Hidden threat lurking in extensive hand hygiene during the Covid-19 pandemic: investigation of sensitizing molecules in gel products by hyphenated chromatography techniques

During the Covid-19 pandemic, health agencies worldwide have recommended frequent handwashing and sanitizing. A variety of hand gel products were made available on the market, often with fragrances added to curtail the strong smell of alcohol. Commonly used Citrus fragrances contain volatile aroma constituents and non-volatile oxygen heterocyclic compounds (OHCs), consisting mostly of polymethoxyflavones, coumarins, and furocoumarins. The latter have long been investigated for their phototoxic properties, and their safety as cosmetic product ingredients has been debated recurrently. To this concern, twelve commercial Citrus-scented products were investigated in this study. An extraction method was optimized for thirty-seven OHC compounds, obtaining absolute mean recovery values in the 73.5-116% range with only few milliliters of solvent consumption. Analysis by ultra-high-pressure liquid chromatography with tandem mass spectrometry detection evidenced that three samples did not conform to the labeling requirements for fragrance allergens (coumarin) laid down by the European Union Regulation on Cosmetic Products. The total furocoumarin (FC) content of the samples investigated was in the 0.003-3.7ppm range, with some noteworthy exceptions. Specifically, in two samples, the total FCs were quantified as 89 and 219 ppm, thus exceeding the safe limits recommended up to a factor of 15. Finally, the consistency of the volatile fingerprint attained by gas chromatography allowed drawing conclusions on the authenticity of the Citrus fragrances labeled, and several products did not conform to the information reported on the label concerning the presence of essential oils. Besides the issue of product authenticity, analytical tools and regulatory actions for widespread testing of hand hygiene products are urgent, to protect consumers' health and safety.

Investigation of cytotoxic and antioxidative activity of 1,2,3-triazolyl-modified furocoumarins and 2,3-dihydrofurocoumarins

High biological activity of natural furocoumarins is often linked to a series of adverse side effects, e.g., genotoxicity. This makes it desirable to develop semi-synthetic derivatives with reduced negative activity while retaining or even enhancing the positive properties. Previously, we have studied the genotoxic activity of a library of twenty-one 1,2,3-triazolyl-modified furocoumarins and 2,3-dihydrofurocoumarins and identified modifications that minimize the negative properties. In the current article, we report on an investigation into the cytotoxic activity of the same library. We have aimed to rank the substances in order of the severity of their cytotoxicity and therefore to predict, with the use of statistical processing, the most promising substituents for the furocoumarin scaffold.

Linear retention index approach applied to liquid chromatography coupled to triple quadrupole mass spectrometry to determine oxygen heterocyclic compounds at trace level in finished cosmetics

In the European Union, cosmetic products are regulated by the Cosmetics Regulation (EC) No. 1223/2009. The Analytical Working Group of the International Fragrance Association (IFRA) suggested that a new sensitive analytical method is needed to determine psoralens in finished cosmetic products. This research provides an HPLC-MS/MS method for the quality control of 20 furocoumarins, 8 coumarins and 7 polymethoxyflavones in cosmetics. Thanks to the high sensitivity of the tandem mass spectrometry detection in Multiple Reaction Monitoring mode, psoralens contained in trace have been quantified in different products. The Limits of Quantifications were in the range 0.3-74 μg L^-1. A reliable identification was achieved combining the Linear Retention Index (LRI) system with the MS and MS/MS libraries. In particular, the attribution was based on the spectra similarity filtered by the LRI parameter. The robustness and reproducibility of the LRI approach was demonstrated by the comparison of the HPLC-MS/MS results here reported with those obtained in our previous study, by using an HPLC-PDA system. This method could be taken into account for quality control of furocoumarins in cosmetics, and by the main associations, such as IFRA, for the purpose of issuing new opinions.

Margarita Burn: Recognition and Treatment of Phytophotodermatitis

Phytophotodermatitis is a cutaneous reaction caused by direct contact with phototoxic agents and subsequent sunlight exposure. Furocoumarins and psoralens are 2 phototoxic agents that can cause this reaction, and these organic chemical compounds are found in many plant species consumed by humans. Following contact exposure to such foods and ultraviolet radiation exposure via direct sunlight, phytophotodermatitis can occur. Due to the etiology of these rashes relating closely to the outdoor consumption of margaritas, the rash may be known by patients as "margarita burn." There is a classically described sequence of rash progression: erythematous macules or patches, which later become vesicles and seem similar to second-degree burns, followed by an asymptomatic hyperpigmentation. This case presents a 26-year-old female diagnosed with phytophotodermatitis following use of citrus fruits for margaritas while outdoors in direct sunlight. The diagnosis of phytophotodermatitis is often made clinically but can be complicated due to its similarity in appearance to many other common cutaneous reactions. In this patient, the differential diagnosis included solar erythema, contact dermatitis (type IV hypersensitivity reaction), polymorphic light eruption, or drug-related photosensitivity. Careful history taking is essential in not only narrowing down the differential diagnosis but also in avoiding unnecessary tests or ineffective treatments.

Ultrasonic-enhanced surface-active ionic liquid-based extraction and defoaming for the extraction of psoralen and isopsoralen from Psoralea corylifolia seeds

Recently, integrated and sustainable methods for extracting active substances from plant materials using green solvents, i.e., ionic liquids, have gained increasing attention. Ionic liquids showsuperiority over conventional organic solvents; however, they also exhibit negative factors and problems, such as high viscosity, poor water intermiscibility, intensive foaming and poor affinity for fat-soluble substances. The proposed method utilizes ultrasonic-enhanced surface-active ionic liquid-based extraction and defoaming (UESILED) to improve the extraction efficiency of ionic liquids. Single-factor experiments and a Box-Behnken design (BBD) were utilized to optimize the extraction procedure. The optimal conditions were as follows: extraction solvent, [C₁₀MIM]Br; ultrasonic treatment time, 28 min; ultrasonic irradiation power, 437 W; liquid-solid ratio, 10 mL/g; particle size, 60 ~ 80 mesh; ultrasonication temperature, 313 K; and [C₁₀MIM]Br solution concentration, 0.5 mol/L. In comparison with those of other reference extraction methods, the proposed method exhibited higher yields of two furocoumarins and operational feasibility. Moreover, the mechanism of UESILED was elaborated in terms of accelerating infiltration, dissolution and defoaming. The feasible and efficient ultrasonic-enhanced ionic liquid-based extraction established in this study strongly contributes to overcoming the limitations of ionic liquid solvents. The present research indicates that this improved process will be beneficial for the extraction of other fat-soluble substances and provides promising concepts and experimental data.

Furocoumarins as multi-target agents in the treatment of cystic fibrosis

Multi-target molecular entities, offer a path to progress both in understanding causes of disease and in defining effective small molecule treatments. Coumarin and its derivatives belong to an important group of natural compounds with diverse biological properties. They are found in vegetables and plants for which literature reports thousands of publications for the great variety of biological applications among which the photoprotective effects, thus being considered multi-targeting agents. Their furan condensed analogues constitute the family of furocoumarins, less represented in the literature, endowed with photosensitizing properties and often used for the treatment of skin diseases such as vitiligo and psoriasis. Despite the study of biological properties of linear and angular furocumarins dates back to ancient times, mainly as photosensitizers, these small molecules still represent an attractive scaffold for further development and applications in several therapeutic fields. The aim of the present review is to summarize the most promising chemical entities belonging to the class of furocumarins and coumarins, emerged in the last decades, and the methods used for their synthesis with a particular focus on main targets involved in the cystic fibrosis treatment.

Phototoxicity of 7-oxycoumarins with keratinocytes in culture

Seventy-one 7-oxycoumarins, 66 synthesized and 5 commercially sourced, were tested for their ability to inhibit growth in murine PAM212 keratinocytes. Forty-nine compounds from the library demonstrated light-induced lethality. None was toxic in the absence of UVA light. Structure-activity correlations indicate that the ability of the compounds to inhibit cell growth was dependent not only on their physiochemical characteristics, but also on their ability to absorb UVA light. Relative lipophilicity was an important factor as was electron density in the pyrone ring. Coumarins with electron withdrawing moieties - cyano and fluoro at C₃ - were considerably less active while those with bromines or iodine at that location displayed enhanced activity. Coumarins that were found to inhibit keratinocyte growth were also tested for photo-induced DNA plasmid nicking. A concentration-dependent alteration in migration on neutral gels caused by nicking was observed.

Inactivation of plant-pathogenic fungus Colletotrichum acutatum with natural plant-produced photosensitizers under solar radiation

The increasing tolerance to currently used fungicides and the need for environmentally friendly antimicrobial approaches have stimulated the development of novel strategies to control plant-pathogenic fungi such as antimicrobial phototreatment (APT). We investigated the in vitro APT of the plant-pathogenic fungus Colletotrichum acutatum with furocoumarins and coumarins and solar radiation. The compounds used were: furocoumarins 8-methoxypsoralen (8-MOP) and 5,8-dimethoxypsoralen (isopimpinellin), coumarins 2H-chromen-2-one (coumarin), 7-hydroxycoumarin, 5,7-dimethoxycoumarin (citropten) and a mixture (3:1) of 7-methoxycoumarin and 5,7-dimethoxycoumarin. APT of conidia with crude extracts from 'Tahiti' acid lime, red and white grapefruit were also performed. Pure compounds were tested at 50μM concentration and mixtures and extracts at 12.5mgL(-1). The C. acutatum conidia suspension with or without the compounds was exposed to solar radiation for 1h. In addition, the effects of APT on the leaves of the plant host Citrus sinensis were determined. APT with 8-MOP was the most effective treatment, killing 100% of the conidia followed by the mixture of two coumarins and isopimpinellin that killed 99% and 64% of the conidia, respectively. APT with the extracts killed from 20% to 70% of the conidia, and the extract from 'Tahiti' lime was the most effective. No damage to sweet orange leaves was observed after APT with any of the compounds or extracts.

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.

Novel furocoumarins as potential HIV-1 integrase inhibitors

A series of seven novel, rationally designed N-substituted 3-{3,5-dimethylfuro[3,2-g]coumarin-6-yl}propanamides have been prepared as potential HIV-1 integrase (IN) inhibitors via a five-step pathway commencing with resorcinol and diethyl 2-acetylglutarate, and the HIV-1 IN inhibition potential of these compounds has been examined relative to raltegravir, a known HIV-1 IN inhibitor.

Quantification and repair of psoralen-induced interstrand crosslinks in human cells

Bi-functional alkylating agents that cause crosslinks are commonly used in chemotherapy. However, there is no conclusive knowledge for human cells regarding the number of induced interstrand crosslinks (ICLs) and the unhooking rate when the lesion is removed from one of the DNA strand. Using a newly developed method, we quantified the number of induced ICLs for the five furocoumarins; psoralen, 5-methoxypsoralen, 8-methoxypsoralen, tri-methoxypsoralen and angelicin. In quantitative terms, the results were in agreement with the values found by others. In kinetic studies using mammalian cells, we found that half of the psoralen-induced ICLs were unhooked within 2.5h. The rate in normal human diploid fibroblasts was found to be 20,000 ICLs/h/cell. In comparison to survival, 2500 ICLs per cell led to 50% toxicity, indicating that the unhooking of the ICLs is not the crucial step for ICL tolerance. Surprisingly, only 3500 ICLs per cell corresponded to a significant delay in the replication fork elongation. The results indicate involvements of additional pathway(s) for the delay since the effect on replication elongation could be monitored when only 10% of the replication forks encounter an ICL.

Furocoumarins and coumarins photoinactivate Colletotrichum acutatum and Aspergillus nidulans fungi under solar radiation

The increasing tolerance to currently-used fungicides is a major problem both in clinical and agricultural areas leading to an urgent need for the development of novel antifungal strategies. This study investigated the in vitro antimicrobial photo treatment (APT) of conidia of the plant-pathogenic fungus Colletotrichum acutatum and the ascomycete Aspergillus nidulans with the furocoumarins 8-methoxypsoralen (8-MOP) and isopimpinellin, and a mixture of two coumarins (7-methoxy coumarin and citropten). Subcellular localization of the photosensitizer 8-MOP was also determined in C. acutatum conidia. Additionally, the effects of APT on the leaves of the plant host Citrus sinensis were determined. APT with 8-MOP (50μM) led to a reduction of approximately 4 logs in the survival of the conidia of both species, and the mixture of the two coumarins (12.5mgL(-1)) resulted in a reduction of approximately 4 logs for A. nidulans and 3 logs for C. acutatum. Isopimpinellin (50μM) displayed a reduction of 4 logs for A. nidulans but less than 2 logs for C. acutatum. Washing the conidia to remove unbound photosensitizers before light exposure reduced the photodynamic inactivation of C. acutatum both with 8-MOP and the mixture of the two coumarins. The reduction was smaller for A. nidulans. 8-MOP spread throughout the cytoplasm and accumulated in structures such as lipid bodies of C. acutatum conidia. No damage to orange tree leaves was observed after APT with any of the photosensitizers.

Modulation of the UVB-induced lethality by furocoumarins in Staphylococcus aureus

Furocumarins (FCs) are photoactive compounds capable of binding to DNA, and once excited by UVA light (∼365nm), they form photoadducts which can lead to mutagenicity and lethality. However, the biological effects of FCs combined with UVB light (312nm) is still little investigated. In the present study, the lethal effect of UVB light alone and combined with different concentrations of 8-methoxypsoralen (8-MOP), 4,5',8-trimethylpsoralen (TMP) and 3-carbethoxypsoralen (3-CPs) was evaluated in a strain of Staphylococcus aureus. 8-MOP-UVB and TMP-UVB were more effective in inducing lethality compared to UVB alone, indicating that these FCs act as photosensitizing agents for UVB. The increase in concentration of 8-MOP resulted in a greater mortality. On the contrary, a decrease in mortality was found with an increase in TMP concentration. 3-CPs protected bacteria against damage induced by UVB, which can be attributed to the inhibition of cyclobutyl pyrimidine dimer formation. The different modulatory effects on lethality induced by UVB shown by the FCs tested could be related to differences in the specificity of each compound for particular nucleotide sequences, as well as other chemical characteristics of each molecule could influence the number and types of adducts formed, contributing to the photosensitizing or photoprotective effects observed.

Synthesis of imperatorin analogs and their evaluation as acetylcholinesterase and butyrylcholinesterase inhibitors

In this study, we synthesized several imperatorin analogs using imperatorin and xanthotoxin as substrates. The anti-cholinesterase activities of all compounds were evaluated in in vitro experiments according to the modified Ellman's method. For each synthesized compound, IC50 values for both enzymes were established. Galantamine hydrobromide was used as a positive control in the enzymatic experiments. All active compounds showed selectivity toward butyrylcholinesterase (BuChE) rather than acetylcholinesterase. The most active ones were 8-(3-methylbutoxy)-psoralen and 8-hexoxypsoralen with IC50 values for BuChE of around 16.5 and 16.4 µM, respectively. The results of our study may be considered as the beginning of a search for potential anti-Alzheimer's disease drugs based on the structure of natural furocoumarins.

Antiviral activity of angelicin against gammaherpesviruses

Human gammaherpesviruses including Epstein-Barr virus (EBV) and Kaposi's sarcoma-associated herpesvirus (KSHV) are important pathogens as they persist in the host and cause various malignancies. However, few antiviral drugs are available to efficiently control gammaherpesvirus replication. Here we identified the antiviral activity of angelicin against murine gammaherpesvirus 68 (MHV-68), genetically and biologically related to human gammaherpesviruses. Angelicin, a furocoumarin naturally occurring tricyclic aromatic compound, efficiently inhibited lytic replication of MHV-68 in a dose-dependent manner following the virus entry. The IC50 of angelicin antiviral activity was estimated to be 28.95μM, while the CC50 of angelicin was higher than 2600μM. Furthermore, incubation with angelicin efficiently inhibited 12-O-tetradecanoylphorbol-13-acetate (TPA)-induced lytic replication of human gammaherpresviruses in both EBV- and KSHV-infected cells. Taken together, these results suggest that MHV-68 can be a useful tool to screen novel antiviral agents against human gammaherepsviruses and that angelicin may provide a lead structure for the development of antiviral drug against gammaherpesviruses.

Biosynthesis of Psoralen: Mechanism of a Cytochrome P450 Catalyzed Oxidative Bond Cleavage

In contrast to the stepwise oxidative dealkylation of steroids [Eq. (1)], (+)-marmesin (1) is directly converted by the psoralen synthase (a cytochrome P450) into the phototoxic furanocoumarin psoralen (2) and acetone. The dealkylation proceeds as a syn elimination.