Studies on biosynthesis of okaramines, insecticidal indole alkaloids.

当在奥卡拉上生长时，分离物简青霉ATCC 90288（以前的AK-40）产生豆渣胺A和B。它们是具有独特结构的吲哚生物碱，口服对家蚕三龄幼虫具有杀虫活性。我们不断努力寻找新的okaramine同类物，以阐明结构-活性关系，并使okaramines的生物合成，导致okaramines D，E和F的分离。它们的化学结构被确定为新的okaramine同类物。Okaramines似乎是由两摩尔色氨酸和两摩尔异戊二烯衍生的。为了阐明这一假说，我们进行了固体培养的补料实验。不幸的是，我们发现没有DL-色氨酸-d_8掺入奥卡胺。[2-被<13>认为是奥卡胺前体的化合物没有被掺入奥卡胺的原因之一是培养真菌的条件。我们寻找另一种培养条件，液体培养。菌株ATCC 90288在静态液体培养中表现出良好的生长。采用Czapek、Sabourad、麦芽提取物、麦芽酵母提取物和马铃薯葡萄糖培养基，表明麦芽提取物和马铃薯葡萄糖培养基有利于生长。以奥卡胺的量作为杀虫活性进行测定，表明生产力较差。作为下一个试验，我们将奥卡拉提取物补充到培养基中。令人感兴趣的是，当将奥卡拉的提取物添加到培养基中时，该菌株显示出更好的生长。当添加奥卡拉提取物时，甚至在Czapek或Sabouraud培养基、半合成培养基中也产生奥卡拉胺。利用该液体培养系统进行饲养实验。

An isolate Penicillium simplicissimum ATCC 90288 (formerly AK-40) produces okaramines A and B when grown on okara. They are indole alkaloids with unique structures which exhibit insecticidal activity against third instar larvae of silkworm uopn oral administration. Our continuous efforts to find new okaramine congeners to elucidate the structre-activity relationship and also to enable the biosynthesis of okaramines have led to the isolation of okaramines D,E,and F.Their chemical structures were determined to be new congeners of okaramine.Okaramines seem to be derived from two moles of tryptophan and two mole of isoprene. In order to clarify this hypothesis, we tried feeding experiment in solid culture. Unfortunately we found that no DL-tryptophan-d_8 was incorporated into okaramines. [2-^<13>C] -Acetic acid was not incorporated too.One of the reasons why the compounds, which are considered to be precursors of okaramines, were not incorporated into okaramines is the condition of cultureing the fungus. We searched for another cultural condition, liquid culture. A strain ATCC 90288 showed a good growth in a static liquid culture. Czapek, Sabourad, malt extract, maltyeast extract, and potato-glucose media were used, showing that malt extract and potatoglucose media were good for the growth. The amount of okaramines were measeured as insecticidal activity, indicating that the productivity was poor. As a next trial we supplemented the okara extract to the media. It is of interest that the strain showed better growth when the extract of okara was added to the medium. Okaramines were produced even in a Czapek or Sabouraud media, semi-synthetic media, when the extract of okara being added. Feeding experiment will be carried out using this liquid culture system.