Studies on pyranonigrins-isolation of pyranonigrin E and biosynthetic studies on pyranonigrin A
Studies on pyranonigrins-isolation of pyranonigrin E and biosynthetic studies on pyranonigrin A
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DOI：
10.1038/ja.2013.91
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发表时间：
2014-02-01
影响因子：
3.3
通讯作者：
Shindo, Kazutoshi
中科院分区：
文献类型：
--
作者：
Riko, Risa;Nakamura, Hitomi;Shindo, Kazutoshi
在固体培养条件下，黑曲霉LL-LV3020产生的次生代谢物为吡喃葡萄糖苷A、B、C、D和S。1，2对2，2-二苯基-1-苦基肼的清除活性也已有报道。3、4吡喃黑素具有独特的结构(图1)；然而，尚未对其进行生物合成研究。我们最近发现生长在马铃薯葡萄糖琼脂上的黑曲霉NBRC5374的丙酮提取物具有很强的清除2，2-二苯基-1-苦基肼自由基的活性，并分离到一个新的吡喃黑素衍生物(吡喃黑素E)，它是除了吡喃黑素A和S之外的抗氧化化合物。本文报道了吡喃黑素E的分离、结构测定和清除2，2-二苯基-1-苦基肼自由基的活性，并用[1-13C]乙酸钠、[2-13C]乙酸钠、[1，2-13C2]乙酸钠和[1-13C]甘氨酸对其进行了饲喂实验，结果表明其由4个单位的乙酸酯和1个单位的甘氨酸组成。将1ml黑曲霉NBRC5374孢子液(每毫升1106个孢子)滴在装在Erlenmeyer烧瓶中的马铃薯葡萄糖琼脂(100ml)上，铺满其表面。20个摇瓶在301℃下静态培养48h(30h后开始形成孢子，48h后趋于稳定)。
Pyranonigrins A, B, C, D and S have been shown to be secondary metabolites produced by Aspergillus niger LL-LV3020 when grown on a solid culture. 1, 2 The 2, 2-diphenyl-1-picrylhydrazyl radical scavenging activity of pyranonigrin A was also reported in previous studies. 3, 4 Pyranonigrins possess unique structures (Figure 1); however, biosynthetic studies on pyranonigrins have not been conducted. We recently found that an acetone extract of A. niger NBRC5374 grown on potato dextrose agar shows a potent 2, 2-diphenyl-1-picrylhydrazyl radical scavenging activity and isolated a new pyranonigrin derivative (pyranonigrin E) in addition to pyranonigrins A and S as the antioxidative compounds. In this study, we report the isolation, structural determination and 2, 2-diphenyl-1-picrylhydrazyl radical scavenging activity of pyranonigrin E. We also investigated the biosynthesis of pyranonigrin A in feeding experiments using sodium [1-13C] acetate, sodium [2-13C] acetate, sodium [1, 2-13C2] acetate and [1-13C] glycine, and showed that it was composed of four units of acetate and one unit of glycine.To produce and isolate pyranonigrin E, 1ml of the A. niger NBRC5374 spore solution (1Â 106 spores per ml) was dropped on the potato dextrose agar agar (100ml) in an Erlenmeyer flask and spread all over its surface. Twenty flasks were cultured statically for 48h at 301C (spore formation started after 30h and became stationary after 48h).