Anders Boman

Identification of 15-Hydroperoxyabietic Acid as a Contact Allergen in Portuguese Colophony

Abstract— 15‐Hydroperoxyabietic acid (15‐HPA) has been isolated from Portuguese colophony of the gum rosin type and identified as its methyl ester. The structure of the compound was elucidated using UV, IR, NMR and mass spectrometry. 15‐HPA methyl ester was found to be an elicitor when tested in colophony‐sensitized guinea‐pigs. The sensitizing capacity was verified in the same species and 15‐HPA methyl ester was considered to be a strong allergen. The eliciting potential was also verified in patients with known allergy to colophony. The Portuguese gum rosin investigated contained approximately 1% of 15‐HPA. Based on its allergenicity and the amounts isolated, we conclude that 15‐HPA is a main contact allergen in Portuguese gum rosin.

Contact allergy to dehydroabietic acid derivatives isolated from Portuguese colophony

7‐oxodehydroabietic acid and 15‐hydroxydehydroabietic acid were isolated as their methyl esters from Portuguese colophony of the gum rosin type and identified as contact allergen. Another oxidation product of dehydroabietic acid, 15‐hydroxy‐7‐oxodehydroabietic acid, was synthesized and identified as a component of Portuguese gum rosin. 7‐oxodehydroabietic acid was found to a be a grade III allergen according to the GPMT method. Guinea pigs induced with gum rosin showed only a low response to the isolated compounds, while patients with a known allergy to gum rosin reacted to a greater extent. The result imply that the content of oxidized dehydroabietic acids in gum rosin is too low to give a marked sensitization in the animals. However, the patients might have come in contact with the allergens in technically modified rosins. The compounds showed a pattern of cross‐reactivity in the animal experiments as well as among the patch tested patients.

Experiences with Freund's complete adjuvant test (FCAT) when screening for contact allergens in colophony.

A procedure, using Freunds complete adjuvant test (FCAT), for the determination of the allergenic potential of fractions and components in colophony of the gum rosin type is described and discussed. Gum rosin was shown to be a potent sensitizer in 11 test series (153 animals). FCAT is compared with the guinea pig maximization test (GPMT). Gum rosin was a potent sensitizer according to this method as well. The FCAT method was found to be advantageous over the GPMT method in that it is technically simpler to use and a smaller amount of test substance is needed. However, closed challenge was preferred to the prescribed open challenge. The importance of statistical evaluation of the results obtained in predictive testing is stressed.

In vitro measurement of transepidermal water loss : A rapid alternative to tritiated water permeation for assessing skin barrier functions

Abstract Transepidermal water loss (TEWL), as measured with an evaporimeter, was used as a rapid assessment of the integrity of the barrier properties of skin as part of in vitro skin permeation studies. For a variety of physical and chemical treatments (i.e. solvent extraction, surfactants, mechanical abrasion and bases) TEWL correlated strongly with tritiated water permeation at short times. In contrast to the tedious process of measuring permeation of a finite dose of tritiated water, TEWL is a rapid, convenient measurement, and it provides a clear indication of the time dependence of barrier integrity.

Hydrogenation reduces the allergenicity of colophony (rosin)

Abietic acid is the main component of rosin. It is readily oxidized by air and its oxidation products are considered to be mainly responsible for the allergenic effect. Hydrogenation of the conjugated double bonds of abietic acid decreases its susceptibility to air oxidation and would thus reduce the allergenicity of rosin. Portuguese gum rosin was therefore hydrogenated and its allergenicity was compared with that of unmodified rosin in animal experiments and by patch testing in humans. Its sensitizing potential was determined in 2 studies. No. response was found according to the FCAT method while the GPMT gave significant response in the animals challenged with highest test concentration. Hydrogenated rosin showed no eliciting activity in animals induced with unmodified rosin according to the GPMT method. A marked decrease was found in the frequency of allergy reactions to hydrogenated rosin compared to the reactions to unmodified rosin in patients with known allergy to gum rosin. We conclude that elimination of the unsaturated non‐aromatic compounds by hydrogenation considerably reduces the allergenicity of Portuguese gum rosin.

Percutaneous absorption of 3 organic solvents in the guinea pig. III: Effect of barrier creams

The efficacy of 4 barrier preparations presented as cream or foam against percutaneous absorption of organic solvents was investigated in the guinea pig. An ordinary hand cream, was also tested. Slight reduction in blood concentration of the solvents was seen when normal skin treated with barrier creams was exposed. Absorption of butanol through stripped skin treated with barrier creams was higher than absorption through skin not so treated. Barrier creams can he considered to give poor skin protection against the organic solvents investigated.

Percutaneous absorption of 3 organic solvents in the guinea pig. IV: Effect of protective gloves

The efficacy of 3 protective glove materials against percutaneous absorption of organic solvents was investigated in the guinea pig. All 3 materials gave a reduction in blood concentration of the solvents, particularly in the early phase of exposure. Of the tested materials, butyl rubber showed the best protective effect, followed by PVC and natural rubber. Gloves of polymeric material can be considered as offering sufficient protection against percutaneous absorption of organic solvents only if their selection is based on results obtained in a controlled and adequately performed test.

Contact allergy to colour developing agents in the guinea pig

Colour developing agents, derivatives of p‐phenylenediamine, can cause contact allergy. Patch test reactions to more than one colour developer are sometime seen in patients. To study whether this is due to simultaneous sensitization or cross‐reactivity, guinea pig maximization tests (GPMT) with CD‐2. CD‐3 and CD‐4 were carried out. 5 experiments were performed, using pet, or water as vehicles. When pet, was used, the challenge concentrations could be raised and cross‐between the colour developers, but not with p‐phenylenediamine‐dihydrochloride, was revealed When water was used as vehicle, the challenge concentrations were limited because of staining of the test sins and irritation. CD‐1. CD‐2 and CD‐3 were found to be extreme sensitizers according to the classification by Magnusson and Kligman The importance of using an appropriate vehicle to obtain optimal conditions for the GPMT is stressed.

Contact allergy to a cyclohexanone resin in humans and guinea pigs

5 patients with allergic contact dermatitis caused by various paints were demonstrated to be sensitive to a cyclohexanone resin (C‐R) present in the paints. Sensitization studies in guinea pigs with C‐R and cyclohexanone showed one batch of C‐R to be a sensitizer.

Permeation testing of protective gloves by using two different permeation cells in an open-loop system (neoprene-toluene).

Two permeation test cells of different sizes were used in a study of the permeation of toluene through two neoprene gloves and special neoprene sheet stock. Three flow rates of the collecting medium through the test cells were used to explore to what extent variation in flow rate would affect the breakthrough times and the steady-state permeation rate. The breakthrough time values were not affected to a significant degree by cell size or by increasing the flow rate of the collecting medium from 60 to 120 mL/min. The steady-state permeation rate values were evidently influenced by the flow rate of the collecting medium and by the size and configuration of the test cell.