New 1, 2-naphthoquinone-derived pigments from the mycobiont of lichen Trypethelium eluteriae Sprengel.

A new yellow pigment trypethelonamide A (1), and a new dark violet-red pigment 5'-hydroxytrypethelone (2), as well as three known dark violet-red pigments (+)-8-hydroxy-7-methoxytrypethelone (3), (+)-trypethelone (4) and (-)-trypethelone (5) were isolated from the cultured lichenized fungus Trypethelium eluteriae. The structures of 1 and 2 were determined to be 1, 2-naphthoquinone derivatives by extensive spectroscopic analysis. The absolute configurations of 1 and 2 were assigned by quantum electronic circular dichroism (ECD) calculation. All isolated compounds were evaluated for cytotoxicities against A549, HepG2 and RKO cell lines, and antioxidant effects on DPPH. Compounds 1-5 showed moderate and weak cytotoxicities against RKO cell line with IC50 from 22.6 to 113.5 μM.