Novel Aromatic Carotenoid Derivatives from Sulfur Photosynthetic Bacteria in Sediments.

Novel aromatic carotenoid derivatives 7 and 8 have been identified by synthesis of reference compounds in a H2/PtO2-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.