51(P-19) Trichoderma sp. USF-2690株の生産するDPPHラジカル捕捉物質 : Bisorbicillinoidの生合成研究(ポスター発表の部)

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In the course of our screening to find 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavengers, we isolated eleven sorbicillin-related compounds, including seven novel compounds, from the fermentation broth of a Trichoderma sp. USF-2690 strain. The "bisorbicillinoids" was recently defined by Nicolaou et al. as the term used to designate a group composed of dimeric sorbicillin-related natural products, on which their diverse structures and interesting biological activities were reported by several groups. On the other hand, biogenesis of bisorbicillinoids had been also described by a few research groups, and consequently some distinguishable biosynthetic routes had been presented. Herein we report that the strain produces a functional quinol, sorbicillinol (1), postulated as a key compound in bisorbicillinoids biosynthesis for a long time, and bisorbibetanone (bislongi-quinolide 3) and bisorbicillinolide (4) are biosynthesized from an intermediate of bisorbicillinol (2). In our observation for products of the strain by a method of HPLC-analysis, we found an unidentified product appeared at Rt 4.3. The product, named USF2690M, gradually decreased with production of bisorbicillinoids. General solvent extraction and concentration of the broth to dryness of the cultured broth caused the disappearance of USF2690M's peak in the HPLC chromatogram. The LC-ESI-MS (negative) analysis for USF2690M gave m/z 247 as (M-1) ion peak. These results suggested that USF2690M was the quinol 1. Synthetic 6-acetoxyquinol (6) prepared according to Corey's method was hydrolized by 0.05M KOH, and then analyzed on LC-ESI-MS (negative) method to reveal m/z 247 as (M-1) ion peak. Acetylation of USF2690M in aqueous solution gave 6 as 6S-isomer. All the results indicated that USF2690M was identical with the postulated quinol 1. The real quinol 1 was designated as sorbicillinol. Our experiments for incorporation of [1-^<13>C] or [2-^<13>C]-labeled sodium acetate gave two kinds of labeled bisorbicillinol (2). Each labeled bisorbicillinol (2) was utilized as a precoursor for production of bisorbibetanone (bislongiquinolide 3) and bisorbicillinolide (4) in the experiment using a resting cell of the strain. The ^<13>C-NMR spectra of 3 and 4, obtaind from the experiment, showed the ^<13>C-enriched positions corresponded to those of partially labeled 2. The results of incorporation study of partially labeled 2 satisfied the proof that a biosynthetic route from 2 to 3 and from 2 to 4 existed.
天然有機化合物討論会の論文
2000-10-01

51(P-19) Trichoderma sp. USF-2690株の生産するDPPHラジカル捕捉物質 : Bisorbicillinoidの生合成研究(ポスター発表の部)

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