Novel aromatic carotenoid derivatives from sulfur photosynthetic bacteria in sediments

Abstract Novel aromatic carotenoid derivatives 7 and 8 have been identified by synthesis of reference compounds in a H 2 /PtO 2 -hydrogenated fraction from the organic extract of a lake sediment (lake Cadagno, Switzerland). They derive from unreported carotenoids presumably biosynthesized by purple sulfur photosynthetic bacteria ( Chromatiaceae ) and represent potential biomarkers to establish the occurrence of photic zone anoxia in ancient ecosystems.