Antimicrobial Isopropenyl-dihydrofuranoisoflavones from Crotalaria lachnophora

Abstract

Two new isopropenyl-dihydrofuranoisoflavones exhibiting antimicrobial properties have been isolated along with eight known compounds from the Cameroonian medicinal plant Crotalaria lachnophora. The structures of the new compounds were elucidated by 1D and 2D NMR spectroscopy and high-resolution mass spectrometry as 7,2',4'-trihydroxy-5''-isopropenyl-4'',5''-dihydrofurano[2'',3'':5,6]isoflavone (1) and 4,8-dihydroxy-2-isopropenyl-2,3-dihydro-5H-[1]benzofuro[2,3-b]furo[3,2-g]chromen-5-one (2). The CH(2)Cl(2)/MeOH (1:1) extract and the compounds isolated were subjected to in vitro antimicrobial assays against a panel of pathogenic microorganisms, including Gram-positive and Gram-negative bacteria and fungi. The new compounds, named lachnoisoflavones A (1) and B (2), showed moderate inhibitory activities against Escherichia coli and Klebsiella pneumoniae.

Superbanone, A New 2‐Aryl‐3‐benzofuranone and Other Bioactive Constituents from the Tube Roots of Butea superba

“…Compounds 3 -21 were identified by comparison of their spectroscopic data with those reported in the literature values as flemichapparin B (3), [10] [11] anhydrovariabilin (4), [12] 3,6a, 9-trimethoxypterocarpan (5), [13] (-)-variabilin (6), [14] (À)-phaseolin (7), [15] medicarpin (8), [16] (-)-maackiain (9), [6] phaseollidin (10), [17] biochanin A (11), [18] sophorophenolone (12), [19] 8-O-methylretusin (13), [20] afromosine (14), [21] formononetin (15), [22] cajanin (16), [22] and 4 0 ,7-dihydroxy-2 0 ,6-dimethoxyisoflavone (17). [23] The chemical property of the acetylated sub-fraction of this plant led to the isolation of isoflavone derivatives named 3-(benzo[d] [1,3]dioxol-5-yl)-4-oxo-4H-chromen-7-yl acetate (18), 7-acetoxy-4 0 -methoxyisoflavone (19), [24] 4 0 ,6 0 -diacetoxy-5-hydroxy-7-methoxyisoflavone (20), and 4 0 -acetoxy-5-hydroxy-7-methoxyisoflavone (21) which can be inferred back to the previously assigned structures named pseudobaptigenin, [25] formononetin (15), and cajanin (16), respectively (Fig.…”

Isoflavones and pterocarpans from Caragana changduensis

“…Compounds 14 and 15 usually co-occur in the same plant (Chin et al, 2008;Jutiviboonsuk et al, 2005) and 15 has also been isolated from Caragana rosea (Cui et al, 2003). Compound 13 was previously reported from Annona senegalensis (Annonaceae) (You et al, 1995), Phacellaria compressa (Santalaceae) (Zhang et al, 2006), and Acanthopanax senticosus (Araliaceae) (Zhang et al, 2012), suggesting these families may share some similar metabolic pathways.…”

“…Phytochemical investigations of Caragana species have led to the identifications of a variety of compounds as potential bioactive constituents, including flavonoids (Shi et al, 2003), stilbenoids (Luo et al, 2001), terpenoids (Sun et al, 2004 and phenylpropanoids (Cui et al, 2003). A review of phytochemical studies of the genus Caragana revealed that flavonoids constituted the majority of the isolated compounds (Meng et al, 2009).…”

“…Compound 9 has been obtained from Taverniera abyssinica (Duddeck et al, 1987) and Dalbergia sissoo (Shrestha et al, 2007), and compound 10 has been obtained from Dalbergia spruceana (Cook et al, 1978), Sophora stenophylla (Ohyama et al, 1988), and Psorothamnus arborescens (Salem and Werbovetz, 2006). The occurrence of compounds 9 and 10 in genera that belong to the Fabaceae demonstrates that the capability to biosynthesize pterocarpans is common to genera within this family.…”

“…(Basha et al, 2013), 7,3 0 ,4 0 -trihydroxyisoflavone (3)(Wang et al, 2010), calycosin (4)(Cui et al, 1993), 6,7,3 0 -trihydroxy-4 0 -methoxy-isoflavone (5)(Shrestha et al, 2007), cajanin (6)(Awouafack et al, 2011), (À)-maackiain (7)(Baruah et al, 1984), (6aR,11aR)-4-hydroxy-3,9-dimethoxypterocarpan (8)(Lotti et al, 2010), (6aR,11aR)-3,4-dihydroxy-9-methoxypterocarpan(9)(Piccinelli et al, 2005), (6aR,11aR)-3,4-dihydroxy-8,9-methylenedioxypterocarpan (10) (Salem and Werbovetz., 2006), isoliquiritigenin (11) (Kitagawa et al, 1993), (3R)-vestitol (12) (Yahara et al, 1989), 2,3-bis [(4-hydroxy-3,5-dimethoxyphenyl)-methyl]-1,4-butanediol (13) (Perez et al, 1995), 5-methoxy-(þ)-isolariciresinol (14) (Zhang et al, 1999), (þ)-isolariciresinol (15) (Okuyama et al, 1995) (Fig. 1).…”