Validation of a microdialysis-gas chromatographic-mass spectrometric method to assess 8-methoxypsoralen in psoriatic patient dermis.

8-Methoxypsoralen (8-MOP) is currently used in PUVA therapy (psoralen+UVA) to treat dermatological diseases such as psoriasis, vitiligo and atopic dermatitis. The aim of this work was to validate a method for collecting 8-MOP from patient dermis by a non invasive technique, microdialysis, and then to assess this molecule by gas chromatography-mass spectrometry (GC-MS). 5-Methoxypsoralen (5-MOP) was used as an internal standard. The calibration curve demonstrated a linear relationship between the peak areas of 8-MOP and 5-MOP over a wide range of 8-MOP concentrations (0.9-100 ng/ml). Within- and between-run precisions were measured, using four different 8-MOP concentrations, which varied from 98.0 to 102.0% and from 98.5 to 101.8%, respectively. The limits of detection and quantification were 0.29 and 0.52 ng/ml, respectively. The method was validated and then applied to determine the pharmacokinetic of 8-MOP in ten psoriatic patient dermis, after oral intake of this drug. The results demonstrated that the association of microdialysis with the GC-MS method was an efficient procedure to collect and assess 8-MOP in human dermis, in vivo.

Assessment of principal parabens used in cosmetics after their passage through human epidermis-dermis layers (ex-vivo study).

Concern is continuously raised about the safety of parabens which are present in most of the cosmetic preparations. In this investigation, methyl-, ethyl-, propyl- and butyl paraben (MP, EP, PP, BP), in a commercial cosmetic lotion, were deposited on human skin fragments, collected after surgical operations. Permeated parabens were determined after their passage through human epidermis-dermis layers, fixed on Franz diffusion cells. Bovine serum albumin (3%) was employed as receptor fluid. Then, parabens were assessed by liquid chromatography. The objective of this research was to determine the permeation of these molecules through human epidermis-dermis layers, and their possible passage to body tissues and/or accumulation in skin layers. Two groups of experiments were performed. In the first experimental group (G1), unique doses of the cosmetic were deposited on skin fragments fixed on Franz cells (n = 6), at time 0 h, followed with different withdrawn times of the receptor fluid at 12, 24 and 36 h. G1 results demonstrated that parabens penetration was influenced by their lipophilicity: more lipophilic the parabens were (BP > PP > EP > MP), less they crossed the skin layers (BP < PP < EP < MP). The second experimental group (G2) was constituted of three equal deposits on each Franz cell (n = 6) at different hour times 0, 12 and 24 h followed with three withdrawn times of the receptor fluid at 12, 24 and 36 h. The G2 results indicated that investigated parabens had significant increasing permeations in skin layers. This situation provokes the accumulation of these molecules which were considered by some authors as the cause of skin toxicities and carcinogenicity.

Evaluation of a sunscreen photoprotective effect by ascorbic acid assessment in human dermis using microdialysis and gas chromatography mass spectrometry.

Ultraviolet irradiation causes adverse effects like sunburn, photosensitivity reactions or immunologic suppression. The aim of this study was to evaluate the photo-protective outcome of a sunscreen cream (SPF8) by the determination of erythema indexes and the assessment of ascorbic acid and its metabolites in human dermis. These substances were used as markers of oxidative effect. Eight healthy female subjects were enrolled in this study. Two abdominal areas were exposed to solar simulated irradiation with three minimal erythema dose, one with SPF8 application and the other site without SPF8 application. Two other areas were used as control, one without SPF8 application and the other site after SPF8 application. Ascorbic acid and its metabolites (dehydroascorbic acid, threonic acid, oxalic acid and xylose) were collected from human dermis by microdialysis and assessed by gas chromatography mass spectrometry. Irradiated site without sunscreen application had significantly demonstrated lower dermis ascorbic acid concentrations and a higher erythema index than the three other sites (P < 0.05). Threonic acid, oxalic acid and xylose dermis concentrations were significantly higher in site III than in the control site I (P < 0.05). The protected-irradiated site did not show erythema formation and there was stability of ascorbic acid dermis concentrations with non-variation in its metabolites. The assessment of ascorbic acid and its metabolites in human dermis could be an efficient tool to demonstrate the oxidative process and consequently to control the efficiency of sunscreen creams against undesirable UV effects.

High iron and low ascorbic acid concentrations in the dermis of atopic dermatitis patients.

BACKGROUND: Atopic dermatitis (AD) is a chronic inflammatory skin disease in which reactive oxygen species (ROS) may be involved. Iron catalyses ROS formation and ascorbic acid (AA) scavenges these species. OBJECTIVE: The aim of this work was to determine iron and AA levels in AD patients' dermis and to compare their concentrations with those of healthy volunteers' dermis. METHODS: Five AD patients and 5 healthy subjects (controls) were enrolled in this study. Iron and AA were collected from human dermis by microdialysis and assessed by atomic absorption spectrometry and gas chromatography-mass spectrometry, respectively. RESULTS: The AD dermis demonstrated higher iron concentrations (44.3 +/- 4.6 microg/l) compared to controls (21.8 +/- 1.2 microg/l) as well as a significantly lower concentration of AA (46.7 +/- 0.6 vs. 176.8 +/- 14.5 microg/ml, respectively). CONCLUSION: These results suggest that iron and AA dermis levels could be indicators of inflammatory tissues and might be implicated in dermatological diseases such as AD.

Iron and ascorbic acid concentrations in human dermis with regard to age and body sites.

BACKGROUND: Reactive oxygen species (ROS) contribute to processes relating to cutaneous aging. Iron catalyses ROS formation whereas ascorbic acid (AA) plays a fundamental role in defending the organism against undesirable ROS action. OBJECTIVE: The aim of this work was to determine the ex vivo iron and AA concentrations in human dermis from different age groups to better understand their role. METHODS: Skin fragments were collected from 66 female patients during surgical operations and were grouped according to age: group I (<15 years, before puberty, n = 12), group II (15-50 years, adults, n = 42), and group III (>50 years, advanced age adults, n = 12). Two sites were investigated: the abdomen (unexposed areas) and face (exposed sites). Iron and AA were collected from human dermis by microdialysis and assessed by atomic absorption spectrometry and gas chromatography mass spectrometry, respectively. RESULTS: Iron concentrations in the dermis were significantly higher in group III (27.4 +/- 20.9 microg/l) than in group I (13.8 +/- 3.3 microg/l; p< 0.05 ). An inverse correlation between AA dermis levels and increasing age was detected. For groups III and I, iron and AA concentrations were significantly different in dermis from the face compared to that of the abdomen (p < 0.05). CONCLUSION: This study shows for the first time that there is a direct relationship between iron and AA concentrations in the dermis and aging. Moreover, iron and AA concentrations differed according to body site.

In vivo assessment of iron and ascorbic acid in psoriatic dermis.

Reactive oxygen species play an important role in inflammatory skin diseases such as psoriasis. Reactive oxygen species synthesis is catalysed by iron and some species are scavenged by ascorbic acid. The aim of this work was to assess iron and ascorbic acid in uninvolved and involved psoriatic dermis and to compare the corresponding concentrations in the dermis of healthy subjects. Microdialysis associated with atomic absorption spectrometry and gas chromatography-mass spectrometry was used to assess iron and ascorbic acid, respectively. Seven psoriatic patients and five healthy volunteers were studied. Iron concentrations in the involved (57.1 +/- 19.3 microg/l) and uninvolved (49.7 +/- 27.1 microgl/l) psoriatic dermis were higher than the corresponding value determined in the dermis of healthy subjects (21.8 +/- 2.4 microg/l) (p<0.05). Ascorbic acid in involved (47.3 +/- 8.2 microg/ml) and uninvolved (42.0 +/- 14.0 microg/ml) psoriatic dermis was statistically lower than that found in healthy dermis (176.8 +/- 29.0 microg/ml) (p<0.05). These results demonstrate that psoriatic patients exhibit high iron and low ascorbic acid concentrations in the dermis, but there were no significant differences between involved and uninvolved skin.