MOLECULAR TOXICOLOGY Ravindra P. Singh Æ Raj Khanna Æ Jawahar L. Kaw Subhash K. Khanna Æ Mukul Das Comparative effect of benzanthrone and 3-bromobenzanthrone on hepatic xenobiotic metabolism and anti-oxidative defense system in guinea pigs Received: 10 December 2001 / Accepted: 2 July 2002 / Published online: 17 December 2002 Ó Springer-Verlag 2002 Abstract Benzanthrone (BA) and 3-bromobenzan- throne (3-BBA) are important dye intermediates used in the manufacture of various vat and disperse dyes. BA has been implicated as a cause of hepatic malfunctions and dermal lesions in workers. However, not much in- formation on halogenated BAs, especially 3-BBA, is available. Experiments were designed to undertake a comparative safety assessment of both BA and 3-BBA, given orally at a dose of 50 mg/kg body weight for 10 days to guinea pigs. There was a significant decrease (25%) in body weight with 3-BBA, whereas BA treat- ment did not cause any change. Serum glutamate oxa- loacetate transaminase and glutamate pyruvate transminase were found to be significantly (P<0.05) increased in 3-BBA- as well as in BA-treated animals. 3-BBA and BA led to substantial depletion of ascorbic acid in both liver and adrenal glands. However, deple- tion of ascorbic acid was more pronounced with 3-BBA (19.2–28.3%) than with BA (13.5–16.6%). 3-BBA and BA treatments caused 80% and 24% depletion of he- patic free sulfydryl content, while lipid peroxidation showed a significant enhancement of 73% and 47%, respectively. BA and 3-BBA caused decreases in cyto- chrome P-450 content and phase I enzymes particularly ethoxyresorufin-O-deethylase and aryl hydrocarbon hy- droxylase, whereas phase II enzymes (quinone reductase and glutathione-S-transferase) were substantially in- creased. Activities of bio-antioxidant enzymes, viz., glutathione peroxidase, glutathione reductase, superox- ide dismutase and catalase, were significantly increased by 153, 104, 20 and 67% in the 3-BBA-treated group, whereas the degree of increase in these parameters was relatively less in BA-treated group. The data indicate that both BA and 3-BBA can disturb membrane integ- rity by decreasing endogenous glutathione and ascorbic acid levels with a concomitant increase in lipid peroxi- dative damage. This may in turn lead to impairment of hepatic P-450-dependent monooxygenase, while the changes in antioxidant enzymes reveal oxidative stress. 3-BBA treatment caused dilation of portal triad with thickening of arterial wall, hyperplasia of Kupffer cells and influx of inflammatory cells between hepatic cords, which could be due to formation of Br • radical or due to formation of semiquinone type of intermediate follow- ing oxidation. The results may be interpreted to mean that industrial workers exposed to 3-BBA are at higher risk than those exposed to BA, and necessary precau- tions should be taken to safeguard their exposure risks. Keywords Ascorbic acid Æ Glutathione Æ Lipid peroxidation Æ 3-Bromobenzanthrone Æ Benzanthrone Æ Bio-antioxidant enzymes Introduction 3-Bromobenzanthrone (3-BBA) is derived from ben- zanthrone (BA) (Fig. 1) and both are used in the syn- thesis of various polycyclic vat and disperse dyes (Venkatraman 1952; Lubs 1955; Society of Dyers and Colourists 1971). Epidemiological studies indicate that skin, respiratory, gastrointestinal, genitourinary, ner- vous and hemopoietic systems are affected during BA exposure (NIOSH 1979; Singh et al. 1990). Experimental studies have confirmed histopathological lesions in skin, liver, testis, kidney and urinary bladder, and distur- bances in hemopoietic system in animal species (Singh et al. 1967; Chandra and Singh 1968; Das et al. 1994). BA is bio-transformed to a variety of fluorescent metabolites by hepatic cytochrome P-450 heme protein and some of these metabolites are excreted in the urine of rats (Das et al. 1989a). One of the major mechanisms Arch Toxicol (2003) 77: 94–99 DOI 10.1007/s00204-002-0396-9 R.P. Singh Æ R. Khanna Department of Biochemistry, Lucknow University, Lucknow, India J.L. Kaw Æ S.K. Khanna Æ M. Das (&) Industrial Toxicology Research Centre, PB No. 80, M.G. Marg, Lucknow, India E-mail: mditre@hotmail.com E-mail: mdas@itrc.res.in