Isoquercitrin isolated from Hyptis fasciculata reduces glioblastoma cell proliferation and changes beta-catenin cellular localization. Anticancer Drugs. 2009;20:543-552. [PMID: 19491660 DOI: 10.1097/cad.0b013e32832d1149]

Phytochemical strategies in glioblastoma therapy: Mechanisms, efficacy, and future perspectives

Glioblastoma (GBM) is foremost the most aggressive primary brain tumor, presenting extensive therapeutic challenges due to its high invasiveness, genetic complexity, and resistance to established treatments. Despite substantial advances in surgical and chemotherapeutic interventions, the median survival rate for patients is only 14.6 months, and the prognosis remains poor. This review focuses on the molecular hallmarks of GBM, including the activation of the PI3K/Akt pathway, genomic instability, and the deregulation of epidermal growth factor receptor (EGFR), all of which contribute to the tumor's aggressive behavior. Current therapies, such as Temozolomide and Bevacizumab, have limitations, highlighting the need for novel treatment strategies. Phytochemicals, bioactive compounds found in plants, have emerged as potential therapeutic agents by targeting multiple cellular pathways involved in GBM progression. This review provides an overview of key phytochemicals, including quercetin, curcumin, apigenin, and resveratrol. These compounds have shown promise in preclinical studies, with their anti-invasive, anti- angiogenic, pro-apoptotic, and anti-proliferative properties positioning them as strong candidates for GBM therapy. While phytochemicals offer a promising avenue for GBM treatment, further research is required to fully understand their mechanisms of action and to evaluate their efficiency in clinical settings. Developing multi-targeted, safer, and cost-effective anti-GBM therapies could significantly improve patient outcomes.

Potential of Natural Products in the Treatment of Glioma: Focus on Molecular Mechanisms

Despite the waning of traditional treatments for glioma due to possible long-term issues, the healing possibilities of substances derived from nature have been reignited in the scientific community. These natural substances, commonly found in fruits and vegetables, are considered potential alternatives to pharmaceuticals, as they have been shown in prior research to impact pathways surrounding cancer progression, metastases, invasion, and resistance. This review will explore the supposed molecular mechanisms of different natural components, such as berberine, curcumin, coffee, resveratrol, epigallocatechin-3-gallate, quercetin, tanshinone, silymarin, coumarin, and lycopene, concerning glioma treatment. While the benefits of a balanced diet containing these compounds are widely recognized, there is considerable scope for investigating the efficacy of these natural products in treating glioma.

A review of natural products and small-molecule therapeutics acting on central nervous system malignancies: Approaches for drug development, targeting pathways, clinical trials, and challenges

In 2021, the World Health Organization released the fifth edition of the central nervous system (CNS) tumor classification. This classification uses histopathology and molecular pathogenesis to group tumors into more biologically and molecularly defined entities. The prognosis of brain cancer, particularly malignant tumors, has remained poor worldwide, approximately 308,102 new cases of brain and other CNS tumors were diagnosed in the year 2020, with an estimated 251,329 deaths. The cost and time-consuming nature of studies to find new anticancer agents makes it necessary to have well-designed studies. In the present study, the pathways that can be targeted for drug development are discussed in detail. Some of the important cellular origins, signaling, and pathways involved in the efficacy of bioactive molecules against CNS tumorigenesis or progression, as well as prognosis and common approaches for treatment of different types of brain tumors, are reviewed. Moreover, different study tools, including cell lines, in vitro, in vivo, and clinical trial challenges, are discussed. In addition, in this article, natural products as one of the most important sources for finding new chemotherapeutics were reviewed and over 700 reported molecules with efficacy against CNS cancer cells are gathered and classified according to their structure. Based on the clinical trials that have been registered, very few of these natural or semi-synthetic derivatives have been studied in humans. The review can help researchers understand the involved mechanisms and design new goal-oriented studies for drug development against CNS malignancies.

Isoquercitrin promotes ferroptosis and oxidative stress in nasopharyngeal carcinoma via the AMPK/NF-κB pathway

Isoquercitrin has been discovered with various biological properties, including anticancer, anti-inflammation, antioxidation, and neuroprotection. The aim of this study is to explore the efficacy of isoquercitrin in nasopharyngeal carcinoma (NPC) and to disclose its potential regulating mechanisms. CNE1 and HNE1 cells were treated with various concentrations of isoquercitrin. Ferrostatin-1 (Fer-1, a ferroptosis inhibitor) and alpha-lipoic acid (ALA, an activator of the AMP-activated protein kinase [AMPK] pathway) treatments were conducted to verify the effects of isoquercitrin, respectively. Cell viability, proliferation, reactive oxygen species (ROS) generation, and lipid peroxidation were determined, respectively. GPX4 expression and ferroptosis- and pathway-related protein expression were measured. A xenograft tumor model was constructed by subcutaneously inoculating CNE1 cells into the middle groin of each mouse. We found that the IC50 values of CNE1 and HNE1 cells were 392.45 and 411.38 μM, respectively. CNE1 and HNE1 viability and proliferation were both markedly reduced with the increasing concentration of isoquercitrin. ROS generation and lipid peroxidation were both enhanced with declined ferroptosis-related markers under isoquercitrin treatment. The nuclear factor kappa B (NF-κB) pathway, the AMPK pathway, and the interleukin (IL)-1β expression were all markedly suppressed by isoquercitrin. Moreover, isoquercitrin restrained the tumor growth and enhanced lipid peroxidation and ferroptosis in vivo. Interestingly, both Fer-1 and ALA treatments distinctly offset isoquercitrin-induced effects in vitro and in vivo. These findings indicated that isoquercitrin might enhance oxidative stress and ferroptosis in NPC via AMPK/NF-κB p65 inhibition.

Bioactive compounds from Actinidia arguta fruit as a new strategy to fight glioblastoma

In recent years, there has been a significant demand for natural products as a mean of disease prevention or as an alternative to conventional medications. The driving force for this change is the growing recognition of the abundant presence of valuable bioactive compounds in natural products. On recent years Actinia arguta fruit, also known as kiwiberry, has attracted a lot of attention from scientific community due to its richness in bioactive compounds, including phenolic compounds, organic acids, vitamins, carotenoids and fiber. These bioactive compounds contribute to the fruit's diverse outstanding biological activities such as antioxidant, anti-inflammatory, neuroprotective, immunomodulatory, and anti-cancer properties. Due to these properties, the fruit may have the potential to be used in the treatment/prevention of various types of cancer, including glioblastoma. Glioblastoma is the most aggressive form of brain cancer, displaying 90 % of recurrence rate within a span of 2 years. Despite the employment of an aggressive approach, the prognosis remains unfavorable, emphasizing the urgent requirement for the development of new effective treatments. The preclinical evidence suggests that kiwiberry has potential impact on glioblastoma by reducing the cancer self-renewal, modulating the signaling pathways involved in the regulation of the cell phenotype and metabolism, and influencing the consolidation of the tumor microenvironment. Even though, challenges such as the imprecise composition and concentration of bioactive compounds, and its low bioavailability after oral administration may be drawbacks to the development of kiwiberry-based treatments, being urgent to ensure the safety and efficacy of kiwiberry for the prevention and treatment of glioblastoma. This review aims to highlight the potential impact of A. arguta bioactive compounds on glioblastoma, providing novel insights into their applicability as complementary or alternative therapies.

Modulatory Effect of Pyrus pyrifolia Fruit and its Phenolics on Key Enzymes against Metabolic Syndrome: Bioassay-Guided Approach, HPLC Analysis, and In Silico Study

This study aims to isolate the active constituents of Pyrus pyrifolia Nakai fruits using a bioassay-guided fractionation approach, test their activity in vitro against key enzymes for metabolic disorders, and support it with molecular docking simulations. The antioxidant potential of the methanolic extract (ME), its polar (PF), and non-polar fractions (NPF), along with the inhibitory activity against α-glucosidase, α-amylase, lipase, angiotensin I converting enzyme (ACE), renin, inducible nitric oxide synthase (iNOS), and xanthine oxidase (XO) were assessed. The PF exhibited the highest antioxidant and enzyme inhibitory activity. Purification of PF yielded rutin, isoquercitrin, isorhamnetin-3-O-β-D-glucoside, chlorogenic acid, quercetin, and cinnamic acid. HPLC-UV analysis of the PF allowed for the quantification of 15 phenolic compounds, including the isolated compounds. Cinnamic acid was the most powerful antioxidant in all assays and potent enzyme inhibitor against the tested enzymes (α-glucosidase, α-amylase, lipase, ACE, renin, iNOS, and XO). Additionally, it showed high affinity to target α-glucosidase and ACE active sites with high docking scores (calculated total binding free energy (ΔGbind) -23.11 kcal/mol and - 20.03 kcal/mol, respectively]. A 20-ns molecular dynamics simulation using MM-GBSA analysis revealed a stable conformation and binding patterns in a stimulating environment of cinnamic acid. Interestingly, the isolated compounds' dynamic investigations including RMSD, RMSF, and Rg demonstrated a stable ligand - protein complex to the active site of iNOS with ΔGbind ranging from - 68.85 kcal/mol to -13.47 kcal/mol. These findings support the notion that P. pyrifolia fruit is a functional food with multifactorial therapeutic agents against metabolic syndrome-associated diseases.

Oral chronic toxicity and carcinogenicity study of alpha-glycosyl isoquercitrin (AGIQ) in Sprague Dawley rats

alpha-Glycosyl isoquercitrin (AGIQ) is a flavonoid that possesses antioxidant and tumor suppressive capabilities and is marketed as a food additive in Japan. The aim of this study was to assess the potential for oral chronic toxicity and carcinogenicity of AGIQ in male and female Sprague Dawley rats following up to 5.0% dietary exposure. In the chronic toxicity study, rats were exposed to AGIQ or vehicle for one year with a 6-month interim termination point; for the carcinogenicity study, rats were treated for 24 months. No signs of AGIQ-related toxicity clinically or histologically were observed for up to one year except for yellow discoloration of bone. In the carcinogenicity study, a statistically significant increase in the incidence of malignant glioma of the brain or spinal cord was observed in female rats exposed to 5.0% AGIQ compared to those exposed to control feed. A Scientific Advisory Panel of experienced neuropathologists reviewed the gliomas (routine stains and glial cell markers) and concluded that the gliomas were a rare, spontaneous, rat-specific neoplasm: malignant microglial tumor. The lesions could not definitively be attributed to AGIQ exposure and have limited implications with respect to predicting human cancer risk.

The Flavonol Quercitrin Hinders GSK3 Activity and Potentiates the Wnt/β-Catenin Signaling Pathway

The Wnt/β-catenin signaling pathway dictates cell proliferation and differentiation during embryonic development and tissue homeostasis. Its deregulation is associated with many pathological conditions, including neurodegenerative disease, frequently downregulated. The lack of efficient treatment for these diseases, including Alzheimer’s disease (AD), makes Wnt signaling an attractive target for therapies. Interestingly, novel Wnt signaling activating compounds are less frequently described than inhibitors, turning the quest for novel positive modulators even more appealing. In that sense, natural compounds are an outstanding source of potential drug leads. Here, we combine different experimental models, cell-based approaches, neuronal culture assays, and rodent behavior tests with Xenopus laevis phenotypic analysis to characterize quercitrin, a natural compound, as a novel Wnt signaling potentiator. We find that quercitrin potentiates the signaling in a concentration-dependent manner and increases the occurrence of the Xenopus secondary axis phenotype mediated by Xwnt8 injection. Using a GSK3 biosensor, we describe that quercitrin impairs GSK3 activity and increases phosphorylated GSK3β S9 levels. Treatment with XAV939, an inhibitor downstream of GSK3, impairs the quercitrin-mediated effect. Next, we show that quercitrin potentiates the Wnt3a-synaptogenic effect in hippocampal neurons in culture, which is blocked by XAV939. Quercitrin treatment also rescues the hippocampal synapse loss induced by intracerebroventricular injection of amyloid-β oligomers (AβO) in mice. Finally, quercitrin rescues AβO-mediated memory impairment, which is prevented by XAV939. Thus, our study uncovers a novel function for quercitrin as a Wnt/β-catenin signaling potentiator, describes its mechanism of action, and opens new avenues for AD treatments.

Quercetin and Glioma: Which signaling pathways are involved?

Abstract:

Gliomas are the most common brain tumors. These tumors commonly exhibit continuous growth without invading surrounding brain tissues. Dominant remedial approaches suffer limited therapy and survival rates. Although some progress has been made in conventional glioma treatments, these breakthroughs have not yet proven sufficient for treating this malignancy. The remedial options are limited given gliomas' aggressive metastasis and drug resistance. Quercetin, a flavonoid, is an anti-oxidative, anti-allergic, antiviral, anti-inflammatory, and anticancer compound. Multiple lines of evidence have shown that Quercetin has anti-tumor effects, documenting this natural compound exerts its pharmacological effects by targeting a variety of cellular and molecular processes, i.e., apoptosis, metastasis, and autophagy. Herein, we summarize various cellular and molecular pathways that are affected by Quercetin in gliomas.

Antioxidative effect of dietary flavonoid isoquercitrin on human ovarian granulosa cells HGL5 in vitro

This study aimed to examine the effect of dietary flavonoid isoquercitrin on ovarian granulosa cells using the immortalized human cell line HGL5. Cell viability, survival, apoptosis, release of steroid hormones 17beta-estradiol and progesterone, and human transforming growth factor-beta2 (TGF-beta2) and TGF-beta2 receptor as well as intracellular reactive oxygen species (ROS) generation were investigated after isoquercitrin treatment at the concentration range of 5-100 microg.ml-1. It did not cause any significant change (p>0.05) in cell viability as studied by AlamarBlue assay in comparison to control. No significant change was observed (p>0.05) in the proportion of live, dead and apoptotic cells as revealed by apoptotic assay using flow cytometry. Similarly, the release of 17beta-estradiol, progesterone, TGF-beta2 and its receptor were not affected significantly (p>0.05) by isoquercitrin as detected by ELISA, in comparison to control. Except for the highest concentration of 100 microg.ml-1, which led to oxidative stress, isoquercitrin exhibited antioxidative activity at lower concentration used in the study (5, 10, 25, and 50 microg.ml-1) by hampering the production of intracellular ROS, in comparison to control, as detected by chemiluminescence assay (p<0.05). Findings of the present study indicate an existence of the antioxidative pathway that involves inhibition of intracellular ROS generation by isoquercitrin in human ovarian granulosa cells.

Review On Documented Medicinal Plants Used For The Treatment Of Cancer

Background:

Cancer is a frightful disease and it is the second leading cause of death worldwide. Naturally derived compounds are gaining interest of research workers as they have less toxic side effects as compared to currently used treatments such as chemotherapy. Plants are the pool of chemical compounds which provides a promising future for research on cancer.

Objective:

This review paper provides updated information gathered on medicinal plants and isolated phytoconstituents used as anticancer agents and summarises the plant extracts and their isolated chemical constituents exhibiting anticancer potential on clinical trials.

Methods:

An extensive bibliographic investigation was carried out by analysing worldwide established scientific databases like SCOPUS, PUBMED, SCIELO, ScienceDirect, Springerlink, Web of Science, Wiley, SciFinder and Google Scholar etc. In next few decades, herbal medicine may become a new epoch of medical system.

Results:

Many researches are going on medicinal plants for the treatment of cancer but it is a time to increase further experimental studies on plant extracts and their chemical constituents to find out their mechanism of action at molecular level.

Conclusion:

The article may help many researchers to start off further experimentation that might lead to the drugs for the cancer treatment.

LC/MS-MS Analyses and in vitro anticancer activity of Tourneuxia variifolia extracts

Several Saharan plants, despite their abundance of natural compounds, have received little attention. In this study, the chemical composition of polar extracts of Tourneuxia variifolia Coss. (Asteraceae), an endemic species to Algerian Sahara, was investigated and their anticancer activity was evaluated in vitro. The phytoconstituents of both ethyl acetate (EtOAc) and n-butanol (n-BuOH) extracts were screened using LC/MS-MS technique. The anticancer activity of the above extracts was measured against human cervical adenocarcinoma (HeLa) cell line. The LC/MS-MS analyses results revealed that twenty-seven phytochemicals in EtOAc extract and twenty-three in n-BuOH extract were identified and quantified from which isoquercetin and astragalin were the most present. Moreover; the EtOAc extract was found to have a strong anticancer activity (IC₅₀: 46.797 ± 0.060 µg/mL). These findings identified T. variifolia as a potential plant exhibiting anticancer properties.

13-Weeks subchronic toxicity of isoquercitrin-γ-cyclodextrin (IQC-γCD) molecular inclusion complex in Sprague-Dawley rats

Flavonoids such as quercetin and its glycoside Isoquercitrin and are abundantly present in the diet and have various pharmacological effects. However, limited data about its potential toxicity is available. In this study, we aim to evaluate the subchronic toxicity of the isoquercitrin-γ-cyclodextrin (IQC-γCD) molecular inclusion complex (SunActive® QCD/EN) in Sprague-Dawley (SD) rats. The IQC-γCD was administrated orally to 40 male and 40 female SD rats at dietary doses up to 5.0 % for 13 consecutive weeks. During the experiment periods, the general clinical signs, mortality, hematological, urinalysis values, biochemical, and histopathological parameters were examined. All animals survived until the scheduled necropsy, and no statistically significant or clinical sign of toxicologically relevant differences including pathology parameters, and histopathological endpoints were observed in any of the IQC-γCD treatment groups, compared with the control group. However, certain observations were noted in the male rats treated with the highest concentration (5.0 %), but these were not seen in female rats. A slight inhibition of weight gain was observed, probably linked to a fall in red blood cells, and hematocrit index in female rats. Statistically significant changes were noted in some clinical measures, such as plasma bilirubin level, alkaline phosphatase total bile acid without evidence of systemic clinical toxicity. The results support no observed adverse effect level (NOAEL) of IQC-γCD of 5.0 % in the diet for males (3338.55 mg/kg/day), and 3.0 % in the diet for females (2177.33 mg/kg/day) SD rats. Therefore, in this 13 weeks repeated-dose SD rat study there were no treatment-related adverse clinical or pathological findings for IQC-γCD of 5.0 % in the diet for males, and 3.0 % in the diet for females SD rats. The results of the present study support the safe use of IQC-γCD as a functional food, food additive, and natural ingredient.

alpha-Glycosyl Isoquercitrin (AGIQ) and its lack of carcinogenicity in rasH2 mice

alpha-Glycosyl Isoquercitrin (AGIQ), is used in Japan as a food additive and was granted generally recognized as safe (GRAS) status in 2005 (FEMA) and 2007 (FDA). The safety and toxicity information for AGIQ is sparse and therefore, the carcinogenicity potential of AGIQ was examined in the CByB6F1-Tg(HRAS)2Jic (rasH2) model. One hundred female and male rasH2 mice, each, were allocated to one of four designated dose groups; 0 (control)%, 1.5%, 3.0% or 5.0% AGIQ. Animals were administered the diets for six months and an additional 10 females and 10 males, each, were administered a positive control, N-methyl-N-nitrosourea (MNU). Body weights and clinical observations were collected. A full screen necropsy, organ weights, clinical chemistry, urinalysis and histopathology were performed. The positive control animals elicited appropriate responses specific to this strain (rasH2) of mice. There were statistically significant sporadic non-dose-dependent changes in clinical chemistries without corresponding pathological correlation. No microscopic AGIQ-related findings were noted; the range of pathology observations were all considered background findings, either specific to rasH2 mice or common to inbred strains of mice. Therefore, under the study conditions, the no-observed-adverse-effect level (NOAEL) was determined to be more than 5.0% (7215.4 mg/kg BW/day in male mice and 14685.5 mg/kg/day in female mice).

Hyptis mociniana: phytochemical fingerprint and photochemoprotective effect against UV-B radiation-induced erythema and skin carcinogenesis

Skin cancer is a public health problem due to its high incidence. Ultraviolet radiation (UVR) is the main etiological agent of this disease. Photochemoprotection involves the use of substances to avoid damage caused by UV exposure. The aim of this work was to determine the phytochemical fingerprint and photochemoprotective effect against UVB radiation-induced skin damage such as erythema and carcinogenesis of H. mociniana methanolic extract (MEHm). The chemical composition of the MEHm was analysed by LC/ESI-MS/MS. Three quercetin derivatives, two pectinolides, and two caffeic acid derivatives were identified in the methanolic extract. MEHm has antioxidant effect and it is not cytotoxic in HaCaT cells. Phytochemicals from H. mociniana have a photochemopreventive effect because they absorb UV light and protect HaCaT cells from UVR-induced cell death. Also, in SKH-1 mice -acute exposure-, it decreased erythema formation, modulating the inflammatory response, reduced the skin damage according to histological analysis and diminished p53 expression. Finally, MEHm protects from photocarcinogenesis by reducing the incidence and multiplicity of skin carcinomas in SKH-1 mice exposed chronically to UVB radiation.

Isoquercitrin induces apoptosis and autophagy in hepatocellular carcinoma cells via AMPK/mTOR/p70S6K signaling pathway

Hepatocellular carcinoma (HCC) is an aggressive malignancy with high rates of metastasis and relapse. Isoquercitrin (ISO), a natural flavonoid present in the Chinese bayberry and other plant species, reportedly exerts notable inhibitory effects on tumor cell proliferation, though the mechanism is unknown. In the present study, we exposed HepG2 and Huh7 human liver cancer cells to ISO and examined the roles of autophagy and apoptosis in ISO-mediated cell death. We found that ISO exposure inhibited cell viability and colony growth, activated apoptotic pathway, and triggered dysregulated autophagy by activating the AMPK/mTOR/p70S6K pathway. Autophagy inhibition using 3-methyladenine (3-MA) or Atg5-targeted siRNA decreased the Bax/Bcl-2 ratio, caspase-3 activation, and PARP cleavage and protected cells against ISO-induced apoptosis. Moreover, autophagy inhibition reversed the upregulation of AMPK phosphorylation and downregulation of mTOR and p70S6K phosphorylation elicited by ISO. By contrast, application of a broad-spectrum caspase inhibitor failed to inhibit autophagy in ISO-treated cells. These data indicate that ISO simultaneously induced apoptosis and autophagy, and abnormal induction of autophagic flux contributed to ISO-triggered caspase-3-dependent apoptosis.

The Flavonol Isoquercitrin Promotes Mitochondrial-Dependent Apoptosis in SK-Mel-2 Melanoma Cell via the PI3K/AKT/mTOR Pathway

Isoquercitrin (IQ), a major flavonol present in Prunus mume fruit, has gained much attention in recent studies because of its superior bioavailability and physiological effects. In this study, the anti-cancer mechanism of IQ against human melanoma, particularly its effect on the mitochondria-mediated apoptosis, was investigated. Treatment with IQ at 25 μM concentration effectively inhibited the proliferation of SK-MEL-2 skin cancer cells while the same concentration did not exhibit cytotoxicity against human keratinocytes HaCaT. Morphological analysis and clonogenic assay also showed that IQ can alter the growth and long-term survival of SK-MEL-2 cells. IQ also induced apoptosis in the melanoma cells as manifested in the nuclear morphology changes, DNA fragmentation, increase in the apoptosis rate (17.69% at 25 μM) and accumulation of sub-G1 cell cycle phase population (19.55% at 25 μM). Western blot analysis revealed the involvement of the mitochondrial apoptosis signaling pathway in the anti-cancer property of IQ. Treatment with IQ resulted in the decrease in the levels of procaspase-8 and -9, and Bcl-2 protein, and an increase in the expression of cleaved PARP and Bax. Moreover, AIF and Endo G protein expression increased, indicating a caspase-independent mitochondrial-mediated apoptosis. The anti-proliferative activity of IQ against SK-MEL-2 can also be attributed to the downregulation of the PI3K/AktmTOR signaling pathway. These findings showed that IQ can be developed into a chemopreventive therapeutic agent against the melanoma cells.

Anti-neoplastic Potential of Flavonoids and Polysaccharide Phytochemicals in Glioblastoma

Clinically, gliomas are classified into four grades, with grade IV glioblastoma multiforme being the most malignant and deadly, which accounts for 50% of all gliomas. Characteristically, glioblastoma involves the aggressive proliferation of cells and invasion of normal brain tissue, outcomes as poor patient prognosis. With the current standard therapy of glioblastoma; surgical resection and radiotherapy followed by adjuvant chemotherapy with temozolomide, it remains fatal, because of the development of drug resistance, tumor recurrence, and metastasis. Therefore, the need for the effective therapeutic option for glioblastoma remains elusive. Previous studies have demonstrated the chemopreventive role of naturally occurring pharmacological agents through preventing or reversing the initiation phase of carcinogenesis or arresting the cancer progression phase. In this review, we discuss the role of natural phytochemicals in the amelioration of glioblastoma, with the aim to improve therapeutic outcomes, and minimize the adverse side effects to improve patient's prognosis and enhancing their quality of life.

Piperine suppresses the Wnt/β-catenin pathway and has anti-cancer effects on colorectal cancer cells

More than 94% of colorectal cancer cases have mutations in one or more Wnt/β-catenin signaling pathway components. Inactivating mutations in APC or activating mutations in β-catenin (CTNNB1) lead to signaling overactivation and subsequent intestinal hyperplasia. Numerous classes of medicines derived from synthetic or natural small molecules, including alkaloids, have benefited the treatment of different diseases, including cancer, Piperine is a true alkaloid, derived from lysine, responsible for the spicy taste of black pepper (Piper nigrum) and long pepper (Piper longum). Studies have shown that piperine has a wide range of pharmacological properties; however, piperine molecular mechanisms of action are still not fully understood. By using Wnt/β-catenin pathway epistasis experiment we show that piperine inhibits the canonical Wnt pathway induced by overexpression of β-catenin, β-catenin S33A or dnTCF4 VP16, while also suppressing β-catenin nuclear localization in HCT116 cell line. Additionally, piperine impairs cell proliferation and migration in HCT116, SW480 and DLD-1 colorectal tumor cell lines, while not affecting the non-tumoral cell line IEC-6. In summary, piperine inhibits the canonical Wnt signaling pathway and displays anti-cancer effects on colorectal cancer cell lines.

Anti-Anaphylactic Activity of Isoquercitrin (Quercetin-3-O-β-d-Glucose) in the Cardiovascular System of Animals

Effects of isoquercitrin (IQ) on anaphylactic responses were examined in cardiovascular systems of experimental animals. In pithed rats, IQ at 30 and 100 mg/kg (intravenous) significantly blunted both the initial hypertensive and the ensuing hypotensive responses during anaphylaxis. Death rate and tachycardia were also significantly inhibited after the same IQ doses in these rats. In isolated guinea pig hearts, IQ infusion at 30–100 μg/mL markedly reduced anaphylaxis-related coronary flow decrease, contractile force change, and heart rate responses (both tachycardia and arrhythmia). Cardiac histamine and creatine kinase releases were similarly diminished by IQ during anaphylaxis in the isolated guinea pig hearts. In two different isolated guinea pig vasculatures, the pulmonary artery and mesenteric arterial bed, anaphylactic vasoconstriction was reduced by IQ 30 and 100 μg/mL. It was observed that IQ had a marked inhibitory effect on histamine release from rat mast cells, and this mechanism was suggested as the major anti-anaphylactic mechanism. Direct inhibition of histamine-induced muscle contraction did not seem to be relevant, but IQ treatment successfully repressed intracellular calcium influx/depletion in mast cells. Overall, this study provided evidence for the beneficial effect of IQ on cardiac anaphylaxis, thus suggesting its potential applications in the treatment and prevention of related diseases.

Identification of compound causing yellow bone discoloration following alpha-glycosyl isoquercitrin exposure in Sprague-Dawley rats

Previous rat toxicity studies of alpha-glycosyl isoquercitrin (AGIQ), a water-soluble flavonol glycoside derived from rutin, revealed systemic yellow bone discoloration. This investigative study was conducted to determine the AGIQ metabolite(s) responsible for the discoloration. Female Sprague-Dawley rats were administered dietary AGIQ at doses of 0%, 1.5%, 3.0%, or 5.0% (0, 1735.0, 3480.8, and 5873.7 mg/kg/day, respectively) for 14 days, followed by a 14- or 28-day recovery period. Measurements of quercetin in urine and quercetin, quercetin 3-O-glucuronide, kaempferol, and 3-o-methylquercetin metabolites of AGIQ in bone (femur), white and brown fat, and cerebrum samples were conducted following the exposure period and each recovery period. Gross examination of the femur revealed yellow discoloration that increased in intensity with dose and was still present in a dose-related manner following both recovery periods. Quercetin, at levels correlating with AGIQ dose, was measured in the urine following the 14-day exposure period and, at lower concentrations, 14 or 28 days following cessation of AGIQ exposure. All four metabolites were present in a dose-dependent manner in the femur following 14 days of dietary exposure; only quercetin, quercetin 3-O-glucuronide, and 3-o-methylquercetin were present during the recovery periods. Quercetin, quercetin 3-O-glucuronide, and 3-o-methylquercetin were detected in white fat (along with kaempferol), brown fat (excluding quercetin due to analytical interference), and cerebrum samples, indicating systemic availability of the metabolites. Collectively, these data implicate quercetin, quercetin 3-O-glucuronide, or 3-o-methylquercetin (or a combination thereof) as the most likely metabolite of AGIQ causing the yellow discoloration of bone in rats administered dietary AGIQ.

Neuroprotective effects of isoquercitrin in diabetic neuropathy via Wnt/β-catenin signaling pathway inhibition

Diabetic neuropathy is a peripheral nervous system disorder affecting both somatic and autonomic components of nervous system. A growing body of evidence have depicted that high glucose levels can induce activation of the Wnt/β-catenin pathway, however there are no studies targeting this pathway in DN. The intent of the present study was to investigate the effects of isoquercitrin (ISQ), a Wnt/β-catenin signaling pathway inhibitor, in diabetic neuropathy. Streptozotocin (50 mg/kg, i.p.) was used to induce diabetes in rats. 6-week diabetic rats were treated intrathecally with ISQ at 10 and 30 μM doses for 3 days. Furthermore, to confirm the results of the intrathecal study, a 2-week intraperitoneal treatment of ISQ was given to diabetic rats. After 6 weeks, diabetic rats developed neuropathy which was evident from reduced thermal and mechanical hyperalgesia thresholds and significant deterioration in motor nerve conduction velocity (MNCV), nerve blood flow (NBF). Sciatic nerves of diabetic neuropathy rats showed increased expression of Wnt pathway proteins namely β-catenin, c-myc and MMP2. Treatment with ISQ, both intrathecally (10 and 30 μM) and intraperitoneally (10 mg/kg), significantly ameliorated the alterations in behavioral pain thresholds and improved functional parameters in diabetic rats. Moreover, ISQ also downregulated the expression of Wnt/β-catenin pathway proteins significantly in diabetic rats as compared to vehicle-treated diabetic rats. Results of the present study suggest the neuroprotective potential of ISQ in the treatment of DN via inhibition of Wnt/β-catenin signaling pathway.

Antioxidant and Anti-Proliferative Properties of Hagenia abyssinica Roots and Their Potentially Active Components

Hagenia abyssinica (Bruce) J. F. Gmel. is a multipurpose dioecious tree that has been used to treat various ailments, for example, the flowers of H. abyssinica have been widely used as a tea to treat intestinal parasites by local residents and the roots of H.abyssinica could also be used for anticancer purposes. Antioxidant activity could be one of the most important pathways to suppress cancer and there is hardly any information available on the specific chemical components corresponding to the bioactivities of H. abyssinica to date. The present study intended to screen and evaluate the antioxidant and anti-proliferative properties of five different fractions from H. abyssinica along with their corresponding total flavonoid and phenolic contents and then further identify those compounds with the most potent antioxidant and anti-proliferative activities using high performance liquid chromatography (HPLC) coupled to mass spectrometry (MS) and nuclear magnetic resonance (NMR). The total flavonoid and phenolic content assays showed that the ethyl acetate (EA) fraction of H. abyssinica had higher flavonoid and phenolic levels than the other four fractions. Furthermore, the 2,2-diphenyl-1-picrylhydrazyl (DPPH) superoxide radical scavenging abilities, total antioxidant capacity (TAC) assay with 2,2′-azino-bis(3-ethylbenzthiazoline-6-sulfonic acid (ABTS), and ferric-reducing antioxidant power (FRAP) were measured to evaluate the antioxidant activities of the five fractions and some pure compounds isolated from the EA fraction, which displayed higher antioxidant properties than that of the other fractions. Caffeic acid from the EA fraction showed even stronger DPPH scavenging ability (IC₅₀ 7.858 ± 0.31 µg/mL) than that of Vc (IC₅₀ 8.27 ± 0.11 µg/mL) as the positive control. The anti-proliferative properties of four fractions and the ethanol extract were evaluated by the 3-(4,5)-dimethylthiahiazo (-z-y1)-3,5-di-phenytetrazoliumromide (MTT) assay and the EA fraction exhibited higher anti-proliferative activities against three cancer cell lines than that of the other fractions. Additionally, the compounds with good antioxidant activity from the EA fraction of H. abyssinica were screened and identified using LC-MS and NMR and were also found to possess good anti-proliferative activity. In the MTT assay, the quercetin showed the strongest dose-dependent anti-proliferative activities to colon cancer cells (HT-29) and liver cancer cells (HepG2) among all of the compounds isolated. This study provided valuable information on the synergistic antioxidant and anti-proliferative properties of H. abyssinica.

Embryo-fetal developmental toxicity study of alpha-glycosyl isoquercitrin administered orally to New Zealand White rabbits

An embryo-fetal survival and development study was conducted to augment the toxicity database for alpha-glycosyl isoquercitrin (AGIQ), a generally recognized as safe (GRAS) additive and flavor in food and beverages. In Phase I, 24 naturally mated New Zealand white (NZW) female rabbits per group were administered AGIQ by oral gavage at 0, 250, 500, or 1000 mg/kg/day once daily during gestation days 6–28, followed by necropsy. There was no evidence of maternal or fetal toxicity except for equivocal findings of unilateral absent kidney and ureter in one and two unrelated fetuses at 500 and 1000 mg/kg/day, respectively. To more thoroughly assess fetal kidney/ureter development, in Phase II groups of time mated NZW rabbits were administered AGIQ at 0, 500, or 1000 mg/kg/day, under the same conditions as Phase I. No occurrences of absent kidney/ureter were noted in the AGIQ-treated Phase II dams or fetuses; although, one control fetus had unilateral missing kidney/ureter. Given the lack of reproducibility following treatment with AGIQ in Phase II using 48 animals per group, the missing kidney/ureter observations in Phase I were considered unrelated to treatment. Since oral gavage administration of AGIQ to pregnant female NZW rabbits at dose levels of 250, 500, or 1000 mg/kg/day was well-tolerated with no adverse treatment-related effects on the maternal animal, pregnancy, or the developing conceptus, the no-observed-adverse-effect-level (NOAEL) for maternal toxicity and embryo-fetal survival, growth, and development was 1000 mg/kg/day.

The Chalcone Lonchocarpin Inhibits Wnt/β-Catenin Signaling and Suppresses Colorectal Cancer Proliferation

The deregulation of the Wnt/β-catenin signaling pathway is a central event in colorectal cancer progression, thus a promising target for drug development. Many natural compounds, such as flavonoids, have been described as Wnt/β-catenin inhibitors and consequently modulate important biological processes like inflammation, redox balance, cancer promotion and progress, as well as cancer cell death. In this context, we identified the chalcone lonchocarpin isolated from Lonchocarpus sericeus as a Wnt/β-catenin pathway inhibitor, both in vitro and in vivo. Lonchocarpin impairs β-catenin nuclear localization and also inhibits the constitutively active form of TCF4, dnTCF4-VP16. Xenopus laevis embryology assays suggest that lonchocarpin acts at the transcriptional level. Additionally, we described lonchocarpin inhibitory effects on cell migration and cell proliferation on HCT116, SW480, and DLD-1 colorectal cancer cell lines, without any detectable effects on the non-tumoral intestinal cell line IEC-6. Moreover, lonchocarpin reduces tumor proliferation on the colorectal cancer AOM/DSS mice model. Taken together, our results support lonchocarpin as a novel Wnt/β-catenin inhibitor compound that impairs colorectal cancer cell growth in vitro and in vivo.

In vitro response of human ovarian cancer cells to dietary bioflavonoid isoquercitrin

Isoquercitrin is a dietary bioflavonoid used as a food supplement. We studied the mechanism underlying its effect in human ovarian cancer cells using OVCAR-3 cell line. Viability, survival, apoptosis, release of human transforming growth factor-β1 (TGF-β1) and TGF-β1 receptor, and intracellular reactive oxygen species (ROS) generation by OVCAR-3 cells were examined after isoquercitrin treatment at concentrations 5, 10, 25, 50, and 100 μg mL^-1. AlamarBlue assay revealed that isoquercitrin did not cause any significant change (P > 0.05) in cell viability as compared to control. Apoptotic assay using flow cytometry did not find any significant change (P > 0.05) in the proportion of live, dead and apoptotic cells as compared to control. ELISA also showed that the release of human TGF-β1 and TGF-β1 receptor were not significantly (P > 0.05) affected by isoquercitrin as compared to control. Chemiluminescence assay demonstrated that lower concentrations (5, 10, and 25 μg mL^-1) were able to exhibit beneficial effects by inhibiting the generation of intracellular ROS. In contrast, elevated concentrations of 50 and 100 μg mL^-1 led to oxidative stress (P < 0.05). We concluded that the beneficial effect of isoquercitrin on ovarian cancer cells may be mediated by an antioxidative pathway that involves inhibition of intracellular ROS generation, thereby limiting oxidative stress.

Flavonoids modulate multidrug resistance through wnt signaling in P-glycoprotein overexpressing cell lines

BACKGROUND

Wnt signaling has been linked with P-glycoprotein (P-gp) overexpression and which was mainly mediated by β-catenin nuclear translocation. Flavonoids have already been reported as modulators of the Wnt/β-catenin pathway and hence they may serve as promising agents in the reversal of P-gp mediated cancer multi drug resistance (MDR).

METHODS

In this study, we screened selected flavonoids against Wnt/β-catenin signaling molecules. The binding interaction of flavonoids (theaflavin, quercetin, rutin, epicatechin 3 gallate and tamarixetin) with GSK 3β was determined by molecular docking. Flavonoids on P-gp expression and the components of Wnt signaling in drug-resistant KBCH^R8-5 cells were analyzed by western blotting and qRT-PCR. The MDR reversal potential of these selected flavonoids against P-gp mediated drug resistance was analyzed by cytotoxicity assay in KBCH^R8-5 and MCF7/ADR cell lines. The chemosensitizing potential of flavonoids was further analyzed by observing cell cycle arrest in KBCH^R8-5 cells.

RESULTS

In this study, we observed that the components of Wnt/β-catenin pathway such as Wnt and GSK 3β were activated in multidrug resistant KBCH^R8-5 cell lines. All the flavonoids selected in this study significantly decreased the expression of Wnt and GSK 3β in KBCH^R8-5 cells and subsequently modulates P-gp overexpression in this drug-resistant cell line. Further, we observed that these flavonoids considerably decreased the doxorubicin resistance in KBCH^R8-5 and MCF7/ADR cell lines. The MDR reversal potential of flavonoids were found to be in the order of theaflavin > quercetin > rutin > epicatechin 3 gallate > tamarixetin. Moreover, we observed that flavonoids pretreatment significantly induced the doxorubicin-mediated arrest at the phase of G2/M. Further, the combinations of doxorubicin with flavonoids significantly modulate the expression of drug response genes in KBCH^R8-5 cells.

CONCLUSION

The present findings illustrate that the studied flavonoids significantly enhances doxorubicin-mediated cell death through modulating P-gp expression pattern by targeting Wnt/β-catenin signaling in drug-resistant KBCH^R8-5 cells.

Isoquercitrin, a flavonoid glucoside, exerts a positive effect on osteogenesis in vitro and in vivo

Isoquercitrin (quercetin-3-O-β-d-glucopyranoside) possess various pharmacological effect as a biologically active compound. The aim of the present study was to investigate its potential effects on the proliferation and osteoblastic differentiation of bone marrow-derived mesenchymal stem cells (BMSCs) in vitro and bone formation in the mid-palatal suture during rapid maxillary expansion (RME) in vivo. Cell proliferation of rat BMSCs was detected by cell-counting kit- 8 (CCK-8) assay. Alkaline phosphatase (ALP) activity assay and alizarin red staining were used to evaluate osteogenic differentiation of BMSCs. Furthermore, the expression levels of osteogenesis-related genes including runt-related transcription factor 2 (Runx2), bone sialoprotein (BSP) and activating transcription factor 6 (ATF6) were measured by real-time RT-PCR. In vivo, thirty-six male 6-week-old Wistar rats with or without suture expansion receive systemic administration of isoquercitrin or saline solution. Micro-CT, HE and Masson staining were used to compare the morphological changes between the groups. Bone morphogenetic protein 2 (BMP2) expression in the suture was detected using immunohistochemical staining. Our results showed that isoquercitrin significantly promoted cell proliferation, ALP activity and mineral deposition in the range from 0.01 to 1 μM. Moreover, the expression levels of Runx2, BSP and ATF6 were also upregulated. The measurement of micro-CT imaging and histological examinations demonstrated that daily oral administration of isoquercitrin (10 mg/kg) increased bone formation compared to the other groups. Furthermore, the expression level of BMP2 was also augmented in the presence of isoquercitrin. Consequently, those findings showed that isoquercitrin exerts stimulatory effects on osteogenesis in vitro and in vivo, suggesting that isoquercitrin could be a potential candidate for preventing relapse following RME within palatal sutures.

Comprehensive evaluation of the flavonol anti-oxidants, alpha-glycosyl isoquercitrin and isoquercitrin, for genotoxic potential

Quercetin and its glycosides possess potential benefits to human health. Several flavonols are available to consumers as dietary supplements, promoted as anti-oxidants; however, incorporation of natural quercetin glycosides into food and beverage products has been limited by poor miscibility in water. Enzymatic conjugation of multiple glucose moieties to isoquercitrin to produce alpha-glycosyl isoquercitrin (AGIQ) enhances solubility and bioavailability. AGIQ is used in Japan as a food additive and has been granted generally recognized as safe (GRAS) status. However, although substantial genotoxicity data exist for quercetin, there is very little available data for AGIQ and isoquercitrin. To support expanded global marketing of food products containing AGIQ, comprehensive testing of genotoxic potential of AGIQ and isoquercitrin was conducted according to current regulatory test guidelines. Both chemicals tested positive in bacterial reverse mutation assays, and exposure to isoquercitrin resulted in chromosomal aberrations in CHO-WBL cells. All other in vitro mammalian micronucleus and chromosomal aberration assays, micronucleus and comet assays in male and female B6C3F1 mice and Sprague Dawley rats, and Muta™ Mouse mutation assays evaluating multiple potential target tissues, were negative for both chemicals. These results supplement existing toxicity data to further support the safe use of AGIQ in food and beverage products.

Simultaneous determination and pharmacokinetic study of three flavonoid glycosides in rat plasma by LC-MS/MS after oral administration of Rubus chingii Hu extract

A simple and sensitive liquid chromatography tandem mass spectrometry (LC-MS/MS) method was developed for the simultaneous determination of isoquercitrin, kaempferol-3-O-rutinoside and tiliroside in rat plasma. Plasma samples were deproteinized with methanol and separated on a Hypersil Gold C₁₈ column (2.1 × 50 mm, i.d., 3.0 μm) using gradient elution with the mobile phase of water and methanol at a flow rate of 0.4 mL/min. Mass spectrometric detection was performed with negative ion electrospray ionization in selected reaction monitoring mode. All analytes showed good linearity over their investigated concentration ranges (r²  > 0.99). The lower limit of quantification was 1.0 ng/mL for isoquercitrin and 2.0 ng/mL for kaempferol-3-O-rutinoside and tiliroside, respectively. Intra- and inter-day precisions were <8.2% and accuracy ranged from -11.5 to 9.7%. The mean extraction recoveries of analytes and IS from rat plasma were >80.4%. The assay was successfully applied to investigate the pharmacokinetic study of the three ingredients after oral administration of Rubus chingii Hu to rats.

Isoquercitrin protects against pulmonary hypertension via inhibiting PASMCs proliferation

Pulmonary vascular remodelling is a common feature among the heterogeneous disorders that cause pulmonary arterial hypertension (PAH), and pulmonary arterial smooth muscle cells (PASMCs) proliferation impact the long-term prognosis of the patient. Isoquercitrin (IQC) is a flavonoid with anti-oxidative, anti-inflammatory and anti-proliferative activations. This study aimed to investigate whether IQC could prevent PASMCs proliferation and vascular remodelling in monocrotaline (MCT) induced PAH. Male Wistar rats were administered with Vehicle or 0.1% IQC maintain feed after MCT (40 mg/kg) injection. Haemodynamic changes, right ventricular hypertrophy and lung morphological features were assessed 3 weeks later. MCT-induced PAH, pulmonary vascular remodelling and PASMCs proliferation in Vehicle-treated rats. IQC reduced the right ventricle systolic pressure (RVSP), the ratio of RV/LV+S and the RV hypertrophy. IQC significantly alleviated the expression of proliferating cell nuclear antigen (PCNA), smooth muscle α-actin (α-SMA), and the percentage of fully muscularized small arterioles. In vitro studies, PASMCs were pretreated with IQC and stimulated with platelet-derived growth factor (PDGF)-BB (20 ng/mL). IQC suppressed PDGF-BB-induced PASMCs proliferation and caused G0/G1 phase cell cycle arrest. IQC downregulated the expression of Cyclin D1 and CDK4 as well as inhibited p27Kip1 degradation. Meanwhile, IQC negatively modulated PDGF-BB-induced phosphorylation of PDGF-Rβ, Akt/GSK3β and ERK1/2. IQC ameliorated MCT-induced pulmonary vascular remodelling via suppressing PASMCs proliferation and blocking PDGF-Rβ signalling pathway.

Microglia-glioblastoma interactions: New role for Wnt signaling

Glioblastoma, the most aggressive and fatal type of brain tumor, is capable of interacting with brain immune cells such as microglia, which contributes to the growth of these tumors. Various molecules, including growth factors and cytokines, have been identified as regulators of microglia-glioblastoma interaction. Recent studies suggest that the Wnt family of lipoglycoproteins plays an important role, not only in biological events during development, but also in cancer progression, and can be part of microglia recruitment to glioblastoma as well as of tumor growth and invasion. Here, we discuss recent interesting findings that support a role for Wnt signaling pathways in the microglia-glioblastoma crosstalk.

Enhancing the thermostability of α-L-rhamnosidase from Aspergillus terreus and the enzymatic conversion of rutin to isoquercitrin by adding sorbitol

Background

Thermally stable α-L-rhamnosidase with cleaving terminal α-L-rhamnose activity has great potential in industrial application. Therefore, it is necessary to find a proper method to improve the thermal stability of α-L-rhamnosidase.

Results

In this study, addition of sorbitol has been found to increase the thermostability of α-L-rhamnosidase from Aspergillus terreus at temperatures ranging from 65 °C to 80 °C. Half-life and activation free energy with addition of 2.0 M sorbitol at 70 °C were increased by 17.2-fold, 8.2 kJ/mol, respectively. The analyses of the results of fluorescence spectroscopy and CD have indicated that sorbitol helped to protect the tertiary and secondary structure of α-L-rhamnosidase. Moreover, the isoquercitrin yield increased from 60.01 to 96.43% with the addition of 1.5 M of sorbitol at 70 °C.

Conclusion

Our findings provide an effective approach for enhancing the thermostability of α-L-rhamnosidase from Aspergillus terreus, which makes it a good candidate for industrial processes of isoquercitrin preparation.

Electronic supplementary material

The online version of this article (doi:10.1186/s12896-017-0342-9) contains supplementary material, which is available to authorized users.

Isoquercitrin inhibits bladder cancer progression in vivo and in vitro by regulating the PI3K/Akt and PKC signaling pathways

Bladder cancer is the most common malignancy of the urinary system and is also one of the 10 most common cancers of the human body. Currently, clinical treatment of bladder cancer mainly utilizes partial or total cystectomy, supplemented by conventional chemotherapy. However, such treatment has not fully improved the prognosis of patients and is associated with various side effects. Studies have found that flavonoids extracted from plants can be used in radiotherapy and chemotherapy for the prevention of postoperative recurrence and metastasis but also alone for the treatment of advanced tumors. Both applications can ameliorate clinical symptoms, improve the quality of life, and prolong the survival of patients. Based on the above information, the present study investigated the effect of isoquercitrin, a type of flavonoid found in Bidens pilosa L. extracts, on bladder cancer progression, with the goal of understanding the biological characteristics of isoquercitrin by which it participates in bladder cancer progression. Using in vitro experiments, we found that therapeutic doses of isoquercitrin significantly inhibited cell proliferation and induced apoptosis in human bladder cancer cells and that the cell cycle was arrested in the G1 phase. Isoquercitrin inhibited phosphatidylinositol 3-kinase (PI3K) and Akt phosphorylation expression levels, thus inhibiting proliferation and inducing apoptosis in the cancer cells. In addition, we found that isoquercitrin reduced protein kinase C (PKC) protein expression levels in the human bladder cancer cell lines. We also showed via in vivo experiments that isoquercitrin inhibited xenograft tumor growth in nude mice. In conclusion, our study confirmed that isoquercitrin inhibits bladder cancer progression in vivo and demonstrated that the molecular mechanism of this inhibition may be closely associated with the PI3K/Akt and PKC signaling pathways.

Hesperidin Attenuates Ultraviolet B-Induced Apoptosis by Mitigating Oxidative Stress in Human Keratinocytes

Human skin cells undergo pathophysiological processes via generation of reactive oxygen species (ROS) upon excessive exposure to ultraviolet B (UVB) radiation. This study investigated the ability of hesperidin (C₂₈H₃₄O₁₅) to prevent apoptosis due to oxidative stress generated through UVB-induced ROS. Hesperidin significantly scavenged ROS generated by UVB radiation, attenuated the oxidation of cellular macromolecules, established mitochondrial membrane polarization, and prevented the release of cytochrome c into the cytosol. Hesperidin downregulated expression of caspase-9, caspase-3, and Bcl-2-associated X protein, and upregulated expression of B-cell lymphoma 2. Hesperidin absorbed wavelengths of light within the UVB range. In summary, hesperidin shielded human keratinocytes from UVB radiation-induced damage and apoptosis via its antioxidant and UVB absorption properties.

Review of anticancer mechanisms of isoquercitin

This review was based on a literature search of PubMed and Scielo databases using the keywords “quercetin, rutin, isoquercitrin, isoquercitin (IQ), quercetin-3-glucoside, bioavailability, flavonols and favonoids, and cancer” and combinations of all the words. We collected relevant scientific publications from 1990 to 2015 about the absorption, bioavailability, chemoprevention activity, and treatment effects as well as the underlying anticancer mechanisms of isoquercitin. Flavonoids are a group of polyphenolic compounds widely distributed throughout the plant kingdom. The subclass of flavonols receives special attention owing to their health benefits. The main components of this class are quercetin, rutin, and IQ, which is a flavonoid and although mostly found as a glycoside, is an aglycone (lacks a glycoside side chain). This compound presents similar therapeutic profiles to quercetin but with superior bioavailability, resulting in increased efficacy compared to the aglycone form. IQ has therapeutic applications owing to its wide range of pharmacological effects including antioxidant, antiproliferative, anti-inflammatory, anti-hypertensive, and anti-diabetic. The protective effects of IQ in cancer may be due to actions on lipid peroxidation. In addition, the antitumor effect of IQ and its underlying mechanism are related to interactions with Wnt signaling pathway, mixed-lineage protein kinase 3, mitogen-activated protein kinase, apoptotic pathways, as well proinflammatory protein signaling. This review contributed to clarifying the mechanisms of absorption, metabolism, and actions of IQ and isoquercitrin in cancer.

Isoquercitrin Inhibits Hydrogen Peroxide-Induced Apoptosis of EA.hy926 Cells via the PI3K/Akt/GSK3β Signaling Pathway

Oxidative stress plays a critical role in endothelial injury and the pathogenesis of diverse cardiovascular diseases, including atherosclerosis. Isoquercitrin (quercetin-3-glucoside), a flavonoid distributed widely in plants, exhibits many biological activities, including anti-allergic, anti-viral, anti-inflammatory, and anti-oxidative effects. In the present study, the inhibitory effect of isoquercitrin on H₂O₂-induced apoptosis of EA.hy926 cells was evaluated. MTT assays showed that isoquercitrin significantly inhibited H₂O₂-induced loss of viability in EA.hy926 cells. Hoechst33342/PI and Annexin V-FITC/PI fluorescent double staining indicated that isoquercitrin inhibited H₂O₂-induced apoptosis of EA.hy926 cells. Western blotting demonstrated that isoquercitrin prevented H₂O₂-induced increases in cleaved caspase-9 and cleaved caspase-3 expression, while increasing expression of anti-apoptotic protein Mcl-1. Additionally, isoquercitrin significantly increased the expression of p-Akt and p-GSK3β in a dose-dependent manner in EA.hy926 cells. LY294002, a PI3K/Akt inhibitor, inhibited isoquercitrin-induced GSK3β phosphorylation and increase of Mcl-1 expression, which indicated that regulation of isoquercitrin on Mcl-1 expression was likely related to the modulation of Akt activation. These results demonstrated that the anti-apoptotic effect of isoquercitrin on H₂O₂-induced EA.hy926 cells was likely associated with the regulation of isoquercitrin on Akt/GSK3β signaling pathway and that isoquercitrin could be used clinically to interfere with the progression of endothelial injury-associated cardiovascular disease.

Effects of Flavonoids from Food and Dietary Supplements on Glial and Glioblastoma Multiforme Cells

Quercetin, catechins and proanthocyanidins are flavonoids that are prominently featured in foodstuffs and dietary supplements, and may possess anti-carcinogenic activity. Glioblastoma multiforme is the most dangerous form of glioma, a malignancy of the brain connective tissue. This review assesses molecular structures of these flavonoids, their importance as components of diet and dietary supplements, their bioavailability and ability to cross the blood-brain barrier, their reported beneficial health effects, and their effects on non-malignant glial as well as glioblastoma tumor cells. The reviewed flavonoids appear to protect glial cells via reduction of oxidative stress, while some also attenuate glutamate-induced excitotoxicity and reduce neuroinflammation. Most of the reviewed flavonoids inhibit proliferation of glioblastoma cells and induce their death. Moreover, some of them inhibit pro-oncogene signaling pathways and intensify the effect of conventional anti-cancer therapies. However, most of these anti-glioblastoma effects have only been observed in vitro or in animal models. Due to limited ability of the reviewed flavonoids to access the brain, their normal dietary intake is likely insufficient to produce significant anti-cancer effects in this organ, and supplementation is needed.

Derricin and derricidin inhibit Wnt/β-catenin signaling and suppress colon cancer cell growth in vitro

Overactivation of the Wnt/β-catenin pathway in adult tissues has been implicated in many diseases, such as colorectal cancer. Finding chemical substances that can prevent this phenomenon is an emerging problem. Recently, several natural compounds have been described as Wnt/β-catenin inhibitors and might be promising agents for the control of carcinogenesis. Here, we describe two natural substances, derricin and derricidin, belonging to the chalcone subclass, that show potent transcriptional inhibition of the Wnt/β-catenin pathway. Both chalcones are able to affect the cell distribution of β-catenin, and inhibit Wnt-specific reporter activity in HCT116 cells and in Xenopus embryos. Derricin and derricidin also strongly inhibited canonical Wnt activity in vitro, and rescued the Wnt-induced double axis phenotype in Xenopus embryos. As a consequence of Wnt/β-catenin inhibition, derricin and derricidin treatments reduce cell viability and lead to cell cycle arrest in colorectal cancer cell lines. Taken together, our results strongly support these chalcones as novel negative modulators of the Wnt/β-catenin pathway and colon cancer cell growth in vitro.

An effective biphase system accelerates hesperidinase-catalyzed conversion of rutin to isoquercitrin

Isoquercitrin is a rare, natural ingredient with several biological activities that is a key precursor for the synthesis of enzymatically modified isoquercitrin (EMIQ). The enzymatic production of isoquercitrin from rutin catalyzed by hesperidinase is feasible; however, the bioprocess is hindered by low substrate concentration and a long reaction time. Thus, a novel biphase system consisting of [Bmim][BF4]:glycine-sodium hydroxide (pH 9) (10:90, v/v) and glyceryl triacetate (1:1, v/v) was initially established for isoquercitrin production. The biotransformation product was identified using liquid chromatography-mass spectrometry, and the bonding mechanism of the enzyme and substrate was inferred using circular dichroism spectra and kinetic parameters. The highest rutin conversion of 99.5% and isoquercitrin yield of 93.9% were obtained after 3 h. The reaction route is environmentally benign and mild, and the biphase system could be reused. The substrate concentration was increased 2.6-fold, the reaction time was reduced to three tenths the original time. The three-dimensional structure of hesperidinase was changed in the biphase system, which α-helix and random content were reduced and β-sheet content was increased. Thus, the developed biphase system can effectively strengthen the hesperidinase-catalyzed synthesis of isoquercitrin with high yield.