We demonstrated that the rox gene of Nocardia farcinica encodes a rifampicin monooxygenase capable of converting rifampicin to a new compound 2¢-N-hydroxy-4-oxo-rifampicin with a markedly lowered antibiotic activity. The deletion mutation (Drox) of the rox gene gave no significant influence to the rifampicin resistance of N. farcinica. However, transformation with a plasmid containing an overexpressing the rox gene markedly raised the rifampicin resistance in the strain with the deletion mutation of the rpoB2 gene as the principal rifampicin resistance determinant. On the other hand, rifampicin was decolorized by the wild-type strain, whereas it remained intact when incubated with the Drox strain. Based on these results, it will be conclusive that the rox gene is capable of initiating rifampicin degradation with a new metabolite formation at the first step and having a role as the secondary rifampicin resistance factor in N. farcinica.

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The syntheses of (+ )-5 3H-eudesma-3,11 -diene [1], (-)-5 ß -eudesmane-4ß, 11-diol [2], and (+ )-5ß -1 5 -4 , 11-diol [15] were carried out by an unambiguous procedure starting from -santonin. The diene 1 was identical with a natural product which was isolated previously as a termite defense substance. Although structure 2 was recently proposed for a new eudesmane-1,4-diol [A] isolated from Pluchea arguta, synthetic 2 and its C-4 epimer, 15, were not identical with this natural eudesmane-4,11-diol when their physical and spectroscopic parameters were compared. The structure of this natural eudesmane-4,11-diol has been revised from 2 to 3 (7 ßH-eudesmane-4 , 11-diol) as a result of the analysis of the Hand ,3Cnmr spectra of related natural and unnatural eudesmane derivatives.

The structures of two novel isopentyl phloroglucinol dimers, designated as sideroxylonals A and B were deduced on the basis of proton magnetic resonance, 13C-nuclear magnetic resonance and mass spectral evidences.

Neurotrophic factors such as nerve growth factor (NGF) are involved in survival, growth, and differentiation in normal and neoplastic nerve cells. 1,2 At least three receptors bearing tyrosine kinase activity for neurotrophic factors have beeen cloned; 3-5 TRK-A encodes a high-affinity receptor for NGF and also binds neurotrophin-3 (NT-3) and neurotrophin-4/5 (NT-4/5). 6-8 TRK-B encodes a receptor for brain-derived neurotrophic factor (BDNF) and also binds NT-3 and NT-4/5, and TRK-C encodes a receptor for NT-3. 9-11 Despite high sequence homology among the receptors, the developmental and physiological functions of each neurotrophic factor appear to be different, suggesting that each factor has a unique role.In addition, it has been reported that most benign neuroblastomas express high levels of TRK-A, while malignant neuroblastomas, especially those with N-myc amplification, express little or no detectable TRK-A mRNA. 12-16 NGF is expected to induce the differentiation of benign neuroblastomas to neurons, but NGF has no effect on malignant neuroblastomas lacking NGF receptors. Therefore, compounds which induce the differentiation of neuroblastomas might be good candidates for pharmaceutical agents for various neurodegenerative diseases.We have screened microbial products to discover neuritogenic compounds which induced neurite outgrowth in the human neuroblastoma cell line SH-SY5Y that lacks significant TRK family mRNAs. 17,18 During the screening, we isolated a novel, non-protein neurotrophic compound, epolactaene (Figure 1), produced by Penicillium sp. 1689-P, having an epoxide-containing γ-lactam ring in the molecule. 19 However, only small quantities of epolactaene could be isolated from the fungus; furthermore, the compound was unstable under light because of a labile triene group in the side chain and an epoxide fused to a γ-lactam ring. In the present paper, we prepared a number of epolactaene derivatives, 3-substituted 3-pyrrolin-2-ones possessing a double bond in the γ-lactam ring, to find compounds with more effective neuritogenic activity. In addition, we described the structure-activity relationship of 3-substituted 3-pyrrolin-2-ones on the neuritogenic effect in SH-SY5Y cells. MT-5, 3-acetyl-4,5-dimethyl-5-octadecyloxy-3-pyrrolin-2-one, the most effective derivative for neuritogenic activity in SH-SY5Y cells, also arrested cell cycle progression at G0/G1 like epolactaene.Chemistry. We focused on the γ-lactam ring of epolactaene in developing derivatives that have more simple structure and potent activity. The intermediates were synthesized essentially according to the procedure of Howard et al., 20 in which R, -diketones, including aliphatic diketones, react smoothly in aqueous solution pH 7-10 at room temperature with a variety of acetamides possessing a strong electron-withdrawing group in the R-position to give 3-substituted 5-hydroxy-3-pyrrolin-2-ones. For example, as shown in Scheme 1, R, -diketone (1) reacted with acetoacetamide (2) to give 3 and the following treatment with alcohols under aci...