Two sydowic acid derivatives and a sulfonyl metabolite from the endophytic fungus Aspergillus sydowii

Two new sydowic acid derivatives, a pair of enantiomers, involving (+)-sydowiccal (1a) and (-)-sydowiccal (1b), a new sulfonyl metabolite of 2-methoxy-5-methyl-3-(methylsulfonyl)phenol (2), as well as three known sydowic acid derivatives, were isolated from Aspergillus sydowii, an endophytic fungus of Rhododendron mole. The structures of these new compounds were elucidated by analyzing their NMR and HRESIMS data, and the absolute configurations of enantiomers were determined on the basis of the CD spectrum. Three new metabolites showed weak anti-inflammation on nitric oxide (NO) production in LPS-induced RAW 264.7 cells.