Studies On The Secondary Metabolites And Bioactivities Of Chaetomium Globosum And Periconia Sp.

The paper is divided into three chapters.The first chapter mainly discusses the chemical constituents and biological activities of Chaetomium globosum isolated from Armadillidium vulgare.The second chapter introduces the studies on secondary metabolites and biological activities of Periconia sp.,and proposes the biosynthetic pathway of the isolated new ergostane skeleton.The third chapter reviews the research progresses of rearranged ergostane-type natural products in the recent literature.Fungi are a large group of eukaryotic organismsand belong toa fungal kingdom different from plants,animals,and bacteria.The fungal kingdom encompasses an enormous diversity of taxa with varied ecologies,life cycle strategies,and morphologies ranging from unicellular aquatic chytrids to large mushrooms.However,little is known about the true biodiversity of kingdom fungi,which have been estimated at 2.2 million to 3.8 million species.Of these,only about 120,000 have been described,with over 8,000 species known to be detrimental to plants and at least 300 that can be pathogenic to humans.The metabolites produced by fungi are also diverse and mostly have good bioactivity.Many fungal metabolites have been developed into drugs that we use today,such as most antibiotics,lovastatin produced in Aspergillus terreus,and so on.In the previous study,our research team isolated a strain of Chaetomium globosum from Armadillidium vulgare.A large number of structural complex cytochalasins have been isolated by large-scale fermentation of rice solids.In order to further excavate the chemical diversity of metabolites of this strain,the culture conditions were changed during the solid fermentation,and many previously undescribed structures were were isolated.A total of 45 compounds were isolated from methanol extracts,including 17 new compounds,the main components of which are cytochalasin compounds.Azaphilones and other types of compounds have also been isolated.Their structures including absolute configurations were elucidated by means of NMR spectroscopy,single-crystal X-ray crystallography,and comparison of the experimental electronic circular dichroism(ECD)spectra.Structurally,we obtained the first tyrosine-derived cytochalasan alkaloid characterized by a 13-membered carbocyclic ring system,chaetoglobosin analogues processing a rare 19,20-seco-chaetoglobosin skeleton,and the first cases of 1?-N-methyl-chaetoglobosins,which were possibly biosynthesized from the additive 1-MT rather than tryptophan.We have initially screened the cytotoxic activity of some of the isolated compounds,some of which showed certain biological activity.At the same time,we also evaluated the activity of some compounds against drug-resistant microorganisms,and some of them showed good potential.Our reaserch can provided compound bases for further research against drug-resistant microorganisms.In addition,we studied the secondary metabolites of the methanol extracts of solid fermentation of Periconia sp.from the leaves of the Rosa chinensis Jacq..A total of 25 compounds,including 16 new compounds were isolated.Among them,there is a rare new ergostane-type steroid possesssing a bicyclo[2.2.2]octane system,compared with the typical 6/6/6/5 tetracyclic skeleton of the steroid,it forms a new ring system;There is also novel ergostane-type steroid derivative with a bicyclo[3.3.1]nonane motif.Furthermore,triterpenes,sesquiterpenes and chain small molecule compounds were also isolated.In this paper,we systematically studied the secondary metabolites of Chaetomium globosum isolated from Armadillidium vulgare and the Periconia sp.isolated from the leaves of the Rosa chinensis Jacq..The results show that both endophytic fungi have strong genetic coding ability for novel and unique secondary metabolites.At the same time,through the bioactivity screening,these findingslay a solid foundation for further pharmacological researches.