Effect of hesperetin, a citrus flavonoid, on bacterial enzymes and carcinogen-induced aberrant crypt foci in colon cancer rats: a dose-dependent study

Antioxidants from different citrus peels provide protection against cancer

Cancer is one of the leading causes of death. Despite significant advancements in the discovery of medications for the treatment of cancer, these drugs are hindered by applicability and efficacy issues and frequently exhibit major side effects that can further impair patients 'quality of life. Therefore, the development of therapeutically sound anti-cancer medicines derived from natural products has gained prominence in the field of functional foods. Some of these compounds have shown efficacy in the prevention and treatment of cancer as well as low toxicity. Additionally, many recent studies have explored the recycling of agro-industrial waste to create bioactive chemicals. Citrus peels are produced in vast quantities in the food processing sector; due to their abundance of flavonoids, they may be inexpensive sources of protection against several cancers. Citrus is a common type of fruit that contains a variety of nutrients. In particular, the antioxidant chemicals found in citrus peel have been identified as potential cancer-fighting agents. Antioxidant substances such as flavonoids prevent the development of cancer by inhibiting the metastatic cascade, decreasing the mobility of cancer cells in the circulatory system, promoting apoptosis, and suppressing angiogenesis. To explore the most effective uses of citrus peel-derived antioxidants, this review presents background information, an overview of the role of citrus antioxidants in cancer therapy, and a discussion of the key underlying molecular mechanisms.

A Scientometric Study to a Critical Review on Promising Anticancer and Neuroprotective Compounds: Citrus Flavonoids

Flavonoids derived from citrus plants are favored by phytomedicinal researchers due to their wide range of biological activities, and relevant studies have been sustained for 67 years (since the first paper published in 1955). In terms of a scientometric and critical review, the scientometrics of related papers, chemical structures, and pharmacological action of citrus flavonoids were comprehensively summarized. The modern pharmacological effects of citrus flavonoids are primarily focused on their anticancer activities (such as breast cancer, gastric cancer, lung cancer, and liver cancer), neuroprotective effects (such as anti-Alzheimer’s disease, Parkinson’s disease), and metabolic diseases. Furthermore, the therapeutic mechanism of cancers (including inducing apoptosis, inhibiting cell proliferation, and inhibiting cancer metastasis), neuroprotective effects (including antioxidant and anti-inflammatory), and metabolic diseases (such as non-alcoholic fatty liver disease, type 2 diabetes mellitus) were summarized and discussed. We anticipate that this review could provide an essential reference for anti-cancer and neuroprotective research of citrus flavonoids and provide researchers with a comprehensive understanding of citrus flavonoids.

Impacts of hesperidin on whey protein functionality: Interacting mechanism, antioxidant capacity, and emulsion stabilizing effects

The objective of this work was to explore the possibility of improving the antioxidant capacity and application of whey protein (WP) through non-covalent interactions with hesperidin (HES), a citrus polyphenol with nutraceutical activity. The interaction mechanism was elucidated using several spectroscopic methods and molecular docking analysis. The antioxidant capacity of the WP-HES complexes was analyzed and compared to that of the proteins alone. Moreover, the resistance of oil-in-water emulsions formulated using the WP-HES complexes as antioxidant emulsifiers to changes in environmental conditions (pH, ion strength, and oxidant) was evaluated. Our results showed that HES was incorporated into a single hydrophobic cavity in the WP molecule, where it was mainly held by hydrophobic attractive forces. As a result, the microenvironments of the non-polar tyrosine and tryptophan residues in the protein molecules were altered after complexation. Moreover, the α-helix and β-sheet regions in the protein decreased after complexation, while the β-turn and random regions increased. The antioxidant capacity of the WP-HES complexes was greater than that of the proteins alone. Non-radiative energy transfer from WP to HES was detected during complex formation. Compared to WP alone, the WP-HES complexes produced emulsions with smaller mean droplet diameters, exhibited higher pH and salt stability, and had better oxidative stability. The magnitude of these effects increased as the HES concentration was increased. This research would supply valuable information on the nature of the interactions between WP and HES. Moreover, it may lead to the creation of dual-function antioxidant emulsifiers for application in emulsified food products.

Structural Investigation of Hesperetin-7-O-Glucoside Inclusion Complex with β-Cyclodextrin: A Spectroscopic Assessment

Flavonoids are biologically active natural products of great interest for their potential applications in functional foods and pharmaceuticals. A hesperetin-7-O-glucoside inclusion complex with β-cyclodextrin (HEPT7G/βCD; SunActive^® HCD) was formulated via the controlled enzymatic hydrolysis of hesperidin with naringinase enzyme. The conversion rate was nearly 98%, estimated using high-performance liquid chromatography analysis. The objective of this study was to investigate the stability, solubility, and spectroscopic features of the HEPT7G/βCD inclusion complex using Fourier-transform infrared (FTIR), Raman, ultraviolet–visible absorption (UV–vis), ¹H- and ¹³C- nuclear magnetic resonance (NMR), differential scanning calorimetry (DSC), liquid chromatography/mass spectroscopy (LC–MS), scanning electron microscopy (SEM), and powdered X-ray diffraction (PXRD) spectroscopic techniques including zeta potential, Job’s plot, and phase solubility measurements. The effects of complexation on the profiles of supramolecular interactions in analytic features, especially the chemical shifts of β-CD protons in the presence of the HEPT7G moiety, were evaluated. The stoichiometric ratio, stability, and solubility constants (binding affinity) describe the extent of complexation of a soluble complex in 1:1 stoichiometry that exhibits a greater affinity and fits better into the β-CD inner cavity. The NMR spectroscopy results identified two different configurations of the HEPT7G moiety and revealed that the HEPT7G/βCD inclusion complex has both –2S and –2R stereoisomers of hesperetin-7-O-glucoside possibly in the –2S/–2R epimeric ratio of 1/1.43 (i.e., –2S: 41.1% and –2R: 58.9%). The study indicated that encapsulation of the HEPT7G moiety in β-CD is complete inclusion, wherein both ends of HEPT7G are included in the β-CD inner hydrophobic cavity. The results showed that the water solubility and thermal stability of HEPT7G were apparently increased in the inclusion complex with β-CD. This could potentially lead to increased bioavailability of HEPT7G and enhanced health benefits of this flavonoid.

Bioactivity of hamamelitannin, flavokawain A, and triacetyl resveratrol as natural compounds: Molecular docking study, anti‐colon cancer and anti‐Alzheimer potentials

In this study, we worked on anticolon cancer effects and anti-Alzheimer's disease with molecular docking studies. Hamamelitannin, flavokawain A, and triacetyl resveratrol compounds showed good inhibitory activities on acetylcholinesterase (AChE) and butyrylcholinesterase (BuChE) enzymes. The inhibition effects of flavokawain A, hamamelitannin, and triacetyl resveratrol on AChE and BuChE enzymes were determined spectrophotometrically conforming to Ellman. IC₅₀ values of these enzymes were ranging between 0.95 ± 0.12 and 93.27 ± 8.14 nM for AChE and 5.71 ± 0.77 and 52.10 ± 8.41 nM for BuChE. The inhibitory activities of some chemical compounds such as flavokawain A, hamamelitannin, and triacetyl resveratrol were assessed by performing the molecular docking study in the presence of AChE and BuChE. Also, the features of the ligand-enzyme complex had value of -7.722 kcal/mol for flavokawain A against AChE and -5.530 kcal/mol against BuChE. The molecular docking calculations indicated the probable interactions and their characteristics at an atomic level. Due to the outcomes gained from docking, the affinity of the chemical compounds to the enzymes was considerable. In vitro cell viabilities of flavokawain A, hamamelitannin, and triacetyl resveratrol with various concentrations on SW620, DLD-1, HT29, HCT8, and HCT116 were investigated by MTT assay with Doxorubicin as the control compound.

Potential effects of fructus aurantii ethanol extracts against colitis-associated carcinogenesis through coordination of Notch/NF-κB/IL-1 signaling pathways

Colitis-associated cancer (CAC) is the colorectal cancer (CRC) subtype that is difficult to treat, and shows high mortality. The consumption of flavonoid-rich fructus aurantii extracts (FAE) has been associated with multiple beneficial effects including anti-inflammatory and anti-cancer properties, but the potential effects on the colitis-associated carcinogenesis have not been thoroughly investigated. Recent clinical data show that, as yet, few agents clearly inhibited CRC development in long-standing inflammatory bowel diseases. Here, we identified that FAE showed significant efficiency to inhibit HT-29 cell proliferation. The potential of FAE in vivo was further evaluated in an AOM/DSS-induced CAC mouse model. Intriguingly, FAE diminished the number of polyps in mice. Furthermore, FAE inhibited CAC by regulating the gene expression of Notch/ NF-κB/IL-1 signaling pathways. Collectively, these results were indicative of FAE has great potential in CAC prevention and treatment.

Regulation of endoplasmic reticulum stress by hesperetin: Focus on antitumor and cytoprotective effects

BACKGROUND

Cancer is still an all-times issue due to a large and even increasing number of deaths. Impaired genes regulating cell proliferation and apoptosis are targets for the development of novel cancer treatments.

HYPOTHESIS

Increased transcription of NADPH oxidase activator (NOXA), Bcl2-like11 (BIM), BH3-only proteins and p53 unregulated apoptosis modulator (PUMA) is caused by the imbalance between pro- and anti-apoptotic Bcl-2 proteins due to endoplasmic reticulum (ER) stress. The membranous network of ER is present in all eukaryotic cells. ER stress facilitates the interaction between Bax and PUMA, triggering the release of cytochrome C. As a main intracellular organelle, ER is responsible for translocation as well as post-translation modification and protein folding.

RESULTS

Hesperetin is a cytoprotective flavonone, which acts against ER stress and protects from cell damage induced by reactive oxygen species (ROS) and reactive nitrogen species (RNS). Hesperetin inhibits lipid peroxidation induced by Fe²⁺ and l-ascorbic acid in rat brain homogenates.

CONCLUSION

This review deals with the anticancer effects of hesperetin regarding the regulation of ER stress as a principal mechanism in the pathogenesis of tumors.

Neuroprotective Effects and Therapeutic Potential of the Citrus Flavonoid Hesperetin in Neurodegenerative Diseases

Neurodegenerative disorders affect more than fifty million Americans each year and represent serious health threats as the population ages. Neuroinflammation and oxidative stress are critical in the onset, progression, and pathogenesis of neurodegenerative diseases such as Alzheimer’s (AD), Parkinson’s (PD), and amyotrophic lateral sclerosis (ALS). A wide range of natural compounds has been investigated because of their antioxidant, anti-inflammatory, and neuroprotective properties. The citrus flavonoid hesperetin (HPT), an aglycone of hesperidin found in oranges, mandarins, and lemons, has been extensively reported to exert neuroprotective effects in experimental models of neurogenerative diseases. This review has compiled multiple studies on HPT in both in vivo and in vitro models to study neurodegeneration. We focused on the modulatory effects of hesperetin on the release of cellular anti-inflammatory and antioxidative stress mediators. Additionally, this review discusses the hesperetin effect in maintaining the levels of microRNA (miRNA) and modulating autophagy as it relates to hesperetin’s protective mechanisms against neurodegeneration. Moreover, this review is focused on providing experimental data for hesperetin’s potential as a neuroprotective compound and discusses reported evidence that HPT crosses the blood–brain barrier. In summary, this review shows the evidence available in the literature to indicate the efficacy of hesperetin in delaying the onset of neurodegenerative diseases.

Inhibitory Effect of Lotus Leaf-Enriched Flavonoid Extract on the Growth of HT-29 Colon Cancer Cells through the Expression of PI3K-Related Molecules

Objectives

Lotus leaf is rich in flavonoids, and this study is aimed at examining the inhibitory effect of lotus leaf-enriched flavonoid extract (LLEFE) on HT-29 colon cancer cells through phosphatidylinositol 3-kinase/protein kinase B (PI3K/Akt) expression regulation.

Methods

Lotus leaves were extracted by ethanol and purified using FL-3 macroporous resin to create the LLEFE. HT-29 colon cancer cells were tested using various methods: their proliferation was observed by 3-(4,5)-dimethylthiahiazo(-z-y1)-3,5-di-phenytetrazoliumromide (MTT) assay, their survival status was observed by fluorescence staining, their oxidative stress level was observed by biochemical kits, and their mRNA expression was determined by quantitative polymerase chain reaction (qPCR) assay. Additionally, the composition of the flavonoids in lotus leaf was determined by HPLC.

Results

The results showed that the proliferation of NCM460 normal human colon cells was not affected by 0–500 μg/mL LLEFE but the proliferation of HT-29 human colon cancer cells decreased. LLEFE increased the LDH level in an HT-29 colon cancer cell culture medium; also increased the superoxide dismutase (SOD), catalase (CAT) activities, and glutathione (GSH) level in HT-29 cells; and decreased the malondialdehyde (MDA) level. Further experimental results showed that LLEFE upregulated the expression of SOD1, CAT, and GSH mRNA and downregulated the expression of PI3K, Akt, and mammalian target of rapamycin (mTOR) in HT-29 cells. The high-performance liquid chromatography (HPLC) results showed that kaempferin, hyperoside, astragaloside, phloridzin, and quercetin were the main chemical constituents of lotus leaf.

Conclusion

Lotus leaves contain functional flavonoids that inhibit the proliferation of HT-29 colon cancer cells and regulate the expression of PI3K/Akt through five important chemicals.

Pharmacological Significance of Hesperidin and Hesperetin, Two Citrus Flavonoids, as Promising Antiviral Compounds for Prophylaxis Against and Combating COVID-19

Hesperidin and hesperetin are flavonoids that are abundantly present as constituents of citrus fruits. These compounds have attracted attention as several computational methods, mostly docking studies, have shown that hesperidin may bind to multiple regions of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) (spike protein, angiotensin-converting enzyme 2, and proteases). Hesperidin has a low binding energy, both with the SARS-CoV-2 “spike” protein responsible for internalization, and also with the “PLpro” and “Mpro” responsible for transforming the early proteins of the virus into the complex responsible for viral replication. This suggests that these flavonoids could act as prophylactic agents by blocking several mechanisms of viral infection and replication, and thus helping the host cell to resist viral attack.

Antioxidant and Anti-Inflammatory Effects of Citrus Flavonoid Hesperetin: Special Focus on Neurological Disorders

Neurodegenerative disorders have emerged as a serious health issue in the current era. The most common neurodegenerative disorders are Alzheimer's disease (AD), Parkinson's disease, multiple sclerosis, and amyotrophic lateral sclerosis (ALS). These diseases involve progressive impairment of neurodegeneration and memory impairment. A wide range of compounds have been identified as potential neuroprotective agents against different models of neurodegeneration both in vivo and in vitro. Hesperetin, a flavanone class of citrus flavonoid, is a derivative of hesperidin found in citrus fruits such as oranges, grapes, and lemons. It has been extensively reported that hesperetin exerts neuroprotective effects in experimental models of neurodegenerative diseases. In this systematic review, we have compiled all the studies conducted on hesperetin in both in vivo and in vitro models of neurodegeneration. Here, we have used an approach to lessen the bias in each study, providing a least biased, broad understanding of findings and impartial conclusions of the strength of evidence and the reliability of findings. In this review, we collected different papers from a wide range of journals describing the beneficial effects of hesperetin on animal models of neurodegeneration. Our results demonstrated consistent neuroprotective effects of hesperetin against different models of neurodegeneration. In addition, we have summarized its underlying mechanisms. This study provides the foundations for future studies and recommendations of further mechanistic approaches to conduct preclinical studies on hesperetin in different models.

Design and application of oral colon administration system

Oral colon administration system has become a new method to treat intestinal diseases. The implementation of colon drug delivery system is restricted by many aspects, including physical and chemical properties, drug delivery mode, gastrointestinal physiological factors, and so on. Delivery methods to overcome these challenges revolve around the mechanisms of drug delivery, including the use of rational dosage forms to avoid the complex pH environment, and the prevention of drug release and absorption in the upper digestive tract.

Natural flavonoids for the prevention of colon cancer: A comprehensive review of preclinical and clinical studies

Flavonoids comprise a group of natural polyphenols consisting of more than 5,000 subtypes mostly existing in fruits and vegetables. Flavonoids consumption could potentially attenuate the incidence and recurrence risk of colorectal cancers through their antiperoxidative, antioxidant, and anti-inflammatory effects. In addition, these compounds regulate the mitochondrial function, balance the bacterial flora and promote the apoptosis process in cancerous cells. However, some previous data failed to show the effectiveness of flavonoids in reducing the risk of colorectal cancer. In this study, we have reviewed the efficacy of different flavonoids subtypes on the risk of colon cancer and molecular mechanisms involved in this process in both clinical and animal studies. In addition, we tried to elucidate the potential synergy between these compounds and current colorectal cancer treatments.

Hesperetin induces an apoptosis-triggered extrinsic pathway and a p53- independent pathway in human lung cancer H522 cells

We studied the chemoprevention property of hesperetin on H522 cells using MTT, an apoptosis assay, an analysis of cell cycle progression, and the mitochondrial membrane potential, and apoptotic marker gene expression was determined using quantitative PCR. Hesperetin enhanced apoptotic cell death and mitochondrial membrane potential loss in H522 cells. Hesperetin up-regulated the levels of Fas, FADD, and caspase-8 expression and downregulted the levels of caspase-3 and caspase-9, p53, and Bax expression in H522 cells. This study shows that hesperetin induces apoptosis in H522 cells via a pathway independentof p53 and Bax but triggers the death-receptor Fas-initiated FADD/ caspase-8-dependent apoptotic pathway.

Flavanones: Citrus phytochemical with health-promoting properties

Citrus fruit and juices represent one of the main sources of compounds with a high potential for health promoting properties. Among these compounds, flavanones (such as hesperetin, naringenin, eriodictyol, isosakuranetin, and their respective glycosides), which occur in quantities ranging from ∼180 to 740 mg/L (depending on the Citrus species and cultivar) are responsible for many biological activities. These compounds support and enhance the body's defenses against oxidative stress and help the organism in the prevention of cardiovascular diseases, atherosclerosis, and cancer. Moreover, among other properties, they also show anti-inflammatory, antiviral, and antimicrobial activities. This review analyzes the biochemistry, pharmacology, and biology of Citrus flavanones, emphasizing the occurrence in Citrus fruits and juices and their bioavailability, structure-function correlations and ability to modulate signal cascades both in vitro and in vivo. © 2017 BioFactors, 43(4):495-506, 2017.

Citrus fruits as a treasure trove of active natural metabolites that potentially provide benefits for human health

Citrus fruits, which are cultivated worldwide, have been recognized as some of the most high-consumption fruits in terms of energy, nutrients and health supplements. What is more, a number of these fruits have been used as traditional medicinal herbs to cure diseases in several Asian countries. Numerous studies have focused on Citrus secondary metabolites as well as bioactivities and have been intended to develop new chemotherapeutic or complementary medicine in recent decades. Citrus-derived secondary metabolites, including flavonoids, alkaloids, limonoids, coumarins, carotenoids, phenolic acids and essential oils, are of vital importance to human health due to their active properties. These characteristics include anti-oxidative, anti-inflammatory, anti-cancer, as well as cardiovascular protective effects, neuroprotective effects, etc. This review summarizes the global distribution and taxonomy, numerous secondary metabolites and bioactivities of Citrus fruits to provide a reference for further study. Flavonoids as characteristic bioactive metabolites in Citrus fruits are mainly introduced.

Hesperetin Induces the Apoptosis of Gastric Cancer Cells via Activating Mitochondrial Pathway by Increasing Reactive Oxygen Species

BACKGROUND

Hesperetin, has been shown to exert biological activities on various types of human cancers. However, few related studies on gastric cancer are available.

AIM

In this study, we sought to investigate the effect of hesperetin on gastric cancer and clarify its specific mechanism.

MATERIALS AND METHODS

Cell Counting Kit-8, 2',7'-dichlorofluorescin diacetate, JC-1, Hoechst 33258 staining, and western bolt were used to detect cell viability, levels of intracellular reactive oxygen species (ROS), changes in mitochondrial membrane potential (△ψ m), cell apoptosis, and expressions of mitochondrial pathway proteins, respectively. Meanwhile, xenograft tumor models in nude mice were made to evaluate the effect of hesperetin on gastric cancer in vivo.

RESULTS

Compared with the control group, the proliferation of gastric cancer cells in hesperetin groups was significantly inhibited (P < 0.05), and dose- and time-dependent effects were observed. Pretreatment with H2O2 (1 mM) or N-acetyl-L-cysteine (5 mM) enhanced or attenuated the hesperetin-induced inhibition of cell viability (P < 0.05). Percentages of apoptotic cells, levels of intracellular ROS, and △ψ m varied with the dose and treatment time of hesperetin (P < 0.05), and hesperetin caused an increase in the levels of AIF, Apaf-1, Cyt C, caspase-3, caspase-9, and Bax and a decrease in Bcl-2 levels (P < 0.05). Meanwhile, hesperetin significantly inhibited the growth of xenograft tumors (P < 0.05).

CONCLUSION

Our study suggests that hesperetin could inhibit the proliferation and induce the apoptosis of gastric cancer cells via activating the mitochondrial pathway by increasing the ROS.

Hydrolyzed Methylhesperidin Induces Antioxidant Enzyme Expression via the Nrf2-ARE Pathway in Normal Human Epidermal Keratinocytes

Methylhesperidin (MHES) is a mixture of methylated derivatives of the citrus flavonoid hesperidin and is used as a food or pharmaceutical additive. Dietary MHES could be hydrolyzed by gut microflora to give aglycons. Therefore, we prepared hydrolyzed methylhesperidin (h-MHES) and assessed its pharmacological activity in human epidermal keratinocytes. h-MHES promoted nuclear factor erythroid 2-related factor 2 (Nrf2) nuclear translocation and the expression of cytoprotective genes (e.g., heme oxygenase-1 (HO-1) and glutamate cysteine ligase catalytic subunit (GCLC)). h-MHES also increased intracellular glutathione levels and reduced UVB-induced reactive oxygen species. Moreover, h-MHES increased phosphorylation of p38 mitogen-activated protein kinase (MAPK), and a p38 MAPK inhibitor significantly attenuated h-MHES-induced HO-1 and GCLC expression. Furthermore, when we purified the components of h-MHES, we identified two methoxy-chalcones as novel Nrf2 activators. Our study demonstrates that h-MHES can induce cytoprotective gene expression and reduce oxidative stress via the Nrf2-ARE pathway in keratinocytes, suggesting that MHES may contribute to the suppression of UVB-induced skin damage in vivo.

Oral supplementation with troxerutin (trihydroxyethylrutin), modulates lipid peroxidation and antioxidant status in 1,2-dimethylhydrazine-induced rat colon carcinogenesis

The present study was aimed to investigate the chemopreventive potential of troxerutin on 1,2-dimethylhydrazine (DMH) induced rat colon carcinogenesis by evaluating the antioxidant and lipid peroxidation (LPO) status. Rats were randomly divided into six groups. Group I rats served as control. Group II rats received troxerutin (50 mg/kgb.w., p.o.) for 16 weeks. Groups III-VI rats received subcutaneous injections of DMH (20 mg/kgb.w., s.c.) once a week, for the first 4 weeks. In addition to DMH, groups IV-VI rats received troxerutin at the doses of 12.5, 25 and 50 mg/kgb.w., respectively. In DMH treated rats, our results showed decreased activities of antioxidants and increased levels of LPO in the liver. Moreover, LPO and antioxidants in the colon were found to be significantly diminished in DMH the treated rats. Furthermore, enhanced activity of colonic vitamin C and vitamin E levels were observed in DMH alone treated rats (group III), which was significantly reversed on troxerutin supplementation. Troxerutin at the dose of 25 mg/kgb.w. had shown profound beneficial effects by exhibiting near normal biochemical profile and well-preserved colon histology as compared to the other two tested doses (12.5 and 50 mg/kgb.w.). These findings suggest that troxerutin could serve as a novel agent for colon cancer chemoprevention.

Modulatory effect of troxerutin on biotransforming enzymes and preneoplasic lesions induced by 1,2-dimethylhydrazine in rat colon carcinogenesis

Colon cancer is the third most global oncologic problem faced by medical fraternity. Troxerutin, a flavonoid present in tea, coffee, cereal grains, and a variety of fruits and vegetables, exhibits various pharmacological and biological activities. This study was carried out to investigate the effect of troxerutin on xenobiotic metabolizing enzymes, colonic bacterial enzymes and the development of aberrant crypt foci (ACF) during 1,2-dimethylhydrazine (DMH) induced experimental rat colon carcinogenesis. Male albino Wistar rats were randomly divided into six groups. Group 1 served as control. Group 2 received troxerutin (50 mg/kg b.w., p.o. every day) for 16 weeks. Groups 3-6 received subcutaneous injections of DMH (20 mg/kg b.w.) once a week, for the first four weeks. In addition, groups 4-6 received different doses of troxerutin (12.5, 25, 50 mg/kg b.w., p.o. every day respectively) along with DMH injections. Our results reveal that DMH treated rats exhibited elevated activities of phase I enzymes such as cytochrome P450, cytochrome b5, cytochrome P4502E1, NADPH-cytochrome P450 reductase and NADH-cytochrome b5 reductase and reduced activities of phase II enzymes such as glutathione-S-transferase (GST), DT-diaphorase (DTD) and uridine diphospho glucuronyl transferase (UDPGT) in the liver and colonic mucosa of control and experimental rats. Furthermore, the activities of fecal and colonic mucosal bacterial enzymes, such as β-glucronidase, β-glucosidase, β-galactosidase and mucinase were found to be significantly higher in DMH alone treated rats than those of the control rats. On supplementation with troxerutin to DMH treated rats, the alterations in the activities of the biotransforming enzymes, bacterial enzymes and the pathological changes were significantly reversed, the effect being more pronounced when troxerutin was supplemented at the dose of 25 mg/kg b.w. Thus troxerutin could be considered as a good chemopreventive agent against the formation of preneoplastic lesions in a rat model of colon carcinogenesis.

The apoptotic effect of hesperetin on human cervical cancer cells is mediated through cell cycle arrest, death receptor, and mitochondrial pathways

Hesperetin, a flavonoid from citrus fruits, has several bioactivities such as anti-inflammatory, antihypertensive, antiatherogenic effects. However, studies elucidating the role and the mechanism(s) of action of hesperetin in cervical cancer are sparse. In this study, we investigated the mechanism of the antiproliferative and apoptotic actions exerted by hesperetin on human cervical cancer SiHa cells. The viability of SiHa cells was evaluated using the MTT assay, apoptosis by acridine orange/ethidium bromide, propidium iodide, TUNEL assay, and Annexin V-Cy3, cell cycle distribution and mitochondrial transmembrane potential using flow cytometry, and apoptotic marker genes using quantitative real-time PCR. The treatment of SiHa cells with hesperetin (IC50, 650 μm) showed a marked concentration- and time-dependent inhibition of proliferation and induced the G2/M phase in a dose-dependent manner after 24 h. There was an attenuation of mitochondrial membrane potential with increased expression of caspase-3, caspase-8, caspase-9, p53, Bax, and Fas death receptor and its adaptor protein Fas-associated death domain-containing protein (FADD), indicating the participation of both death receptor- and mitochondria-related mechanisms. Furthermore, hesperetin-induced apoptosis was confirmed by TUNEL and Annexin V-Cy3. This study shows that hesperetin exhibits a potential anticancer activity against human cervical cancer cell lines in vitro through the reduction in cell viability and the induction of apoptosis. Altogether, these data sustain our contention that hesperetin has anticancer properties and merits further investigation as a potential therapeutic agent.

Antiproliferative efficacy of hesperetin (citrus flavanoid) in 1,2-dimethylhydrazine-induced colon cancer

Cancer is the second leading cause of death worldwide and is increasing at an alarming rate. The present study was to evaluate the antiproliferative effects of hesperetin, a flavonoid commonly found in many herbal medicines and foods, on aberrant crypt foci (ACF), argyrophylic nucleolar organizer regions (AgNORs) and proliferating cell nuclear antigen (PCNA) in 1,2-dimethylhydrazine (DMH)-induced colon carcinogenesis in rats. Rats were given subcutaneous injections of DMH (20 mg/kg body weight) weekly for 15 weeks to induce carcinogenesis, and hesperetin was administered orally at the dose of 20 mg/kg body weight. DMH exposure alone produced a high incidence of ACF and showed positive staining for PCNA and AgNORs in colonic tissues. Supplementation with hesperetin lowered the PCNA labeling index and suppressed the formation of ACF in the rats with colon cancer. These results clearly reveal that dietary hesperetin possesses antiproliferative ability against chemically induced colon tumourigenesis.

Topical hesperidin improves epidermal permeability barrier function and epidermal differentiation in normal murine skin

Orange peel extract appears to exhibit beneficial effects on skin whitening, inflammation, UVB protection, as well as keratinocyte proliferation. In the present study, we determine whether topical hesperidin influences epidermal permeability barrier function and its underlying mechanisms. Hairless mice were treated topically with 2% hesperidin or 70% ethanol alone twice daily for 6 days. At the end of treatment, basal transepidermal water loss (TEWL) was measured 2 and 4 h post barrier disruption. Epidermal proliferation and differentiation were evaluated by immunohistochemical staining and Western blot analysis. Additionally, lamellar body density and secretion were assessed by electron microscopy. Although there were no significant differences in basal barrier function, in comparison with control animals, topical hesperidin significantly accelerated barrier recovery at both 2 and 4 h after acute barrier abrogation. Enhanced barrier function in hesperidin-treated skin correlated with stimulation of both epidermal proliferation and differentiation, as well as enhanced lamellar body secretion. These results indicate that topical hesperidin enhances epidermal permeability barrier homeostasis at least in part due to stimulation of epidermal proliferation, differentiation, as well as lamellar body secretion.

The intestinal microbiota, gastrointestinal environment and colorectal cancer: a putative role for probiotics in prevention of colorectal cancer?

Colorectal cancer (CRC) is the third most commonly diagnosed cancer in the United States, and, even though 5-15% of the total CRC cases can be attributed to individual genetic predisposition, environmental factors could be considered major factors in susceptibility to CRC. Lifestyle factors increasing the risks of CRC include elevated body mass index, obesity, and reduced physical activity. Additionally, a number of dietary elements have been associated with higher or lower incidence of CRC. In this context, it has been suggested that diets high in fruit and low in meat might have a protective effect, reducing the incidence of colorectal adenomas by modulating the composition of the normal nonpathogenic commensal microbiota. In addition, it has been demonstrated that changes in abundance of taxonomic groups have a profound impact on the gastrointestinal physiology, and an increasing number of studies are proposing that the microbiota mediates the generation of dietary factors triggering colon cancer. High-throughput sequencing and molecular taxonomic technologies are rapidly filling the knowledge gaps left by conventional microbiology techniques to obtain a comprehensive catalog of the human intestinal microbiota and their associated metabolic repertoire. The information provided by these studies will be essential to identify agents capable of modulating the massive amount of gut bacteria in safe noninvasive manners to prevent CRC. Probiotics, defined as "live microorganisms which, when administered in adequate amounts, confer a health benefit on the host" (219), are capable of transient modulation of the microbiota, and their beneficial effects include reinforcement of the natural defense mechanisms and protection against gastrointestinal disorders. Probiotics have been successfully used to manage infant diarrhea, food allergies, and inflammatory bowel disease; hence, the purpose of this review was to examine probiotic metabolic activities that may have an effect on the prevention of CRC by scavenging toxic compounds or preventing their generation in situ. Additionally, a brief consideration is given to safety evaluation and production methods in the context of probiotics efficacy.

Apigenin and naringenin suppress colon carcinogenesis through the aberrant crypt stage in azoxymethane-treated rats

Epidemiological evidence suggests that a diet abundant in fruits and vegetables may protect against colon cancer. Bioactive compounds, including flavonoids and limonoids, have been shown to possess antiproliferative and antitumorigenic effects in various cancer models. This experiment investigated the effects of four citrus flavonoids and one limonoid mixture at the promotion stage of chemically induced colon cancer in rats. Male Sprague-Dawley rats (n = 10 rats/group) were randomly allocated to one of six diets formulated to contain 0.1% apigenin, 0.02% naringenin, 0.1% hesperidin, 0.01% nobiletin, 0.035% limonin glucoside/obacunone glucoside mixture or a control diet (0% flavonoid/limonoid). Rats received experimental diets for 10 weeks and were injected with azoxymethane (15 mg/kg) at weeks 3 and 4. Excised colons were evaluated for aberrant crypt foci (ACF) formation, colonocyte proliferation (proliferating cell nuclear antigen assay), apoptosis (terminal deoxynucleotidyl transferase dUTP nick end labeling assay) and expression of inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2) (immunoblotting). When compared with the control diet, apigenin lowered the number of high multiplicity ACF (HMACF >4 aberrant crypts/focus) by 57% (P < 0.05), while naringenin lowered both the number of HMACF by 51% (P < 0.05) and the proliferative index by 32% (P < 0.05). Both apigenin and naringenin increased apoptosis of luminal surface colonocytes (78% and 97%, respectively; P < 0.05) when compared with the control diet. Hesperidin, nobiletin and the limonin glucoside/obacunone glucoside mixture did not affect these variables. The colonic mucosal protein levels of iNOS or COX-2 were not different among the six diet groups. The ability of dietary apigenin and naringenin to reduce HMACF, lower proliferation (naringenin only) and increase apoptosis may contribute toward colon cancer prevention. However, these effects were not due to mitigation of iNOS and COX-2 protein levels at the ACF stage of colon cancer.

Passive asymmetric transport of hesperetin across isolated rabbit cornea

Hesperetin, an aglycone of the flavanone hesperidin, is a potential candidate for the treatment of diabetic retinopathy and macular edema. The purpose of this investigation was to determine solubility, stability and in vitro permeability characteristics of hesperetin across excised rabbit corneas. Aqueous and pH dependent solubility was determined using standard shake flask method. Solution stability was evaluated as a function of pH (1.2-9) and temperature (25 and 40 degrees C). Permeability of hesperetin was determined across the isolated rabbit cornea utilizing a side-bi-side diffusion apparatus, in the apical to basolateral (A-B) and basolateral to apical (B-A) directions. Hesperetin displayed asymmetrical transcorneal transport with a 2.3-fold higher apparent permeability in the B-A direction compared to the A-B direction. The transport process was observed to be pH dependent. Surprisingly, however, the involvement of efflux transporters or proton-coupled carrier-systems was not evident in this asymmetric transcorneal diffusion process. The passive and pH dependent corneal transport of hesperetin could probably be attributable to corneal ultrastructure, physicochemical characteristics of hesperetin and the role of transport buffer components.

Absorption, conjugation and excretion of the flavanones, naringenin and hesperetin from alpha-rhamnosidase-treated orange juice in human subjects

We have determined the absorption, conjugation and excretion of naringenin-7-O-rutinoside (narirutin) compared to the corresponding glucoside in an orange juice matrix in human subjects. Healthy volunteers (eight men and eight women), in a double blind, randomised, crossover study, consumed orange juice with (1) natural content of naringenin-7-O-rutinoside; (2) alpha-rhamnosidase-treated to yield naringenin-7-O-glucoside. Blood was sampled at twelve time points and three fractions of urine were collected over 24 h. The area under the plasma-time curve of naringenin from (2) alpha-rhamnosidase-treated orange juice was increased about 4-fold (P < 0.0001), peak plasma concentration (Cmax) was 5.4-fold higher (P < 0.0001) and Tmax was decreased from 311 to 92 min (P = 0.002) compared to untreated orange juice (1), indicating a change in absorption site from the colon to the small intestine. Furthermore, the amount in urine was increased from 7 to 47 % (P < 0.0001) of the dose after consumption of the alpha-rhamnosidase-treated orange juice (2). All urine samples contained both naringenin-7- and -4'-O-glucuronides. In addition, to examine the effect of dose and alpha-rhamnosidase treatment on hesperetin conjugate profiles, a further treatment where (3) orange juice fortified with three times the original content of hesperetin-7-O-rutinoside was used. Five hesperetin metabolites (3'-O-glucuronide; 7-O-glucuronide; 5,7-O-diglucuronide; 3',7-O-diglucuronide; 3'-O-sulphate) were present after all treatments (1-3), with the same profile of the conjugates. The present data show that bioavailability of naringenin is increased by conversion from rutinoside to glucoside, but the profile of the conjugates of flavanones formed and excreted in urine is neither affected by the absorption site nor by a 3-fold change in dose.