Antimicrobial and antiinsectan phenolic metabolites of Dalea searlsiae.
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.
Department of Chemistry, Central Washington University , Ellensburg, Washington 98926, United States.
Gil
G
Belofsky
Mario
M
Aronica
Eric
E
Foss
Jane
J
Diamond
Felipe
F
Santana
Jacob
J
Darley
Patrick F
PF
Dowd
Christina M
CM
Coleman
Daneel
D
Ferreira
D000818:Animals; D000890:Anti-Infective Agents / Q000737:chemistry / Q000302:isolation & purification* / Q000494:pharmacology*; D007887:Fabaceae / Q000737:chemistry*; D044950:Flavanones / Q000737:chemistry / Q000302:isolation & purification* / Q000494:pharmacology*; D005419:Flavonoids / Q000737:chemistry; D007814:Larva / Q000187:drug effects; D008826:Microbial Sensitivity Tests; D015394:Molecular Structure; D010068:Oxacillin / Q000494:pharmacology; D010636:Phenols / Q000737:chemistry / Q000302:isolation & purification* / Q000494:pharmacology*; D018517:Plant Roots / Q000737:chemistry; D018411:Spodoptera / Q000187:drug effects; D013211:Staphylococcus aureus / Q000187:drug effects / Q000235:genetics
D000890:Anti-Infective Agents; D044950:Flavanones; D005419:Flavonoids; D010636:Phenols; D010068:Oxacillin; C028610:flavanone