Biosynthesis of cytotoxic sesquiterpenoids by higher basidiomycetes

描述(申请人提供)：高等担子菌，通常被称为蘑菇，已经在传统医学中使用了几个世纪，众所周知，它可以合成一系列具有生物活性的天然产品。蘑菇被认为是发现新的生物活性化合物的最大未开发资源之一。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。 众所周知，蘑菇可以产生多种倍半萜，其独特的骨架是微生物或植物中没有的。倍半萜类化合物中的一类，即伊卢丹类化合物，因其具有较强的抗肿瘤和抗菌活性而备受关注。由绿灯蘑菇产生的伊卢丁M和S在包括多药耐药肿瘤在内的几种人类肿瘤细胞系中表现出纳摩尔浓度的细胞毒和细胞抑制特性。半合成的伊洛富烯和酰基富烯具有更好的治疗指数和显著的抗肿瘤活性，目前正在进行几个针对几种实体瘤类型的I期和II期试验。 然而，这类倍半萜类化合物的生物合成尚不清楚。这项拟议的研究将是第一次对这种重要和独特的真菌高级倍半萜天然产物进行生物合成研究。这一建议的具体假设是：(1)伊利丁是通过一种新型环化酶合成的原环丙烷骨架衍生的；(2)伊利丁中活性环丙烷环的安装发生在最初的环化反应之后，可能是通过P450单加氧酶催化的反应。人们建议：(1)鉴定和鉴定负责形成原吡喃丹支架的环化酶，(2)鉴定和鉴定附加的伊鲁丁生物合成基因，(3)探索原吡喃丹支架修饰酶的底物范围。 这项研究的长期目标是研究高等真菌中不同原青藤烷型倍半萜类化合物的生物合成，目的是利用已鉴定的生物合成酶来探索合成具有强大抗肿瘤活性和改善治疗性能的新的功能化倍半萜类化合物。蘑菇被认为是发现新的生物活性化合物的最大未开发资源之一；但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。一类倍半萜类化合物，伊卢丹，由杰克·奥灯蘑菇Omphalotus olearius产生，在包括多药耐药肿瘤在内的几种人类肿瘤细胞系中显示出强大的细胞毒和细胞抑制特性。本研究的目的是研究蘑菇中伊卢丹倍半萜类化合物的生物合成，目的是利用已鉴定的生物合成酶来探索合成具有强大的抗肿瘤活性和改善治疗性能的新的倍半萜结构。

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.