Giriraj B. Singh

Biochemical toxicology of argemone oil. IV short-term oral feeding response in rats

Consumption of edible oils contaminated with Argemone mexicana seed oil is known to cause various clinical manifestations. In the present study, the effect of dietary intake of argemone oil on histopathological changes, haematological indices and selected marker parameters of toxicity was investigated to observe the exact sites and mode of action of argemone oil in rats. Histopathological changes in the liver showed increased fibrosis, hyperplasia of bile ducts and congestion in a few portal tracts. Lungs of argemone oil-fed animals indicated congestion and thickening of interalveolar septa. Alveolar spaces were disorganised and irregular. Kidneys showed vascular and glomerular congestion and patchy tubular lesions. At 30 days only mild congestion was noted in the myocardium. Cardiac muscle fibres showed degenerative changes at 60 days which were more marked in the auricular wall. Haematological examination showed appearance of anaemia in experimental animals. Hepatic alkaline phosphatase, alanine transaminase and aspartate transaminase activities were inhibited by 30, 29 and 29% after 30 days of argemone intake along with concomitant enhancement in serum by 27, 29 and 66%, respectively. Liver showed decrease in glutathione (32-63%) content along with significant stimulation of lipid peroxidation (49-105%) in argemone-intoxicated animals. These results suggest that liver, lungs, heart and kidneys are the target tissues of argemone oil toxicity and that membrane destruction may be a possible mode of action.

Toxicity studies on metanil yellow in rats

Abstract 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.

Modulation by ascorbic acid of the cutaneous and hepatic biochemical effects induced by topically applied benzanthrone in mice

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.

In vitro studies on the biotransformation of metanil yellow

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.

Studies on the protein binding mechanism of p-aninodiphenylamine: A hair dye constituent

p-Aminodiphenylamine (p-ADPA) has got a binding capacity with tissue proteins. Aspartic and glutamic acids are presumably the responsible units in the protein chain involved in this binding with p-ADPA. p-ADPA is changed into a quinone structure after atmospheric oxidation in Krebs-Ringer-Bicarbonate buffer, pH 7.4 in the presence of trace metal ions. This oxidised form of p-ADPA binds with aspartic acid at pH 7.4 and temperature 40° in 2 hrs. The derivative thus formed absorbs at 450 nm instead of 430 nm.

Attenuation of Benzanthrone Toxicity by Ascorbic Acid in Guinea Pigs

Oral administration of benzanthrone (BA) (50 mg/kg body wt/day) to guinea pigs for 30 days resulted in depletion of ascorbic acid (ASA) in the liver, adrenals, and blood serum and in growth retardation (36%) and an increase (18%) in relative liver weight when compared to controls. BA treatment showed a tendency toward normocytic anemia with a decrease in hemoglobin content, reduction in RBC counts, and lowered packed cell volume. Guinea pigs treated with BA showed histopathological changes in liver including fibrosis, bile duct proliferation, and focus necrosis. Testes showed marked damage of seminiferous tubules with vacuolar degeneration and irregular and distorted interstitial spaces. BA showed evidence of patchy glomerular congestion, tubular lesions, and damaged epithelial cells in kidney, while urinary bladders had mild congestion in lamina propria and submucosa. Hepatic GOT, GPT, and LDH were found to be significantly decreased (17.5-33.5%), whereas activities of these enzymes showed a significant elevation in serum of BA-exposed guinea pigs. BA treatment also led to significant decrease of testicular hyaluronidase (29.8%) and LDH (19.8%) and significant depletion of lactic acid content (14.7%). Prior daily oral supplementation with ASA (50 mg/kg body wt) to BA-administered guinea pigs resulted in marked improvement of histopathological and biochemical changes observed in liver, testis, kidney, and urinary bladder of BA-exposed animals. These results suggest that extra supplementation of ASA could attenuate the toxic manifestations of BA.

Bio-elimination and organ retention profile of benzanthrone in scorbutic and non-scorbutic guinea pigs

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.

Transport of metanil yellow in the rat plasma and interaction of its metabolite, p‐aminodiphenylamine with serum proteins

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.

Effect of extraneous supplementation of ascorbic acid on the bio-disposition of benzanthrone in guinea pigs

The bio-elimination and organ retention of orally administered [14C]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 (gastro-intestinal 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.

COMPARATIVE STUDY OF THE BIODISPOSITION OF BENZANTHRONE IN DIFFERENT RODENT SPECIES

The bio-elimination and organ retention of [14C]benzanthrone, an anthraquinone dye intermediate, were determined in rats, mice and guinea pigs. Urinary excretion of benzanthrone during 96 hr was higher in guinea pigs (28%) compared with rats and mice (19%). However, faecal elimination during 96 hr was higher in rats (39%) and mice (42%) than in guinea pigs (25%). Urinary elimination of benzanthrone in rats and mice was highest between 12 and 24 hr, while guinea pigs showed a peak value between 24 and 48 hr. The maximum amount of radiolabelled benzanthrone was eliminated through faeces at 24-48 hr in all the three animal species. The retention of [14C]benzanthrone in the liver was comparable in rats (11.2%) and mice (11.9%), while in guinea pigs it was substantially higher (21.9%). The testes of rats and mice were devoid of radioactivity, whereas those of guinea pigs showed a marginal retention (1.25%) of 14C. The present study suggests that guinea pigs are more prone to benzanthrone toxicity than are rats and mice since the bio-elimination of this compound is slower and its organ retention is higher in this species.