New diketopiperazine dimers and 4-hydroxyphenylacetates from an endolichenic fungus Aspergillus sp.

Two novel diketopiperazine dimers (1 and 2) and two new 4-hydroxyphenylacetates (5 and 6), along with two previously known diketopiperazine dimers were isolated from the culture of the endolichenic fungus Aspergillus sp. CPCC 400810. Their structures were determined through comprehensive spectroscopic analysis, including high-resolution electrospray ionization mass spectrometry (HRESIMS) and 1D and 2D nuclear magnetic resonance (NMR) data. The absolute configurations of the new compounds were confirmed using Marfey's method and chemical synthesis.
Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.
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