Antimicrobial and Antiinsectan Phenolic Metabolites of Dalea searlsiae

Abstract

Continued interest in the chemistry of Dalea spp. led to investigation of Dalea searlsiae, a plant native to areas of the western United States. Methanol extractions of D. searlsiae roots and subsequent chromatographic fractionation afforded the new prenylated and geranylated flavanones malheurans A–D (1–4) and known flavanones (5 and 6). Known rotenoids (7 and 8) and isoflavones (9 and 10) were isolated from aerial portions. Structure determination of pure compounds was accomplished primarily by extensive 1D- and 2D-NMR spectroscopy. The absolute configurations of compounds 1–5, 7, and 8 were assigned using electronic circular dichroism spectroscopy. Antimicrobial bioassays revealed significant activity concentrated in the plant roots. Compounds 1–6 exhibited MICs of 2–8 μg/mL against Streptococcus mutans, Bacillus cereus, and oxacillin-sensitive and -resistant Staphylococcus aureus. Aerial metabolites 7–10 were inactive against these organisms, but the presence of 7 and 8 prompted investigation of the antiinsectan activity of D. searlsiae metabolites toward the major crop pest Spodoptera frugiperda (fall armyworm). While compounds 1–10 all caused significant reductions in larval growth rates, associated mortality (33–66%) was highest with flavanone 4 and rotenoids 7 and 8. These findings suggest a differential allocation of antimicrobial and antiinsectan plant resources to root and aerial portions of the plant, respectively.

Flavanoids from Dalea elegans: Chemical reassignment and determination of kinetics parameters related to their anti-tyrosinase activity

“…2). This structure has been reported in other species of Dalea genus (Nanayakkara et al, 2002;Belofsky et al, 2014).…”

Phenolic Metabolites of Dalea ornata Affect Both Survival and Motility of the Human Pathogenic Hookworm Ancylostoma ceylanicum

“…31 Specific rotations for these four compounds confirmed the absolute configurations that were previously established via ECD data. 31 The structures of the known compounds 5, 6 , and 9 were readily elucidated with 1D and 2D NMR spectroscopic data (Figures S19–S28, S33–S37, Supporting Information) and by HRESIMS data analysis.…”

“…31 Specific rotations for these four compounds confirmed the absolute configurations that were previously established via ECD data. 31 The structures of the known compounds 5, 6 , and 9 were readily elucidated with 1D and 2D NMR spectroscopic data (Figures S19–S28, S33–S37, Supporting Information) and by HRESIMS data analysis. Comparison of the 1D NMR data and specific rotations with published values confirmed the structures and absolute configurations of (−)-euchrenone-a7 ( 5 ), 36,37 (2 S )-leachianone G ( 6 ), 38–40 and (−)-deguelin ( 9 ) 41 as shown.…”

An Aspergillus flavus secondary metabolic gene cluster containing a hybrid PKS–NRPS is necessary for synthesis of the 2-pyridones, leporins

“…Freeze-dried diet disks were treated with either control solvent (acetone) or the LIC at a level to yield 1% in the rehydrated diet disk, then handled as described previously for caterpillar assays with 20 total caterpillars per treatment (Belofsky et al, 2014). The mortality and weights of survivors were recorded after two (corn earworm) or four (fall armyworm) days.…”