Synonyms: Viroisin,3-[(S)-4,5-dihydroxy-L-leucine]-;1H-Pyrrolo[1,2-a][1,4,7,10,13,16,19]heptaazacycloheneicosine, cyclic peptidederiv.; Cyclo[L-alanyl-2-(methylsulfonyl)-L-tryptophyl-(S)-4,5-dihydroxy-L-leucyl-L-valyl-D-threonyl-D-seryl-(3R-trans)-3,4-dihydroxy-L-prolyl]