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1640. Second thoughts on rubratoxin B
NATURAL PRODUCTS
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clusion that I interferes with the synthesis of nuclear ribonucleic acid, probably as a result of the binding of the toxin to DNA and the inhibition of DNA-dependent RNA-polymerase. 1640. Second thoughts on rubratoxin B Moss, M. O., Robinson, F. V. & Wood, A. B. (1968). Rubratoxin B, a toxic metabolite of Penicilliurn rubrum. Chemy Ind. p. 587. The structural formula previously assigned to rubratoxin B, one of the two toxic components ofPenicillium rubrum (Moss et al. Chemy lnd, 1967, 755) has now been revised. Chemists at the Tropical Products Institute have shown that a free carboxyl group is not present as was previously thought. Instead, the acidic character is attributed to the presence of a disubstituted maleic anhydride function with an ct,~-unsaturated 8-1actone taking the place of the carboxyl group. The ketone group formerly postulated in the aliphatic side chain of the molecule now gives way to a - C H O H grouping. Despite this reshuffle, the complete picture of the rubratoxin B molecule is still lacking but elucidation of the full structure should soon be accomplished. 1641. A toxic abortifaeient Lipton, A. (1967). Abortifacient and toxic actions of the glycoside 'albitocin' extracted from some Albizia species. J. Pharm. Pharrnac. 19, 792. Albitocin is a glycoside isolated from some species of the Albizia plant. East African witch-doctors have found it useful in accelerating labour and as an abortifacient. Its acute toxicity and abortifacient activity have now been studied. The acute oral LDso in guinea-pigs was found to be 19 mg/kg and the parenteral LDsos in mice, rats, guinea-pigs, rabbits and monkeys ranged from 1 to 6 mg/kg. These doses are quite close to those required to produce abortion, the EDso being in all cases more than half as great as the LDso. It seems likely, however, that the human uterus is more sensitive than that of lower animals to albltocin and that oral doses well below the toxic level are effective in accelerating labour. Animals given lethal doses survived 12-170 hr, exhibiting increasing apathy and anorexia and resulting loss of weight. Necrosis of the renal tubules was found in rabbits at autopsy, and previous workers have reported liver necrosis in rats and mice. (3uinea-pig foetuses that were aborted near term, even from females given lethal doses, survived and developed normally, indicating that the drug either has a low foetal toxicity or does not cross the placenta. 1642. Natural antifertility agents Newton, J. E. & Betts, J. E. (1968). Seasonal oestrogenic activity of various legumes. J. agric. Sci., Camb. 70, 77. Lightfoot, R. J., Croker, K. P. & Nell, H. (3. (1967). Failure of sperm transport in relation to ewe infertility following prolonged grazing on oestrogenic pastures. Aust. J. agric. Res. 18, 755. Matsui, Adelina S., Rogers, Joan, Woo, Y.-K, & Cutting, W. C. (1967). Effects of some natural products on fertility in mice. Medna Pharmac. exp. 16, 414. Doubts have been raised over the possibility that plant oestrogens may be responsible for reduced fertility in grazing cattle (Cited in F.C.T. 1968, 6, 108). Using the teat-length bioassay in wether lambs, Newton & Betts (cited above) demonstrated oestrogenic activity in grazing areas of red and white clover, lucerne and sainfoin. Whereas red clover was active throughout its growing period, white clover and lucerne were v.c.'r.
615--1
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clusion that I interferes with the synthesis of nuclear ribonucleic acid, probably as a result of the binding of the toxin to DNA and the inhibition of DNA-dependent RNA-polymerase. 1640. Second thoughts on rubratoxin B Moss, M. O., Robinson, F. V. & Wood, A. B. (1968). Rubratoxin B, a toxic metabolite of Penicilliurn rubrum. Chemy Ind. p. 587. The structural formula previously assigned to rubratoxin B, one of the two toxic components ofPenicillium rubrum (Moss et al. Chemy lnd, 1967, 755) has now been revised. Chemists at the Tropical Products Institute have shown that a free carboxyl group is not present as was previously thought. Instead, the acidic character is attributed to the presence of a disubstituted maleic anhydride function with an ct,~-unsaturated 8-1actone taking the place of the carboxyl group. The ketone group formerly postulated in the aliphatic side chain of the molecule now gives way to a - C H O H grouping. Despite this reshuffle, the complete picture of the rubratoxin B molecule is still lacking but elucidation of the full structure should soon be accomplished. 1641. A toxic abortifaeient Lipton, A. (1967). Abortifacient and toxic actions of the glycoside 'albitocin' extracted from some Albizia species. J. Pharm. Pharrnac. 19, 792. Albitocin is a glycoside isolated from some species of the Albizia plant. East African witch-doctors have found it useful in accelerating labour and as an abortifacient. Its acute toxicity and abortifacient activity have now been studied. The acute oral LDso in guinea-pigs was found to be 19 mg/kg and the parenteral LDsos in mice, rats, guinea-pigs, rabbits and monkeys ranged from 1 to 6 mg/kg. These doses are quite close to those required to produce abortion, the EDso being in all cases more than half as great as the LDso. It seems likely, however, that the human uterus is more sensitive than that of lower animals to albltocin and that oral doses well below the toxic level are effective in accelerating labour. Animals given lethal doses survived 12-170 hr, exhibiting increasing apathy and anorexia and resulting loss of weight. Necrosis of the renal tubules was found in rabbits at autopsy, and previous workers have reported liver necrosis in rats and mice. (3uinea-pig foetuses that were aborted near term, even from females given lethal doses, survived and developed normally, indicating that the drug either has a low foetal toxicity or does not cross the placenta. 1642. Natural antifertility agents Newton, J. E. & Betts, J. E. (1968). Seasonal oestrogenic activity of various legumes. J. agric. Sci., Camb. 70, 77. Lightfoot, R. J., Croker, K. P. & Nell, H. (3. (1967). Failure of sperm transport in relation to ewe infertility following prolonged grazing on oestrogenic pastures. Aust. J. agric. Res. 18, 755. Matsui, Adelina S., Rogers, Joan, Woo, Y.-K, & Cutting, W. C. (1967). Effects of some natural products on fertility in mice. Medna Pharmac. exp. 16, 414. Doubts have been raised over the possibility that plant oestrogens may be responsible for reduced fertility in grazing cattle (Cited in F.C.T. 1968, 6, 108). Using the teat-length bioassay in wether lambs, Newton & Betts (cited above) demonstrated oestrogenic activity in grazing areas of red and white clover, lucerne and sainfoin. Whereas red clover was active throughout its growing period, white clover and lucerne were v.c.'r.
615--1