Application of the concept of relative photomutagenic potencies to selected furocoumarins in V79 cells

Bergamottin: location, aggregation and interaction with the plasma membrane

Bioactive furanocoumarins, a group of natural secondary metabolites common in higher plants, are recognized for their benefits to human health and have been shown to have numerous biological properties. However, the knowledge of its biomolecular mechanism is not known. One of the main furanocoumarins is bergamottin (BGM), which is characterized by a planar three-ringed structure and a hydrocarbon chain, which give BGM its high lipid/water partition coefficient. Because of that, and although the biological mechanism of BGM is not known, BGM bioactive properties could be ascribed to its potential to interact with the biological membrane, modulating its structure, changing its dynamics and at the same time that it might interact with lipids. For our goal, we have applied molecular dynamics to determine the position of BGM in a complex membrane and discern the possibility of certain interactions with membrane lipids. Our findings establish that BGM tends to locate in the middle of the hydrocarbon layer of the membrane, inserts in between the hydrocarbon chains of the phospholipids in an oblique position with respect to the membrane plane, increasing the fluidity of the membrane. Significantly, BGM tends to be surrounded by POPC molecules but exclude the molecule of CHOL. Outstandingly, BGM molecules associate spontaneously creating aggregates, which does not preclude them from interacting with and inserting into the membrane. The bioactive properties of BGM could be ascribed to its membranotropic effects and support the improvement of these molecules as therapeutic molecules, giving place to new opportunities for potential medical improvements.Communicated by Ramaswamy H. Sarma.

Evaluation of photocytotoxicity liposomal form of furanocoumarins Sosnowsky's hogweed

Sosnovsky's hogweed, Heracleum sosnowskyi has a high photosensitizing ability. Although Sosnovsky's hogweed is known as a poisonous plant, its chemical composition and phototoxicity are poorly studied. We analyzed the chemical composition of the Sosnovsky's hogweed juice that grew in natural conditions. It was found that the content of 8-methoxypsoralen in the juice is 1332.7 mg/L, and that of 5-methoxypsoralen is 34.2 mg/L. We have developed and analyzed liposomes containing furanocoumarins of Sosnovsky's hogweed juice and studied their photocytotoxicity in L929 mouse fibroblast cell culture. It was found that liposomes containing furanocoumarins of Sosnovsky's hogweed juice are more toxic for L929 cells in comparison with liposomal forms of pure substances 8-methoxypsoralen and 5-methoxypsoralen. It was found that when exposed to UV radiation at 365 nm at a dose of 22.2 J/cm², the liposomal form of furanocoumarins Sosnovsky's hogweed is 3 times more toxic to L929 cells than in the dark. It was found that the photocytotoxic effect of liposomal furanocoumarins Sosnovsky's hogweed is a strongly stimulation of apoptosis.The data obtained suggest that the raw material of Sosnovsky's hogweed claims to be a source of furanocoumarins, and the liposomal form, given the hydrophobic properties of furanocoumarins, is very suitable for creating a phototherapeutic drug.

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.

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.

Citrus Consumption and Risk of Cutaneous Malignant Melanoma in the Women's Health Initiative

Citrus products are rich sources of furocoumarins, a class of photoactive compounds. Certain furocoumarins combined with ultraviolet radiation can induce skin cancer. We examined the relationship between citrus consumption and cutaneous melanoma risk among 56,205 Caucasian postmenopausal women in the Women's Health Initiative. Cox proportional hazards models were used to estimate hazard ratios (HRs) and 95% confidence intervals (CIs) of melanoma by citrus intake level. During a mean follow-up of 15.7 years, 956 incident melanoma cases were documented. In multivariable adjusted models, the HR (95% CI) for melanoma was 1.12 (0.91, 1.37) among the highest citrus consumers (1.5+ servings/day of fruit or juice) versus the lowest (<2 servings/week), 0.95 (0.76, 1.20) among the highest citrus fruit consumers (5+ servings/week) versus non-consumers, and was 1.13 (0.96, 1.32) for the highest citrus juice consumers (1+ servings/day) versus the lowest (<1 serving/week). In stratified analyses, an increased melanoma risk associated with citrus juice intake was observed among women who spent the most time outdoors in summer as adults; the HR for the highest versus lowest intake was 1.22 (1.02, 1.46) (p trend = 0.03). Further research is needed to explore the association of melanoma with citrus juices among women with high sun exposure.

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.

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.

Novel benzopsoralen analogues: synthesis, biological activity and molecular docking studies

New benzopsoralen analogues were synthesized and their inhibitory effect on the growth of tumourtumour cell lines (MDA MB231 and TCC-SUP) was evaluated. The in vitro antitumour activity of the new benzopsoralen analogues was discussed in terms of structure-activity relationship. Molecular docking studies with human-CYP2A6 enzymes were also carried out with the synthesized compounds to evaluate the potential of these molecules to interact with the haem group of the enzymes. The results demonstrated that the compounds that are able to interact with the iron ion of the haem cofactor and at the same time with active site Asn297 are those that have better anti-proliferative activity.

Phototoxicity of herbal plants and herbal products

Plants are used by humans in daily life in many different ways, including as food, herbal medicines, and cosmetics. Unfortunately, many natural plants and their chemical constituents are photocytotoxic and photogenotoxic, and these phototoxic phytochemicals are widely present in many different plant families. To date, information concerning the phototoxicity and photogenotoxicity of many plants and their chemical constituents is limited. In this review, we discuss phototoxic plants and their major phototoxic constituents; routes of human exposure; phototoxicity of these plants and their constituents; general mechanisms of phototoxicity of plants and phototoxic components; and several representative phototoxic plants and their photoactive chemical constituents.

Furanocoumarins in celeriac from different farming systems: a 3-year study

BACKGROUND

The aim of this 3-year study was to investigate the effect of different celeriac cultivation strategies on the content of naturally occurring toxicants furanocoumarins, represented by psoralen, bergapten, xanthotoxin and isopimpinellin. The products from organic farming in which anaerobically fermented pig slurry was used were compared against those obtained from other treatment systems: mineral, combined and non-fertilised.

RESULTS

The average levels of furanocoumarins for all 3 years (determined by gas chromatography-mass spectrometry) in varieties Albin and Kompakt were 2.6 mg kg⁻¹ and 10.2 mg kg⁻¹, respectively. In all crop years higher levels were found in variety Kompakt. By using linear discriminant analysis it was possible to separate the whole data set according to variety from 85.7%, in individual crop years the recognition ability was more than 90%. According to the crop year, it was possible to separate tested samples from 70.8%, for individual variety the separation was 100%.

CONCLUSIONS

The method of fertilisation did not have a significant effect on the levels of plant secondary metabolites, furanocoumarins. The climatic conditions, in particular the growing periods and the celeriac variety, had an important role in the occurrence of furanocoumarins.

Feasibility of using multiphoton excited tissue autofluorescence for in vivo human histopathology

Rapid and direct imaging of microscopic tissue morphology and pathology can be achieved by multiphoton imaging of intrinsic tissue fluorophores and second harmonic signals. Engineering parameters for developing this technology for clinical applications include excitation levels and collection efficiencies required to obtain diagnostic quality images from different tissue types and whether these levels are mutagenic. Here we provide data on typical average powers required for high signal-to-noise in vivo tissue imaging and assess the risk potential of these irradiance levels using a mammalian cell gene mutation assay. Exposure times of ~16 milliseconds per cell to 760 nm, ~200 fs raster-scanned laser irradiation delivered through a 0.75 NA objective produced negligible mutagenicity at powers up to about 50 mW.