Isolierung und Strukturaufklärung von Naturstoffen aus Pilzen der Gattungen Mycena, Megacollybia und Tricholomopsis

Abstract

In the present work, new secondary metabolites were isolated from the higher fungi Mycena epipterygia, Megacollybia platyphylla and Tricholomopsis decora and their structure elucidated. Their ecological role was investigated by testing their antibacterial and herbicidal activity, so as to determine if they protect the fungi against bacteria or predators. In addition, more NMR data were collected for the full characterization of mycenarubin C 58 , first isolated from Mycena rosea by Peters. Mycenarubin C (33) has been known to evolve from the reaction of mycenarubin A (31) with formaldehyde, the latter being enzymatically released after injury of the fruiting body of Mycena rosea. This information was used to optimise the amount of mycenarubin C isolated from the fungi by treating the raw extract with a formaldehyde solution. The desired compound could then be isolated in high purity and the necessary experiments for its full characterization were performed. Mycenarubin A (31) Mycenarubin C (33) Subsequently, two new yellow compounds were isolated from Mycena epipterygia, another fungus of the genus Mycena. The molecular formula, as well as information about fragments of the first compound, denoted A, could be obtained from HR-( )-ESI-MS measurements. NMR experiments revealed the presence of more than one compound in the sample, making it difficult to interpret the different spectra. Attempts to clean the sample by size exclusion chromatography or the use of different solvents and gradient programmes for the HPLC separation remained unsuccessful. The second compound, denoted B, exhibited the same mass and similar fragmentation pattern as compound A in HR-( )-ESI-MS measurements. A distinct separation of both compounds on a C18ec column could not be achieved as they eluted in an interval of 0.5 min. Further investigations were hindered due to lack of more mushroom material. To obtain sufficient amount of both compounds for further investigation, large quantities of fruiting bodies would be required since Mycena epipterygia is a small fungus. Megacollybia platyphylla delivered two new chorismic acid derivatives, 3-(1-carboxyvinyloxy)-5-hydroxy-4-methoxybenzoic acid (42) and 3-(1-carboxyvinyloxy)-4, 5-dihydroxybenzoic acid (43). Their structures were fully characterized and their biological activity tested. Even though related compounds were found to exhibit antibacterial activity, compounds 42 and 43 neither showed inhibitory activity against the tested organisms nor did they exhibit herbicidal activity against the garden cress Lepidium sativum. 42: R = CH3 43: R = H An orange compound, denoted D, was isolated from the fungus Tricholomopsis decora. ESI-MS measurements exhibited an M H ion at m/z 804. Generating a molecular formula from such a high molecular mass proved to be very challenging, since six formulas were retained as potential candidates. By applying of the a seven golden rules for heuristic filtering of molecular formulasa and mostly due to the comparison of isotopic patterns, a molecular formula could be postulated. NMR experiments did not generate conclusive results due to the very low yield obtained from the HPLC separation. Further probing here again was interrupted due to shortage of the mushroom. Large quantities of fruiting bodies of Tricholomopsis decora would be needed for further investigations because compound D seems to occur in very low amount in the fungus.