1248 (Merck) with 3 solvent systems consisting of ethanol-acetic acid-water (65 : 1 : 34), 1-propanol-water (7 : 3), and 1-propanol- 34% ammonium hydroxide (7:3), or on precoated cellulose plates (Funakoshi) with a solvent system of 1-butanol-acetic acid-water (60:15:25), the purified arsenic compound gave a single spot in each system. The spot, which was positive to iodine vapor and the Dragendorff reagent but negative to nin- hydrin, appeared at an Rf value identical with that of arseno- betaine. The homogeneity of the purified compound was further evidenced by electrophoresis on cellulose acetate strips (Sartorius); with a buffer system of pyridine-acetic acid-water (1:10:89; pH 3.6), its mobility was the same as that of arseno- betaine. The purified arsenic compound exhibited no characteristic UV absorption band. Its IH-NMR spectrum (100 MHz, D20 ) gave 2 signals at 6 1.87 (singlet, 9 H) and 3.30 (singlet, 2 H). The field desorption mass spectrum showed a molecular ion peak at m/z 179 and a base peak at m/z 135 (M+-COz). These spectral data coincided well with those reported for arseno- betaine 3,7, ~2 Judging from these results, the purified arsenic compound from the shrimp S. lucens was identified as arsenobetaine (CH3)3A+CH2COO -. As mentioned above, about 90% of the total arsenic in the shrimp was found in the water-soluble fraction. In addition, 90% of the arsenic in the water-soluble fraction was adsorbed by Dowex 50 x 2 (H + form) and it was attributed to arsenobetaine because no arsenic compounds other than arsenobetaine were detected in any steps of the succeeding purification procedure. Therefore, arsenobetaine seemed to account for approximately 80 % of the total arsenic of the shrimp. Fukui et al. H previously suggested the presence of an arseno- betaine-containing oligopeptide in the shrimp. However, the suggestion should now be accepted with doubt because their final preparation was apparently contaminated with a large amount of impurities and its arsenic content was as low as 0.092%. Actually, just when we started this work, Norin et al. a2 also reported from the behavior of the compounds in TLC and electrophoresis that not an arsenobetaine-containing oligopeptide but arsenobetaine and arsenocholine were present in shrimps whose scientific names were not given. Our results prove the presence of arsenobetaine in the shrimp S. lucens and support those of Norin et al. We could not, however, detect arsenocholine in the shrimp. It seems reasonably safe to as- sume that, apart from arsenocholine, arsenobetaine is a com- mon arsenic compound in shrimps. All the marine animals in which the presence of arsenobetaine has been reported so far are carnivores. The present study, together with that of Norin et al. ~2, confirmed the presence of arsenobetaine in shrimps which are typical non-carnivores and plankton-feeders. This finding is very interesting from the point of view of the marine ecosystem. Although the arsenic in Experientia 40 (1984), Birkhfiuser Verlag, CH-4010 Basel/Switzerland marine animals in higher tropfiic levels is present chiefly in organic forms such as arsenobetaine, they cannot transform inorganic arsenic, which is the major form of arsenic in sea water, into organic arsenic in their own bodies 13. It is very likely, therefore, that the inorganic arsenic in sea water is first incorporated and metabolized to organic arsenic compounds such as arsenobetaine and its precursor by plankton. The shrimp and other plankton-feeders will accumulate arseno- betaine directly from the plankton or will incorporate a pre- cursor from them and convert it to arsenobetaine. Finally, carnivorous animals will get arsenobetaine from their food, including shrimps. Another pathway, from arsenosugars found in the brown kelp to arsenobetaine in marine animals, has also been suggested by Edmonds et alJ 4. For more detailed discus- sion on the arsenic cycle in the marine ecosystem it will be necessary to elucidate the chemical forms of arsenic in a wide variety of marine animals in connection with feeding habits. 1 We are grateful to Drs N. Fusetani and S. Matsunaga, the Univer- sity of Tokyo, for estimating the IH-NMR and field desorption mass spectra of the isolated arsenic compound. We also wish to thank Dr M. Chiba, Research Station, Agriculture Canada, Vine- land Station, Ontario, Canada, for revising this manuscript. This work was partly supported by a grant from the Ministry of Educa- tion, Science and Culture of Japan. 2 The National Research Council, Arsenic, National Academy of Sciences, Washington, D.C. 1977. 3 Edmonds, J.S., Francesconi, K.A., Cannon, J.R., Raston, C.L., Skelton, B.W., and White, A.H., Tetrahedron Lett. 1977, 1543. 4 Kurosawa, S., Yasuda, K., Taguchi, M., Yamazaki, S., Toda, S., Morita, M., Uehiro, T., and Fuwa, K., Agric. biol. Chem. 44 (1980) 1993. 5 Cannon, J.R., Edmonds, J.S., Francesconi, K.A., Raston, C.L., Saunders, J.B., Skelton, B.W., and White, A.H., Aust. J. Chem. 34 (1981) 787. 6 Edmonds, J.S., and Francesconi, K.A., Chemosphere 10 (1981) 1041. 7 Shiomi, K., Shinagawa, A., Yamanaka, H., and Kikuchi, T., Bull. Jap. Soc. scient. Fish. 49 (1983) 79. 8 Shiomi, K., Shinagawa, A., Azuma, M., Yamanaka, H., and Kiku- chi, T., Comp. Biochem. Physiol. 74C (1983) 393. 9 Edmonds, J.S., and Francesconi, K.A., J. chem. Soc. Perkin Trans. 1 (1983) 2375. 10 Edmonds, J.S., Francesconi, K.A., Healy, P.C., and White, A.H., J. chem. Soc. Perkin Trans. 1 (1982) 2989. 11 Fukui, S., Hirayama, T., Nohara, M., and Sakagarni, Y., J. Fd- Hyg. Soc. Japan 22 (1981) 513. 12 Norin, H., and Christakopoulos, A., Chemosphere 11 (1982) 287. 13 Maeda, S., and Takeshita, T., Kagaku no Ryoiki (J. Japan. Chem.) 36 (1982) 686. 14 Edmonds, J.S., Francesconi, K.A., and Hansen, J.A., Experientia 38 (1982) 643. 0014-4754/84/111247-0251.50 + 0.20/0 9 Birkh/iuser Verlag Basel, 1984 Alteichin: an unusual phytotoxin from Alternaria eichorniae, a fungal pathogen of water hyacinth I D. Robeson 2-, G. Strobel, G.K. Matusumoto, E.L. Fisher, M.H. Chen and J. Clardy Plant Pathology Department, Montana State University, Bozeman (Montana 59717, USA), and Department of Chemistry, Baker Laboratory, Cornell University, Ithaca (New York 14853, USA), 31 August 1983 Summary. The phytopathogenic fungus Alternaria eichorniae attacks water hyacinth, an economically significant aquatic weed. The novel phytotoxin alteichin was isolated from liquid cultures of this fungus and its structure was deduced by X-ray crystallo- graphic analysis. Altheichin is a doubly hydrated form of 4,9-dihydroxy perylene-3, 10-quinone. A single step dehydration of alteichin to anhydroalteichin is catalyzed both by acid and by a crude enzyme preparation from water hyacinth. Key words. Fungus, phytopathogenic; Alternaria eichorniae; phytotoxins; altheichin.