Biosynthesis of cytotoxic sesquiterpenoids by higher basidiomycetes

描述（由申请人提供）：高等担子菌，通常称为蘑菇，已在传统医学中使用了几个世纪，并且已知其合成了一系列具有生物活性的天然产物。蘑菇被认为是发现新的生物活性化合物的最大的未开发资源之一。尽管高等担子菌具有极其丰富的化学多样性和发现新药的前景，但蘑菇直到最近才引起药物化学家和生物化学家的注意。 已知蘑菇产生多种具有在微生物或植物中未发现的独特骨架的倍半萜。其中一类倍半萜烯类化合物，伊鲁烷类化合物，由于其有效的抗肿瘤和抗菌活性而受到相当大的关注。由Jack O 'Lantern蘑菇Omptus olearius产生的Illudin M和S在几种人类肿瘤细胞系（包括多重耐药肿瘤）中以纳摩尔浓度表现出细胞毒性和细胞抑制特性。已经合成了具有改善的治疗指数和显著的抗肿瘤活性的半合成伊鲁啶类似物irofulvene和酰基fulvene，并且目前正在针对几种实体瘤类型的几个I期和II期试验中进行研究。 然而，这类Illuminescence倍半萜的生物合成是未知的。该研究将是首次对这一重要而独特的高等真菌倍半萜类天然产物进行生物合成研究。这一建议的具体假设是：（1）Illudin是通过一种新型环化酶合成的原Illudin骨架衍生的，（2）Illudin中反应性环丙烷环的安装发生在最初的环化反应之后，推测是通过P450单加氧酶催化的反应。提出了（1）鉴定和表征负责形成原伊鲁藻支架的环化酶，（2）鉴定和表征另外的伊鲁藻素生物合成基因，和（3）探测原伊鲁藻支架修饰酶的底物范围。 本研究的长期目标是研究高等真菌中不同原伊鲁烷型倍半萜类化合物的生物合成，目的是使用鉴定的生物合成酶来探索具有有效抗肿瘤特性和改善治疗特性的新功能化倍半萜类化合物的合成。人们认为蘑菇是发现新的生物活性化合物的最大的未开发资源之一;但是，尽管高等担子菌具有极其丰富的化学多样性和发现新药的前景，蘑菇直到最近才引起药物化学家和生物化学家的注意。由Jack O 'Lantern蘑菇Omptus olearius产生的一类倍半萜烯，即伊鲁烷，在几种人类肿瘤细胞系中表现出有效的细胞毒性和细胞抑制特性，包括多重耐药肿瘤。本研究的目的是研究蘑菇中的Illuminescent倍半萜类化合物的生物合成，目的是使用已鉴定的生物合成酶来探索具有有效抗肿瘤特性和改善治疗特性的新倍半萜类化合物结构的合成。

DESCRIPTION (provided by applicant): Higher basidiomycetes, commonly referred to as mushrooms, have been used for centuries in traditional medicine and are known to synthesize an array of biologically active natural products. It is thought that mushrooms are among the greatest unexplored resources for the discovery of novel biologically active compounds. Despite the extremely rich chemodiversity of higher basidiomycetes and the prospects for the discovery of new drugs, mushrooms have only recently caught the attention of medicinal chemists and biochemists. Mushrooms are known to produce a variety of sesquiterpenes with unique skeletons not found in microbes or plants. One class of sesquiterpenoids, the illudanes, has received considerable attention because of their potent antitumor and antibacterial activity. Illudins M and S produced by the Jack O'Lantern mushroom Omphalotus olearius exhibit cytotoxic and cytostatic properties at nanomolar concentrations in several human tumor cell lines, including multiple drug resistant tumors. Semi-synthetic illudin analogues irofulvene and acylfulvene with improved therapeutic indexes and remarkable antitumor activities have been synthesized and are currently under investigation in several phase I and II trials against several solid tumor types. The biosynthesis, however, of this class of illudane sesquiterpenoids is not known. The proposed research will be the first biosynthetic investigation of this important and unique class higher fungal sesquiterpene natural products. The specific hypotheses of this proposal are that: (1) Illudins are derived via a protoilludane skeleton synthesized by a new type of cyclase and (2) installment of the reactive cyclopropane ring in illudins occurs after the initial cyclization reaction presumably via a P450 monooxygenase catalyzed reaction. It is proposed to (1) identify and characterize the cyclase responsible for formation of the protoilludane scaffold, (2) identify and characterize additional illudin biosynthetic genes and (3) probe the substrate range of protoilludane scaffold modifying enzymes. The long-term goal of this research is to investigate biosynthesis of different protoilludane-type sesquiterpenoids in higher fungi with the goal of using the identified biosynthetic enzymes to explore synthesis of new functionalized sesquiterpenoids with potent antitumor properties and improved therapeutic properties. It is thought that mushrooms are among the greatest unexplored resources for the discovery of novel biologically active compounds; but despite the extremely rich chemodiversity of higher basidiomycetes and the prospects for the discovery of new drugs, mushrooms have only recently caught the attention of medicinal chemists and biochemists. One class of sesquiterpenoids, the illudanes, produced by the Jack O'Lantern mushroom Omphalotus olearius exhibit potent cytotoxic and cytostatic properties in several human tumor cell lines, including multiple drug resistant tumors. The goal of this research is to investigate biosynthesis of illudane sesquiterpenoids in mushrooms with the goal of using the identified biosynthetic enzymes to explore synthesis of new sesquiterpenoid structures with potent antitumor properties and improved therapeutic properties.