93(P34) Trichoderma sp. USF-2690株の生産するDPPHラジカル捕捉物質 : Sorbicillin関連化合物の化学構造とDPPHラジカル捕捉活性(ポスター発表の部)

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Recently, free radicals have been known to mediate a wide range of diseases such as atherosclerosis, ischemia reperfusion injury, inflammation, carcinogenesis, and senescence. Free radical scavengers are expected to be effective preventive and/or therapeutic agents through the decrease in free radical levels. In the course of our screening to detect 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavengers, we isolated ten yellowish compounds, namely bisorbicillinol (1), demethyl-trichodimerol (2), bisorbicillinolide (3), bisorbibetanone (4), demethylsorbicillin (5), oxosorbicillinol (6), bisvertinolone (7), trichodimerol (8), bisorbibutenolide (bislongiquinolide, 9), and sorbicillin (10), from the fermentation broth of a Trichoderma sp. USF-2690 strain isolated from a soil sample collected in Shizuoka City, Shizuoka, Japan. In particular, compounds 1-6 had been unknown as sorbicillin-related compounds yet. The planar structures of 1-6 were determined by elucidation of spectroscopic evidence, especially two dimensional NMR spectra. The relative stereochemistry were elucidated through NOESY spectra, and the absolute stereostructure of 4 was confirmed based on analysis of the CD spectrum, resulting from the chiral exciton coupling between two enol-sorbyl chromophores. Compounds 1-4, 7-10, α-tocopherol and BHT were submitted to the assay system with DPPH. The evaluation on their ED_<50> values in this assay at less than a 500μM dosage was as follows: 1, 31.4μM; 2, 42.4μM; 3, 500μM; 4, 62.5μM; 7, 44.3μM; 8, 53.7μM; 9, >500μM; 10, >500μM; α-tocopherol, 22.0μM; BHT, 27.0μM. We continued to observe the DPPH radical scavenging activity of 3, 9 and 10 for 24hr; consequently, we found that 3, 9 and 10 slowly scavenged the DPPH radical. After standing for 24hr, the evaluation on their ED_<50> values in this assay was as follows: 3, 88.8μM; 9, 80.8μM; 10, 152.3μM. Furthermore, we elucidated the biogenesis of sorbicillin-related compounds. The structures of compounds 5 and 6 suggested methylation at C-6 and oxidation at C-1 of the sorbicillin skeleton were controlled in the early polyketide stage before the formation of oxidized sorbicillin dimers. Therefore, it seemed that these compounds provided us with important hints to clarify the biosynthetic pathway, which yielded the diversity of structures in the group of oxidized sorbicillin dimers.
1999-09-01

93(P34) Trichoderma sp. USF-2690株の生産するDPPHラジカル捕捉物質 : Sorbicillin関連化合物の化学構造とDPPHラジカル捕捉活性(ポスター発表の部)

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