Toxicological Assessment of Furocoumarins in Foodstuffs

Isolating Antipathogenic Fungal Coumarins from Coriaria nepalensis and Determining Their Primary Mechanism In Vitro

Through bioassay-guided isolation, eight undescribed coumarins (1-8), along with six reported coumarins (9-14), were obtained from Coriaria nepalensis. The new structures were determined by using IR, UV, NMR, HRESIMS, and ECD calculations. The results of the biological activity assays showed that compound 9 exhibited broad spectrum antifungal activities against all tested fungi in vitro and a significant inhibitory effect on Phytophthora nicotianae with an EC50 value of 3.00 μg/mL. Notably, compound 9 demonstrated greater curative and protective effects against tobacco balack shank than those of osthol in vivo. Thus, 9 was structurally modified to obtain new promising antifungal agents, and the novel derivatives (17b, 17j, and 17k) exhibited better effects on Sclerotinia sclerotiorum than did lead compound 9. Preliminary mechanistic exploration illustrated that 9 could enhance cell membrane permeability, destroy the morphology and ultrastructure of cells, and reduce the exopolysaccharide content of P. nicotianae mycelia. Furthermore, the cytotoxicity results revealed that compound 9 exhibited relatively low cytotoxicity against HEK293 cell lines with an inhibition rate of 33.54% at 30 μg/mL. This research is promising for the discovery of new fungicides from natural coumarins with satisfactory ecological compatibility.

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.

Influence of Citrus Flavor Addition in Brewing Process: Characterization of the Volatile and Non-Volatile Profile to Prevent Frauds and Adulterations

In the last few years, the flavored beer market has increased significantly. In particular, consumers showed a growing interest in citrus-flavored beers. Citrus fruits contain, among other class of compounds, terpenes and terpenoids and oxygenated heterocyclic compounds. The absence of a specific legislation concerning beer flavored production and ingredients reported on the labels makes these beers subject to possible adulterations. Solid phase micro extraction (SPME) followed by gas chromatographic–mass spectrometry (GC-MS) and gas chromatographic-flame ionization detector (GC-FID) analysis of the volatile profile together with the characterization of the oxygen heterocyclic compounds through high performance liquid chromatography coupled to tandem mass spectrometry (HPLC-MS/MS) demonstrated to be a powerful analytical strategy for quality control. In this study, we combined the volatile and non-volatile profiles of “citrus flavored mainstream beers”, in order to evaluate the authenticity and determine markers to prevent food frauds. The changes in the aroma composition of the unflavored types after the addition of peel, or citrus essential oil were also evaluated. The linear retention index (LRI) system was used for both techniques; in particular, its application in liquid chromatography is still limited and represents a novelty. The coupling of the high sensitivity of the HPLC MS/MS method with the LRI system, it has made possible for the first time a reliable identification and an accurate quantification of furocoumarins in citrus-flavored beers.

Matrix-dependent absorption of 8-methoxypsoralen in extracorporeal photopheresis

BACKGROUND

Extracorporeal photopheresis (ECP) is an effective immunomodulatory therapy for various diseases. Autologous leukocytes are collected, photoactivated with a photosensitizer (8-methoxypsoralen, 8-MOP) and UVA light, and subsequently reinfused back to the patient. Leukapheresis and UVA irradiation systems can be integrated into one device (inline) or handled by two separate devices (offline). ECP works via intercalation of 8-MOP into DNA helices and UVA-based interactions to inhibit DNA replication. 8-MOP is known to adhere to plastic materials, which might reduce its availability for intercalation. In the present study we examined the bioavailability of 8-MOP when different plastic materials and solvents are used as matrices.

METHODS

Varying amounts of shredded ethylene vinyl acetate (EVA) and polyvinylchloride (PVC) from the MacoGenic irradiation bag (EVA1), UVA PIT irradiation bag (EVA2), UVA PIT recirculation bag (PVC A) and UVA PIT tubing (PVC B) by MacoPharma and PIT Medical Systems, respectively, were incubated with 200 ng mL^-1 8-MOP dissolved in diisopropyl ether (DIPE) plus toluene 90/10 vol%, deionized water or plasma. After 2 h 8-MOP concentrations were determined by GC-MS.

RESULTS

After incubation, 8-MOP concentrations varied depending on the amount and type of plastic (PVC > EVA) and solvent (water > plasma > DIPE/toluene). Absorption to 200 mg EVA1 or EVA2 resulted in 8-MOP concentrations of 57% or 32% in water, 91% or 80% in plasma, and 93% or 92% in DIPE/toluene, while 200 mg PVC A and PVC B yielded recovery rates of 26% and 10% in water, 76% and 75% in plasma, and 55% and 30% in DIPE/toluene, respectively. Remaining 8-MOP differed significantly between container materials (EVA vs. PVC; p < 0.022) but not manufacturers (MacoPharma vs. PIT Medical Systems).

CONCLUSION

Absorption loss of 8-MOP depends on the type of plastic and solvent and is more pronounced with water than with plasma. As the DNA binding effect of 8-MOP is dose-dependent, ECP starting doses should be adjusted to ensure that a sufficient concentration of free bioavailable 8-MOP is present during UV irradiation.

Relationship between Furocoumarin Intake and Melanoma History among US Adults in the National Health and Nutrition Examination Survey 2003-2012

Furocoumarins are a group of phototoxic compounds found in numerous edible plants. Data from cohort studies have suggested that consumption of certain furocoumarin-rich foods may increase skin cancer risk. However, no study has specifically tested this hypothesis by estimating furocoumarin intake and assessing its relationship with skin cancer. This study aimed to estimate average daily furocoumarin intake of US adults using the National Health and Nutrition Examination Survey (NHANES) 2003-2012 and to examine the relationship between furocoumarin intake and melanoma history. A database of the contents of seven furocoumarins in 29 popular foods was linked to dietary data in NHANES 2003-2012. Mean total intake of the selected furocoumarins among US adults was 81.4 μg/day (standard error = 5.5). A total of 75 participants reported a history of melanoma. Using non- and low consumers (<50th percentile) as a reference, and after adjusting for potential confounders, OR (with 95% confidence interval) of melanoma history for the top 10 percent, 80-90th percentiles, and 50-80th percentiles were 1.75 (0.43-7.20), 1.66 (0.39-7.16), and 0.90 (0.45-1.78), respectively. Furocoumarins are widely consumed among US adults, and a trend towards higher odds of melanoma history was observed among those with higher furocoumarin intake, although this relationship was not statistically significant.

Methoxsalen and Bergapten Prevent Diabetes-Induced Osteoporosis by the Suppression of Osteoclastogenic Gene Expression in Mice

This study evaluated whether bergapten and methoxsalen could prevent diabetes-induced osteoporosis and its underlying mechanism. For 10 weeks, bergapten or methoxsalen (0.02%, w/w) was applied to diabetic mice that were provided with a high-fat diet and streptozotocin. Bone mineral density (BMD) and microarchitecture quality were significantly reduced in the diabetic control group; however, both bergapten and methoxsalen reversed serum osteocalcin, bone-alkaline phosphatase and femur BMD. These coumarin derivatives significantly increased bone volume density and trabecular number, whereas they decreased the structure model index of femur tissue in diabetic mice. Conversely, tartrate-resistant acid phosphatase 5 (TRAP) staining revealed that these derivatives reduced osteoclast numbers and formation in diabetic bone tissue. Additionally, both bergapten and methoxsalen tended to downregulate the expression of osteoclast-related genes such as receptor activator of nuclear factor kappa-B ligand (RANKL), nuclear of activated T-cells, cytoplasmic 1 (NFATc1) and TRAP in diabetic femurs, with NFATc1 and TRAP expression showing significant reductions. Our data suggest that both bergapten and methoxsalen prevent diabetic osteoporosis by suppressing bone resorption.

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.

The effect of pre-treatment and modified atmosphere packaging on contents of phenolic compounds and sensory and microbiological quality of shredded celeriac

BACKGROUND

The aim of this study was to determine the effect of washing (4 °C, 120 s) or soaking (4 °C, 600 s) of shredded celeriac in tap water on changes in contents of phenolic compounds, including furanocoumarins, and sensory and microbiological quality during 12 days of storage. The product was packaged in air or modified atmosphere containing 2/10/88 kPa O2/CO2/N2.

RESULTS

The applied pre-treatment consisting of washing or soaking of shredded celeriac in water resulted in decreases in 8-methoxypsoralen content by approximately 50 and 70% respectively and phenolic content by 30% compared with samples that were not subjected to pre-treatment. During storage of shredded celeriac, a further significant (P ≤ 0.05) reduction in phenolic compounds and an approximately 2.5-fold increase in the total content of furanocoumarins were found. The application of modified atmosphere packaging had a significant effect on the maintenance of good sensory and microbiological quality of the tested product.

CONCLUSION

Modified atmosphere packaging of shredded celeriac not subjected to pre-treatment made it possible to obtain a product with good sensory and microbiological quality and the highest content of phenolic compounds. The level of furanocoumarins recorded in the tested product does not constitute a health hazard.

Insights into structure-activity relationship of GABAA receptor modulating coumarins and furanocoumarins

The coumarins imperatorin and osthole are known to exert anticonvulsant activity. We have therefore analyzed the modulation of GABA-induced chloride currents (I(GABA)) by a selection of 18 coumarin derivatives on recombinant α(1)β(2)γ(2S) GABA(A) receptors expressed in Xenopus laevis oocytes by means of the two-microelectrode voltage clamp technique. Osthole (EC(50)=14 ± 1 μM) and oxypeucedanin (EC(50)=25 ± 8 μM) displayed the highest efficiency with I(GABA) potentiation of 116 ± 4 % and 547 ± 56 %, respectively. I(GABA) enhancement by osthole and oxypeucedanin was not inhibited by flumazenil (1 μM) indicating an interaction with a binding site distinct from the benzodiazepine binding site. In general, prenyl residues are essential for the positive modulatory activity, while longer side chains or bulkier residues (e.g. geranyl residues) diminish I(GABA) modulation. Generation of a binary classification tree revealed the importance of polarisability, which is sufficient to distinguish actives from inactives. A 4-point pharmacophore model based on oxypeucedanin - comprising three hydrophobic and one aromatic feature - identified 6 out of 7 actives as hits. In summary, (oxy-)prenylated coumarin derivatives from natural origin represent new GABA(A) receptor modulators.

Risks and benefits of dietary isoflavones for cancer

A high intake of fruits and vegetables is associated with a lower risk of cancer. In this context, considerable attention is paid to Asian populations who consume high amounts of soy and soy-derived isoflavones, and have a lower risk for several cancer types such as breast and prostate cancers than populations in Western countries. Hence, interest focuses on soyfoods, soy products, and soy ingredients such as isoflavones with regard to their possible beneficial effects that were observed in numerous experiments and studies. The outcomes of the studies are not always conclusive, are often contradictory depending on the experimental conditions, and are, therefore, difficult to interpret. Isoflavone research revealed not only beneficial but also adverse effects, for instance, on the reproductive system. This is also the case with tumor-promoting effects on, for example, breast tissue. Isoflavone extracts and supplements are often used for the treatment of menopausal symptoms and for the prevention of age-associated conditions such as cardiovascular diseases and osteoporosis in postmenopausal women. In relation to this, questions about the effectiveness and safety of isoflavones have to be clarified. Moreover, there are concerns about the maternal consumption of isoflavones due to the development of leukemia in infants. In contrast, men may benefit from the intake of isoflavones with regard to reducing the risk of prostate cancer. Therefore, this review examines the risks but also the benefits of isoflavones with regard to various kinds of cancer, which can be derived from animal and human studies as well as from in vitro experiments.

Bioassay directed identification of natural aryl hydrocarbon-receptor agonists in marmalade

Citrus fruit and citrus fruit products, like grapefruit, lemon and marmalade were shown to contain aryl hydrocarbon receptor (AhR) agonists, as detected with the DR CALUX bioassay. This is of interest regarding the role of the Ah-receptor pathway in the adverse effects of dioxins, PCBs and other aromatic hydrocarbons. So far it is unclear which compounds in citrus fruit are responsible for the AhR-mediated activity and whether regular exposure to these compounds can cause effects comparable to, e.g. dioxins. The present study aimed at developing a method for identifying unknown Ah-receptor agonists in citrus products based on bioassay directed analysis, using marmalade as a first target. Following extraction with hexane and purification on an aluminium oxide-column, the extract was fractionated by HPLC using a C-18 semi-preparative column. Fractions were extracted, solvent-exchanged into dimethylsulfoxide and subsequently tested with DR CALUX. Extracts were shown to contain primarily coumarins, furocoumarins (FCs) and polymethoxyflavones (PMFs). Identification of fractions most active in the bioassay via LC/MS revealed that bergapten (an FC) is the most important Ah-receptor agonist in marmalade. The approach and method developed resulted in the successful identification of the bioactive component. However, potential pitfalls of the procedure will be discussed.

Distribution of flavonoids and furocoumarins in juices from cultivars of Citrus bergamia Risso

HPLC separation of flavonoids and furocoumarins in the crude juices of three cultivars of Citrus bergamia Risso ("Castagnaro", "Fantastico", and "Femminello") was carried out on a C18 reversed phase column. The analysis was performed in a single run using a DAD detector coupled with an ESI-MS-MS source. Two furocoumarins (bergapten and bergamottin) were detected and quantified simultaneously with the sixteen flavonoid components previously found in industrial bergamot juice. Full characterization of the furocoumarins was performed by (1)H NMR analysis on samples separated by means of preparative HPLC. The free-radical scavenging ability of cultivar juices was assessed by using DPPH radical. The data presented show that the "Femminello" cultivar, even though it is the least common of the three, is by far the richest in health-promoting bioactive compounds (both flavonoids and furocoumarins). Given the range of applications of furocoumarins, the preparative separation described herein is proposed as a simple and rapid method to obtain this class of compounds in good yield from crude juice.

The increase in melanoma: are dietary furocoumarins responsible?

According to most cancer registries the incidence of cutaneous melanoma (CM) has been increasing for several decades. Unlike other skin cancers, CM does not clearly correlate with exposure to ultraviolet radiation. The strongest etiological evidence for CM in man is genetic predisposition, evidenced by very high risks in primary relatives of melanoma patients, and photochemotherapy with 8-methoxy psoralen in combination with ultraviolet-A radiation (PUVA) to treat psoriasis and vitiligo. Retrospective studies of PUVA patients show significantly increased incidence of CM. Psoralens, and other furocoumarins, are phototoxic and photocarcinogenic, intercalate DNA and photochemically induce mutations. Furocoumarins are botanical phytoalexins found to varying extents in a variety of vegetables and fruits, notably citrus fruits. The levels of furocoumarins present in our diets, while normally well below that causing evident acute phototoxicity, do cause pharmacologically relevant drug interactions. For the past approximately 50 years CM has increased at similar rates as the increased availability and consumption of citrus products. Recently in a large study of nurses, only orange juice drinking, indicative of dietary preference for citrus, was positively associated with significantly increased risk of developing CM. We hypothesize that the increases in cutaneous melanoma incidence may be in part related to concomitant increases in dietary photocarcinogenic furocoumarins.