Antiviral anthraquinones and azaphilones produced by an endophytic fungus Nigrospora sp. from Aconitum carmichaeli.

Abstract A new hydroanthraquinone derivative, 6- O -demethyl-4-dehydroxyaltersolanol A ( 1 ), and two new azaphilones, 8,11-didehydrochermesinone B ( 6 ) and (7 S )-7-hydroxy-3,7-dimethyl-isochromene-6,8-dione ( 8 ), along with five known analogues ( 2–5 and 7 ), were isolated from the culture broth of Nigrospora sp. YE3033, an endophytic fungus obtained from Aconitum carmichaeli . Their structures were elucidated on the basis of spectroscopic analyses. Biological activity test indicated that compounds 1 – 3 , and 7 exhibited the inhibitory effects on influenza viral strain of A/Puerto Rico/8/34 (H1N1) with the IC 50 values of 2.59, 8.35, 7.82, and 0.80 μg/mL, respectively, while the low cytotoxicity of 7 with the CC 50 value of 184.75 μg/mL, displaying a promising potential of 7 in the development of anti-influenza A virus drugs.