Depigmentation due to para tertiary butyl catechol

Chemical leukoderma: An insight of pathophysiology and contributing factors

Chemical leukoderma, or chemical-based vitiligo, is a dermal disease triggered by exposure to chemicals and characterized by the emergence of depigmentation or hypopigmentation of the skin. The etiology of this condition is associated with exposure to various chemical substances present in both occupational and non-occupational settings. The precise mechanism that underlies chemical leukoderma remains elusive and is believed to result from the demise of melanocytes, which are responsible for producing skin pigments. This condition has gained particular prominence in developing countries like India. An interesting connection between chemical leukoderma and vitiligo has been identified; studies suggest that exposure to many household chemicals, which are derivatives of phenols and catechol, may serve as a primary etiological factor for the condition. Similar to autoimmune diseases, its pathogenesis involves contributions from both genetic and environmental factors. Furthermore, over the last few decades, various studies have demonstrated that exposure to chemicals plays a crucial role in initiating and progressing chemical leukoderma, including cases stemming from occupational exposure.

Para-tertiary butyl catechol (PTBC), an industrial antioxidant induces human platelet apoptosis

The catecholic derivative para-tertiary butyl catechol (PTBC) is a conventional antioxidant and polymerization inhibitor, which exhibits melanocytotoxic effects and contact dermatitis often leading to occupational leucoderma or vitiligo. Although numerous industrial workers will be in constant exposure to PTBC and its chances of getting entry into blood are most expected, its effect on blood components is still undisclosed. As platelets play a prominent role in dermatitis, inflammation, and immunity, in this study we have evaluated the effect of PTBC on human platelets in vitro. Exposure of platelets to PTBC showed increased reactive oxygen species (ROS), intracellular calcium, cardiolipin oxidation, mitochondrial permeability transition pore (MPTP) formation, activation of caspases, phosphatidylserine (PS) externalization and decreased mitochondrial membrane potential. In addition, there was a significant decrease in cellular glutathione level, increased γ-glutamyltransferase (GGT) activity and cell death. These findings demonstrate that PTBC could induce toxic effects on blood components, which is often ignored field of research. Since dermal exposure of humans to toxic chemicals covers an important issue in various industries, there is a need of such work to understand and update the long-term toxicities induced by PTBC usage in industrial sectors and public domain.

Para-tertiary butyl catechol induces eryptosis in vitro via oxidative stress and hemoglobin leakage in human erythrocytes

Exposure of human population to industrial chemicals is believed as a significant contributing factor to the outgrowth of occupational diseases especially in developing countries due to improper safety measures and sanitary conditions. Para-tertiary butylcatechol (PTBC) widely employed in petrochemical, thermofax and phototypesetting industries, induces melanocytotoxicity and contact dermatitis leading to occupational leukoderma/vitiligo. Few vitiligo patients were reported for oxidative stress-induced hemolytic anemia and thrombocytopenia, however its impact on blood components is still not clear. Erythrocytes are the major cell population in circulation and play a prominent role in various diseases. In this work, the effect of PTBC on human erythrocytes is evaluated in vitro. PTBC induces oxidative stress-mediated eryptosis (erythrocyte death) causing detrimental changes such as depleted antioxidant levels, altered surface morphology, hemoglobin denaturation and heinz body formation. These findings validate that PTBC could induce toxic effects on human erythrocytes. Exposure of humans to toxic chemicals constitutes an important issue in various industries; one such issue is the exposure of PTBC at work place resulting in a spectrum of dermal complications. Therefore, it is imperative to appraise the long-term toxicities in order to further delineate the mechanisms of resultant disorders associated with PTBC and to establish the therapeutic interventions.

Active sensitization and occupational allergic contact dermatitis caused by para-tertiary-butylcatechol

Para-tertiary-butylcatechol (PTBC) is a rare allergen which is used in the rubber, paint and petroleum industries. We present 9 patients who were sensitized to PTBC and examined at the Finnish Institute of Occupational Health (FIOH) between 1974 and 1995. 3 of the patients had been exposed to PTBC in their work. 2 of them also had allergic reactions to para-tertiary-butylphenol (PTBP)-formaldehyde resin and to PTBP. 5 of the patients became sensitized to PTBC from patch testing. PTBC was found to be one of the most common causes of active sensitization in our clinic. Accordingly, at the FIOH, the patch test concentration of PTBC was lowered to 0.25% and this lower concentration is recommended for general use.

Stimulation of pheomelanogenesis in cultured B16 melanoma cells by 4-tertiary butylcatechol

Intermediates of pheomelanin in tissue cultured B16 melanoma cells were analyzed by high performance liquid chromatography, and reduced glutathione (GSH), L-dopa, 2-[(L)-S-cysteinyl]-L-dopa (2-SCD) and 5-[(L)-S-cysteinyl]-L-dopa (5-SCD) were quantified. The effects of 4-tertiary butylcatechol (TBC), an antioxidant which causes skin depigmentation, on the levels of the intermediate were then examined. A concentration of 10(-4) M TBC increased the intracellular levels of GSH, 2-SCD and 5-SCD, whereas the L-dopa level was unchanged. The time-course of the increased intermediates corresponded to the elevation of glutathione-metabolizing enzyme activities previously reported by Kawashima et al. [J. invest. Derm. 82, 53 (1984)] in the same cell line exposed to 10(-4) M TBC. The findings establish chemical evidence that TBC stimulates pheomelanogenesis in melanocytes.

Effects of 4-tertiary butyl catechol on glutathione-metabolizing enzymes in vivo and in vitro

4-Tertiary butyl catechol (TBC) causes depigmentation in humans and animals and stimulates formation of pheomelanosomes. In this study, we investigated the effects of noncytotoxic doses of TBC on glutathione S-transferase (GST) activity in the skin of Uscd strain mice and B16 murine melanoma cells in culture, in relation to changes in activities of glutathione reductase (GR) and gamma-glutamyl transpeptidase (GGT) reported to be involved in pheomelanogenesis. Occurrence of pheomelanosomes in skin melanocytes was demonstrated by electron microscopy and reduction (25%) of eumelanin content in melanoma cells was shown by spectrophotometry. Topical application of 1 M TBC-DMSO-acetone solution on the ear skin elevated GST activity about 27%, and activities of GGT and GR to 35% and 19%, respectively, within 1 week. Melanoma cells cultured in 10(-4) M TBC-containing medium for 2 h showed no changes in GST and GGT activities, but 12% increase of GR activity during the first 12 h. Activities of all 3 enzymes was elevated (11-17%) 24 h later. The elevation detected by 48 h was 25% for GST, 26% for GGT, and 14% for GR. The findings were interpreted to show that depigmentation produced by the antioxidant results from stimulated pheomelanogenesis through activation of glutathione-metabolizing enzymes and suppressed oxidation of eumelanin intermediates.

Glutathione reductase activity in skin exposed to 4-tertiary butyl catechol

The effect of 4-tertiary butyl catechol (TBC), a potent depigmenting chemical, on glutathione reductase (GR) in pigmented ear skin of hairless mice was investigated. Three topical applications of TBC, which cause neither skin color changes nor melanocyte degeneration, induced an increase in enzyme activity. Since the same treatment resulted in pheomelanin formation as evidenced by electron microscopy, it is suggested that the GR increase correlates at least in part with changes in melanocyte metabolism. This enzyme generates a reduced form of glutathione which may be involved in the formation of glutathionedopas, substrates for hydrolytic enzymes to produce cysteinyldopas, and pheomelanin. Elevation of GR may be an indication of melanogenesis before clinical skin color changes due to TBC appear. It may be used for the early detection of occupational leukoderma.