Abstract
Seven resorcylic acid lactones (RALs) including five new analog rhinoclactones, A–E (1, 2, 4–6), were isolated from an endophytic fungus Rhinocladiella similis in the plant Agriophyllum squarrosum collected from the Tengger Desert of the Ningxia Province, China. The structures of these new compounds were determined by HR-ESI-MS (High Resolution Electrospray Ionization Mass Spectrometry), NMR data, modified Mosher’s method, and X-ray diffraction experiments. All compounds isolated from this fungus possessed the 16-OMe/14-OH, not the common 16-OH/14-OH or 16-OH/14-OMe groups on the aromatic ring, which are rarely found in nature. Compound 7 displayed cytotoxic activities against HCT116 and HeLa cancer cell lines. The possible biosynthesis of 1–7 is suggested, and the potential ecological roles of these fungal secondary metabolites is discussed.
Highlights
Resorcylic acid lactones (RALs) are fungal polyketides constructed by a 1, 3-benzenediol moiety fused with a macrocyclic lactone ring
The different degree of oxidation, unsaturation, and rearrangement on the macrolide ring together with methylation and chlorination on the aromatic ring diversify this group of natural products [1,2,3,4]
C-18) in RAL structures play a crucial role in the inhibition of Heat shock protein 90 (Hsp90) [4]
Summary
Resorcylic acid lactones (RALs) are fungal polyketides constructed by a 1, 3-benzenediol moiety fused with a macrocyclic lactone ring. In order to further mine new/novel and bioactive secondary metabolites from this special member of fungi, seven RAL analogs (1–7), including five new varieties (1, 2, 4–6) with different modifications on the macrolactone ring and phenolic ring, were isolated from an endophytic fungus Rhinocladiella similis from the plant. Molecules 2019, 24, x including the relative and absolute configurations, were established by NMR data, X-ray diffraction. 2019, 1405 chemical including the24,relative and absolute configurations, established by NMR data,and. Possible biogenetic pathways of 1–7 are presented, and theevaluations potentially ecological roles of thisthe endophytic biogenetic ofBioactive. 1–7 are presented, the potentially of thispathways endophytic fungus are pathways discussed. 1–7 are presented, and the potentially ecological roles of this endophytic fungus are discussed
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