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At least 19 recordsLinked to original sources
PubMed2006

Carbazole is a naturally occurring inhibitor of angiogenesis and inflammation isolated from antipsoriatic coal tar.

Coal tar is one of the oldest and an effective treatment for psoriasis. Coal tar has been directly applied to the skin, or used in combination with UV light as part of the Goeckerman treatment. The use of coal tar has caused long-term remissions in psoriasis, but has fallen out of favor because the treatment requires hospitalization and coal tar is poorly acceptable aesthetically to patients. Thus, determining the active antipsoriatic component of coal tar is of considerable therapeutic interest. We fractionated coal tar into its components, and tested them using the SVR angiogenesis inhibitor assay. Treatment of SVR endothelial cells with coal tar fractions resulted in the isolation of a single fraction with antiangiogenic activity. The active antiangiogenic compound in coal tar is carbazole. In addition to antiangiogenic activity, carbazole inhibited the production of inflammatory IL-15 by human mononuclear cells. IL-15 is elevated in psoriasis and is thought to contribute to psoriatic inflammation. Carbazole treatment also reduced activity of inducible nitric oxide synthase (iNOS), which is proinflammatory and elevated in psoriasis. The effect of carbazole on upstream pathways in human psoriasis was determined, and carbazole was shown to inhibit signal transducer and activator of transcription (stat)3-mediated transcription, which has been shown to be relevant in human psoriasis. IL-15, iNOS, and stat3 activation require the activation of the small GTPase rac for optimal activity. Carbazole was found to inhibit rac activation as a mechanism for its inhibition of downstream inflammatory and angiogenic pathways. Given its antiangiogenic and anti-inflammatory activities, carbazole is likely a major component of the antipsoriatic activity of coal tar. Carbazole and derivatives may be useful in the therapy of human psoriasis.

Angiogenesis Inhibitors↗
PubMed2000

7H-benzo[c]fluorene: a major DNA adduct-forming component of coal tar.

Coal tar is a complex mixture that exhibits high carcinogenic potency in lungs of animals when administered in the diet. Studies have noted that lung tumor induction does not correlate with the benzo[a]pyrene content of coal tar, suggesting that other hydrocarbons may be involved in the observed tumorigenicity. Our previous studies have demonstrated that a major 'unknown' chemical-DNA adduct is formed in the lung of mice exposed to coal tar. We have used an in vitro rat microsomal activation system to generate the 'unknown' adduct with neat coal tar and fractions of coal tar obtained by chemical fractionation and HPLC. Chemical-DNA adduct formation was evaluated by (32)P-postlabeling using both multi-dimensional TLC and HPLC. GC-MS analysis of the coal tar fractions obtained from HPLC, which produced the 'unknown' adduct in vitro, demonstrated that the adducting hydrocarbon had a mass of 216. A careful evaluation of candidate hydrocarbons led to the conclusion that a benzofluorene derivative may be responsible for forming the 'unknown' chemical-DNA adduct. Comparative in vitro and in vivo studies on the adducting properties of all three isomers of benzofluorene indicated that 7H-benzo[c]fluorene is responsible for producing the 'unknown' adduct observed in the lung of mice ingesting coal tar. Animal feeding studies also demonstrated that 7H-benzo[c]fluorene formed considerably more lung DNA adducts than 11H-benzo[a]fluorene and 11H-benzo[b]fluorene. These data indicate that the four-ring polycyclic aromatic hydrocarbon 7H-benzo[c]fluorene, a hydrocarbon not previously shown to form DNA adducts in lung, is in fact a potent lung DNA adductor and is a candidate PAH for causing lung tumors in animals treated with coal tar.

Animals↗
PubMed1978

Human skin aryl hydrocarbon hydroxylase. Induction by coal tar.

Coal tar products, which are widely used in treating dermatologic disease, contain numerous polycyclic aromatic hydrocarbons, including 3,4-benzo[a]pyrene (BP). BP is among the most potent environmental chemical carcinogens and is known to evoke tumors in the skin of experimental animals and perhaps also of man. In this study the effect of cutaneous application of coal tar solution (U. S. Pharmacopeia) on aryl hydrocarbon hydroxylase (AHH) activity in the skin of patients usually treated with this drug was investigated. AHH, a cytochrome P-450 dependent carcinogen-metabolizing enzyme appears to play an important role in the activation of polycyclic hydrocarbons into reactive moieties that can bind to DNA and that may directly induce cancer. Application of coal tar solution to human skin caused a two to five-fold induction of cutaneous AHH in nine subjects. In further studies, the incubation of human skin with coal tar solution in vitro also caused variable induction of cutaneous AHH. Maximum responses in both systems occurred after 24 h and enzyme activity in vitro was time- and tissue- and substrate-concentration dependent. Studies in experimental animals showed that topical application of coal tar solution caused induction of AHH in skin and, after percutaneous absorption, in liver as well. Assay of several defined constituents of coal tar for AHH induction showed that BP was the most potent inducer of AHH tested. These studies indicate that topical application of coal tar solution in doses ordinarily used in treating dermatologic disease causes induction of AHH in human skin and suggest that such induced enzymatic activity could relate to carcinogenic responses to this agent in skin or, after percutaneous absorption, in other tissues as well.

Animals↗
PubMed2002

Highly increased urinary 1-hydroxypyrene excretion rate in patients with atopic dermatitis treated with topical coal tar.

Coal tar preparations, as used in dermatological practice, contain numerous polycyclic aromatic hydrocarbons of which many are proven animal carcinogens. Increased urinary 1-hydroxypyrene excretion in patients with atopic dermatitis treated with topical coal tar preparations has been demonstrated. Little is known about the relationship between the dermal uptake of polycyclic aromatic hydrocarbons on the one hand and the amount of tar applied to the skin, the total body area affected, the condition of the epidermal barrier and the severity of the dermatitis on the other. We compared urinary 1-hydroxypyrene excretion rate with these variables. The urinary 1-hydroxypyrene excretion rate was highly dependent on the total amount of tar applied to the skin and the total body area affected, and less on the severity of the atopic dermatitis or the condition of the epidermal barrier. Exposure to therapeutic doses of coal tar leads to much higher rates of urinary 1-hydroxypyrene excretion than occupational exposure. Because of the potential carcinogenicity of coal tar, as clearly demonstrated both in animal studies and from occupational exposure, careful consideration should be given to the use of coal tar preparations in dermatological practice. However, the risk of short-term high exposure is unknown. Restriction of the use of coal tar should be based on epidemiological studies and/or appropriate risk models taking into account its relative safety established over many years of clinical use.

Absorption↗
PubMed1985

[Effect of coal tar on cignolin erythema--1 hour treatment of psoriasis with high-dose cignolin with and without tar].

Coal tar applied simultaneously showed a suppressive effect on anthralin erythema. This effect was demonstrated by an epicutaneous test 24 hours (27 patients) and 1 hour (46 patients) after application of various concentrations of anthralin combined with tar 3%. In a clinical study on 9 patients, anthralin 3% alone or combined with tar 10% were administered in a right and left comparison on symmetrical chronic psoriatic lesions for 1 hour daily. Anthralin plus tar exhibited a stronger anti-psoriatic effect than anthralin alone did. Tar reduced the anthralin erythema in the perilesional skin. These findings favor the combination of coal tar and anthralin in the 1-hour treatment schedule of psoriasis.

Adult↗
PubMed1982

New coal tar extract and coal tar shampoos. Evaluation by epidermal cell DNA synthesis suppression assay.

Coal tar therapy has been used for many years in the treatment of scaling skin diseases, including psoriasis and eczema. Previous studies of the potential effectiveness of tar have utilized phototoxic erythema assays with long-wave ultraviolet light (UV-A). However, in clinical use, coal tar is rarely used with UV-A, particularly for scalp disease. Therefore, we investigated a nonphototoxic approach to evaluate different coal tar products. Coal tar was found to suppress epidermal cell DNA synthesis in the hairless mouse model, and this is the basis for the assay presented. Using the epidermal cell DNA synthesis suppression assay, we observed that crude coal tar and a new extract of crude coal tar were equally effective and that a concentration gradient effect was achieved. In addition, four commercial coal tar shampoos assayed varied greatly in their ability to suppress epidermal cell DNA synthesis. One shampoo was washed after ten minutes and no significant alteration of suppressive effect was seen.

Animals↗
PubMed1985

1-hydroxypyrene in human urine after exposure to coal tar and a coal tar derived product.

A method for isolating 1-hydroxypyrene from urine is described. The presence of 1-hydroxypyrene in urine was identified by fluorescence excitation and emission scanning after HPLC-separation. 1-Hydroxypyrene could be detected in the urine of rats following oral administration of as little as 0.5 microgram pyrene. The dose-dependence of 1-hydroxypyrene in urine was evident after a wide range of pyrene dosing. After therapeutical coal tar treatment of dermatological patients the enhanced excretion of 1-hydroxypyrene was highly significant. Employees of a creosote impregnating plant showed an excretion pattern of 1-hydroxypyrene which could be related to their work. 1-Hydroxypyrene in urine of non-exposed people was very low, but detectable. It is suggested that the method reported is suitable for the assessment of uptake of man to pyrene, a compound that is commonly present in work environments which are associated with pollution of polycyclic aromatic hydrocarbons.

Adult↗
PubMed2001

Comparative analysis of PAH:DNA adducts formed in lung of mice exposed to neat coal tar and soils contaminated with coal tar.

7H-Benzo[c]fluorene (benzo[c]fluorene) is a major DNA adduct forming component of coal tar in lung of mice. The present study evaluated the types of PAH:DNA adducts formed from different neat coal tar samples and soils contaminated with coal tar. Mice were fed diets containing coal tar either neat or as a contaminant in an environmental soil sample for 14 days, and the types of chemical:DNA adducts formed in lung were evaluated using 32P-postlabeling and HPLC analysis. Three major DNA adducts derived respectively from benzo[b]fluoranthene (B[b]F), benzo[a]pyrene (B[a]P), and benzo[c]fluorene were detected in three of the four neat coal tar samples evaluated. In contrast, only a single major DNA adduct derived from benzo[c]fluorene was observed with the remaining tar sample. Ingestion of coal tar contaminated soil resulted in DNA adducts primarily derived from benzo[c]fluorene and B[b]F; a B[a]P derived DNA adduct was not detected. The DNA adducts derived from benzo[c]fluorene and B[b]F but not B[a]P were also observed with animals fed methylene chloride extracts of three of these soils but not the one designated A1000H soil. However, the extract of A1000H resulted in a B[a]P:DNA adduct being detected along with adducts formed from B[b]F and benzo[c]fluorene. The selective formation of the benzo[c]fluorene:DNA adduct with coal tar contaminated soils indicates that the in vivo systemic bioavailability and/or metabolism of benzo[c]fluorene is relatively high when compared to other DNA adducting hydrocarbons within coal tar. Benzo[c]fluorene may play a critical role in the potential of contaminated soil to induce a toxicological response in animals.

Administration, Oral↗
PubMed2004

Double-blind, randomised, multicentre, parallel group study comparing a 1% coal tar preparation (Exorex) with a 5% coal tar preparation (Alphosyl) in chronic plaque psoriasis.

BACKGROUND: Exorex lotion is a novel formulation of prepared coal tar indicated for the treatment of psoriasis. OBJECTIVES: To compare the efficacy and tolerability of 1% prepared coal tar lotion versus 5% coal tar extract in patients with mild to moderate plaque psoriasis. PATIENTS AND METHODS: This was a double-blind, randomised controlled study. Patients initially entered a 7-day washout period, during which they applied a yellow soft paraffin plus emulsifying wax ointment used as an emollient three times a day to their plaques. They were then randomised to receive treatment with 1% coal tar (Exorex) lotion or 5% conventional coal tar lotion (Alphosyl), three times a day for 12 weeks. Both treatment groups continued to apply the emollient throughout the duration of the study. Two target plaques were selected at entry for assessment. The clinical measures used were: 1) Total Sign Score (TSS), the sum of 5-point rating scores for erythema, induration and scaling averaged for the two target plaques (range 0-12), 2) the Psoriasis Area and Severity Index (PASI), and 3) patient and investigator 7-point global assessments of improvement at 12 weeks. Patients were assessed at 0, 4, 8 and 12 weeks during the treatment period or at the point of withdrawal. Spontaneously reported and observed adverse events were noted. RESULTS: Three hundred and twenty four of 338 randomised patients were evaluable (ITT analysis): 158 patients received 1% coal tar lotion and 166 patients received conventional coal tar. Both groups showed decreases from baseline to end of treatment in mean TSS (decrease of 2.4 points from 5.6 to 3.2 with 1% coal tar lotion and 1.8 points from 5.5 to 3.7 with conventional coal tar), and mean PASI (decrease of 2.4 points with 1% coal tar lotion and 1.5 points with conventional coal tar). Two hundred and twenty eight patients completed the full course of treatment. There was a statistically significant treatment difference in the percentage change in mean TSS at week 12, in favour of 1% coal tar lotion (-10.6%, 95% CI -20.6% to -0.5%, p=0.04). There was also a difference between treatments in the change in mean PASI in favour of 1% coal tar that was of borderline statistical significance (-11.7%, 95% CI -23.8% to 0.4%, p=0.06). Investigator global assessments also favoured 1% coal tar lotion (38% vs. 27% of patients showed clearance or marked improvement). The 1% coal tar lotion had a similar safety profile to 5% conventional coal tar lotion with the majority of treatment-related events being mild to moderate in severity. CONCLUSIONS: 1% coal tar lotion is more effective than a conventional coal tar lotion in mild to moderate psoriasis and may be preferred for first-line topical treatment.

Adolescent↗
PubMed1983

Coal tar phototherapy for psoriasis reevaluated: erythemogenic versus suberythemogenic ultraviolet with a tar extract in oil and crude coal tar.

Recent studies have questioned the therapeutic value of coal tar versus ultraviolet (UV) radiation and their relative necessity in phototherapy for psoriasis. In this investigation, different aspects of tar phototherapy have been studied in single-blind bilateral paired comparison studies. The effects of 1% crude coal tar were compared with those of petrolatum in conjunction with erythemogenic and suberythemogenic doses of ultraviolet light (UVB) using a FS72 sunlamp tubed cabinet. Crude coal tar was clinically superior to petrolatum with suberythemogenic ultraviolet. With the erythemogenic UVB, petrolatum was equal in efficacy to crude coal tar. Suberythemogenic UVB was also used adjunctively to compare the effects of a 5% concentration of a tar extract in an oil base to 5% crude coal tar in petrolatum or the oil base without tar. The tar extract in oil plus suberythemogenic UVB produced significantly more rapid improvement than the oil base plus UVB. The direct bilateral comparison of equal concentrations of tar extract in oil base versus crude coal tar in petrolatum in a suberythemogenic UV photo regimen revealed no statistical differences between treatments. In a study comparing tar extract in oil and the oil base without ultraviolet radiation, the tar extract in oil side responded more rapidly. This demonstrates a direct effect of tar alone in therapy. We have also studied the effects of erythemogenic and suberythemogenic UVB with and without tar extract in oil in the hairless mouse epidermal deoxyribonucleic acid (DNA) synthesis suppression assay. It was found that erythemogenic dosages of UVB produced near maximal inhibition of DNA synthesis with or without coal tars. Suberythemogenic dosages of UVB produced submaximal suppression of DNA synthesis that was enhanced by adjunctive coal tar but not by vehicle, findings which are consistent with the above clinical results. These studies suggest that coal tars combined with suberythemogenic UVB therapy is a practical alternative (to more aggressive UVB therapy without coal tar) which reduces the UVB exposure to the patient.

Animals↗
PubMed1989

Low concentration dithranol and coal tar (Psorin) in psoriasis: a comparison with alcoholic coal tar extract and allantoin (Alphosyl).

Psoriasis is difficult to manage in general practice, mainly because the standard treatments produce side effects, or are ineffective in both the short and long term. In recent years, the main topical therapies have included extracts of coal tar or dithranol. In a six-week within-patient trial, 23 patients applied two different treatments to the left and right halves of their bodies. A new preparation (Psorin, Thames Laboratories), containing relatively low concentrations of dithranol and crude coal tar, was significantly more effective and more acceptable than a refined alcoholic extract of coal tar with allantoin (Alphosyl, Stafford Miller Ltd).

Adolescent↗
PubMed1978

Biochemical decomposition of coal-tar dyes. II. Acute toxicity of coal-tar dyes and their decomposed products.

Twenty kinds of coal-tar dyes were subjected to median tolerance limit (TLm) test by use of Himedaka (Oryzias latipes) for the comparision of their acute toxicities. It became clear that 4 kinds of halogens substituted xanthene compounds dyes showed strong acute toxicities. From the fact that uranine had the lower acute toxicity than halogens substituted compounds and the toxicities of these 4 dyes increased through irradiation, it was assumed that halogen atoms in dyes might be responsible for these strong acute toxicities to fish.

Anaerobiosis↗
PubMed1990

Wood tars allergy, cross-sensitization and coal tar.

In a population of 1883 patients tested for allergic contact dermatitis (1985-1988), a prevalence of 5.4% (103 cases) was seen for wood tars (ICDRG allergen, 12% pet.) sensitization. In this group (n = 103), retrospectively, a combined allergy was seen to wood tars and fragrance mix in 43% and to wood tars and balsam of Peru in 31%. A combined allergy to wood tars and coal tar was seen in 19 patients (18.5%): 14 to liquor carbonis detergens (LCD), 8 to lianthral and 3 to both LCD and lianthral. Within the group with wood tars allergy (n = 103), a minority (n = 37) had a history of atopic dermatitis. Comparison of the test results in atopic and non-atopic subgroups (within the group of 103) revealed a higher incidence of combined wood tars-fragrance mix allergy in the atopic group (n = 37). In this group, a lower incidence of combined wood tars-coal tar sensitization was seen in comparison with the non-atopic group (n = 66). The authors believe that combined "wood tars-coal tar" allergy could be the consequence of cross-sensitization rather than due to long-term previous topical treatment with tar derivatives. The high % of cross-allergy between wood tars and fragrance mix emphasizes the role of wood tars as an important indicator allergen in perfume allergy.

Coal Tar↗
PubMed1980

Studies on the toxicity of coal-tar dyes. III. Reason of acute toxicity to fish caused by coal-tar dyes and their industrial effluents.

Reason of acute toxicity to fish caused by coal-tar dyes and their industrial effluents were studied from the three points of view. 1) Partition coefficient (n-octanol/water) was determined on several coal-tar dyes, and it was found that the larger the ratio was, the stronger was toxicity to fish. 2) As a result of determination about existent form of xanthene dyes under photo-irradiation, it was clarified that dyes in solution were in the form of excited triplet state and halogen in dye molecule was liberated in free form. 3) When coal-tar dyes were treated with sodium hypochlorite, harmful chloroform was detected from dye solution. Chloroform and its homologous compounds showed the low TLm value and had the serious effect on fish.

Animals↗