From the rhizomes of Iris nigricans (Iridaceae), two new isoflavones, 4'-hydroxy-5-methoxy-6, 7-methy lenedioxyisoflavone [1](nigricin) and 4'-hydroxy-5, 3'-dimethoxy-6, 7-methylenedioxyisoflavone [3](nigricanin), were isolated and characterized, along with 5, 4'-dihydroxy-6, 7-methylenedioxyisoflavone [4](irilone), 5, 3'-dihydroxy-4', 5'-dimethoxy-6, 7-methylenedioxyisoflavone [5], acetovanillone, ferulic acid, ß-sitosterol and sucrose. The new structures were established by spectroscopic and chemical methods.

Iris nigricans Dinsmore (Iridaceae) is a perennial herb with a stout and compact rhizome. It is endemic in the fallow fields and steppe habitats of Jordan and is known by the common name “sawsan aswad,” which refers to the dark brown-purple color of the flower (1, 2). There have been no reports on the chemical constituents of this species. The genus, however, is rich in isoflavonoidcompounds (3-6). Isoflavonoids have drawn considerable attention, because they have anti-mutagenic activity (7), and inhibitory effects on protein tyrosine kinase (8) and on pulmonary tumor promotion (9). In addition, cytotoxic compounds have been isolated from I. missouriensis (3, 4). This paper deals with the isolation and characterization of two new isoflavones, 1 and 3·