Cytochalasans Isolated From Chaetomium Globosum And Their Bioact1vity

Fungi have abundant species and are widely distributed. Since penicillin was found,fungal metabolities have been of considerable importance as novel active compounds forplant protection as well as medicine.Chaetomium has been proved to be a huge source of structurally diverse natural products.Up to now, it is reported that a variety of more than200secondary metabolites were isolatedfrom the fungus, including alkaloids, azaphilones, chromones and terpenoids. A majority ofthe compouds, especially chaetoglobosins, have possess significant bioactivity, such asanti-inflammatory, antitumor, antibiotic.By means of OSMAC(One strain many compounds), a study of alkaloids of endophytefrom the leaves of Ginkgo biloba is carried out. And their toxicity against brine shrimps andantimicrobial activities were assayed:Four compouds were isolated from C. globosum. Based on spectroscopic methods theirstructures were identified as chaetoglobosin V(1), chaetoglobosin Vb(2), chaetoglobosin G(3)and cyclo-(Gly-Phe)(4). Among them, chaetoglobosin Vb(2) is a new cytochalasan alkaloid.The co-occurrence of compounds1-3in the fungal cultures suggests that the three metaboliteshad the same biogenetic pathway. In biomimetic transformation, chaetoglobosin G could beconverted into chaetoglobosins V and Vbunder alkali conditions.In bioassay, chaetoglobosin G exhibited weak toxicity at the concentration of25μg·mL-1.Chaetoglobosins V and G showed significant antifungal activity towards Alternaria solani,with the minimum inhibitory concentration (MIC) of25μg·mL-1; chaetoglobosin G was moreactive against Alternaria alternate than against Fusarium graminearum. Chaetoglobosins Vand G were also discovered to possess moderate antibacterial activity against Pseudomonasaeruginosa and Bacillus cereusi. Besides, chaetoglobosins G exhibited inhibiting activityagainst Staphylococcus aureus, with their MICs of50μg·mL-1.In summary, the alkaloids isolated from the C. globosum in Ginkgo biloba and theirbioactivity were studied. Four metabolites were obtained, including a new compound.Furthermore, chaetoglobosins V and G had antimicrobial bioactivity.