Dietary furocoumarins and skin cancer: A review of current biological evidence

Quantitative Analysis of Isopimpinellin from Ammi majus L. Fruits and Evaluation of Its Biological Effect on Selected Human Tumor Cells

Ammi majus L. (Apiaceae) is a medicinal plant with a well-documented history in phytotherapy. The aim of the present work was to isolate isopimpinellin (5,8-methoxypsoralen; IsoP) from the fruit of this plant and evaluate its biological activity against selected tumor cell lines. The methanol extract obtained with the use of an accelerated solvent extraction (ASE) method was the most suitable for the quantitative analysis of coumarins in the A. majus fruit matrix. The coumarin content was estimated by RP-HPLC/DAD, and the amount of IsoP was found to be 404.14 mg/100 g dry wt., constituting 24.56% of the total coumarin fraction (1.65 g/100 g). This, along with the presence of xanthotoxin (368.04 mg/100 g, 22.36%) and bergapten (253.05 mg/100 g, 15.38%), confirmed A. majus fruits as an excellent source of these compounds. IsoP was isolated (99.8% purity) by combined liquid chromatography/centrifugal partition chromatography (LC/CPC) and tested for the first time on its antiproliferative activity against human colorectal adenocarcinoma (HT29, SW620), osteosarcoma (Saos-2, HOS), and multiple myeloma (RPMI8226, U266) cell lines. MTT assay results (96 h incubation) demonstrated a dose- and cell line-dependent decrease in cell proliferation/viability, with the strongest effect of IsoP against the Saos-2 cell line (IC50; 42.59 µM), medium effect against U266, HT-29, and RPMI8226 (IC50 = 84.14, 95.53, and 105.0 µM, respectively), and very weak activity against invasive HOS (IC50; 321.6 µM) and SW620 (IC50; 711.30 µM) cells, as well as normal human skin fibroblasts (HSFs), with IC50; 410.7 µM. The mechanistic study on the Saos-2 cell line showed that IsoP was able to reduce DNA synthesis and trigger apoptosis via caspase-3 activation. In general, IsoP was found to have more potency towards cancerous cells (except for HOS and SW620) than against healthy cells. The Selective Index (SI) was determined, underlining the higher selectivity of IsoP towards cancer cells compared to healthy cells (SI = 9.62 against Saos-2). All these results suggest that IsoP might be a promising molecule in the chemo-prevention and treatment of primary osteosarcoma.

Mechanism-Based Inactivation of CYP2D6 by Phellopterin and Related Drug-Drug Interaction with Metoprolol

Phellopterin (PLP) is a linear furanocoumarin widely found in citrus fruits and herbal medicines. The study aims to comprehensively investigate the mechanism of inhibition of CYP2D6 enzyme activity by PLP and its alteration of metoprolol pharmacokinetics. PLP was found to irreversibly inhibit CYP2D6 in time-, concentration-, and nicotinamide adenine dinucleotide phosphate-dependent manners. Coincubation with quinidine, which is a competitive inhibitor of CYP2D6, attenuated this time-dependent inhibition. Glutathione (GSH) and catalase/superoxide dismutase failed to reverse the PLP-induced CYP2D6 inactivation. GSH trapping experiments provided strong evidence that PLP metabolic activation produces epoxide or γ-ketoaldehyde intermediates. In addition, pretreatment with PLP resulted in significant increases in Cmax and area under curve of plasma metoprolol in rats.

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.

Overview of Recent Liquid Chromatography Mass Spectrometry-Based Methods for Natural Toxins Detection in Food Products

Natural toxins include a wide range of toxic metabolites also occurring in food and products, thus representing a risk for consumer health. In the last few decades, several robust and sensitive analytical methods able to determine their occurrence in food have been developed. Liquid chromatography mass spectrometry is the most powerful tool for the simultaneous detection of these toxins due to its advantages in terms of sensitivity and selectivity. A comprehensive review on the most relevant papers on methods based on liquid chromatography mass spectrometry for the analysis of mycotoxins, alkaloids, marine toxins, glycoalkaloids, cyanogenic glycosides and furocoumarins in food is reported herein. Specifically, a literature search from 2011 to 2021 was carried out, selecting a total of 96 papers. Different approaches to sample preparation, chromatographic separation and detection mode are discussed. Particular attention is given to the analytical performance characteristics obtained in the validation process and the relevant application to real samples.

Citrus-Gene interaction and melanoma risk in the UK Biobank

High citrus consumption may increase melanoma risk; however, little is known about the biological mechanisms of this association, or whether it is modified by genetic variants. We conducted a genome-wide analysis of gene-citrus consumption interactions on melanoma risk among 1563 melanoma cases and 193 296 controls from the UK Biobank. Both the 2-degrees-of-freedom (df) joint test of genetic main effect and gene-environment (G-E) interaction and the standard 1-df G-E interaction test were performed. Three index SNPs (lowest P-value SNP among highly correlated variants [r²  > .6]) were identified from among the 365 genome-wide significant 2-df test results (rs183783391 on chromosome 3 [MITF], rs869329 on chromosome 9 [MTAP] and rs11446223 on chromosome 16 [DEF8]). Although all three were statistically significant for the 2-df test (4.25e-08, 1.98e-10 and 4.93e-13, respectively), none showed evidence of interaction according to the 1-df test (P = .73, .24 and .12, respectively). Eight nonindex, 2-df test significant SNPs on chromosome 16 were significant (P < .05) according to the 1-df test, providing evidence of citrus-gene interaction. Seven of these SNPs were mapped to AFG3L1P (rs199600347, rs111822773, rs113178244, rs3803683, rs73283867, rs78800020, rs73283871), and one SNP was mapped to GAS8 (rs74583214). We identified several genetic loci that may elucidate the association between citrus consumption and melanoma risk. Further studies are needed to confirm these findings.

Genistein protects against ultraviolet B-induced wrinkling and photoinflammation in in vitro and in vivo models

Background

Chronic exposure to ultraviolet (UV) rays causes severe skin damage by inducing oxidative stress and inflammation. Identifying a safe and natural substance for skin protection is a crucial research goal.

Objective

The aim of this study was to clarify the effects of genistein on skin inflammation and photoaging by using 3 models (humans: skin parameters; animals: wrinkle formation; and cells: anti-inflammatory effects).

Methods

Food frequency questionnaire data and serum and skin parameter data from 120 volunteers (a group with a genistein-rich diet [RG group] and a control group). Human keratinocytes were pretreated with genistein before ultraviolet B (UVB) irradiation. Genistein was topically applied to the dorsal skin of rats.

Results

The blood samples of the RG group had lower serum uric acid levels and blood urea nitrogen levels. The dynamic elasticity level in the RG group was higher than that in the controls. Genistein pretreatment suppressed the expression of proinflammatory cytokines (CXCL1, IL-1, MIF, and PLANH1) and the proteins released by UVB-treated keratinocytes. Topical application of genistein to the dorsal skin of rats reduced the severity of UVB-induced wrinkling. Both intake and topical application of genistein combated UVB-induced inflammation and aging.

Conclusions

Genistein could be used as a safe and natural compound for use in novel anti-inflammatory agents for topical application.

Graphical abstract

The experimental design procedure, including the skin parameter and blood serum measurements of 137 participants. Genistein-rich compounds provide protection against UVB-induced inflammation, as determined using in vitro and in vivo animal model experiments.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12263-022-00706-x.

Safety Profile of Nutraceuticals Rich in Coumarins: An Update

Coumarins are a family of benzopyrones largely distributed in the natural kingdom, being present in the seeds, fruits, flowers, or roots of various plant species. Natural coumarin compounds are found in significant concentrations in some herbs or spices used as nutraceuticals, but they are also present in cosmetics or household products, due to their pleasant odor. Therefore, an accidental exposure to high doses of coumarins, could lead to the development of harmful effects in some patients. This review summarizes the latest published data from preclinical and clinical studies with natural coumarins, focused on the investigation of general and specific toxicity, with the aim of a better understanding of the safety profile of these valuable compounds. Regulatory aspects concerning the use of natural coumarins in several world regions are also reviewed.

Diet-Related Phototoxic Reactions in Psoriatic Patients Undergoing Phototherapy: Results from a Multicenter Prospective Study

Vegans and vegetarians often consume foods containing photosensitizers capable of triggering phytophotodermatitis. The potential effect of vegan and vegetarian diets on the response of psoriatic patients undergoing phototherapy is not well characterized. We assessed clinical outcomes of vegan, vegetarian and omnivore adult psoriatic patients undergoing band ultraviolet B phototherapy (NB-UVB). In this multicenter prospective observational study, we enrolled 119 adult, psoriatic patients, of whom 40 were omnivores, 41 were vegetarians and 38 were vegans, with phototherapy indication. After determining the minimum erythemal dose (MED), we performed NB-UVB sessions for 8 weeks. The first irradiation dosage was 70.00% of the MED, then increased by 20.00% (no erythema) or by 10.00% (presence of erythema) until a maximum single dose of 3 J/cm² was reached and constantly maintained. All the enrolled patients completed the 8 weeks of therapy. Severe erythema was present in 16 (42.11%) vegans, 7 (17.07%) vegetarians and 4 (10.00%) omnivores (p < 0.01). MED was lowest among vegans (21.18 ± 4.85 J/m²), followed by vegetarians (28.90 ± 6.66 J/m²) and omnivores (33.63 ± 4.53 J/m², p < 0.01). Patients with severe erythema were more likely to have a high furocumarin intake (OR 5.67, 95% CI 3.74-8.61, p < 0.01). Vegans consumed the highest amount of furocumarin-rich foods. A model examining erythema, adjusted for gender, age, skin type, MED, phototherapy type, number of phototherapies and furocumarin intake, confirmed that vegans had a lower number of treatments. Vegans had more frequent severe erythema from NB-UVB, even after adjustment of the phototherapy protocol for their lower MED. Assessing diet information and adapting the protocol for vegan patients may be prudent.

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.

Bergapten: A review of its pharmacology, pharmacokinetics, and toxicity

Bergapten is a natural furocoumarin, also known as 5-methoxypsoralen, and its medicinal value has been paid more and more attention. By sorting out the pharmacological literature of bergapten, we found that bergapten has a wide range of pharmacological effects, including neuroprotection, organ protection, anticancer, antiinflammatory, antimicrobial, and antidiabetes effects. However，bergapten has complex impacts on the hepatic metabolic enzyme. Moreover, pharmacokinetic studies showed that bergapten has higher absolute bioavailability and can cross the blood-brain barrier and has a great potential for treating brain disease, but the mechanism needs further clarification to make greater use of its ability to treat brain diseases. Furthermore, the phototoxicity of bergapten combined with ultraviolet light has always been mentioned. In view of its wide range of pharmacological activities, bergapten is expected to be a potential drug candidate for the treatment of diabetes and diabetes-induced osteoporosis, epilepsy, Alzheimer's disease, depression, and cancer. However, further studies are needed to elucidate its molecular mechanisms and targets. The phototoxicity of bergapten as a side effect should be further avoided. On the other hand, the photoactivation of bergapten in the anticancer aspect can be better utilized.

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.

Citrus Consumption and the Risk of Non-Melanoma Skin Cancer in the Women's Health Initiative

Simple Summary

Citrus products are rich in furocoumarins, which can increase the risk of incident non-melanoma skin cancer (NMSC) when combined with ultraviolet radiation. However, few observational studies have evaluated the link between citrus intake and NMSC incidence. The aim of this study was to determine whether citrus intake was related to the NMSC incidence in participants of the Women’s Health Initiative Observational Study. The results of this study indicated that high citrus juice consumption was associated with a higher risk of incident NMSC compared to low consumption. These findings add further evidence of the potentially carcinogenic nature of certain citrus products and highlight the need to continue investigations in identifying risk factors and mechanisms.

Abstract

Evidence from animal studies suggests that furocoumarins, compounds present in citrus products, can increase the risk of non-melanoma skin cancer (NMSC) when combined with ultraviolet radiation. The objective of this study was to determine the relationship between citrus intake and NMSC risk among postmenopausal women from the Women’s Health Initiative (WHI) Observational Study, who were aged 50–79 years at enrollment (1993–1998). The consumption of citrus fruit, citrus juice, and non-citrus fruit and juice were measured at the baseline of the study using a food frequency questionnaire (FFQ). NMSC cases (basal or squamous cell carcinomas) were self-reported during annual follow-up surveys. The outcome data used for this analysis were collected through March 2020. The relative risk (RR) for incident NMSC by citrus consumption was calculated. Among 49,007 non-Hispanic white participants, there were 8642 cases of incident NMSC. Using less than one serving of citrus juice per week as reference, the RRs and 95% confidence intervals (CI) for incident NMSC by citrus juice intake were 1.03 (0.95, 1.10) for one serving/week, 1.06 (1.00, 1.12) for two to four servings/week, 0.98 (0.90, 1.07) for five to six servings/week, and 1.08 (1.02, 1.13) for one or more serving/day (p-trend = 0.007). Subgroup analyses did not reveal meaningful associations by sun exposure variables. In conclusion, there were indications of a slightly higher risk of incident NMSC among citrus juice consumers; however, further longitudinal and mechanistic studies are needed to confirm the key risk factors.

Safety and efficacy of feed additives consisting of expressed lemon oil and its fractions from Citrus limon (L.) Osbeck and of lime oil from Citrus aurantiifolia (Christm.) Swingle for use in all animal species (FEFANA asbl)

Following a request from the European Commission, the EFSA Panel on Additives and Products or Substances used in Animal Feed (FEEDAP) was asked to deliver a scientific opinion on the safety and efficacy of expressed lemon oil and distilled lemon oil from Citrus limon (L.) Osbeck and lime oil from Citrus aurantiifolia (Christm.) Swingle, when used as sensory additives in feed for all animal species. The use of the expressed lemon oil and its residual fraction and the use of lime oil in feed is not expected to increase the exposure to furocoumarins and methoxycoumarins and perillaldehyde of those target species that are already fed citrus by-products a relevant extent (< 10%). For companion animals and ornamental fish not normally exposed to citrus by-products, no conclusion can be drawn. For the other species and for the distilled fraction of expressed lemon oil, the FEEDAP Panel concludes that the additives under assessment are safe at the maximum proposed or at reduced use levels in complete feed. The Panel considers that the use in water for drinking is safe provided that the total daily intake of the additive does not exceed the daily amount that is considered safe when consumed via feed. No concerns for consumer safety were identified following the use of the additives at the maximum proposed use level in feed. The additives under assessment should be considered as irritants to skin and eyes and the respiratory tract and as skin sensitisers. Since expressed lemon oil and its fractions contain furocoumarins, they may cause phototoxicity. The use of the additives under the proposed conditions of use in animal feed is not expected to pose a risk for the environment. Since C. limon and C. aurantiifolia and their preparations are recognised to flavour food and its function in feed would be essentially the same as that in food, no further demonstration of efficacy is considered necessary.

Bifunctional mechanisms of autophagy and apoptosis regulations in melanoma from Bacillus subtilis natto fermentation extract

Melanoma is one of the most dangerous malignant epidermal cancers. Natto freeze-drying extract (NFDE) and natto water extract (NWE) were isolated from natto, soybeans fermented by Bacillus subtilis natto, which were assessed as potential anti-melanoma agents. Cell cytotoxicity assays revealed significant anti-melanoma effects of NFDE and NWE in a dose-dependent manner, and exhibited low influences on normal skin cells, including Hs68, HaCaT and adipose tissue-derived stem cells (ADSCs), respectively. Through a flow cytometer assay and autophagy acridine orange staining, the cellular death phenomenon shifted from autophagy to apoptosis with the increased dosages. Reactive oxygen species (ROS) were enhanced using DCFDA (2,7-dichlorodihydrofluorescein diacetate) staining when melanoma cells were treated with the extract. NFDE and NWE treatments increase the oxidative stress of cancer cells and cause apoptosis by inhibiting AMP-activated protein kinase (AMPK). NFDE and NWE were considered to play a critical role in cell death through ROS adjustment, autophagy regulation and apoptosis promotion.

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.

Synthesis and Photoactivated Toxicity of 2-Thiophenylfuranocoumarin Induce Midgut Damage and Apoptosis in Aedes aegypti Larvae

Furanocoumarins are photoactive compounds derived from secondary plant metabolites. They possess many bioactivities, including antioxidative, anticancer, insecticidal, and bactericidal activities. Here, we designed a new scheme for synthesizing 2-arylfuranocoumarin derivatives by condensation, esterification, bromination, and Wittig reaction. We found that 2-thiophenylfuranocoumarin (Iy) had excellent photosensitive activity. Three Iy concentrations (LC₂₅, LC₅₀, and LC₇₅) were used to treat the fourth instar larvae of Aedes aegypti (A. aegypti). The photoactivated toxicity, sublethal dose, mitochondrial dysfunction, oxidative stress level, intestinal barrier dysfunction, and apoptosis were studied. The results showed that Iy induced reactive oxygen species (ROS) production in midgut cells under ultraviolet light. Ultrastructural analysis demonstrated that mitochondria were damaged, and the activities of related enzymes were inhibited. Ultimately, Iy exposure led to excessive ROS production followed by the inhibition of antioxidant enzymes, including SOD, CAT, GPx, and GR, which diminished ROS elimination and escalated oxidative stress in midgut cells, aggravating the degree of oxidative damage in these cells. Histopathological changes were observed in the midgut, which led to intestinal barrier dysfunction. When the elimination of ROS was blocked and it accumulated in cells, apoptosis-related genes, including AeDronc, AeCaspase7, and AeCaspase8, were induced and activated. In addition, Iy affected the growth and development of A. aegypti at sublethal concentrations, and there was an obvious post-lethal effect. Thus, we found that Iy caused midgut damage and apoptosis in A. aegypti larvae under ultraviolet light, which preliminarily revealed the mode of action of Iy in A. aegypti.

Psoralen-Induced Phytophotodermatitis

Phytophotodermatitis is a cutaneous reaction that occurs after exposure to plant-derived furocoumarins and ultraviolet A light. Psoralen is the most common phototoxic furocoumarin and is present in varying levels within many different plant species. This article focuses on the diagnosis and management of psoralen-induced phytophotodermatitis along with other clinical applications.

Citrus intake and risk of skin cancer in the European Prospective Investigation into Cancer and Nutrition cohort (EPIC)

Citrus intake has been suggested to increase the risk of skin cancer. Although this relation is highly plausible biologically, epidemiologic evidence is lacking. We aimed to examine the potential association between citrus intake and skin cancer risk. EPIC is an ongoing multi-center prospective cohort initiated in 1992 and involving ~ 520,000 participants who have been followed-up in 23 centers from 10 European countries. Dietary data were collected at baseline using validated country-specific dietary questionnaires. We used Cox proportional hazards regression models to compute hazard ratios (HR) and 95% confidence intervals (CI). During a mean follow-up of 13.7 years, 8448 skin cancer cases were identified among 270,112 participants. We observed a positive linear dose-response relationship between total citrus intake and skin cancer risk (HR = 1.10, 95% CI 1.03-1.18 in the highest vs. lowest quartile; Ptrend = 0.001), particularly with basal cell carcinoma (BCC) (HR = 1.11, 95% CI 1.02-1.20, Ptrend = 0.007) and squamous cell carcinoma (SCC) (HR = 1.23, 95% CI 1.04-1.47, Ptrend = 0.01). Citrus fruit intake was positively associated with skin cancer risk (HR = 1.08, 95% CI 1.01-1.16, Ptrend = 0.01), particularly with melanoma (HR = 1.23, 95% CI 1.02-1.48; Ptrend = 0.01), although with no heterogeneity across skin cancer types (Phomogeneity = 0.21). Citrus juice was positively associated with skin cancer risk (Ptrend = 0.004), particularly with BCC (Ptrend = 0.008) and SCC (Ptrend = 0.004), but not with melanoma (Phomogeneity = 0.02). Our study suggests moderate positive linear dose-response relationships between citrus intake and skin cancer risk. Studies with available biomarker data and the ability to examine sun exposure behaviors are warranted to clarify these associations and examine the phototoxicity mechanisms of furocoumarin-rich foods.

Fanconi anemia-independent DNA inter-strand crosslink repair in eukaryotes

DNA inter-strand crosslinks (ICLs) are dangerous lesions that can be caused by a variety of endogenous and exogenous bifunctional compounds. Because covalently linking both strands of the double helix locally disrupts DNA replication and transcription, failure to remove even a single ICL can be fatal to the cell. Thus, multiple ICL repair pathways have evolved, with the best studied being the canonical Fanconi anemia (FA) pathway. However, recent research demonstrates that different types of ICLs (e.g., backbone distorting vs. non-distorting) can be discriminated by the cell, which then mounts a specific repair response using the FA pathway or one of a variety of FA-independent ICL repair pathways. This review focuses on the latter, covering current work on the transcription-coupled, base excision, acetaldehyde-induced, and SNM1A/RecQ4 ICL repair pathways and highlighting unanswered questions in the field. Answering these questions will provide mechanistic insight into the various pathways of ICL repair and enable ICL-inducing agents to be more effectively used as chemotherapeutics.

Association between Citrus Consumption and Melanoma Risk in the NIH-AARP Diet and Health Study

It has been hypothesized that consumption of citrus, a group of foods particularly rich in a class of photoactive compounds known as furocoumarins, may increase the risk of malignant melanoma. However, this hypothesis has not been rigorously studied in a general sample of US men and women. This study examined the relationship between citrus intake and melanoma risk in subjects of the NIH-AARP Diet and Health Study. Among 388,467 adults, 3,894 melanoma cases were identified during a median follow-up of 15.5 years. After adjustment for relevant potential confounders, total citrus consumption was not significantly associated with melanoma risk in this cohort. Among those with higher estimated exposure to ultraviolet radiation, and among those aged 60+ years at baseline, there were significant trends toward increased melanoma risk associated with whole citrus fruit consumption (P trends = 0.01 and 0.02, respectively), but the hazard ratios of the top consumers (2+ cups per week) vs. nonconsumers were nonsignificant. Further research is needed to explore associations of citrus with melanoma risk among older adults and those with high sun exposure.

Anticancer Potential of Furanocoumarins: Mechanistic and Therapeutic Aspects

Cancer is one of the most extreme medical conditions in both developing and developed countries around the world, causing millions of deaths each year. Chemotherapy and/or radiotherapy are key for treatment approaches, but both have numerous adverse health effects. Furthermore, the resistance of cancerous cells to anticancer medication leads to treatment failure. The rising burden of cancer overall requires novel efficacious treatment modalities. Natural medications offer feasible alternative options against malignancy in contrast to western medication. Furanocoumarins' defensive and restorative impacts have been observed in leukemia, glioma, breast, lung, renal, liver, colon, cervical, ovarian, and prostate malignancies. Experimental findings have shown that furanocoumarins activate multiple signaling pathways, leading to apoptosis, autophagy, antioxidant, antimetastatic, and cell cycle arrest in malignant cells. Additionally, furanocoumarins have been shown to have chemo preventive and chemotherapeutic synergistic potential when used in combination with other anticancer drugs. Here, we address different pathways which are activated by furanocoumarins and their therapeutic efficacy in various tumors. Ideally, this review will trigger interest in furanocoumarins and their potential efficacy and safety as a cancer lessening agents.

Furanocoumarins in anticancer therapy - For and against

Furanocoumarins are a class of natural compounds produced by several plants, including those consumed by humans. They have been used medicinally in eastern countries for ages. Given the growing body of evidence about their anticancer potential and observations that naturally occurring compounds potentiate the antitumor activity of chemotherapeutics, more attention is paid to elucidation of the nature of furanocoumarins and the possibility of using thereof in practice. The general mechanism by which furanocoumarins eliminate cancer cells is based on cell cycle blockage and initiation of programmed death like apoptosis or autophagy. The precise molecular mechanism of such an action depends on the chemical structure of furanocoumarins, which is based on the furan ring attached to the coumarin backbone in a linear or angular form as well as the type, location, and number of the substituents attached. The review summarizes the current evidence of the antitumor properties of linear and angular furanocoumarins with special emphasis on the molecular mechanism of elimination of cancer cells via apoptosis and autophagy. Negative aspects of the use of coumarins in anticancer therapy will be also discussed especially in the context of their phototoxicity and potential cancerogenic effect.

Furocoumarin Content of Fennel-Below the Safety Threshold

Furocoumarins are known for their phototoxic and potential carcinogenic effects. These types of compounds have previously been reported from fennel (Foeniculum vulgare Mill.), a widely used medicinal plant and spice; however, no reliable quantitative data are available on the occurrence of these compounds in fennel fruits. For the first time, we report a comprehensive analysis of fennel fruit samples of different origins, representing a wide range of accessions for their furocoumarin content. Psoralene, 5-methoxypsoralene (bergapten), and imperatorin contents of 33 fennel samples were analyzed using a sensitive liquid chromatography-mass spectrometry (LC-MS) method. When applied at the highest therapeutic dose described in the monograph issued by the European Medicines Agency, the furocoumarin content of the fruits ranged up to 1.22 μg/d, which is below the most restrictive recommendations. Based on our findings, fennel consumption can be considered as safe, at least based on its low furocoumarin content.

Bergapten Ameliorates Vincristine-Induced Peripheral Neuropathy by Inhibition of Inflammatory Cytokines and NFκB Signaling

Bergapten, a furanocoumarin derivative found in a variety of medicinal plants, is documented to possess anti-inflammatory activity. However, whether bergapten is useful in alleviating the symptoms as well as the progress of peripheral neuropathy is not yet studied. The current investigation has been designed to explore the effect of bergapten on vincristine-induced neuropathic pain. Rats were grouped as normal, neuropathic control (vincristine), gabapentin, and bergapten treated groups with five animals in each group. Vincristine (100 μg/kg, i.p.) was administered for 10 days with 2 days break. Gabapentin (60 mg/kg, i.p.) and bergapten (10 mg/kg i.p.) treatments were given once daily for 14 days. The animals were assessed for hyperalgesia and allodynia. After 14 days, animals were sacrificed to detect plasma pro-inflammatory cytokines (TNF α, IL-1β), spinal cord, and sciatic nerve oxidative stress and expression of iNOS, COX-2, and NFkB in the spinal cord. There was a marked reduction in pain behaviors in the bergapten group as compared to the vincristine group. Bergapten also attenuated pro-inflammatory cytokines (TNFα and IL-1β), oxidative stress, and expression of NFkB, COX-2, and iNOS. Overall the current study concludes that bergapten could serve as a potential lead to drug development for the treatment of neuropathic pain.

Botanical Sources, Chemistry, Analysis, and Biological Activity of Furanocoumarins of Pharmaceutical Interest

The aim of this work is to provide a critical review of plant furanocoumarins from different points of view, including their chemistry and biosynthetic pathways to their extraction, analysis, and synthesis, to the main biological activities found for these active compounds, in order to highlight their potential within pharmaceutical science. The limits and the possible improvements needed for research involving these molecules are also highlighted and discussed.

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.