[Translated article] Standard and Expanded Series Patch Testing Update by the Spanish Contact Dermatitis and Skin Allergy Research Group (GEIDAC).

After the meeting held by the Spanish Contact Dermatitis and Skin Allergy Research Group (GEIDAC) back in October 2021, changes were suggested to the Spanish Standard Series patch testing. Hydroxyethyl methacrylate (2% pet.), textile dye mixt (6.6% pet.), linalool hydroperoxide (1% pet.), and limonene hydroperoxide (0.3% pet.) were, then, added to the series that agreed upon in 2016. Ethyldiamine and phenoxyethanol were excluded. Methyldibromoglutaronitrile, the mixture of sesquiterpene lactones, and hydroxyisohexyl 3-cyclohexene (Lyral) were also added to the extended Spanish series of 2022.

Standard and Expanded Series Patch Testing Update by the Spanish Contact Dermatitis and Skin Allergy Research Group (GEIDAC). / Actualización de la batería estándar y batería ampliada de pruebas alérgicas de contacto por el Grupo Español de Investigación en Dermatitis de Contacto y Alergia Cutánea (GEIDAC).

After the meeting held by the Spanish Contact Dermatitis and Skin Allergy Research Group (GEIDAC) back in October 2021, changes were suggested to the Spanish standard series patch testing. Hydroxyethyl methacrylate (2% pet.), textile dye mixt (6.6% pet.), linalool hydroperoxide (1% pet.), and limonene hydroperoxide (0.3% pet.) were, then, added to the series that agreed upon in 2016. Ethyldiamine and phenoxyethanol were excluded. Methyldibromoglutaronitrile, the mixture of sesquiterpene lactones, and hydroxyisohexyl 3-cyclohexene (Lyral) were alo added to the extended Spanish series of 2022.

Skin sensitization to fragrance hydroperoxides: interplay between dendritic cells, keratinocytes and free radicals.

BACKGROUND: Skin sensitization to hydroperoxides (R-OOHs) of the commonly used fragrance terpenes limonene, linalool and citronellol is frequently reported. R-OOHs are believed to initiate the process leading to sensitization and allergic contact dermatitis through mechanisms involving radical intermediates. Thus, radical intermediates, keratinocytes and dendritic cells (DCs) may act in concert to initiate the process. OBJECTIVES: To evaluate individual DC activation profiles by R-OOHs in the context of keratinocytes with regard to frequency, specificity and magnitude of upregulation. METHODS: We used 2D and 3D cocultures with keratinocytes/reconstructed human epidermis (RHE) and DCs to evaluate cell surface levels of the costimulatory molecules CD86, CD80 and the adhesion molecule CD54 on cocultured DCs. Analysis of radical formation from limonene hydroperoxides in RHE was performed using electron paramagnetic resonance combined with the spin trapping technique. RESULTS: R-OOHs induce donor-dependent DC activation. Major differences were found between the limonene-OOHs. Limonene-1-OOH was stronger with respect to both frequency and magnitude of response. Using a 3D coculture model, no DC activation was detected after topical application of 0·2% limonene-OOHs (20 µg cm-2 ), while 1·2% limonene-1-OOH or 2% limonene-2-OOH induced DC activation. Furthermore, we demonstrated differences in the carbon and oxygen radicals formed from the limonene-OOHs using RHE, mimicking what may happen in vivo. CONCLUSIONS: We report clear individual differences in DC maturation induced by the most important hydroperoxides. Response rates and magnitude of response both indicate that very small structural alterations in the hydroperoxides are translated into specific DC responses. In addition, we provide more insight into the amounts of hydroperoxides that can activate DCs and induce sensitization.

[Bullous drug eruption with Nigella sativa oil]. / Éruption bulleuse à l'huile de nigelle.

BACKGROUND: Nigella sativa is classically used for its various therapeutic properties, particularly in the field of allergic diseases. We report a case of bullous eruption following application of Nigella sativa oil to the skin, possibly involving an associated systemic mechanism linked to ingestion of the oil. PATIENTS AND METHODS: A 53-year-old woman was hospitalized for febrile rash consisting of erythematous plaques with vesicles and bullous lesions. She had Nigella sativa oil applied to her skin and ingested it for two weeks. Cutaneous histopathology revealed sub-epidermal detachment and necrosis of the epidermal surface consistent with toxic epidermal necrolysis. The lesions healed slowly, but depigmented macules persisted three months later. Patch tests for Nigella sativa oil were strongly positive. DISCUSSION: Erythema multiforme due to contact with Nigella sativa oil was initially diagnosed on the basis of lesions on skin where the oil was applied, as well as on cutaneous histopathology and positive patch tests. However, a systemic reaction such as toxic epidermal necrolysis could not be ruled out since the patient had also ingested the oil. The most likely diagnosis was thus systemic and contact bullous drug eruption. The discovery of new therapeutic properties of Nigella sativa in other clinical domains underscores the need for particular vigilance regarding future use of this substance on account of the risk of severe drug eruptions.

Principles and methodology for identification of fragrance allergens in consumer products.

Fragrances contain several hundreds of different chemicals, a few major and many minor, which are responsible for the complexity of the odour. Fragrances are a major cause of allergic contact dermatitis. As a diagnostic tool, the current fragrance mix is very useful though not ideal. A 50-year-old woman presented with a pruriginous, erythematous eruption, characterized by papules, vesicles, exudation and crusting over the neck and chest. With the suspicion of fragrance allergy, patch testing was performed. Initially, the only positive reaction observed was with her own eau de toilette named Woman. The TRUE Test fragrance mix patch test was negative. Chemical fractionation of Woman perfume concentrate was combined with a sequenced patch testing procedure and with structure-activity relationship studies. Ingredients supplied by the manufacturer were also included in the study. Benzophenone-2, Lyral, alpha-hexyl cinnamic aldehyde and alpha-damascone were found to be responsible for the patient's contact allergy to the commercial product. These substances contain chemical structural alerts giving them antigenic ability. The common use of new chemicals to manufacture fragrances, and the increased number of patients sensitive to them but with negative fragrance mix reactions, makes it necessary to identify new potential fragrance sensitizers in commercial products.

Lyral is an important sensitizer in patients sensitive to fragrances.

Contact allergy to fragrances is a common problem world-wide. The currently used fragrance mix (FM) for patch testing has only eight constituents and does not identify all fragrance-allergic patients. As perfumes may contain 100 or more substances, the search for markers for allergy continues. The synthetic fragrance 4-(4-hydroxy-4-methylpentyl)-3-cyclohexene carboxaldehyde (Lyral) was tested together with the FM and 11 other fragrance substances on consecutive patients in six European departments of dermatology. All patients were carefully questioned regarding a history of reactions to scented products in the past and were grouped into four categories: 'certain', 'probable', 'questionable' and 'none'. Lyral (5% in petrolatum) gave a positive reaction in 2.7% of 1855 patients (range 1.2-17%) and ranked next to 11.3% with FM allergy. Twenty-four patients reacted to both Lyral and FM, but 21 (1.1%) reacted positively only to Lyral. Of 124 patients with a 'certain' history, 53.2% reacted to the FM and a further 7.2% to Lyral only. If any kind of history of fragrance intolerance was given, 80% (40 of 50) of Lyral positive patients had a 'positive' history while only 58.6% (123 of 210) of FM positive patients had such a history; this difference was significant at P < 0.01. Lyral was identified by gas chromatography-mass spectrometry in some products which had caused an allergic contact dermatitis in four typical patients who showed a patch test positive to Lyral and negative or doubtful to FM. In conclusion, we recommend the testing of 5% Lyral (in petrolatum) in patients suspected of contact dermatitis.

Molecular recognition between a new pentacyclic acridinium salt and DNA sequences investigated by optical spectroscopic techniques, proton nuclear magnetic resonance spectroscopy, and molecular modeling.

A pentacyclic acridine, 1H-2,3-dihydroindolizino[7,6,5-kl]acridinium chloride (1), related in structure to tetra- and pentacyclic marine natural products, has previously been shown to induce apoptosis in breast and non-small-cell lung tumor cell lines and shows significant differences in biological potency and antitumor profile from other intercalating agents based on the acridine framework. We report on the molecular recognition of the acridinium salt with DNA, quantified by optical spectroscopic methods, and have compared these results with the clinical agent amsacrine (m-AMSA). The results point to an intercalative association between 1 and G-C-rich sequences of DNA. We have synthesized a hexamer duplex d(ACGCGT)2, presenting two potential 5'-CpG recipient sites, and have investigated in detail by NMR and molecular modeling methods the orientational preferences of 1, particularly with regard to the pyrrolidine ring system. On the basis of the intermolecular nuclear Overhauser effect (NOE) data, four possible intercalation models were considered; no single model produced a significantly better fit than any of the others. The best fit to the experimental data was obtained by considering a dynamic equilibrium between the different intercalated orientations with the drug maximizing pi-overlap with the G-C base pairs at the intercalation site. We found little evidence for any degree of groove specificity imparted by the pyrrolidine ring. If these simulations have biological relevance they suggest that, at most, the agent induces only a transitory hot spot in the DNA which, evidently, is sufficient to be sensed by damage-recognition mechanisms of the cell.

Identification of coumarin as the sensitizer in a patient sensitive to her own perfume but negative to the fragrance mix.

The aim of this study was to identify the chemicals responsible for the sensitivity of a 44-year-old woman to her own perfume, but showing negative patch test results to the fragrance mix. For this purpose, the perfume concentrate from the eau de toilette was chemically fractionated. Each fraction obtained was afterwards tested on the patient using a ROAT and/or a patch test. Only 1 fraction gave a positive ROAT result. This fraction was analyzed and found to contain coumarin and ethyl vanillin. Coumarin, one of the most widely used fragrance compounds that is not present in the fragrance mix, was confirmed as being the sensitizer.

Antitumour polycyclic acridines. Part 4. Physico-chemical studies on the interactions between DNA and novel tetracyclic acridine derivatives.

The non-covalent interactions between a series of new tetracyclic acridine derivatives (5-11) and DNA have been studied by spectrophotometric analysis, fluorescences quenching, thermal denaturation, and circular and linear dichroism. In order to compare the extent of the DNA binding by compounds 5-11 in their neutral and cationic forms, all experiments were conducted at pH 7.4 (physiological pH) and 5.0. The results indicated that compounds 5-11 are strong DNA-binding ligands with DNA affinities comparable to that of m-AMSA (1) or even higher. They showed a stronger DNA binding activity at pH 5.0 as a result of the N-protonation of the pyridoacridine aromatic chromophore. Ethidium-DNA fluorescence assays showed an A-T base pair preference of the binding distinguishing these novel compounds from simple acridines which show a slight G-C base pair preference. Circular and linear dichroism studies indicated that the drugs bind to DNA by undergoing intercalation inside the duplex macromolecule at high DNA:drug ratios and revealed alternative binding modes at low DNA:drug ratios.

Antitumour polycyclic acridines. Part 2. Physicochemical studies on the interactions between DNA and novel polycyclic acridine derivatives.

The noncovalent interactions between a series of new polycyclic acridine derivatives (1-5) and salmon testes DNA have been studied using several physicochemical techniques. These include spectrophotometric analysis, fluorescence quenching, thermal denaturation, and circular and linear dichroism. In order to compare the extent of the DNA binding by compounds 1-5 in their neutral and cationic forms, all experiments have been conducted at pH 7.4 and at pH 5.0. Other polynucleotides, including [Poly(dA-dT)]2 and [Poly(dG-dC)]2, were used in order to study the DNA base-pair binding specificity of these novel annelated acridine derivatives. The results indicate that the new polycyclic acridines display the following properties: (i) they are strong DNA-binding ligands with affinities 10- to 400-fold greater than that of acridine, 3- to 100-fold greater than that of m-AMSA (6) and 1- to 23-fold greater than that of proflavine at physiological pH (7.4); (ii) they have stronger DNA-binding activity at pH 5.0 as a result of the N-protonation of the aromatic chromophore; (iii) they bind more selectively to [Poly(dA-dT)]2 polynucleotide than to [Poly(dG-dC)]2 polynucleotide; (iv) within the series compound 3 binds to DNA less than compounds 1, 2, 4 and 5 at both pH values studied; and (v) the polycyclic acridines form a molecular complex with DNA undergoing intercalation inside the duplex macromolecule, as shown by linear and circular dichroism. Nevertheless, circular dichroism studies reveal alternative binding modes at low DNA: drug ratios.

Synthesis and photocyclization of alpha-methylene-gamma-butyrolactone-thymine heterodimers.

Two alpha-methylene-gamma-butyrolactone--thymine heterodimers 6 and 7 with 5 and 10 carbon alkyl chains, respectively, were prepared to study the photoreactivity of lactone rings toward thymine and the influence of spacer length on photoadduct geometry. Deoxygenated solutions (10(-3) M) of heterodimers 6 and 7 were irradiated at 365 nm in acetone. Irradiation of compound 6 (5 carbons alkyl chain) gave a single photoadduct 8 (70% yield), while irradiation of compound 7 (10 carbons alkyl chain) gave two photoadducts 9a and 9b in a 3/2 ratio (95% yield). Compound 8 was identified as a cis-syn-endo intramolecular [2 + 2] photoadduct involving the 5",6" double bond of the thymine moiety and the 3,6 exomethylenic group of the lactone. Compound 9a was identified as a cis-syn-exo intramolecular [2 + 2] photoadduct involving the 5",6" double bond of the thymine moiety and the 3,6 exomethylenic group of the lactone, and compound 9b as the corresponding cis-syn-endo intramolecular [2 + 2] photoadduct.