| Abstract
| - Sorgoleone, 2-hydroxy-5-methoxy-3-[(8‘Z,11‘Z)-8‘,11‘,14‘-pentadecatriene]-p-benzoquinone (1), andits corresponding hydroquinone are the major components of the root exudate of Sorghum bicolor.The name sorgoleone includes minor analogues differing in the length or degree of unsaturation ofthe 3-alkyl side chain. These compounds are known to be phytotoxic, probably through inhibition ofphotosystem II (PSII) driven oxygen evolution, as previously demonstrated for 1. Isolation of thesesorgoleone congeners was achieved by C8 column chromatography and argentation thin-layerchromatography, and the purified compounds were structurally characterized. The abilities of theminor sorgoleones to inhibit PSII were similar to that of the major compound, suggesting that all ofthese sorgoleone congeners contribute to the overall allelopathy of sorghum. Keywords: Sorghum; sorgoleone; allelopathy; argentation chromatography; column chromatography;congeners; phytotoxicity; oxygen evolution; roots
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