administrated with other drugs and herbs. Nrf2/Keap1 signaling modulators, especially activators, are common in drugs, herbs and dietary ingredients, even they are developed for other targets. Therefore, drug-drug or herb-drug interactions due to modulation of Nrf2/Keap1 signaling should be considered in cancer therapies. Here we briefly summarize basic biochemistry and physiology functions of Nrf2/Keap1 signaling, Nrf2/Keap1 signaling modulators that cancer patients could be exposed to, and anticancer drugs that are sensitive to Nrf2/Keap1 signaling, aiming to call attention to the potential drug-drug or herb-drug interactions between anticancer drugs and these Nrf2/Keap1 signaling modulators.

A Role of Stress Sensor Nrf2 in Stimulating Thermogenesis and Energy Expenditure

During chronic cold stress, thermogenic adipocytes generate heat through uncoupling of mitochondrial respiration from ATP synthesis. Recent discovery of various dietary phytochemicals, endogenous metabolites, synthetic compounds, and their molecular targets for stimulating thermogenesis has provided promising strategies to treat or prevent obesity and its associated metabolic diseases. Nuclear factor E2 p45-related factor 2 (Nrf2) is a stress response protein that plays an important role in obesity and metabolisms. However, both Nrf2 activation and Nrf2 inhibition can suppress obesity and metabolic diseases. Here, we summarized and discussed conflicting findings of Nrf2 activities accounting for part of the variance in thermogenesis and energy metabolism. We also discussed the utility of Nrf2-activating mechanisms for their potential applications in stimulating energy expenditure to prevent obesity and improve metabolic deficits.

The Interaction of the Flavonoid Fisetin with Human Glutathione Transferase A1-1

Glutathione transferases (GSTs) are a family of Phase II detoxification enzymes that are involved in the development of the multidrug resistance (MDR) mechanism in cancer cells and therefore affect the clinical outcome of cancer chemotherapy. The discovery of nontoxic natural compounds as inhibitors for GSTs is a promising approach for chemosensitizing and reversing MDR. Fisetin (7,3′,4′-flavon-3-ol) is a plant flavonol present in many plants and fruits. In the present work, the interaction of fisetin with human glutathione transferase A1-1 (hGSTA1-1) was investigated. Kinetic analysis revealed that fisetin is a reversible inhibitor for hGSTA1-1 with IC₅₀ 1.2 ± 0.1 μΜ. It functions as a mixed-type inhibitor toward glutathione (GSH) and as a noncompetitive inhibitor toward the electrophile substrate 1-chloro-2,4-dinitrobenzene (CDNB). In silico molecular modeling and docking predicted that fisetin binds at a distinct location, in the solvent channel of the enzyme, and occupies the entrance of the substrate-binding sites. Treatment of proliferating human epithelial colorectal adenocarcinoma cells (CaCo-2) with fisetin causes a reduction in the expression of hGSTA1-1 at the mRNA and protein levels. In addition, fisetin inhibits GST activity in CaCo-2 cell crude extract with an IC₅₀ (2.5 ± 0.1 μΜ), comparable to that measured using purified recombinant hGSTA1-1. These actions of fisetin can provide a synergistic role toward the suppression and chemosensitization of cancer cells. The results of the present study provide insights into the development of safe and effective GST-targeted cancer chemosensitizers.