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

AbstractA 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.