IC202B (1) and C (2) were isolated from the culture filtrate of Streptoalloteichus sp. 1454-19. The structures were elucidated by various NMR spectral analyses including 1H-15N HMBC and FAB-MS experiments. IC202B and C showed immunosuppressive activity on a mixed lymphocyte culture reaction at the same IC50 value of 1.6 μg/ml.
New antibiotics designated decatromicins A and B were isolated from the culture broth of Actinomadura sp. MK73-NF4. They were purified by butyl acetate extraction, silica gel column chromatography, silica gel TLC and Sephadex LH-20 column chromatography. Decatromicins A and B inhibited growth of Gram-positive bacteria including methicillin-resistant Staphylococcus aureus (MRSA).
The structures of decatromicins A and B that strongly inhibit the growth of MRSA were elucidated by the analysis of various NMR experiments. The planar structure was determined by 1H, 13C, COSY, HMQC and HMBC NMR spectra. The relative configuration of aglycone was elucidated by NOESY experiments and the absolute structure was determined by application of the modified Mosher's method. The absolute structure of glycosyl moiety was determined by X-ray analysis of the O-(p-bromobenzoyl) derivative.
We have recently found a novel fatty acid, 11-keto-9(E), 12(E)-octadecadienoic acid (KOD), that enhances fibrinolytic activity of endothelial cells. The mechanism of action of KOD has been investigated. KOD increased 2-fold the plasmin activity of bovine aortic endothelial cells at 250 μM. The stimulation was dependent on plasminogen and was inhibited by anti-urokinase, whereas KOD did not enhance the urokinase-catalyzed plasminogen activation and the resulting plasmin activity in a cell-free system. Neither the production of urokinase nor the conversion of pro-urokinase to the active, two-chain form was elevated by KOD, but it decreased plasminogen activator inhibitor-1 (PAI-1) activity of cells and inactivated PAI-1 irreversibly in a purified system. These results demonstrated that the KOD enhancement of endothelial fibrinolytic activity was mediated, at least in part, by inactivation of PAI-1.
Exposure to immunosuppressant, 15-deoxyspergualin (DSG) induced enhanced formazan producing activity from XTT (2, 3-bis(2-methoxy-4-nitro-5-sulfophenyl)-2H-tetrazolium-5-carboxanilide, sodium salt) in cultured cells, but not from MTT (3-(4, 5-dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide). Formazan generation from XTT is known to be stimulated by cytochrome c oxidase (COX) inhibitors such as KCN and NaN3, whereas MTT reduction is not affected by them. So, the effect of DSG on COX was examined. DSG did not directly inhibit the enzyme, but the cellular enzyme activity was decreased by exposure to DSG. It was thought that stimulation of XTT reduction by DSG resulted from the decrease of cellular cytochrome c oxidase activity.
An actinomycete strain #8 with multiple aminoglycoside (AG) resistance and paromomycin (PRM) sensitivity was examined for its capability of enzymatic modification of AGs. Cell free extracts from the strain converted all of the examined AGs including PRM in the presence of acetyl CoA. PRM was completely modified to at least two products (major and minor spots upon TLC) without significant reduction of the antibiotic activity of the reaction mixture. The structure determination and antibiotic assay of the purified major product revealed 1-N-acetylPRM and its antibiotic activity (12% activity of PRM), indicating the existence of AAC(l). It was thus obvious that the 1-N-acetylation of PRM did not cause PRM resistance. Apramycin, the substrate of the known AAC(l), was not readily acetylated, suggesting that the AAC(l) of strain #8 is a new type. Two diacetylated products (1, 2′'-di-N-acetylPRM and 1, 6′′′-di-N-acetylPRM) were found in the minor spot, suggesting the existence of additional AACs.
The structures of roselipins 1A, IB, 2A and 2B were elucidated by spectroscopic studies including 1H-1H COSY, 13C-1H COSY, 13C-1H HMQC and 13C-1H HMBC NMR experiments, and degradation experiments. They have the common skeleton of 2, 4, 6, 8, 10, 12, 14, 16, 18-nonamethyl-5, 9, 13-trihydroxy-2E, 6E, 10E-icosenoic acid modified with a D-mannose and a D-arabinitol. Roselipin A and B groups were stereoisomers at the arabinitol moiety, which esterified the fatty acid from the different terminal hydroxy residue. Roselipin 2 group was 6′′-O-acetyl roselipin 1 group.