Screening of new insecticidal and acaricidal antibiotics was carried out with reference to anti-brine shrimp activity from actinomycete strains isolated from marine environments. Of 200 actinomycete isolates, one isolate was found to produce a newsubstance, altemicidin. The strain was isolated from sea mudcollected at Gamo, Miyagi Prefecture, Japan, and identified as Streptomyces sioyaensis SA-1758. Altemicidin was purified by Diaion CHP-20P and Sephadex LH-20 column chromatographies. The molecular formula was determined as C13H20N4O7Sby elemental analysis, MSand 13C NMR spectrum. Altemicidin showed not only acaricidal activity but also antitumor activity. The compound showed no antimicrobial activity except the inhibitory activity to Xanthomonas strains.

The structure of bisucaberin, a new siderophore, was determined to be 1,12-dihydroxyl,6,12,17-tetraazacyclodocosane-2,5,13,16-tetrone by spectroscopic analysis and X-ray crystallographic analysis. The molecule of bisucaberin consists of a cyclic dimer of 1-hydroxyl,6-diazaundecane-2,5-dione moiety and is closely related to nocardamine, the trimer of the same moiety.

Alteromonas haloplanktis strain SB-1123 isolated from deep-sea mudproduced a new siderophore, bisucaberin. Bisucaberin rendered tumor cells susceptible to cytolysis mediated by murine peritoneal macrophages which were elicited by Proteose peptone and not yet activated by lymphokine. Bisucaberin exerted its sensitizing activity by both the preincubation with tumor cells and the addition to co-culture of macrophagesand tumor cells. The activity of bisucaberin was specifically inhibited by ferric ion. Bisucaberin showed direct cytostasis for tumor cells but did not cause cytolysis in the absence of macrophages. Cytostasis by bisucaberin was attributable to the specific inhibition of DNAsynthesis in tumor cells.

The structure of altemicidin, a new acaricidal and antitumor agent, was determined to be (l^,25,3a^,7a5)-4-carbamoyl-2-hydroxy-6-methyl-l-(sulfamoylacetamido)-2,3,3a,6,7,7a-hexahydro-6-azaindene-l-carboxylic acid by a combination of spectroscopic and X-ray crystallographic analysis of its derivatives.Altemicidin is a monoterpene alkaloid.Altemicidin, isolated from a culture broth of an actinomycete strain identified as Streptomyces sioyaensis SA-1758, is a new compound having the acaricidal and antitumor activities. We have reported the fermentation, isolation, biological properties and physico-chemical properties of altemicidin in the preceding paper1}.In this report, we describe the structure determination of altemicidin. Results and DiscussionAltemicidin (1, Fig. 1) was obtained as white powder. Its molecular formula was established to be C13H2oN407Sas described in the preceding paper1}. The IR spectrum of 1 showed the presence of amide group (1650 and 1550cm"1) and sulfonyl group (1345 and 1165cm"1)1*. In the 13C NMRspectrum (in D2O)of 1,thirteen carbon signals were observed at

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