Isolation and identification of root-inhibiting compounds from corn gluten hydrolysate

Interest has centered on the use of plantderived compounds as natural herbicides, and they are considered to represent an environmentally sound approach to weed control. Corn gluten hydrolysate, found to have a growth-regulating effect on the root system of germinating grass seeds, has been suggested as a natural herbicide. A protocol was developed to extract, isolate, and identify the root-inhibiting compounds from corn gluten hydrolysate aqueous solution and a perennial ryegrass (Lolium perenne L.). A Petri dish bioassay was used to test the root-inhibiting activity. Five bioactive dipeptides were isolated by using Sephadex G-15 gel filtration, solid-phase extraction, and C18 reversed-phase high-performance liquid chromatography procedures. The five dipeptides were glutaminyl-glutamine, alaninyl-asparagine, alaninyl-glutamine, glycinyl-alanine, and alaninyl-alanine. Their root-inhibiting activity on perennial ryegrass was demonstrated in Petri dish bioassays.Journal Paper No. J-15597 of Iowa Agriculture and Home Economics Experiment Station, Ames, IA Project No. 3149