Hydantocidin1, a new compoundwith potent non-selective herbicidal activity, was found in a submerged culture of Streptomyces hygroscopicus SANK63584. It was isolated from the culture filtrate by the following successive treatments comprised of activated carbon, Diaion HP-20, Dowex 50WX4,and Avicel column chromatographies. Finally it was crystallized as colorless needles from acetone.The molecular formula, C7H10N2O6, was determined by analyses of HRFABmass spectrum in conjunction with 13C NMRspectrometry. The structural elucidation revealed that it has a unique structure with a spiro-bond between ribose and hydantoin moieties in the molecule. The characteristic herbicidal activities against annuals as well as perennials, including monocotyledonous and dicotyledonous weeds, were observed. 293 In the course of screening for new herbicidal substances from culture broths of microorganisms, we found a new compound, hydantocidin, produced by a streptomycete identified as Streptomyces hygroscopicus SANK63584, which was isolated from a soil sample collected in Annaka, GunmaPrefecture, Japan.In this paper, we report the taxonomy, fermentation of the producing strain, isolation, physico-chemical and biological properties of hydantocidin. The detailed herbicidal activity and the structural elucidation of the compoundwill be reported elsewhere (under preparation).

Cornexistint, a new compound demonstrating promising herbicidal activity, was purified from the culture nitrate of a newly-isolated fungus identified as Paecilomyces variotii SANK 21086. The compoundwas extracted with organic solvents from the culture nitrate, purified using column chromatography on Sephadex LH-20 and finally crystallized from methylene chloride. Following analysis of its physico-chemical properties it was identified to be a new compound belonging to the nonadride group. Chemical structure elucidation was conducted by analyses of various spectral data and the structure was finally confirmed by means of X-ray crystallographic analysis. Based on its herbicidal characteristics cornexistin may be classified as a postemergence herbicide active against certain young annual and perennial monocotyledonous and dicotyledonous plants with selective protection for corn.

Streptomyces griseus SANK 60196 produces the novel nucleoside antibiotics A-500359 A, C, D and capuramycin. Enhanced production of capuramycin and A-500359 A was achieved through a number of medium modifications and a series of single colony isolations. The addition of maltose instead of glucose as the carbon source in a primary medium resulted in a 20-fold increase in the productivity of capuramycin. Furthermore, the addition of cobalt chloride (CoCl2) and yeast extract to the medium containing maltose drastically altered the production ratio of A-500359 A to capuramycin. Thus, the yield of A-500359 A increased up to 600 microg/ml in an optimal medium, while the yield in the primary medium was 1 microg/ml.

A novel endothelin-converting enzyme (ECE) inhibitor, B-90063, was isolated from the culture supernatant of the newly discovered marine bacterium Blastobacter sp. SANK 71894. Based on spectral analyses and chemical reactions, the structure of B-90063 was determined to be bis[6-formyl-4-hydroxy-2-(2'-n-pentyloxazol-4'-yl)-4-pyridon-3-yl]-disulfide (1a). Human and rat ECEs were inhibited more potently by B-90063, with NEP and type-I and -IV collagenases.B-90063 also inhibited the binding of ET-1 to rat ETA and bovine ETB receptors, though its antagonistic activities were weak. B-90063, thus, may abolish the physiological actions of endothelins through the ECE inhibitory and receptor antagonistic mechanisms.

In the process of screening for squalene synthase inhibitors from microbial fermentation products we have isolated a novel compound, named schizostatin (Fig. 1), from the culture broth of the mushroom, Schizophyllum communeSANK17785. Schizostatin inhibited rat liver microsomal squalene synthase dose dependently and the IC50 value was 0.84/^m. The inhibition was competitive with respect to farnesylpyrophosphate with a Ki value of 0.45 jllm.