Nigrosphaerin A a new isochromene derivative from the endophytic fungus Nigrospora sphaerica.

Abstract Nigrosphaerin A, a new isochromene derivative ( 1 ), was isolated from the endophytic fungus Nigrospora sphaerica and chemically identified as 3-(3,4-dihydroxyphenyl)-4,6,8-trihydroxy-1H-isochromen-1-one-6-O- β - d -glucopyranoside. In addition nineteen known compounds ( 2 – 20 ) were isolated from the same fungus and chemically identified. Compounds ( 1 – 3 , 5 , and 7 – 16 ) were isolated for the first time from this fungus. In vitro antileukemic, antileishmanial, antifungal, antibacterial and antimalarial activities of ( 1 – 20 ) were examined. Compounds 5 , 7 , 9 and 10 showed good antileukemic activity against HL60 cells with IC 50 values of 0.03, 0.39, 0.2 and 0.4 μg/mL, respectively and against K562 cells with IC 50 values of 0.35, 0.35, 0.49 and 0.01 μg/mL, respectively. Compounds 3 , 4 and 6 showed moderate antileishmanial activity with IC 50 values of 30.2, 26.4 and 36.4 μg/ml, respectively. Compound 7 showed moderate antifungal activity against Cryptococcus neoformans with IC 50 value of 14.8 μg/mL.