A potent tyrosine kinase inhibitor, lavendustin A [1], has been isolated from a butyl acetate extract of Streptomyces griseolavendus culture filtrate. It inhibits epidermal growth factor receptor-associated tyrosine kinase with an IC50 of 4.4 ng/ml, which is about 50 times more inhibitory than erbstatin. It does not inhibit protein kinase A or C. Its structure, determined by spectral data and total synthesis, is novel, having a tertiary amine in the center with substituted benzyl and phenyl groups. Lavendustin A competes with ATP and is noncompetitive with the peptide. Its structure-activity relationship is discussed.

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We have found a novel phospholipid antibiotic (named bacilysocin) which accumulates within (or associates with) the cells of Bacillus subtilis 168 and determined the structure by nuclear magnetic resonance and mass spectrometry analyses. The structure of bacilysocin elucidated was 1-(12-methyltetradecanoyl)-3-phosphoglyceroglycerol. Bacilysocin demonstrated antimicrobial activity, especially against certain fungi. Production of bacilysocin commenced immediately after growth ceased and before the formation of heat-resistant spores. The production of bacilysocin was completely blocked when the ytpA gene, which encodes a protein homologous to lysophospholipase, was disrupted, but blockage of the ytpA gene did not significantly affect growth. Sporulation was also impaired, with a 10-fold reduction in heat-resistant spore titers being detected. Since the ytpA disruptant actually lacked phospholipase activity, we propose that the YtpA protein functions as an enzyme for the biosynthesis of bacilysocin.The gram-positive bacterium Bacillus subtilis produces a large number of antibiotics, which are classified as ribosomal or nonribosomal. Nonribosomally synthesized circular oligopeptides that contain a fatty acid chain exhibit potent antibacterial or antifungal activity, as represented by surfactin, the iturinic group, and fengycin (16). B. subtilis 168 is the beststudied strain in the genus Bacillus, the genome of which was completely sequenced in 1997. Strain 168 is known to produce three ribosomal antibiotics, TasA (12), subtilosin (1), sublancin (10), and two nonribosomal antibiotics, surfactin (14) and bacilysin (9). The production of other antibiotics by strain 168 has also been predicted on the basis of genome sequence analysis, as exemplified by plipastatin (13). The ribosomal peptide antibiotics are synthesized during active growth, while nonribosomal ones are synthesized after growth has ceased. The role of antibiotic production for the producing organism is still under speculation. The best-accepted theory is that nonribosomal antibiotics may play a role in competition with other microorganisms during spore germination (for a review, see references 5 and 16). The detection of novel antibiotics produced by B. subtilis 168 would therefore be helpful in providing an understanding of the intrinsic (if any) role of antibiotics in the life cycle of this organism. In the present paper, we describe the isolation and identification of a new antibiotic (named bacilysocin) produced by B. subtilis 168. MATERIALS AND METHODSStrain, media, and culture conditions. B. subtilis strain 168 (trpC2) was precultured at 30°C for 24 h in NG medium (2) supplemented with 50 g of tryptophan per ml, and then 0.1 ml of the resulting culture was inoculated into 10 ml of fresh NG medium, followed by incubation under shaking at 30°C. The titers of the heat-resistant spores were determined by heating the cultures for 10 min at 80°C and then plating them onto an NG agar plate.Detection and bioassay of bacilysocin. Bacilysocin was extracted wit...

In the course of our screening of /?-glucosidase inhibitor, a culture filtrate of a mushroom, Phellinus sp. strongly inhibited the enzymeactivity. The active substance wasisolated through charcoal separation, column chromatography and crystallization. Spectroscopic and crystallographic analysis revealed that it had a novel cyclitol structure, (15f,2i?,35f,4/?,57?,6i?)-5-hydroxymethyl-7oxabicyclo[4, l ,0]heptane-2,3,4-triol, and we named it cyclophellitol. It inhibited almond-derived /?-glucosidase with an IC50 of 0.8 ug/ml. 49 /?-Glucosidase inhibitors such as castanospermine and 1-deoxynojirimycin have been reported to inhibit syncytium formation and infection of human immunodeficiency virus (HIV), possibly by perturbing gpl20-linked glycan structurelf2). Castanospermine is also known to suppress experimental metastasis possibly by changing the saccharide structure on tumour cell surface3*. Therefore, glucosidase inhibitors may inhibit HIV infection and metastasis. Consequently we screened culture filtrates of microorganisms for inhibitory activity against^-glucosidase. Amonga thousand strains of bacteria, Actinomycetes and mushrooms,we found that a culture filtrate of a mushroomstrain, Phellinus sp., showedinhibitory activity against almond^-glucosidase. Isolation and structure determination of the active principle, established that it was a novel compound. Wehave namedit cyclophellitol. Materials and Methods General /7-Nitrophenyl-^-D-glucopyranoside and almond /?-glucosidase were purchased from Sigma. NMR spectra were recorded on a Jeol JNM-GX400. The MSspectra were taken by a Hitachi M-80H spectrometer. The mp was measured by the micro mp apparatus, MP-S3(Yanagimoto). The UVand IR spectra were measured by a Hitachi 220S and a 260-10 spectrophotometer, respectively. Optical rotations were taken by a Perkin-Elmer 241 polarimeter using micro-cell (light path 10 cm). #-Glucosidase Assay The enzyme activity was assayed by the method described by Saul et al.4\ with slight modifications.

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