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Aflastatins: Streptomyces chất chuyển hóa ức chế sinh tổng hợp Aflatoxin Aflatoxin là một nhóm độc tố nấm mốc sản xuất bởi một số chủng nấm Aspergillus parasiticus, Aspergillus flavus và Aspergillus nomius. Những nấm aflatoxin sản xuất hiện nay ubiquitously trên thế giới, nhưng họ không luôn luôn sản xuất các độc tố. | 16 Aflastatins New Streptomyces Metabolites that Inhibit Aflatoxin Biosynthesis Shohei Sakuda Makoto Ono Hiroyuki Ikeda Masaru Sakurada Jiro Nakayama Akinori Suzuki and Akira Isogai CONTENTS 16.1 Introduction 16.2 Discovery and Isolation of Aflastatins 16.3 Structure of Aflastatin A 16.4 Structure of Aflastatin B 16.5 Structure of Blasticidin A 16.6 Biosynthesis of Aflastatin A 16.7 Inhibitory Activities of Aflastatin and Blasticidin A on Aflatoxin Production 16.8 Effects of Aflastatin A on Production of Other Polyketide Metabolites by Fungi 16.9 Mode of Action of Aflastatin A 16.10 Concluding Remarks References 16.1 Introduction Aflatoxins are a group of mycotoxins produced by some strains of the fungi Aspergillus parasiticus Aspergillus flavus and Aspergillus nomius. These aflatoxin-producing fungi are present ubiquitously in the world but they don t always produce the toxin. Under some environmental conditions of high temperature and humidity especially at tropical or subtropical zones they infect agricultural products such as peanuts or corn and produce aflatoxins not only on the outside but also on the inside. Aflatoxins were first found in 1960 as toxic metabolites produced by A. flavus which killed numerous turkeys in England. They also were shown to have an extremely potent carcinogenicity toward mammals and found as contaminates in a wide variety of food commodities. Aflatoxin is now generally recognized not only as an extremely toxic contaminant in foods and feeds but also as one of the certain risk factors for liver cancer in humans.1 Thus control and management of aflatoxins have become issues of concern.2 1999 by CRC Press LLC FIGURE 16.1 Structures of some inhibitors of aflatoxin biosynthesis. To protect foods and feeds from aflatoxin contamination some antibiotics which inhibit the growth of the producing fungi are useful. However effective fungicides are usually toxic to mammals to some extent and their use can easily produce drug resistant strains.
