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.

Structures of novel antibiotics, napyradiomycins A, Bl, B2, B3, CI and C2 were determined. By X-ray crystallography, napyradiomycin B2 was determined to be (3R,lOaR)-3-chlorolOa-[[(l R,3S)-3-chloro-2,2-dimethyl-6-methylenecyclohexyl]methyl]-3,10a-dihydro-6,8-dihydroxy-2,2-dimethyl-2H-naphtho[2,3-b}oyran-5,10-dione.The structures of other napyradiomycins were elucidated by NMR studies. Napyradiomycins Cl and C2 have unique structures which contain 14-membered ring cyclized by carbon-carbon bond. NapyradiomycinsA, BI, B2, B3, Cl and C2 ( Fig. 1) were isolated from a culture broth of Chainia rubra MG802-AF11) and inhibited the growth of Gram-positive bacteria. We will report herein on the structure determination of these antibiotics.The same chromophore was shown by their UV and NMR spectra. The structure of napyradiomycin B2 which was crystallized as pale yellow needles was determined by X-ray analysis.The assignment of signals on 'H and 13C NMR of B2 was established by the aid of 1H-1H shift correlation spectrum (1H-1H COSY) and 1H-13C shift correlation spectrum (1H-13C COSY). Based on the NMR data including NMR of B2, the structures of other napyradiomycins were determined.The Structure of Napyradiomycin B2The structure of B2 (C"25H28O5Cl2) was determined by X-ray analysis to be (3R,lOaR)-3-chloro- (Fig. 2). The X-ray crystallographic data were as follows.The crystals were grown in methanol solutions as aggregates of thin plates pale yellow in color. The structure was determined by the direct methods and refined by the block-diagonal least-squares

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We prepared methyl 2,.5-dihydroxycinnamate as a stable analogue of erbstatin, a tyrosine kinase inhibitor. This analogue was about 4 times more stable than erbstatin in calf serum. It inhibited epidermal growth factor receptor-associated tyrosine kinase in vitro with an XC, of 0.15 pg/ml. It also inhibited in situ autophosphorylatio~ of epidermal growth factor receptor in A43I cells. Methyl 2,5-dihy~oxycinn~ate was shown to delay the S-phase induction by epidermal growth factor in quiescent normal rat kidney cells, without affecting the total amount of DNA synthesis,The effect of erbstatin on S-phase induction was smaller, possibly because of its shorter life time.

Biosynthetic studies on napyradiomycins were carried out based on the incorporation of [2-13C]acetate and [l,2-13C]acetate. The alignment of acetate units suggested that the B and C rings of napyradiomycins are derived from a pentaketide, while ring Aand the side chain maybe synthesized from mevalonate.The napyradiomycin (NPD) antibiotics have been isolated from the actinomycete Chainia rubroP. They have unique structures which consist of the chromophore of naphtho[2,3-Z>]pyrane-5,10-dione and three types of side chain bonded to ClOa of the chromophore2>3) (Fig. 1). Type A (NPD-A's) have a branched side chain. The side chain of type B (NPD-B's) is cyclized to form a cyclohexane ring and that of type C (NPD-C's) is cyclized between C7 and ClOa of the chromophore to form a 14-membered ring.The biosynthetic pathway of the NPD's was studied since they have unique structures. Although the side chains of the NPD'sare different from each other, their common carbon structures suggest that they may be synthesized from geranyl pyrophosphate of the mevalonate pathway. It seems likely that rings B and C are synthesized from a polyketide precursor.In this report, we give the results of a preliminary biosynthetic study on the incorporation of [2-13C]acetate and [l ,2-13C]acetate into the NPD's. Materials and Methods Sodium salts of [2-13C]aceticacid (93 % enriched) and [l,2-13C]acetic acid (90% enriched) were purchased from Commissariat a 1'Energie Atomique, France. The former was dissolved in water at a concentration of 70 mg/ml. The latter was dissolved in water at a concentration of 72 mg/ml and diluted with an equal volume of non-labeled acetate solution (72 mg/ml). 13C NMRspectra were recorded at 100 MHzon a JEOLJNM-GX400 equipped with a 5-mmprobe. A spectral width of 23 KHzwas taken by 32 K sampling points.Incorporation of 13C-Acetate and Preparation of 13C-Labeled NPD's A seed culture of C. rubra MG802-AF1was made by the method previously described0. Three ml of the seed culture was inoculated into each of several 500-ml Erlenmeyer flasks containing 1 10 ml of medium (composed of Bacto-Soytone (Difco) 1.0%, galactose 2.0%, corn steep liquor 0.5%, dextrin 2.0%, (NH4)2SO4 0.2%, CaCO3 0.2%, silicon oil (Shin-Etsu Chemical Industry, KM-70) 0.03 %, pH 7.4). 13C-Labeled acetate in 0.5 ml of aqueous solution ([2-13C]acetate 35 mg; [l,2-13C]acetate 18 mg labeled and 18 mg non-labeled) was added to each flask at the beginning of NPDproduction, viz., after 41 hours cultivation, and the cultures were then incubated further for 30 hours. 13C-Enriched NPD's were isolated from the cultured broth by solvent extraction, silica gel chrcmatography, Sephadex LH-20 gel filtration, and TLC chromatography as previously reported0. In the experiment on [2-13C]acetate incorporation, 9.4 mg of NPD-B1and 2.0 mg of the mixture of NPD-T Nowdeceased.