The Study On Secondary Metabolites Of Marine Fungi Of Plasma Under The Treatments Mutagenesis And Chemical Induction

The secondary metabolic pathways of marine organisms are different from terrestrial organisms,and the secondary metabolites of marine fungi are more and more valued by the natural product chemists.Marine microorganisms contain rich active substances with novel structures.Most of them are alkaloids,terpenoids,macrolide compounds,unsaturated fatty acids,peptides,cyclic peptides,polyether,quinones,toxins,polysaccharide,enzymes,et al.Many substances have antibacterial,antiviral,antitumor,anti-cardiovascular and anti-cerebrovascular diseases,antioxidant,anti-inflammatory,enzyme inhibitory,anti parasite,and anti allergy effects.The discovery of these compounds provides important lead compounds for drug research and development.In this study,Aspergillus unguis DLEP2008001 was selected as starting strain.Its mutant strain 6-20-6 induced by the dielectric barrier discharge plasma was caltivated by M-PSB culture,for 10 L.Besides,the starting strain was also fermented in a chemical inducing medium Plocain-NaBr-PSB for 20 L.Their crude extracts of fermentation culture were separated and purified using Sephadex LH20 column,silica gel column,reversed phase column,and HPLC preparation.The structures of the compounds were identified by analysis of NMR and MS.A total of 11 compounds were isolated,8 compounds were identified,and some of the compounds were screened for preliminary biological activity.From the fermentation extracts of mutant strain 6-20-6,six compounds were eludidated,which are all depsidones.They were assessed for antibacterial activity,DPPH radical scavenging activity,inhibition of acetylcholinesterase activity.The results show that these depsidones have weak or moderate antibacterial,or anti Alzheimer related activity.This study shows that plasma mutagenesis and chemical induction,as effective mutation and induction means,can stimulate the strain to produce more novel bioactive compounds,fully exploit the strain's metabolism potential,and found new ways to solve 'drug supply',the bottleneck problem of marine drug research and to supply a large number of new candidate compounds.It also lays the foundation for further indepth research on the biosynthesis pathways of the active substances and the biological mechanisms for mutagenesis and induction.