ABSTRACT
Si-enterobactin (2a), a hexacoordinated complex of the siderophore enterobactin (2b) with silicon as the central atom, was isolated from an endophytic Streptomyces sp. occurring in Piper guinensis roots. The structure and absolute configuration were determined from NMR and MS data, and by X-ray diffraction. The orientation of the molecule along the pseudo-3-fold axis shows that the coordination environment of the silicon atom complexed with three bidentate ligands is Δ. We assume that 2a or related complexes may be involved in the transport of silicon in plants, diatoms, or other silicon-dependent organisms.
Subject(s)
Enterobactin/metabolism , Silicon/metabolism , Streptomyces/metabolism , Biological Transport , Crystallography, X-Ray , Enterobactin/chemistry , Ligands , Molecular Conformation , Piper/microbiology , Plant Roots/microbiology , Silicon/chemistryABSTRACT
A new hopene-type triterpenoid, namely sonhafouonic acid 1a was isolated from Zehneria scabra camerunensis, together with eight known compounds. The structure of 1a was established by extensive NMR and high resolution MS techniques and confirmed by single-crystal X-ray crystallographic analysis. Compound 1a exhibited inhibitory activity against mycelial growth of two peronosporomycete phytopathogens Pythium ultimum and Aphanomyces cochliodes and cytotoxicity towards brine shrimp larvae (Artemia salina) at 10 µg/mL.
