Found in old cultures of Pseudomonas pyocyanea. Isoln: Fordos, Compt. Rend. 56, 1128 (1863). Prepd from pyocyanine by the action of 2% NaOH: Wrede, Strack, Z. Physiol. Chem. 140, 12 (1924); by the reaction of pyrogallol monomethyl ether and o-phenylenediamine followed by demethylation of the formed α-methoxyphenazine: Surrey, Org. Synth. coll. vol. III, 753 (1955). Alternate syntheses: Hegedüs, Helv. Chim. Acta 33, 766 (1950); Vivian, Nature 178, 753 (1956).