Studies on biosynthesis of okaramines, insecticidal indole alkaloids.

单纯青霉ATCC 90288（前身为AK-40）的分离株在okara上生长时产生okar胺A和B。它们是具有独特结构的吲哚类生物碱，经口服对家蚕三龄幼虫有杀虫活性。我们不断努力寻找新的卡拉胺同系物，以阐明其构效关系，并使卡拉胺的生物合成成为可能，已经分离出了卡拉胺D、E和f .它们的化学结构被确定为卡拉胺的新同系物。克拉明似乎是由两摩尔色氨酸和两摩尔异戊二烯产生的。为了澄清这一假设，我们进行了固体培养的饲养实验。不幸的是，我们发现没有DL-tryptophan-d_8被掺入到okarines中。[2-^<13>C] -乙酸也未掺入。这些化合物被认为是okamines的前体，而没有被纳入okamines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在静态液体培养中生长良好。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，结果表明，麦芽提取物和马铃薯-葡萄糖培养基有利于生长。测定了其杀虫活性，表明其生产能力较差。作为下一个试验，我们在培养基中添加了冈葵提取物。值得注意的是，在培养基中加入山葵提取物后，菌株的生长效果更好。即使在半合成培养基Czapek或Sabouraud培养基中，当添加了okara提取物时，也能产生okarines。采用该液体培养体系进行饲养试验。

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.