Oxidative biosynthesis of phenylbenzoisochromenones from phenylphenalenones.

Max-Planck-Institut für Chemische Okologie, Beutenberg Campus, Winzerlaer Str. 10, D-07745 Jena, Germany.
Phytochemistry (Impact Factor: 3.05). 03/2003; 62(3):307-12. DOI: 10.1016/S0031-9422(02)00546-0
Source: PubMed

ABSTRACT 13C NMR analysis demonstrated incorporation of two 13C labelled phenylalanine units into phenylphenalenones and phenylbenzoisochromenones co-occurring in Wachendorfia thyrsiflora. These results suggest oxidative formation of phenylbenzoisochromenones following a late branching from a common phenylphenalenone biosynthetic pathway. A dioxygenase-type mechanism, followed by decarboxylation, is suggested for the key steps of this conversion.

  • [Show abstract] [Hide abstract]
    ABSTRACT: The biosynthetic origin of 1,2,5,6-tetraoxygenated phenylphenalenones and the sequence according to which their oxygen functionalities are introduced during the biosynthesis in Wachendorfia thyrsiflora were studied using two approaches. (1) Oxygenated phenylpropanoids were probed as substrates of recombinant W. thyrsiflora polyketide synthase 1 (WtPKS1), which is involved in the diarylheptanoid and phenylphenalenone biosynthetic pathways, (2) Root cultures of W. thyrsiflora were incubated with (13)C-labelled precursors in an (18)O(2) atmosphere to observe incorporation of the two isotopes at defined biosynthetic steps. NMR- and HRESIMS-based analyses were used to unravel the isotopologue composition of the biosynthetic products, lachnanthoside aglycone and its allophanyl glucoside. Current results suggest that the oxygen atoms decorating the phenalenone tricycle are introduced at different biosynthetic stages in the sequence O-1→O-2→O-5. In addition, the incubation of W. thyrsiflora root cultures with (13)C-labelled lachnanthocarpone established a direct biosynthetic precursor-product relationship with 1,2,5,6-tetraoxygenated phenylphenalenones.
    Phytochemistry 03/2012; · 3.05 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: A low loss 3×3-way phase combiner for power amplifier load balancing in 3-sector wireless network cells is presented. Based on an air-filled coaxial double ring structure this design combines very low insertion loss with compact physical profile. Exemplary, the concept is studied for the PCS (personal communication service) transmit band from 1.91 GHz to 1.99 GHz by simulations. Measurements validate the predicted very low insertion loss of 0.05 dB, while return loss and port isolation are both better than 25 dB.
    Microwave Symposium Digest, 2004 IEEE MTT-S International; 07/2004
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Hyphenated liquid chromatography - diode array detection - solid phase extraction - nuclear magnetic resonance spectroscopy (LC-DAD-SPE-NMR) was used to investigate the phytochemical composition of aerial parts and roots of Wachendorfia thyrsiflora (Haemodoraceae). Eleven phenylphenalenones and related compounds were identified in the aerial parts of the plant, ten compounds were found in the roots, and four additional compounds occurred in both plant parts. Twelve compounds are previously unreported natural products including five alkaloids (phenylbenzoisoquinolinones) are described here for the first time. In the work presented here, phenylphenalenones with an intact C(19) core structure were found only in the roots. Oxa analogs with a C(18)O scaffold occurred both in the roots and in the aerial plant parts, while most of the aza analogs with a C(18)N scaffold were detected in the aerial plant parts. This distribution pattern suggests that phenylphenalenones form in the roots, then the intact C(19) skeleton is converted into oxa analogs in the roots, translocated into the leaves and further reacted with amines or amino acids to form aza analogs (phenylbenzoisoquinolin-1,6-dione alkaloids).
    Phytochemistry 06/2012; 81:144-52. · 3.05 Impact Factor