New Isoflavones from Iris nigricans

Abstract

From the rhizomes of Iris nigricans (Iridaceae), two new isoflavones, 4'hydroxy-5 -methoxy-6,7 -methy lenedioxy isoflavone [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-6,7methylenedioxyisoflavone [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 isoflavonoid compounds (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• RESULTS AND DISCUSSIONCompound 1, C17H1206 from hrms, was obtained as yellow needles and showed significant eims ion peaks at miz 194 and 118 arising from the A and B rings by retro-Diels-Alder fission (10), and the number of carbons was confirmed from its 13C-nmr spectrum. The uv spectrum exhibited absorption maxima at 2 68 and 344 (sh) nm which are characteristic for a trioxygenated A-ring of an isoflavone derivative (11). The absorption maxima showed no shifts on addition of A1C13, indicating the absence of a free OH group at C-5 (11); this was also confirmed by the lack of a low-field singlet signal in the 'H-nmr spectrum (10-13 ppm) (10,11). Ir absorption bands were found at 3220 (free OH), 1668 (C=0), and 940 cm"1 (OCH20) (5,6).

New isoflavones fromIris kashmiriana

“…The signal for H-2 in 1-OAc was observed at d 8.33, establishing thereby the presence of the OH group in ring B at the 4 0 position. A one-proton singlet at d 7.02 in the 1 H NMR spectrum of 1 was assigned to C-5, instead of at C-8, on the basis of the fact that H-8 of 6,7-dioxygenated ring A is found at d 6.30 -6.70 [20]. This is also supported by the HSQC and HMBC experiment of 1 ( Figure 1).…”

Isoflavones and Other Compounds from the Roots of Iris marsica I. Ricci E Colas. Collected from Majella National Park, Italy

“…The initial one was 97/3 (v/v) but during the chromatographic run, this was changed in order to raise the polarity of the solution passing to 95/5 (v/v), 9/1 (v/v), 8/2 (v/v), 7/3 (v/v) and lastly, 6/4 (v/v). From this chromatographic separation seven compounds were identified: irigenin S (8) [25] in mixture with irisolidone (5) [17] in ratio 3:1 from fraction 3 for the weight of 6.8 mg; nigricin (6) [32], irigenin (7) as to cure many diseases affecting liver, lungs and uteri and to treat hemorrhoids [19]. Yet this is also true in China where particular species of Iris are utilized to treat coughing and pharyngitis [20,21] and also to reduce inflammation and relieve respiratory disorders [22].…”

“…The internal solvent signal (m5) at 3.31 ppm was used as reference for the spectra recorded in CD 3 OD, instead. Lastly, the HDO signal (s) at 4.78 ppm was set as reference for spectra in D 2 O. MS spectra were, instead, performed on a Q-TOF MICRO spectrometer irigenin S (8) [33] and 1,2-distearoyl-sn-glycerol (3) [30] as a mixture in ratio 1:2:1 from fraction 5 for the total weight of 8.9 mg; nigricin (6) [32] again in mixture with α-irigermanal (4) [34] in ratio 1:2 from the assembly of fractions 15-20 for the total weight of 10.2 mg; irigenin S (8) [25] again in mixture with irisflogenin (9) [17] in ratio 1:1 from the assembly of fractions 50-52 for the total weight of 2.6 mg; irisolidone 7-O-β-Dglucopyranoside (11) [35] as almost pure compound from the assembly of fractions 72-75 for the weight of 11.9 mg; iridin (12) and irilone 4'-O-β-D-glucopyranoside (13) [25] in mixture in ratio 1.5:1 from the assembly of fractions 81-83 for the total weight of 13.4 mg; again iridin (12) [25] but this time in mixture with tectoridin (14) [36] in ratio 2:1 from the assembly of fractions 91-107 for the total weight of 2.7 mg.…”

New Isoflavones and Flavanol from <i>Iris potaninii</i>

“…However, compound 3 is a new natural product. Compounds 4-8 were identified as 3Ј,4Ј,5Ј,5-tetramethoxy-6,7-methylenedioxyisoflavone, 10,13,14) 3Ј-methoxy-4Ј,5-dihydroxy-6,7-methylenedioxyisoflavone, 10,11,15) 3Ј,4Ј-dimethoxy-5Ј,5-dihydroxy-6,7-methylenedioxyisoflavone, 16,17) 4Ј,5-dimethoxy-3-hydroxy-6,7-methylenedioxyisoflavone, 18,19) and 5-methoxy-4Ј-hydroxy-6,7-methylenedioxyisoflavone 10) on the basis of their NMR spectral data and by comparison of their physical 1368 Vol. 50, No.…”