Formed from ergosterol by fungi. Isoln from Penicillium chrysogenum: A. Saito, J. Ferment. Technol. 29, 457 (1951), C.A. 47, 12507f (1953). Structure: idem, ibid. 31, 141 (1953), C.A. 48, 5276d (1954); idem, ibid. 32, 138, 140 (1954), C.A. 49, 9009i (1955).