ABSTRACT
The griseorhodins belong to a family of extensively modified aromatic polyketides that exhibit activities such as inhibition of HIV reverse transcriptase and human telomerase. The vast structural diversity of this group of polyketides is largely introduced by enzymatic oxidations, which can significantly influence the bioactivity profile. Four new compounds, griseorhodins D-F, were isolated from a griseorhodin producer, Streptomyces sp. CN48+, based upon their enhancement of calcium uptake in a mouse dorsal root ganglion primary cell culture assay. Two of these compounds, griseorhodins D1 and D2, were shown to be identical to the major, previously uncharacterized products of a grhM mutant in an earlier griseorhodin biosynthesis study. Their structures enabled the establishment of a more complete hypothesis for the biosynthesis of griseorhodins and related compounds. The other two compounds, griseorhodins E and F, represent new products of post-polyketide synthase tailoring in griseorhodin biosynthesis and showed significant binding activity in a human dopamine active transporter assay.
Subject(s)
Naphthoquinones/isolation & purification , Naphthoquinones/pharmacology , Polyketides/isolation & purification , Polyketides/pharmacology , Streptomyces/chemistry , Animals , Dopamine Agonists/chemistry , Dopamine Agonists/isolation & purification , Humans , Mice , Molecular Structure , Multienzyme Complexes/metabolism , Multigene Family , Naphthoquinones/chemistry , Nuclear Magnetic Resonance, Biomolecular , Philippines , Polyketide Synthases/metabolism , Polyketides/chemistry , Streptomyces/genetics , Telomerase/antagonists & inhibitorsABSTRACT
The bacterium Gordonia sp. 647W.R.1a.05 was cultivated from the venom duct of the cone snail, Conus circumcisus. The Gordonia sp. organic extract modulated the action potential of mouse dorsal root ganglion neurons. Assay-guided fractionation led to the identification of the new compound circumcin A (1) and 11 known analogs (2-12). Two of these compounds, kurasoin B (7) and soraphinol A (8), were active in a human norepinephrine transporter assay with Ki values of 2575 and 867 nM, respectively. No neuroactivity had previously been reported for compounds in this structural class. Gordonia species have been reproducibly isolated from four different cone snail species, indicating a consistent association between these organisms.
Subject(s)
Biological Products/pharmacology , Conus Snail/microbiology , Fatty Alcohols/pharmacology , Gordonia Bacterium/physiology , Action Potentials/drug effects , Animals , Biological Products/chemistry , Biological Products/isolation & purification , Biological Products/metabolism , Cells, Cultured , Fatty Alcohols/chemistry , Fatty Alcohols/isolation & purification , Fatty Alcohols/metabolism , Ganglia, Spinal/cytology , Humans , Mice , Neurons/cytology , Neurons/drug effects , Norepinephrine Plasma Membrane Transport Proteins/metabolism , SymbiosisABSTRACT
In the oceans, secondary metabolites often protect otherwise poorly defended invertebrates, such as shell-less mollusks, from predation. The origins of these metabolites are largely unknown, but many of them are thought to be made by symbiotic bacteria. In contrast, mollusks with thick shells and toxic venoms are thought to lack these secondary metabolites because of reduced defensive needs. Here, we show that heavily defended cone snails also occasionally contain abundant secondary metabolites, γ-pyrones known as nocapyrones, which are synthesized by symbiotic bacteria. The bacteria, Nocardiopsis alba CR167, are related to widespread actinomycetes that we propose to be casual symbionts of invertebrates on land and in the sea. The natural roles of nocapyrones are unknown, but they are active in neurological assays, revealing that mollusks with external shells are an overlooked source of secondary metabolite diversity.
Subject(s)
Actinobacteria/physiology , Mollusca/microbiology , Mollusca/physiology , Polyketides/metabolism , Pyrones/metabolism , Symbiosis , Actinobacteria/chemistry , Animals , Mollusca/chemistry , Polyketides/chemistry , Pyrones/chemistryABSTRACT
New compounds nobilamides A-H and related known compounds A-3302-A and A-3302-B were isolated based upon their suppression of capsaicin-induced calcium uptake in a mouse dorsal root ganglion primary cell culture assay. Two of these compounds, nobilamide B and A-3302-A, were shown to be long-acting antagonists of mouse and human TRPV1 channels, abolishing activity for >1 h after removal of drug presumably via a covalent attachment. Other derivatives also inhibited the TRPV1 channel, albeit with low potency, affording a structure-activity profile to support the proposed mechanism of action. While the activities were modest, we propose a new mechanism of action and a new site of binding for these inhibitors that may spur development of related analogues for treatment of pain.