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Metal-containing novel heterocyclic antibiotics, micacocidin A (1), B (2), and C (3) have been isolated from the culture filtrate of Pseudomonas sp. No. 57-250. The structure and absolute configuration of micacocidin A, an octahedral Zn2+ complex, was determined by X-ray crystallographic analysis. And then, the structures of the two congeners, micacocidin B (Cu2+ complex) and C (Fe3+ complex) were investigated by employing one dimensional and two dimensional homonuclear and heteronuclear NMR spectroscopies and mass spectrometry.In the accompanied paper1), the taxonomy, fermentation, isolation, physico-chemical properties, and biological activities of micacocidin A, B, and C were reported.Herein, we describe the account of the structure determination of micacocidin A (1) and two congeners (2 and 3), metal chelated antibiotics having specific and excellent activity against Mycoplasma species (Fig. 1). Materials and Methods Spectroscopic StudiesLiquid secondary ion mass spectra (LSI-MS) were obtained by using a Hitachi M-90 mass spectrometer (BEE geometry) equipped with cesium ion gun. Samples were dispersed in 3-nitrobenzyl alcohol and introduced into the mass spectrometer on a LSI-MS target. One dimensional (1D) and two dimensional (2D) NMR were

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Abstract

The absolute stereochemistry of (+)-l,8a-dihydro-3,8-dimethylazulene (1), a labile trinorsesquiterpenoid biosynthetic intermediate for 1,4-dimethylazulene (2), isolated from the liverwort Calypogeia granulata Inoue, was determined to be 8a5 by theoretical calculation of CD spectra; the labile biosynthetic intermediate 1 with a unique l,8a-dihydroazulene skeleton shows very intense optical rotation, [c*]D +1165°, and CD Cotton effects, Xext 314.0 nm, +19.7 and Xex, 235.2 nm, -47.4, suggesting a strongly distorted conjugated tetraene system. On the basis of the -electron framework approximation, the CD curve of (8aR)-l,8a-dihydroazulene (5) was calculated by the SCF-CI-dipole velocity MO method. The resultant calculated CD Cotton effects, Xext 313 nm, -13.9 and Xext 219 nm, +46.2, were opposite in sign to those of the natural product 1. Accordingly, the absolute stereochemistry of the labile biosynthetic intermediate (+)-l was theoretically determined to be 8aS. The conclusion was experimentally proved by the synthesis of model compounds (15',8a5)-(+)-l,8a-dihydro-lmethoxy-8a-methylazulene ( 7) and (15',8aS')-(+)-l,8a-dihydro-l-methoxy-6,8a-dimethylazulene (8) as follows. Compounds 7 and 8 were synthesized starting from optically pure Wieland-Miescher ketone (S)-(+)-( 9), [ct]D +98.5°, via reactions of 15 steps, respectively. The product 7, bp 35-45 °C (0.067 kPa) and [a]D +393.3°, shows CD Cotton effects, Xext 321.0 nm, +5.7 and Xext 221.3 nm, -24.5, which are similar, in both sign and shape, to those of the natural product 1. Similarly, compound 8, bp 60-70 °C (0.029 kPa) and [ct]D +323.8°, exhibits CD Cotton effects, Xcxt 318.6 nm, +4.3 and Xext 220.7 nm,-18.1. Therefore, by comparison of the CD spectrum of 1 with those of the model compounds, it was experimentally proved that the natural dextrorotatory l,8a-dihydro-3,8-dimethylazulene (1) had 8aS absolute configuration.Recently much attention has been focused on the chemistry of trinorsesquiterpenes with a 1,4-dimethylazulene skeleton, iso-lated from the sources of marine soft corals or liverworts.2 7 One of us first isolated chiroptically active l,8a-dihydro-3,8-di-

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Growth and the production of volatile sesquiterpenoids by a chlorophyllous cell suspension culture from gametophytes of C. granulata, a leafy liverwort, were examined. Glucose was more effective than 2,4-dichlorophenoxyacetic acid for callus induction, and elimination of glucose from the medium resulted in prompt redifferentiation of plantlets. The cells grew photoheterotrophically, but not in the dark. 1,4-Dimethylazulene, a trinorsesquiterpenoid, was produced as the major volatile sesquiterpenoid in the cultured cells; bicyclogermacrene, compound II, an indene-type aldehyde (a trinorsesquiterpenoid aldehyde), compound I and tetrahydro-1,4-dimethylazulene (a trinorsesquiterpenoid) followed in decreasing order. The azulene was produced both in light and the dark, and its yield was proportional to the growth in light. The yield in light was four times higher than that in the dark. The content of 1,4-dimethylazulene was 0.9-10.% and that of total essential oils was 2.0-3.3% of the dry werght of the cultured cells. The quantity, quality, and proportions of the volatile sesquiterpenoids of the cell culture were almost equal to those of intact (original) plants and redifferentiated plantlets.

A microscale method for identifying the monosaccharide units and their linkages in oligosaccharides is presented. Sugar components are identified by UV and CD spectroscopy of chromophoric degradation products. CD spectral data for approximately 150 different glycopyranoside components are provided for use as reference spectra in the identification of unknown derivatives. Procedures for the conversion of oligosaccharides to monosaccharide subunits bearing 4-bromobenzoate and 4-methoxycinnamate chromophores have been developed based on acetolysis/bromination reactions for glycosidic cleavage of per(bromobenzoy1ated) oligosaccharides. The method offers an alternative means to conventional methylation analysis of oligosaccharides.1. Introduction. -Recent years have seen a rapid growth in the understanding of the important and varied roles of oligosaccharides from glycoproteins and glycolipids [ 11. These oligosaccharides play particularly important biological roles on cell surfaces and have been implicated as the antigenic determinants in a number of systems. Cell-cell recognition, cellular differentiation during development, and the attachment of viruses to cells during infection are all processes in which the cell-surface oligosaccharides are involved. Structurally diverse oligosaccharides are also constituents of other bioactive glycoconjugates such as saponins [2].Determination of linkage structure in oligosaccharides has long relied upon methylation analysis by GLC/MS of partially methylated alditol acetates [3]. These monosaccharide residues are obtained by hydrolysis of permethylated oligosaccharides, reduction of the carbonyl group, and acetylation of the remaining OH groups which were originally involved in linkages. Methylation analysis generally requires a minimum of 25 nmol of material, although capillary GLC with smaller quantities have been reported [4]. The analysis relies heavily on chromatographic separation and comparison of monosaccharide derivative GLC retention times with a large bank of synthetic standards, few of which are commercially available. Linkage analysis generally follows a sugar-component