chapter  3
Chemistry of Fungal Products
Pages 28

Nature has proven to be the richest source of biological and chemical diversity. Natural products still provide the majority of the world with a wide range of drugs and pharmaceuticals. Historically, fungi and actinomycetes have been found to be the most prolific producers of secondary metabolites among all microorganisms studied[1]. Fungi are a large group of ubiquitous microorganisms with more than 200,000 species distributed widely in soil, air, water, and found residing inside or on the skins of plants and animals. According to Whittaker in 1969[2], Kingdom Fungi includes slime molds and true fungi, and can be further classified into three subkingdoms: Gymnomycota (slime molds), Dimastigomycota (oosphere fungi), and Eumycota. Subkingdom Eumycota includes four phyla: Chytridiomycota (true chytrids and related fungi), Zygomycota (conjugation fungi), Ascomycota (sac fungi) and the Basidiomycota (club fungi). As a result of updates in nomenclature and systematic information over the last three decades (intensified even more by DNA sequence analyses), numerous changes have been made in the fungi names to reflect the phylogenetic situation[3]. Currently, Kingdom Fungi (true fungi) is divided into four major phyla: Chytridiomycota, Zygomycota, Ascomycota and Basidiomycota. The deutoromycetes are an additional true fungi group but are not recognized as a formal phylum[4]. The fungal body (thallus) is either a single cell or a threadlike multi-cell structure (hyphae), which constitutes the mycelium, and may give rise to multiform spore-producing cells. In most cases, these spore-producing cells form part of a special structure called the fruit body (sporocarp). “Mushroom” is a popular term applied to fungi that have this structure as seen with the naked eye[5]. Higher fungi (macrofungi or macromycetes), which produce these characteristic macroscopic fruiting bodies used to disperse their spores, include basidiomycetes, known as mushrooms, and members of the Clavicipitaceae, the Hypocreaceae, and the Xylariaceae in ascomycetes. There are approximately 10,000 species of higher fungi known in China, including edible and inedible mushrooms representing about 600 and 500 species, respectively, and some 100 strongly toxic and often lethal species[6].