Furocoumarins from grapefruit juice and their effect on human CYP 3A4 and CYP 1B1 isoenzymes

Natural STAT3 Inhibitors for Cancer Treatment: A Comprehensive Literature Review

Cancer is one of the leading causes of mortality and morbidity worldwide, affecting millions of people physically and financially every year. Over time, many anticancer treatments have been proposed and studied, including synthetic compound consumption, surgical procedures, or grueling chemotherapy. Although these treatments have improved the daily life quality of patients and increased their survival rate and life expectancy, they have also shown significant drawbacks, including staggering costs, multiple side effects, and difficulty in compliance and adherence to treatment. Therefore, natural compounds have been considered a possible key to overcoming these problems in recent years, and thorough research has been done to assess their effectiveness. In these studies, scientists have discovered a meaningful interaction between several natural materials and signal transducer and activator of transcription 3 molecules. STAT3 is a transcriptional protein that is vital for cell growth and survival. Mechanistic studies have established that activated STAT3 can increase cancer cell proliferation and invasion while reducing anticancer immunity. Thus, inhibiting STAT3 signaling by natural compounds has become one of the favorite research topics and an attractive target for developing novel cancer treatments. In the present article, we intend to comprehensively review the latest knowledge about the effects of various organic compounds on inhibiting the STAT3 signaling pathway to cure different cancer diseases.

Content analysis and drug safety evaluation of four furanocoumarins in six pomelos produced in China

The content of 4 6',7'-dihydroxybergamottin (DHB), bergamottin, isoimperatorin and epoxybergamottin of six pomelos produced in China were detected by High-performance liquid chromatography-diode array detection and their safety of related medicines was evaluated by inhibition of medium concentration (IC50) of cytochrome oxidases CYP450-like. The results showed that the total content of the four furanocoumarins in these pomelo juices from high to low in order was Guanximi pomelo > Liangping pomelo > Pinghemi pomelo > grapefruit > Huyou > Shatian pomelo. The concentration of isoimperatorin in grapefruit, DHB, bergamottinand and isoimperatorin in Liangping, bergamottin and epoxybergamottin in Pinghemi and all the four furanocoumarins in Guanximi were exceeded the corresponding IC50; although Huyou and Shatian contained some furanocoumarins, they did not exceed IC50. Therefore, when taking drugs metabolised by CYP450-like enzymes, Guanximi, Liangping, Pinghemi, and grapefruit should be avoided to consume, but it is relatively safe to eat Huyou and Shatian.

Effects of xenobiotics on CYP1 enzyme-mediated biotransformation and bioactivation of estradiol

Endogenous estradiol (E2) exerts diverse physiological and pharmacological activities, commonly used for hormone replacement therapy. However, prolonged and excessive exposure to E2 potentially increases estrogenic cancer risk. Reportedly, CYP1 enzyme-mediated biotransformation of E2 is largely concerned with its balance between detoxification and carcinogenic pathways. Among the three key CYP1 enzymes (CYP1A1, CYP1A2, and CYP1B1), CYP1A1 and CYP1A2 mainly catalyze the formation of nontoxic 2-hydroxyestradiol (2-OH-E2), while CYP1B1 specifically catalyzes the formation of genotoxic 4-hydroxyestradiol (4-OH-E2). 4-OH-E2 can be further metabolized to electrophilic quinone intermediates accompanied by the generation of reactive oxygen species (ROS), triggering DNA damage. Since abnormal alterations in CYP1 activities can greatly affect the bioactivation process of E2, regulatory effects of xenobiotics on CYP1s are essential for E2-associated cancer development. To date, thousands of natural and synthetic compounds have been found to show potential inhibition and/or induction actions on the three CYP1 members. Generally, these chemicals share similar planar polycyclic skeletons, the structural motifs and substituent groups of which are important for their inhibitory/inductive efficiency and selectivity toward CYP1 enzymes. This review comprehensively summarizes these known inhibitors and/or inductors of E2-metabolizing CYP1s based on chemical categories and discusses their structure-activity relationships, which would contribute to better understanding of the correlation between xenobiotic-regulated CYP1 activities and estrogenic cancer susceptibility.

Food-Borne Chemical Carcinogens and the Evidence for Human Cancer Risk

Commonly consumed foods and beverages can contain chemicals with reported carcinogenic activity in rodent models. Moreover, exposures to some of these substances have been associated with increased cancer risks in humans. Food-borne carcinogens span a range of chemical classes and can arise from natural or anthropogenic sources, as well as form endogenously. Important considerations include the mechanism(s) of action (MoA), their relevance to human biology, and the level of exposure in diet. The MoAs of carcinogens have been classified as either DNA-reactive (genotoxic), involving covalent reaction with nuclear DNA, or epigenetic, involving molecular and cellular effects other than DNA reactivity. Carcinogens are generally present in food at low levels, resulting in low daily intakes, although there are some exceptions. Carcinogens of the DNA-reactive type produce effects at lower dosages than epigenetic carcinogens. Several food-related DNA-reactive carcinogens, including aflatoxins, aristolochic acid, benzene, benzo[a]pyrene and ethylene oxide, are recognized by the International Agency for Research on Cancer (IARC) as causes of human cancer. Of the epigenetic type, the only carcinogen considered to be associated with increased cancer in humans, although not from low-level food exposure, is dioxin (TCDD). Thus, DNA-reactive carcinogens in food represent a much greater risk than epigenetic carcinogens.

Bergamottin a CYP3A inhibitor found in grapefruit juice inhibits prostate cancer cell growth by downregulating androgen receptor signaling and promoting G0/G1 cell cycle block and apoptosis

Prostate cancer is the second leading cause of cancer related death in American men. Several therapies have been developed to treat advanced prostate cancer, but these therapies often have severe side effects. To improve the outcome with fewer side effects we focused on the furanocoumarin bergamottin, a natural product found in grapefruit juice and a potent CYP3A inhibitor. Our recent studies have shown that CYP3A5 inhibition can block androgen receptor (AR) signaling, critical for prostate cancer growth. We observed that bergamottin reduces prostate cancer (PC) cell growth by decreasing both total and nuclear AR (AR activation) reducing downstream AR signaling. Bergamottin’s role in reducing AR activation was confirmed by confocal microscopy studies and reduction in prostate specific antigen (PSA) levels, which is a marker for prostate cancer. Further studies revealed that bergamottin promotes cell cycle block and accumulates G0/G1 cells. The cell cycle block was accompanied with reduction in cyclin D, cyclin B, CDK4, P-cdc2 (Y15) and P-wee1 (S642). We also observed that bergamottin triggers apoptosis in prostate cancer cell lines as evident by TUNEL staining and PARP cleavage. Our data suggests that bergamottin may suppress prostate cancer growth, especially in African American (AA) patients carrying wild type CYP3A5 often presenting aggressive disease.

Anti-Cancer and Anti-Inflammatory Potential of Furanocoumarins from Ammi majus L

Secondary metabolites have potential benefits to human being. They are used in the food, agricultural and pharmaceutical industries. The secondary metabolite of furanocoumarins from different plant sources is essential in various skin-related ailments. Biologically, these chemicals are isolated from different plants in the Apiaceae, Fabaceae, Rutaceae and Moraceae families. Ammi Majus L. is one of the most common plants in the family of Apiaceae with a large quantity of derivatives. The furanocoumarin derivatives defend the plant by fighting external enemies by systemic acquired resistance (SAR). Via suppressing or retarding microbial growth in infected parts, these derivatives, along with SAR, help to alleviate inflammation in the human body. Latest evidence of these compounds has been established in the treatment of cancer, but the mechanism that needs to be elaborated is not yet understood. Recent studies have shown that furanocoumarin derivatives bind to DNA base pairs and block DNA replication. This may be a potential pathway that helps to regulate the growth of cancerous cells. This article reflects on the pharmaceutical data of furanocoumarins and their different mechanisms in these cases.

Dietary Intake of Coumarins and Furocoumarins through Citrus Beverages: A Detailed Estimation by a HPLC-MS/MS Method Combined with the Linear Retention Index System

Official regulations concerning the maximum number of substances in food are introduced as a consequence of possible adverse effects, after oral administration. In this regard, analytical methods are necessary in order to determine specific targets. Among oxygen heterocyclic compounds (OHCs, that are furocoumarins, coumarins and polymethoxyflavones), only coumarin is subject to restriction by the Regulation (EC) No 1334/2008 of the European Parliament. Furocoumarins are known for their phototoxicity and other side effects due to their dietary intake; however, an official limit about the maximum content of these compounds in food is still missing. The lack of information about the real amount of these compounds in food is responsible for the conflicting opinions about the introduction of an official limit. The HPLC-MS/MS method here proposed, in combination with the linear retention index system, represents an innovative analytical strategy for the characterization of OHCs in citrus beverages. Several types of drinks were analysed in order to quantify 35 OHCs in total. This method is suitable for the quality control of OHCs in food and the obtained results may be considered as informative data useful for the regulatory authorities in the emission of new opinions and for a potential new regulation in this field.

Investigation of the impact of grapefruit juice, pomegranate juice and tomato juice on pharmacokinetics of brexpiprazole in rats using UHPLC-QTOF-MS

Brexpiprazole (BRX) is approved for the treatment of schizophrenia and major depressive disorders and it is mainly metabolized by CYP3A4 and CYP2D6. Grapefruit juice (GFJ), pomegranate juice (PJ) and tomato juice (TJ) have the potential to inhibit CYP3A4 enzymes in the body. However, fruit juice-drug interactions between BRX and GFJ, PJ and TJ have not been studied extensively. The present study describes the influence of GFJ, PJ and TJ on the pharmacokinetic parameters of BRX in rats. The study samples were analyzed using a mass-accurate and single-step bioanalytical method by ultra-high-performance liquid chromatography-quadrupole time-of-flight mass spectrometry over a wide calibration range of 20-1,500 ng/ml. The results of the pharmacokinetic study denoted that the combined administration of GFJ and PJ could increase systemic exposure of BRX. The area under the curve of BRX increased 3.43- and 1.88-fold with co-administration of GFJ and PJ, respectively, while TJ with BRX had no effect on the area under the curve. Time to peak concentration and half-life were not significantly changed by any juice co-administration. The results show that GFJ and PJ affect the pharmacokinetic profile of BRX and hence advice needs to be given to patients.

Mechanism-Based Inactivation of Cytochrome P450 Enzymes: Computational Insights

Mechanism-based inactivation (MBI) refers to the metabolic bioactivation of a xenobiotic by cytochrome P450s to a highly reactive intermediate which subsequently binds to the enzyme and leads to the quasi-irreversible or irreversible inhibition. Xenobiotics, mainly drugs with specific functional units, are the major sources of MBI. Two possible consequences of MBI by medicinal compounds are drug-drug interaction and severe toxicity that are observed and highlighted by clinical experiments. Today almost all of these latent functional groups (e.g., thiophene, furan, alkylamines, etc.) are known, and their features and mechanisms of action, owing to the vast experimental and theoretical studies, are determined. In the past decade, molecular modeling techniques, mostly density functional theory, have revealed the most feasible mechanism that a drug undergoes by P450 enzymes to generate a highly reactive intermediate. In this review, we provide a comprehensive and detailed picture of computational advances toward the elucidation of the activation mechanisms of various known groups with MBI activity. To this aim, we briefly describe the computational concepts to carry out and analyze the mechanistic investigations, and then, we summarize the studies on compounds with known inhibition activity including thiophene, furan, alkylamines, terminal acetylene, etc. This study can be reference literature for both theoretical and experimental (bio)chemists in several different fields including rational drug design, the process of toxicity prevention, and the discovery of novel inhibitors and catalysts.

Multi-factorial pharmacokinetic interactions: unraveling complexities in precision drug therapy

Introduction: Precision drug therapy requires accounting for pertinent factors in pharmacokinetic (PK) inter-individual variability (i.e., pharmacogenetics, diseases, polypharmacy, and natural product use) that can cause sub-therapeutic or adverse effects. Although each of these individual factors can alter victim drug PK, multi-factorial interactions can cause additive, synergistic, or opposing effects. Determining the magnitude and direction of these complex multi-factorial effects requires understanding the rate-limiting redundant and/or sequential PK processes for each drug.Areas covered: Perturbations in drug-metabolizing enzymes and/or transporters are integral to single- and multi-factorial PK interactions. Examples of single factor PK interactions presented include gene-drug (pharmacogenetic), disease-drug, drug-drug, and natural product-drug interactions. Examples of multi-factorial PK interactions presented include drug-gene-drug, natural product-gene-drug, gene-gene-drug, disease-natural product-drug, and disease-gene-drug interactions. Clear interpretation of multi-factorial interactions can be complicated by study design, complexity in victim drug PK, and incomplete mechanistic understanding of victim drug PK.Expert opinion: Incorporation of complex multi-factorial PK interactions into precision drug therapy requires advances in clinical decision tools, intentional PK study designs, drug-metabolizing enzyme and transporter fractional contribution determinations, systems and computational approaches (e.g., physiologically-based pharmacokinetic modeling), and PK phenotyping of progressive diseases.

Pharmaceutical Excipients and Drug Metabolism: A Mini-Review

Conclusions from previously reported articles have revealed that many commonly used pharmaceutical excipients, known to be pharmacologically inert, show effects on drug transporters and/or metabolic enzymes. Thus, the pharmacokinetics (absorption, distribution, metabolism and elimination) of active pharmaceutical ingredients are possibly altered because of their transport and metabolism modulation from the incorporated excipients. The aim of this review is to present studies on the interaction of various commonly-used excipients on pre-systemic metabolism by CYP450 enzymes. Excipients such as surfactants, polymers, fatty acids and solvents are discussed. Based on all the reported outcomes, the most potent inhibitors were found to be surfactants and the least effective were organic solvents. However, there are many factors that can influence the inhibition of CYP450, for instance type of excipient, concentration of excipient, type of CYP450 isoenzyme, incubation condition, etc. Such evidence will be very useful in dosage form design, so that the right formulation can be designed to maximize drug bioavailability, especially for poorly bioavailable drugs.

Isolation and structure elucidation of constituents of Citrus limon, Isodon japonicus, and Lansium domesticum as the cancer prevention agents

In the course of our research to investigate the cancer prevention potency of natural products derived from plant materials, we isolated fifty-five compounds, including twenty-one new compounds from the peels of Citrus limon, aerial parts of Isodon japonicus, and leaves of Lansium domesticum. The chemical structures of the isolated compounds were elucidated by chemical/physicochemical evidence, and nuclear magnetic resonance spectroscopy and mass spectrometry results. Moreover, the absolute stereochemistry of the new compounds were elucidated by various techniques such as chemical synthesis, modified Mosher’s method, Cu-Kα X-ray crystallographic analysis, and comparison of experimental and predicted electronic circular dichroism data. The antimutagenic effects of the isolated and structure-elucidated compounds against heterocyclic amines, 3-amino-1,4-dimethyl-5H-pyrido [4,3-b]indole (Trp-P-1) and 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP), were evaluated by the Ames test and in vivo micronucleus test. In this review, we present the comprehensive results of the antimutagenic effects of the isolated natural products.

Synthesis of Spin-Labelled Bergamottin: A Potent CYP3A4 Inhibitor with Antiproliferative Activity

Bergamottin (BM, 1), a component of grapefruit juice, acts as an inhibitor of some isoforms of the cytochrome P450 (CYP) enzyme, particularly CYP3A4. Herein, a new bergamottin containing a nitroxide moiety (SL-bergamottin, SL-BM, 10) was synthesized; chemically characterized, evaluated as a potential inhibitor of the CYP2C19, CYP3A4, and CYP2C9 enzymes; and compared to BM and known inhibitors such as ketoconazole (KET) (3A4), warfarin (WAR) (2C9), and ticlopidine (TIC) (2C19). The antitumor activity of the new SL-bergamottin was also investigated. Among the compounds studied, BM showed the strongest inhibition of the CYP2C9 and 2C19 enzymes. SL-BM is a more potent inhibitor of CYP3A4 than the parent compound; this finding was also supported by docking studies, suggesting that the binding positions of BM and SL-BM to the active site of CYP3A4 are very similar, but that SL-BM had a better ∆G_bind value than that of BM. The nitroxide moiety markedly increased the antitumor activity of BM toward HeLa cells and marginally increased its toxicity toward a normal cell line. In conclusion, modification of the geranyl sidechain of BM can result in new CYP3A4 enzyme inhibitors with strong antitumor effects.

Combining linear retention index and electron ionization mass spectrometry for a reliable identification in nano liquid chromatography

The present research is focused on the object to improve identification capability in liquid chromatography (LC), by creating a system as similar as possible to gas chromatography (GC), where the combination/complementarity of Linear Retention Index (LRI) and Electron Ionization Mass Spectrometry (EI-MS) data makes the identification process easy, automatic and reliable. Conversely, in LC the untargeted characterization of real-world samples is still a challenge, due to the not repeatable and poorly informative nature of typical atmospheric pressure ionization mass spectrometry, normally hyphenated to LC. In the last decades the miniaturization of LC instrumentation together with the considerable progresses in MS vacuum pump capability has made the LC-EI-MS hyphenation more feasible. In the present work, a prototypal nanoLC-EI-MS system was used for the determination of typically LC-amenable compunds, such as coumarins, furocoumarins and polymethoxyflavones in citrus essential oils. All the compounds provided high quality EI-MS spectra, evaluated by the comparison with thousands of spectra present in commercial EI-MS libraries. Spectral similarities major than 80% were achieved. Furthermore, an LRI system, based on the use of an alkyl aryl ketone homologue reference series, was proposed as additional filter to achieve a univocal identification. Then, a novel dual-filter LRI/EI-MS library was built and resulted very helpful in the case of isomeric compounds characterized by identical EI-MS spectrum, but different retention behaviour. The very low inter-day variability attained for each LRI value, together with the satisfactory chromatographic resolution of the developed method, led to a 100% reliability of the identification process based on LRI.

Anti-inflammatory Effect of Pomelo Peel and Its Bioactive Coumarins

Citrus grandis (L.) Osbeck is a popular fruit cultivated around the world, and its peels are sometimes used for the treatment of cough, abdominal pain, and indigestion in China. However, the peel is discarded after fruit consumption in most cases, and its chemical constituents and biological activities have not been validated before. The present study focused on evaluation of the chemical and pharmacological profile of coumarins from peels of C. grandis against inflammation. The extracts and phytochemicals from peels of C. grandis were prepared, and anti-inflammatory activities were carried out in vivo and in vitro, including inhibiting xylene-induced ear edema and carrageenan-induced paw edema in mice and the production of inflammatory cytokines (interleukin 1β, prostaglandin 2, and tumor-necrosis factor α) in lipopolysaccharide (LPS)-induced RAW 264.7 cells. Results indicated that methanolic extract, ethyl acetate fraction, and four major coumarins (compounds 7, 8, 13, and 16) inhibited swelling induced by xylene and carrageenan, separately, in vivo. Furthermore, 18 coumarins inhibited inflammatory factor secretion in macrophages primed by LPS, in which compounds 4, 6, 7, 10, 17 showed the most pronounced change, which were comparable to dexamethasone. In summary, peel of C. grandis showed an anti-inflammatory effect and coumarin compounds were responsible for regulating inflammatory mediators and cytokines, which might provide a novel nutritional strategy for inflammatory diseases.

Biomolecular Targets of Oxyprenylated Phenylpropanoids and Polyketides

Oxyprenylated secondary metabolites (e.g. phenylpropanoids and polyketides) represent a rare class of natural compounds. Over the past two decades, this group of phytochemicals has become a topic of intense research activity by several teams worldwide due to their in vitro and in vivo pharmacological activities, and to their great therapeutic and nutraceutical potential for the chemoprevention of acute and chronic diseases affecting humans. Such investigations have provided evidence that oxyprenylated secondary metabolites are able to interact with several biological targets at different levels accounting for their observed anticarcinogenic, anti-inflammatory, neuroprotective, immunomodulatory, antihypertensive, and metabolic effects. The aim of the present contribution is to provide a detailed survey of the so far reported data on the capacities of selected oxyprenylated phenylpropanoids and polyketides to trigger receptors, enzymes, and other types of cellular factors for which they exhibit a high degree of affinity and therefore evoke specific responses. With respect to the rather small amounts of these compounds available from natural sources, their chemical synthesis is also highlighted.

Pharmacological Utilization of Bergamottin, Derived from Grapefruits, in Cancer Prevention and Therapy

Cancer still remains one of the leading causes of death worldwide. In spite of significant advances in treatment options and the advent of novel targeted therapies, there still remains an unmet need for the identification of novel pharmacological agents for cancer therapy. This has led to several studies evaluating the possible application of natural agents found in vegetables, fruits, or plant-derived products that may be useful for cancer treatment. Bergamottin is a furanocoumarin derived from grapefruits and is also a well-known cytochrome P450 inhibitor. Recent studies have demonstrated potent anti-oxidative, anti-inflammatory, and anti-cancer properties of grapefruit furanocoumarin both in vitro and in vivo. The present review focuses on the potential anti-neoplastic effects of bergamottin in different tumor models and briefly describes the molecular targets affected by this agent.

Chemical Constituents of Thai Citrus hystrix and Their Antiausterity Activity against the PANC-1 Human Pancreatic Cancer Cell Line

Human pancreatic cancer cells have an extreme tolerance to nutrition starvation, enabling them to survive in a hypovascular tumor microenvironment. Searching for agents that preferentially inhibit cancer cell viability under nutrition starvation conditions is a novel antiausterity strategy in anticancer drug discovery. In the present study, a hexane extract of the peels of Citrus hystrix fruits showed preferential cytotoxicity against PANC-1 human pancreatic cancer cells using a nutrient-deprived medium. Phytochemical investigation of this bioactive extract led to the isolation of 10 coumarins (1-10) including a new furanocoumarin (1). The isolated compounds were tested for their preferential cytotoxic activity against three different human pancreatic cancer cell lines [PANC-1, MIA PaCa-2, and PSN-1]. Among these, bergamottin (7) was identified as the most active constituent. In real-time live imaging, 7 was found to induce cell shrinkage, membrane blebbing, and disintegration of organelles in PANC-1 cells. Bergamottin (7) was also found to inhibit PANC-1 cell migration and colony formation. Mechanistically, 7 inhibited key survival proteins in the Akt/mTOR signaling pathway. Bergamottin (7) and related compounds are potential antiausterity candidates for drug development against pancreatic cancer.

Nano γ-Fe2O3-Quinuclidine-Based Catalyst as a Recyclable Organic Base for the Diastereoselective Synthesis of Trans-2,3-Dihydrofuro[3,2-C]Coumarins

A nano γ-Fe2O3-quinuclidine-based catalyst as a new, magnetically recyclable heterogeneous organic base was synthesised and used in the efficient synthesis of a series of 11 trans-3-aroyl-2-(4-halobenzoyl)-2,3-dihydro-4H-furo[3,2-c]chromen-4-ones by the reaction of N-(2-(4-halobenzoyl)-2-oxoethyl)pyridinium bromide with 4-hydroxycoumarin and an aryl glyoxal. The catalyst was easily isolated from the reaction mixture using a magnetic bar and reused at least 10 times without significant decrease in its activity.

Cancer chemoprevention revisited: Cytochrome P450 family 1B1 as a target in the tumor and the microenvironment

Cancer chemoprevention is the use of synthetic, natural or biological agents to prevent or delay the development or progression of malignancies. Intriguingly, many phytochemicals with anti-inflammatory and anti-angiogenic effects, recently proposed as chemoprevention strategies, are inhibitors of Cytochrome P450 family 1B1 (CYP1B1), an enzyme overexpressed in a wide variety of tumors and associated with angiogenesis. In turn, pro-inflammatory cytokines were reported to boost CYP1B1 expression, suggesting a key role of CYP1B1 in a positive loop of inflammatory angiogenesis. Other well-known pro-tumorigenic activities of CYP1B1 rely on metabolic bioactivation of xenobiotics and steroid hormones into their carcinogenic derivatives. In contrast to initial in vitro observations, in vivo studies demonstrated a protecting role against cancer for the other CYP1 family members (CYP1A1 and CYP1A2), suggesting that the specificity of CYP1 family inhibitors should be carefully taken into account for developing potential chemoprevention strategies. Recent studies also proposed a role of CYP1B1 in multiple cell types found within the tumor microenvironment, including fibroblasts, endothelial and immune cells. Overall, our review of the current literature suggests a positive loop between inflammatory cytokines and CYP1B1, which in turn may play a key role in cancer angiogenesis, acting on both cancer cells and the tumor microenvironment. Strategies aiming at specific CYP1B1 inhibition in multiple cell types may translate into clinical chemoprevention and angioprevention approaches.

Identification and Quantitation of Furocoumarins in Popularly Consumed Foods in the U.S. Using QuEChERS Extraction Coupled with UPLC-MS/MS Analysis

Furocoumarins are a class of photoactive compounds found in several plant species and may be responsible for the observed association between consumption of citrus products and the risk of skin cancer. Furocoumarin contents of several foods have been reported previously, but no comprehensive database of furocoumarin content of foods is currently available. Therefore, this study aimed to determine the distribution of furocoumarins in popularly consumed foods in the U.S. Samples of three varieties of each of 29 foods known or suspected to contain furocoumarins were purchased, prepared for analysis using a solid phase extraction method, and analyzed using UPLC-MS/MS for the presence of seven major furocoumarins. Most foods measured contained more than one furocoumarin, and some contained all seven of the furocoumarins examined. Total furocoumarin concentration was greatest in fresh parsley (23215 ng/g), grapefruits (21858 ng/g), lime juice (14580 ng/g), grapefruit juice (95341 ng/g), and limes (9151 ng/g). Bergamottin was found in the greatest proportion of foods sampled (23 of 29), followed by bergapten (19 of 29) and 6'7'-dihydroxybergamottin (16 of 29). These measurements will enable more accurate estimation of dietary furocoumarin exposure and will strengthen future epidemiological work investigating the relationships between furocoumarin intake and health outcomes.

Furocoumarin Kinetics in Plasma and Urine of Healthy Adults Following Consumption of Grapefruit (Citrus paradisi Macf.) and Grapefruit Juice

Furocoumarins are a class of organic compounds found in a variety of vegetables and fruits. Relatively little is known about the absorption and excretion of these compounds following ingestion. The objective of this study was to identify furocoumarins in grapefruit and grapefruit juice and observe their kinetics in blood and urine. The furocoumarins detected in grapefruit using UPLC-MS/MS were bergamottin, 6',7'-dihydroxybergamottin (6',7'-DHB), epoxybergamottin, and bergaptol. Bergamottin, 6',7'-DHB, bergaptol, and bergapten were detected in grapefruit juice. In this study of 6 males and 3 females, only bergamottin and 6',7'-DHB were detected in plasma, whereas in urine, four distinct furocoumarin metabolites as well as bergaptol, 6',7'-DHB, 8-methoxypsoralen (8-MOP), bergamottin, and psoralen were identified. Following grapefruit ingestion, furocoumarins were detectable in plasma as early as 15 min and in urine within 1 h. They remained in plasma for up to 3 or more hours and in urine as late as 24 h.

Influence of storage temperature and low-temperature conditioning on the levels of health-promoting compounds in Rio Red grapefruit

Commercial operations use low‐temperature conditioning of citrus fruits to reduce the incidence of chilling injury (CI) during cold storage and quarantine treatments. Rio Red grapefruits (Citrus paradisi Macf) were stored for 12 weeks at 11°C or 5°C; an additional set was temperature conditioned at 16°C for 7 days before storing at 5°C (CD). Every 3 weeks, samples were assessed for chilling injury (CI) and health‐promoting compounds such as ascorbic acid, carotenoids, limonoids, flavonoids, and furocoumarins. Low‐temperature conditioning significantly reduced CI but did not affect the total soluble solids, acidity, and ripening ratio. After 12 weeks of storage, grapefruits showed no significant differences in lycopene, narirutin, poncirin, furocoumarins, and radical scavenging activity in all the three treatments. Limonin was significantly higher (p < .05) in CD fruits, nomilin was significantly higher in fruits stored at 11°C, whereas fruits stored at 5°C had lower levels of naringin, neohesperidin, and didymin after 12 weeks of storage. Low‐temperature conditioning treatment helped fruits to retain similar or higher levels of most of the health‐promoting compounds by the end of storage period while maintaining better quality than the nonconditioned fruits.

Bergamottin isolated from Citrus bergamia exerts in vitro and in vivo antitumor activity in lung adenocarcinoma through the induction of apoptosis, cell cycle arrest, mitochondrial membrane potential loss and inhibition of cell migration and invasion

The objective of the present study was to investigate the in vitro and in vivo anticancer properties of bergamottin, a natural furanocoumarin, against human non-small cell lung carcinoma (NSCLC) A549 cells. We also studied its effect on cell proliferation, cell cycle arrest, cell invasion, cell migration as well as cell apoptosis. Antiproliferative activity of bergamottin was estimated by the MTT assay. Phase contrast and fluorescence microscopy as well as flow cytometry using Annexin V-FITC assay were used to study induction of apoptosis by bergamottin in these cells. The effects of bergamottin on cell cycle phase distribution as well as on mitochondrial membrane potential were also demonstrated using flow cytometry. In vitro wound healing assay was used to study the effect of bergamottin on cell migration. The effects of bergamottin on tumor progression were also observed using a nude mouse model. The mice were divided into 4 groups and treated with bergamottin injected intraperitoneally. Bergamottin induced dose-dependent as well as time-dependent cytotoxic effects as well as inhibition of colony formation in the A549 cancer cells. Bergamottin also suppressed cancer cell invasion as well as cancer cell migration. Phase contrast microscopy and fluorescence microscopy revealed that bergamottin induced cell shrinkage, chromatin condensation and the cells became rounded and detached from each other. Bergamottin also induced a potent cell cycle arrest at the G2/M phase of the cell cycle. Experiments in mice showed that 25, 50 and 100 mg/kg bergamottin injection reduced the tumor weight from 1.61 g in the phosphate-buffered saline (PBS)-treated group (control) to 1.21, 0.42 and 0.15 g in the bergamottin-treated groups, respectively. The results of the present study revealed that bergamottin was able to inhibit lung cancer cell growth both in a cell model and a xenograft mouse model by inducing apoptosis, mitochondrial membrane potential loss, G2/M cell cycle arrest as well as inhibiting cell migration and invasion.

Ethylene degreening modulates health promoting phytochemicals in Rio Red grapefruit

In the current study, we examined the effects of postharvest degreening and storage on phytochemicals in Rio Red grapefruit. Grapefruits were degreened with 3.5 μl/l of ethylene at 21 °C and 80% relative humidity for 72 h, while non-degreened fruits were used as the control. Furthermore, the grapefruits were stored at 11 °C for 3 weeks and then at 21 °C for 2 weeks. Degreening improved the peel colour of the grapefruit without affecting total soluble solids or acidity of the juice. Degreened fruits had significantly more ascorbic acid after 35 days of storage. Degreening had no significant effect on the levels of carotenoids, limonoids and flavonoids as compared to the non-degreened fruits, after 35 days of storage. However, after 7 days, degreened fruits had more limonin and flavonoids and less furocoumarin, namely 6',7'-dihydroxybergamottin. Overall, ethylene treatment had a significant effect on the phytochemical contents of Rio Red grapefruit, especially after 7 days of storage.

Bergamottin, a natural furanocoumarin obtained from grapefruit juice induces chemosensitization and apoptosis through the inhibition of STAT3 signaling pathway in tumor cells

Persistent activation of signal transducers and activator of transcription 3 (STAT3) has been closely related to growth, survival, proliferation, metastasis, and angiogenesis of various cancer cells, and thus its inhibition can be considered a potential therapeutic strategy. In this study, we investigated the role of bergamottin (BGM) obtained from grapefruit juice in abrogating the constitutive STAT3 activation in multiple myeloma (MM) cells. This suppression was mediated through the inhibition of phosphorylation of Janus-activated kinase (JAK) 1/2 and c-Src. Pervanadate reversed the BGM induced down-regulation of STAT3 activation, suggesting the involvement of a protein tyrosine phosphatase (PTP). Furthermore, BGM induced the expression of the tyrosine phosphatase SHP-1, and gene silencing of the SHP-1 by small interfering RNA abolished the ability of BGM to inhibit STAT3 activation, suggesting a critical role for SHP-1 in the action of BGM. BGM also downregulated the expression of STAT3-regulated gene products such as COX-2, VEGF, cyclin D1, survivin, IAP-1, Bcl-2, and Bcl-xl in MM cells. This correlated with induction of substantial apoptosis as indicated by an increase in the sub-G1 cell population and caspase-3 induced PARP cleavage. Also, this agent significantly potentiated the apoptotic effects of bortezomib and thalidomide in MM cells. Overall, these results suggest that BGM is a novel blocker of STAT3 activation pathway thus may have a potential in therapy of MM and other cancers.

Identification and quantification of grapefruit juice furanocoumarin metabolites in urine: an approach based on ultraperformance liquid chromatography coupled to linear ion trap-Orbitrap mass spectrometry and solid-phase extraction coupled to ultraperformance liquid chromatography coupled to triple quadrupole-tandem mass spectrometry

Grapefruit is a rich source of flavonoids but also contains furanocoumarins, which are known to strongly interact with a variety of medications. Thus, characterization of grapefruit furanocoumarin metabolites may help in a better understanding of grapefruit-drug interactions. In the present work, identification of the main metabolites of grapefruit juice furanocoumarins in urine was performed by ultraperformance liquid chromatography (UPLC) coupled to linear ion trap-Orbitrap mass spectrometry (LTQ-Orbitrap). Glucuronides of 6',7'-dihydroxybergamottin and a hydroxybergamottin-like metabolite were identified for the first time as grapefruit juice metabolites. Afterward, a fast and sensitive method based on solid-phase extraction (SPE) and UPLC coupled to triple quadrupole-tandem mass spectrometry (QqQ-MS/MS) was developed for determination of the identified metabolites in urine. The proposed method was applied to urine samples of five volunteers after intakes of moderate doses of grapefruit, lemon, and orange juices. Furanocoumarin metabolites were only detected in urines after consumption of grapefruit juice.

Cytochrome P450 family 1 inhibitors and structure-activity relationships

With the widespread use of O-alkoxyresorufin dealkylation assays since the 1990s, thousands of inhibitors of cytochrome P450 family 1 enzymes (P450s 1A1, 1A2, and 1B1) have been identified and studied. Generally, planar polycyclic molecules such as polycyclic aromatic hydrocarbons, stilbenoids, and flavonoids are considered to potentially be effective inhibitors of these enzymes, however, the details of the structure-activity relationships and selectivity of these inhibitors are still ambiguous. In this review, we thoroughly discuss the selectivity of many representative P450 family 1 inhibitors reported in the past 20 years through a meta-analysis.

Cytochrome P450 CYP1B1 interacts with 8-methoxypsoralen (8-MOP) and influences psoralen-ultraviolet A (PUVA) sensitivity

Background

There are unpredictable inter-individual differences in sensitivity to psoralen-UVA (PUVA) photochemotherapy, used to treat skin diseases including psoriasis. Psoralens are metabolised by cytochrome P450 enzymes (P450), and we hypothesised that variability in cutaneous P450 expression may influence PUVA sensitivity. We previously showed that P450 CYP1B1 was abundantly expressed in human skin and regulated by PUVA, and described marked inter-individual differences in cutaneous CYP1B1 expression.

Objectives

We investigated whether CYP1B1 made a significant contribution to 8-methoxypsoralen (8-MOP) metabolism, and whether individuality in CYP1B1 activity influenced PUVA sensitivity.

Methods

We used E. coli membranes co-expressing various P450s and cytochrome P450 reductase (CPR) to study 8-MOP metabolism and cytotoxicity assays in CYP1B1-expressing mammalian cells to assess PUVA sensitivity.

Results

We showed that P450s CYP1A1, CYP1A2, CYP1B1, CYP2A6 and CYP2E1 influence 8-MOP metabolism. As CYP1B1 is the most abundant P450 in human skin, we further demonstrated that: (i) CYP1B1 interacts with 8-MOP (ii) metabolism of the CYP1B1 substrates 7-ethoxyresorufin and 17-β-estradiol showed concentration-dependent inhibition by 8-MOP and (iii) inhibition of 7-ethoxyresorufin metabolism by 8-MOP was influenced by CYP1B1 genotype. The influence of CYP1B1 on PUVA cytotoxicity was further investigated in a Chinese hamster ovary cell line, stably expressing CYP1B1 and CPR, which was more sensitive to PUVA than control cells, suggesting that CYP1B1 metabolises 8-MOP to a more phototoxic metabolite(s).

Conclusion

Our data therefore suggest that CYP1B1 significantly contributes to cutaneous 8-MOP metabolism, and that individuality in CYP1B1 expression may influence PUVA sensitivity.

Inhibition of Escherichia coli O157:H7 motility and biofilm by β-sitosterol glucoside

BACKGROUND

Escherichia coli O157:H7 (EHEC) is a food borne pathogen, which causes diarrhea and hemolytic uremic syndrome (HUS). There is an urgent need of novel antimicrobials for treatment of EHEC as conventional antibiotics enhance shiga toxin production and potentiate morbidity and mortality.

METHODS

Six bioactive compounds were isolated, identified from citrus and evaluated for the effect on EHEC biofilm and motility. To determine the possible mode of action, a series of genes known to affect biofilm and motility were overexpressed and the effect on biofilm/motility was assessed. Furthermore, the relative expression of genes involved in motility and biofilm formation was measured by qRT-PCR in presence and absence of phytochemicals, to examine the repression caused by test compounds.

RESULTS

The β-sitosterol glucoside (SG) was identified as the most potent inhibitor of EHEC biofilm formation and motility without affecting the cell viability. Furthermore, SG appears to inhibit the biofilm and motility through rssAB and hns mediated repression of flagellar master operon flhDC.

CONCLUSION

SG may serve as novel lead compound for further development of anti-virulence drugs.

GENERAL SIGNIFICANCE

Plant sterols constitute significant part of diet and impart various health benefits. Here we present the first evidence that SG, a plant sterol has significant effect on EHEC motility, a critical virulence factor, and may have potential application as antivirulence strategy.

Pomegranate Juice Does Not Impair Clearance of Oral or Intravenous Midazolam, a Probe for Cytochrome P450-3A Activity: Comparison With Grapefruit Juice

The effect of pomegranate juice (PJ) or grapefruit juice (GFJ) on CYP3A activity was studied in vitro and in healthy human volunteers. In human liver microsomes, the mean 50% inhibitory concentrations (IC(50)) for PJ and GFJ versus CYP3A (triazolam alpha-hydroxylation) were 0.61% and 0.55%, (v/v) respectively, without preincubation of inhibitor with microsomes. After preincubation, the IC(50) for PJ increased to 0.97% (P < .05), whereas the IC(50) for GFJ decreased to 0.41% (P < .05), suggesting mechanism-based inhibition by GFJ but not PJ. Pretreatment of volunteer subjects (n = 13) with PJ (8 oz) did not alter the elimination half-life, volume of distribution, or clearance of intravenous midazolam (2 mg). Administration of PJ also did not affect C(max), total area under the curve (AUC), or clearance of oral midazolam (6 mg). However, GFJ (8 oz) increased midazolam C(max) and AUC by a factor of 1.3 and 1.5, respectively, and reduced oral clearance to 72% of control values. Thus, PJ does not alter clearance of intravenous or oral midazolam, whereas GFJ impairs clearance and elevates plasma levels of oral midazolam.

Grapefruit (Citrus paradisi Macfad) phytochemicals composition is modulated by household processing techniques

Grapefruits (Citrus paradisi Macfad) contain several phytochemicals known to have health maintaining properties. Due to the consumer's interest in obtaining high levels of these phytochemicals, it is important to understand the changes in their levels by common household processing techniques. Therefore, mature Texas "Rio Red" grapefruits were processed by some of the common household processing practices such as blending, juicing, and hand squeezing techniques and analyzed for their phytochemical content by high performance liquid chromatography (HPLC). Results suggest that grapefruit juice processed by blending had significantly (P < 0.05) higher levels of flavonoids (narirutin, naringin, hesperidin, neohesperidin, didymin, and poncirin) and limonin compared to juicing and hand squeezing. No significant variation in their content was noticed in the juice processed by juicing and hand squeezing. Ascorbic acid and citric acid were significantly (P < 0.05) higher in juice processed by juicing and blending, respectively. Furthermore, hand squeezed fruit juice had significantly higher contents of dihydroxybergamottin (DHB) than juice processed by juicing and blending. Bergamottin and 5-methoxy-7 gernoxycoumarin (5-M-7-GC) were significantly higher in blended juice compared to juicing and hand squeezing. Therefore, consuming grapefruit juice processed by blending may provide higher levels of health beneficial phytochemicals such as naringin, narirutin, and poncirin. In contrast, juice processed by hand squeezing and juicing provides lower levels of limonin, bergamottin, and 5-M-7-GC. These results suggest that, processing techniques significantly influence the levels of phytochemicals and blending is a better technique for obtaining higher levels of health beneficial phytochemicals from grapefruits. Practical Application:  Blending, squeezing, and juicing are common household processing techniques used for obtaining fresh grapefruit juice. Understanding the levels of health beneficial phytochemicals present in the juice processed by these techniques would enable the consumers to make a better choice to obtain high level of these compounds.