We do not currently know of any antonyms for polyoxin.
The noun polyoxin is defined as:
Any of a group of nucleosideantibiotics, produced by Streptomyces bacteria, composed of heterocyclicmoieties derived from amino sugars; the simplest being 1-β-(5'-amino5'-deoxy-D-allofuranuronosyl)-5-hydroxy-methyluracil