Synthesis and paralytic activities of squaryl amino acid-containing polyamine toxins
Eight analogs 4a-7a and 4b-7b of philanthotoxin (PhTX) from wasp venom and nephilatoxin-8 (NPTX-8) from spider venom whose tyrosine or asparagine linker is replaced by squaryl (sq) amino acid or 4-amino squaryl (4-asq) amino acid have been synthesized in an efficient manner via coupling of N-acyl squaryl amino acid intermediate 19 or 26 with the corresponding polyamine part. Preliminary bioassay using crickets revealed that the analogs substituted by glutamate-type squaryl amino acid-containing NPTX 7a and 7b showed more potent paralytic activities than that of NPTX-8.
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