The residue of salinomycin in the muscles of olive flounder (Paralichthys olivaceus) and black rockfish (Sebastes Schlegeli) after oral administration analyzed by LC-Tandem-MS.

BACKGROUND: Salinomycin, an antibiotic, have potential as a veterinary drug for fish due to its anti-parasitic activity against several fish parasites. Thus the residual levels of salinomycin in muscles of two significant aquaculture species in Korea, olive flounder and black rockfish, were analyzed using HPLC-MS-MS. RESULTS: The proper method to analyze the residual salinomycin in fish muscles using LC-MS-MS was settled and the method was validated according to CODEX guidelines. The residues in three distinct groups for two fish species were analyzed using the matrix match calibration curves at points of five different times following oral administration. After oral administration, salinomycin rapidly breaks down in both olive flounder and black rockfish. After 7th days, the average residue in all groups of two fish spp. decreased below limit of quantitation (LOQ). CONCLUSION: Due to low residue levels in fish muscles, salinomycin may therefore be a treatment that is safe for both fish and humans. This result could contribute to establishment of MRL (minimal residual limit) for approval of salinomycin for use in aquaculture.

New secondary metabolites produced by Paraphoma radicina FB55 as potential antifungal agents.

Microorganisms in specific environments are rich sources of bioactive natural products as they produce compounds that can aid their survival in harsh environments. In an effort to investigate antifungal compounds produced by microorganisms, the fungal strain Paraphoma radicia FB55, isolated from a marine sediment of the Beaufort Sea, north of Alaska, was subjected to chemical investigation. Chromatography of the culture extracts yielded two new compounds (1 and 2) and eight known compounds (3-10). Their structures were determined using spectroscopic and chemical methods. Compound 1 was a new analog of the known compound (3) with an isobenzofuranone skeleton. The absolute configuration of the chiral center in 1 was established by comparison of its ECD and specific rotation values with those for a known analogue. Compound 2 is a polyketide-amino acid hybrid. Comprehensive Nuclear Magnetic Resonance (NMR) analysis indicated that 2 consisted of two substructures:5-methyl-6-oxo-2,4-heptadienoic acid and isoleucinol. The absolute configuration of the isoleucinol moiety in 2 was determined to be D using Marfey's method. All the isolated compounds were evaluated for antifungal activities. Although the antifungal activity of the isolated compounds was not potent, co-treatment of compounds 7 and 8 with a clinically available amphotericin B (AmB) lowered the IC50 values of AmB by synergism against human pathogenic yeast.

New Anti-Inflammatory ß-Resorcylic Acid Lactones Derived from an Endophytic Fungus, Colletotrichum sp.

The endophytic fungus Colletotrichum gloeosprioides JS0419, isolated from the leaves of the halophyte Suaeda japonica, produced four new ß-resorcylic acid derivatives, colletogloeopyrones A and B (1 and 2) and colletogloeolactones A and B (3 and 4), and seven known ß-resorcylic acid lactones (RALs). The structures of these compounds were elucidated via analysis of the high-resolution mass spectrometry and nuclear magnetic resonance data. Compounds 1 and 2 showed a dihydrobenzopyranone ring with a linear C9 side chain, which is rarely observed in RALs. All isolated compounds were evaluated for their anti-inflammatory activities. Colletogloeopyrone A (1), monocillin II (5), and monocillin II glycoside (6) were effective in reducing nitric oxide production without cytotoxicity. They also inhibited the secretion of interleukin-6 (IL-6) and tumor necrosis factor-α (TNF-α), as demonstrated by the expression of mRNA corresponding to IL-6 and TNF-α. Mechanistically, compounds 5 and 6 significantly inhibited the protein expression of nuclear factor-κB, IκBα, IKKα/ß, inducible nitric oxide synthase, and cyclooxygenase (COX)-2, whereas compound 1 only inhibited COX-2 expression. This study indicated that RAL-type compounds 1, 5, and 6 demonstrated potential anti-inflammatory activity by inhibiting the synthesis of pro-inflammatory cytokines.