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New cytotoxic substances, designated BE-52440A and B, were isolated from the mycelium of Streptomyces sp. A52440. The active principles were extracted from the mycelium by methanol and purified by silica gel column chromatography. BE-52440A and B exhibited cytotoxic activity against murine and human tumor cell lines.

In the course of our bioconversion studies on the derivatives of an indolocarbazole, J-104303, Saccharothrix aerocolonigenes ATCC39243 was found to convert J-104303, which was added into the culture medium, to its glycosylated derivative, J-109384. In order to clone the gene having the ability to convert J-104303 to J-109384, a library of Saccharothrix aerocolonigenes ATCC39243 DNA fragments was constructed using Streptomyces lividans TK21 and pIJ702 as host strain and vector, respectively. By examining more than 5,000 transformants, one was found to convert J-104303 to J-109384. Sequence analysis of the inserted DNA fragment revealed an open reading frame with 1,245 base pairs, named ngt. The transformant containing this ngt gene was also found to introduce a D-glucose moiety into 6-N-methylarcyriaflavin C. Furthermore, when ngt was introduced into Streptomyces mobaraensis BA13793, a producer of J-104303, the resulting transformant produced J-109384 directly.

A new antifungal antibiotic, BE-31405, was isolated from the culture broth of a fungal strain, Penicillium minioluteum F31405. BE-31405 was isolated by adsorption on high porous polymer resin (Diaion HP-20), followed by solvent extraction, precipitation and crystallization. BE-31405 showed potent growth inhibitory activity against pathogenic fungal strains such as Candida albicans, Candida glabrata and Cryptococcus neoformans, but did not show cytotoxic activity against mammalian cells such as P388 mouse leukemia. The mechanism studies indicated that BE-31405 inhibited the protein synthesis of C. albicans but not of mammalian cells.

A new antitumor substance, designated BE-19412A, was isolated from the culture broth of Streptomyces sp. A19412. The active principle was extracted from the mycelium by methanol and purified by Silica gel and Sephadex LH-20 column chromatographies. BE-19412B was prepared by methylation of BE-19412A. BE-19412A and B exhibited cytotoxic activity against murine and human tumor cell lines. BE-19412A prolonged the survival of CDF1 mice bearing i.p. implanted Ehrlich carcinoma cells.

New antitumor substances, designated BE-32030A, B, C, D and E, were isolated from the culture broth of Nocardia sp. A32030. The active principles were extracted from the mycelium by methanol and purified by Sephadex LH-20 and reversed-phase column chromatographies and finally by reversed-phase HPLC. BE-32030A, B, C, D and E inhibited the growth of P388 murine leukemia, DLD-1 human colon cancer, PC-13 human lung cancer and MKN-45 human stomach cancer cell lines.

NB-506 [6-N-formylamino-12,13-dihydro-1,11-dihydroxy-13-(beta-D- glucopyranosyl)-5H-indolo[2,3-a]pyrrolo[3,4-c]carbazole-5,7(6H)-di one d is a new antitumor indolocarbazole compound. The growths of murine M5076 and Ehrlich solid tumors were inhibited 76 and 96%, respectively, by i.v. injection at doses of 300 mg/m2. Furthermore, NB-506 caused regression of nodules of human PC-13 lung cancer and MKN-45 stomach cancer cells at i.v. doses of 90 mg/m2. Human HCT 116 and LS 180 colon cancers also regressed with injections of NB-506. Repeated injections of NB-506 had a stronger antitumor effect than intermittent injections in mice with MKN-45. The cumulative toxicity of NB-506 was low in terms of lethality in mice, i.e., the LD50s on single and 10 repeated i.v. injections into CDF1 mice were 990 and 810 mg/m2/injection, respectively. In conclusion, NB-506 is considered to be an interesting possible candidate as an anticancer drug for treatment of solid tumors in humans.

New antitumor substance, designated BE-18591, was isolated from the culture broth of a streptomycete, strain BA18591. The active principle was extracted from mycelium by methanol and purified by silica gel chromatography. BE-18591 inhibited the growth of MKN-45 human stomach cancer cell line as well as P388 cell line. In in vivo experiments, BE-18591 inhibited the growth of Ehrlich ascites tumor.BE-18591 showed antimicrobial activity against Gram-positive and some Gram-negative bacteria.

A new indolocarbazole compound, ED-110, which was obtained by glucosylating a microbial product (BE-13793C) and is a potent topoisomerase I inhibitor, showed characteristic inhibitory effects on the growth of 12 human tumor cell lines tested. The IC50 values of ED-110 against 9 of the 12 lines ranged from 11.5 micrograms/ml to 0.07 microgram/ml, while the remaining 3 lines were quite resistant (IC50, > 100 micrograms/ml). In in vivo experiments, i.p. treatment with ED-110 increased the survival period by more than two-fold in mice implanted i.p. with P388, L1210, L5178Y or EL4 murine leukemic cells. The minimum effective dose increasing the life-span of mice bearing P388 leukemia by 25% was < 2.5 mg/kg/day x 10 and the maximum tolerated dose was > 160 mg/kg/day x 10. ED-110 was also effective against the spontaneous metastasis of mouse Meth A fibrosarcoma cells and the growth of xenografted MKN-45 human stomach cancer cells as well as s.c. implanted mouse colon 26 and IMC carcinoma cells. These results indicated that ED-110 may have potential as a new antineoplastic agent with a large chemotherapeutic index and a wide range of effective doses.

ED-110 is a new semisynthetic antitumor agent derived from a novel indolocarbazole antibiotic, BE-13793C, produced by an actinomycete. ED-110 induced topoisomerase I-mediated DNA cleavage in vitro as strongly as camptothecin, whereas topoisomerase II-mediated DNA cleavage was not induced by this agent. Exposure of P388 cells to ED-110 caused a typical topoisomerase toxicity, i.e.: formation of cleavable complexes; inhibition of nucleotide synthesis rather than protein synthesis; and cell cycle arrest in G2. ED-110 inhibited the growth of P388 cells, with a 50% growth-inhibitory concentration of 44 nM. ED-110 is distinguished from camptothecin by its very different structure and its ability to intercalate into double-stranded DNA. These results suggest that ED-110 has potential as a novel antitumor agent targeting topoisomerase I.

The structures of novel endothelin-binding inhibitors, BE-18257A and BE-18257B, were elucidated by spectral analyses and chemical studies. Both inhibitors were found to have a cyclic pentapeptide structure containing three D-form amino acid residues, namely, the structures of BE-18257A and BE-18257B were elucidated to be cyclo(-D-Glu-L-Ala-D-Val-L-Leu-D-Trp-) and cyclo(-D-Glu-L-Ala-allo-D-Ile-L-Leu-D-Trp-), respectively.

Two endothelin (ET)-binding inhibitors, BE-18257A and BE-18257B, which antagonized 125I-ET-1 binding to a porcine aortic smooth muscle membrane, were isolated from the mycelium of a strain of Streptomyces misakiensis. These binding inhibitors were extracted with methanol from mycelium and purified by HPLC.

The structure of BE-12406A and BE-12406B, which were isolated from the culture broth of a streptomycete as antitumor substances, were determined by means of spectral analyses and chemical studies. The structure of BE-12406A is 1-hydroxy-10-methoxy-8-methyl-12-alpha- L-rhamnopyranosyloxy-6H-benzo[d]naphtho[1,2-b]pyran-6-one, and that of BE-12406B is 1,10-dihydroxy-8-methyl-12-alpha-L-rhamnopyranosyloxy-6H- benzo[d]naphtho[1,2-b]pyran-6-one.

New antitumor substances, designated BE-12406A and BE-12406B, were isolated from the culture broth of a streptomycete, strain BA 12406. The active principles were extracted from mycelium by methanol and successively purified by silica gel column chromatography and preparative TLC. BE-12406A and BE-12406B inhibited the growth of vincristine-resistant or doxorubicin-resistant P388 murine leukemia cell lines as well as their parent sensitive cell line. In in vivo experiments, BE-12406A inhibited the growth of S-180 murine ascites tumor.

A competitive endothelin (ET) antagonist, BE-18257B, was isolated from the fermentation products of Streptomyces misakiensis. It is a novel cyclic pentapeptide, cyclo(-D-Glu-L-Ala-allo-D-Ile-L-Leu-D-Trp-), and binds to ETA receptors (ET-1 selective) in cardiovascular tissues, but not to ETB receptors (equally sensitive to isopeptides of ET family) in kidney, adrenal gland and cerebellum tissues. BE-18257B also antagonizes ET-1-induced vasoconstriction in rabbit iliac artery and pressor action in rats. Thus it is a selective ETA antagonist and should provide a valuable tool for elucidation of the pharmacological and pathophysiological roles of ET-1.

A new antitumor substance, BE-13793C, which has topoisomerase inhibitory activity was isolated from the culture broth of a strain of actinomycetes. The producing strain, BA13793, isolated from a soil sample collected in Seto, Aichi Prefecture, Japan, has a resemblance to Streptoverticillium mobaraense. The active principle was extracted from the mycelium of strain BA13793 with methanol and purified by Sephadex LH-20 column chromatography. BE-13793C showed strong inhibitory activity against topoisomerases I and II and inhibited the growth of doxorubicin-resistant or vincristine-resistant P388 murine leukemia cell lines, as well as their parent P388 cell line.

Mannostatins have been isolated as part of a program designed to find microorganism-produced inhibitors of alpha-D-mannosidase from Streptoverticillium verticillus var. quintum. They were purified by sequential use of active carbon and Dowex resins and then isolated as colorless powders. Mannostatins A and B have the molecular formula, C6H13NO3S and C6H13NO4S, respectively. They were competitive with the substrate, and the inhibition constants (Ki) of mannostatins A and B were 4.8 x 10(-8) M.