A new photosystem II electron transfer inhibitor from Sorghum bicolor.
Our study of the mechanism(s) by which sorgoleone (1) acts as a photosystem II (PS II) inhibitor led to the isolation of a new benzoquinone derivative, 2-hydroxy-5-ethoxy-3-[(Z,Z)-8',11', 14'-pentadecatriene]-rho-benzoquinone (2), from the root exudate of sorghum. The structure of 2, which is being given the name 5-ethoxy-sorgoleone, was determined by spectroscopic means. A methoxy derivative (3) of 1 was also prepared. Both 2 and 3 caused a reduction in oxygen evolution by thylakoid membranes and induced variable chlorophyll fluorescence. These compounds, however, were less active inhibitors of PS II than 1.
USDA-ARS-NPURU, P.O. Box 8048, University, Mississippi 38677, USA. arimando@asrr.arsusda.gov
A M
AM
Rimando
F E
FE
Dayan
M A
MA
Czarnota
L A
LA
Weston
S O
SO
Duke
D016227:Benzoquinones / Q000737:chemistry / Q000302:isolation & purification* / Q000633:toxicity; D002240:Carbohydrate Sequence; D002734:Chlorophyll / Q000378:metabolism; D004579:Electron Transport / Q000187:drug effects*; D006540:Herbicides / Q000737:chemistry / Q000302:isolation & purification* / Q000633:toxicity; D008055:Lipids; D009682:Magnetic Resonance Spectroscopy; D013058:Mass Spectrometry; D008969:Molecular Sequence Data; D010100:Oxygen / Q000378:metabolism; D010788:Photosynthesis / Q000187:drug effects*; D010946:Plants, Medicinal / Q000737:chemistry*; D013055:Spectrophotometry, Infrared; D013056:Spectrophotometry, Ultraviolet; D018724:Spinacia oleracea / Q000378:metabolism
D016227:Benzoquinones; D006540:Herbicides; D008055:Lipids; C113738:sorgoleone; D002734:Chlorophyll; D010100:Oxygen