Pentacyclic Cytochalasins and Their Derivatives from the Endophytic Fungus Phomopsis sp. xz-18

Abstract

Eight new cytochalasins 1–8 and ten known analogs 9–18 were isolated from the endophytic fungus Phomopsis sp. xz-18. The planar structures of the cytochalasins were determined by HR-ESI-MS and NMR analysis. Compounds 1, 2, 9 and 10 were 5/6/6/7/5-fused pentacyclic cytochalasins; compounds 3 and 4 had conjugated diene structures in the macrocycle; and compound 6 had a β,γ-unsaturated ketone. The absolute configuration of 6 was confirmed for the first time by the octant rule. The acid-free purification process proved that the pentacyclic system was a natural biosynthetic product and not an acid-mediated intramolecular cyclized artifact. The new compounds did not exhibit activities against human cancer cell lines in cytotoxicity bioassays or antipathogenic fungal activity, but compounds 1, 3 and 4 showed moderate antibacterial activity in disk diffusion assays.

Bioactive Compounds Produced by Endophytic Microorganisms Associated with Bryophytes—The “Bryendophytes”

“…For example, Phoma herbarum isolates did not produce any significant beneficial or detrimental effect on M. polymorpha growth [ 45 ]. Studies of endophyte biodiversity in M. polymorpha may also contribute to the knowledge of ecological factors determining the microbiomes assembly because this species is often found as an early colonizer after fire-induced damage [ 47 , 48 ].…”

“…Structurally, cytochalasins have a highly substituted perhydroisoindol-1-one moiety, which is fused with a 9- to 15-membered macrocyclic ring. Many cytochalasins exhibit a wide range of biological activities, such as cytotoxic, antimicrobial, and phytotoxic properties [ 48 , 72 , 73 , 74 ]. Indole alkaloids are another group of compounds represented among plant endophytes.…”