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Modulation of biochemical markers by ascorbic acid was investigated in mice to which benzanthrone (BA) was applied topically (150 nmol/mouse) twice a week for 34 wk. After BA exposure without ascorbic acid, in the skin there were significant decreases in the activities of aryl hydrocarbon hydroxylase (AHH; 38% decrease relative to controls) and ethoxyresorufin-O-deethylase (EROD; 39%), and enhancement of the activities of quinone reductase (41% increase), tyrosinase (82%) and histidine decarboxylase (HDC; 190%). BA exposure also caused significant inhibition of hepatic AHH, EROD and glutathione-S-transferase activities, with concomitant increases in the activities of histidase (52%) and HDC (58%). Ascorbic acid given orally (5 mg/mouse) or topically (1 mg/mouse) twice weekly for 34 wk to BA-treated mice resulted in substantial protection against the effects of BA on these enzyme markers in both the skin and the liver. These results suggest that ascorbic acid could be useful in preventing the biochemical and toxicological manifestations caused by BA in laboratory animals.

Synopsis N-phenyl-p-phenylenediamine (N-PPDA), an industrial intermediate and hair dye ingredient, has been implicated in a variety of toxic symptoms including cutaneous manifestations. However, the role of physiological factors that may determine and modify its absorption and transport within and through the skin is not fully understood. The present study reveals that N-PPDA binds readily to skin showing saturation kinetics with Km and V(max) of 2.54 x 10(-4) M and 4.76 mumol g(-1) skin, respectively. The uptake was dependent upon the area of skin, concentration of the amine, exposure time, temperature and pH of the vehicle. Heat treatment facilitated the binding but temperatures abouv 50 degrees caused significant lowering of the uptake, indicating the possible involvement of collagen matrix. Skin lipids also contributed in the binding of N-PPDA. Bioinhibitors such as KCN, sodium arsenate, NaF, N-ethylmaleimide, cycloheximide, iodoacetic acid and 2,4-dinitrophenol had no effect on the uptake potential, suggesting it to be a non-energy dependent process. Most of the skin-bound N-PPDA was effluxed through serum proteins reaching the target organs via systemic circulation.

The retention and bio-elimination of benzanthrone (BA) in scorbutic and non-scorbutic guinea pigs was investigated to understand the protective role of ascorbic acid. Oral intubation of 14C-BA to scorbutic and non-scorbutic guinea pigs showed a total recovery of around 91% radioactivity through urine, faeces and tissues. Recovery of radiolabelled BA through urine (28%) and faeces (22%) up to 96 hrs averaged 50%, whereas residual radioactivity in liver and testis experienced a recovery of 29% in scorbutic animals. In non-scorbutic animals there was an increased recovery of radioactivity through urine (37%) and faeces (31%) with a decrease in retention (10%) in liver and testis. These results suggest that ascorbic acid facilitates the mobilization and bio-elimination of BA and thereby can decrease the toxicity of the compound.

The bio-elimination and organ retention of orally administered [ 14 C]benzanthrone, an anthraquinone dye intermediate, were determined in control and ascorbic acid-supplemented guinea pigs. Urinary excretion of benzanthrone in control and ascorbic acid-treated animals during 96 hr was 27.9 and 30.5%, respectively, with peak elimination at 48 hr. Faecal elimination in control and supplemented animals during 96 hr was 24.5 and 38.8%, respectively, with a peak at 48 hr. The organ retention of radiolabelled benzanthrone at the end of 96 hr was of the order of 39% in control animals (gastrointestinal tract 16%; liver 22%; testis 1.2%); ascorbic acid supplementation reduced benzanthrone retention to 19.5% (gastro-intestinal tract 12.7%; liver 6.8%). Overall, pretreatment of guinea pigs with ascorbic acid caused a 32% enhancement in the clearance of radiolabelled benzanthrone through the urine and faeces, while organ retention was reduced by about 50%. A prophylactic dose of ascorbic acid may prevent benzanthrone-induced toxic symptoms in exposed workers.

Benzanthrone, an anthraquinone dye intermediate, is commonly used for the synthesis of a number of polycyclic vat and disperse dyes. Our prior studies have shown that benzanthrone can be metabolized by rat hepatic microsomal cytochrome P450 (P450) (Biochem. Int., 18, 1989, 1237). In this study, the interaction of benzanthrone with rat hepatic microsomal P-450 and its effect on xenobiotic metabolism have been investigated. Parenteral administration of benzanthrone (40 mg/kg body weight) for 3, 7, or 21 days caused no change in the relative body weight or organ weight of rats. The levels of P450 were found to be reduced (33%-50%) in all the benzanthrone-exposed animals at all the time periods. In vitro addition of benzanthrone caused a spectral change with oxidized P450 and concentration-dependent reduction in the carbon monoxide spectrum of dithionite-reduced P450. The addition of benzanthrone to hepatic microsomes prepared from phenobarbital-treated rats resulted in spectral changes characterized by an absorbance maximum at 397 nm indicative of type I binding. In vitro addition of benzanthrone showed a concentration-dependent inhibition of hepatic aminopyrine N-demethylase (APD) and ethoxyresorufin-O-deethylase (ERD) activities with respective I50 values of 9.5 × 10−4 and 8.0 × 10−5 M. However, the inhibition of aryl hydrocarbon hydroxylase (AHH) even at the highest concentration of benzanthrone (10−2 M), was of the order of only 29%. In vivo administration of benzanthrone also led to the inhibition of APD, AHH, and ERD activities at all treatment times although the magnitude of inhibition was of a lower order. Benzanthrone treatments caused significant depletion of glutathione content with a concomitant enhancement of lipid peroxidation. Also, benzanthrone resulted in a significant inhibition of the cytosolic enzyme, GSH-transferase (23%–34%), although the other enzyme, quinone reductase, which helps in the removal of toxic quinones, was found to be elevated (184%–199%). These results suggest several mechanisms by which benzanthrone may inhibit P450. This impairment of xenobiotic metabolism as well as the enhancement of lipid peroxidation may be relevant to the observed symptoms of benzanthrone-induced hepatotoxicity.

Adult male albino rats were kept on diets containing 0.0, 0.1, 0.5, and 3.0% metanil yellow for 90 days. Various biochemical and histopathological studies were made. Compared to control animals (0.0%), there was no deviation in food intake and growth rate of metanil yellow-fed rats. No pathological change was observed in any of the body organs except the testis. Examination of the testis showed patchy degeneration of seminiferous tubules at a 3.0% dietary level of metanil yellow. Leydig cells showed normal appearance. No change was noted in the cholesterol content of the testis nor in the fructose content of the coagulating glands and dorsal prostate. Acid phosphatase activity in the ventral prostate and alkaline phosphatase in the seminal vesicle remained unaffected. However, decreases in the activities of testicular hyaluronidase, lactic dehydrogenase, and succinic dehydrogenase and in the content of lactic acid were observed.

The uptake of benzanthrone by rat skin showed saturation kinetics and was dependent upon the weight of skin and time, temperature and pH of the incubation medium. Heating of segments above 50°C caused significant lowering of the uptake. The uptake was irreversibly inhibited by HgCl2 and not by sodium arsenate, KCN, NaF, p-chloromercuriben zoate, N-ethyl-maleimide, cycloheximide, iodoacetic acid and 2,4-dinitrophenol suggesting that the uptake was not energy-dependent. Lipid micelles of the skin accounted for a part of the binding. Most of the benzanthrone taken up by the skin was effluxed through serum proteins.

Biochemical and histological alterations in lungs, liver, and kidney of albino rats at different time intervals after an intratracheal administration of monazite, the chief source of thorium and some rare earth elements of industrial significance, were investigated. The mild enzymatic and morphological changes observed in the lung suggest an inert behaviour of the monazite dust towards this tissue. However, biochemical alterations in liver and kidney indicate slight dissolution of some constituents of this naturally occurring mineral from the pulmonary tissue to other body organs.

The effect of benzanthrone on testis and other accessory sex glands in adult male rats was investigated. The weight of the accessory sex glands and testes was unaffected. Acid and alkaline phosphatase activities of seminal vesicles and ventral prostate, fructose content in coagulating gland, and cholesterol in testis remained unchanged. However, testicular hyaluronidase was significantly decreased. Histopathological studies showed patchy degeneration of seminiferous tubules. Leydig cells showed normal appearance. Dorsal and lateral prostates showed typical alveoli with normal secretory activity.

Binding affinity of metanil yellow and its breakdown product p‐aminodiphenylamine to serum proteins has been studied employing chromatographic separation on Sephadex G‐200 and by paper and polyacrylamide gel electrophoresis. Metanil yellow has more affinity towards albumin than to globulins. The complexing is presumably through electrostatic forces. p‐Aminodiphenylamine on the other hand, preferably binds to globulin fractions of serum protein. However, a stable binding with BSA alone was also observed. The binding was quite stable and was accompanied by a shift in absorbance from 430 nm to 500 nm. Aspartic acid moiety of protein was found to be one of the units involved in the binding of p‐ADPA to proteins.

Metanil yellow, monoazo C.I. acid yellow 36 (13065), the sodium or calcium salt of m [(p-anilinophenyl)azo]benzenesulfonic acid has been toxicologically classified under category CII by the Joint FAO/WHO Expert Committee on Food Additives. Biotransformation of the dye was studied employing liver slices. When incubated with liver slices under anaerobic conditions, the dye is split at the azo linkage resulting in the formation of metanilic acid and p-aminodiphenylamine.

Addition of microgram quantities (5–10 μg per 2 ml) of Mn2+, Fe2+, and Mo2+ increases the intensity of color developed by amino acids two- to three-fold when reacting with ninhydrin. The lowest limit detected by the increased sensitivity of the reaction is 3 nmol of an amino acid. Cd2+, Zn2+, and Al3+ depress the color formation due to reaction between amino acids and ninhydrin. When chromatograms of amino acids are first sprayed with aqueous manganese chloride and later with ninhydrin or with ninhydrin solution containing manganese, not only is the sensitivity increased, but the stained spots retain their color for longer periods.

Workers exposed to dye intermediate, benzanthrone, develop itching, burning sensation, erythema and hyperpigmentation of the skin; which also becomes tender, rough and peals off easily. Earlier experiments have shown that rat skin is capable of picking up benzanthrone. The present study was, therefore, aimed to explore the binding kinetic of skin matrix, of which collagen shares the major proportion. Results revealed that benzanthrone readily binds to reconstituted native collagen fibrils. The uptake is concentration dependent initially and does not in-volve-SH groups. Denaturation (gelatinisation) of collagen by heat or urea treat-ment leads to loss of its binding potential. Serum albumin exhibits a tendency to dissociate benzanthrone prebound to collagen and thus may ultimately assist in efflux of benzanthrone through circulation.