Purification of two substances from bulbs of onion (Allium cepa L.) with nematicidal activity against Meloidogyne exigua Goeldi

Abstract

Abstract To contribute to the development of a new method for Meloidogyne exigua Goeldi control, a nematode widely disseminated through Brazilian coffee fields, this work aimed to purify the nematicidal substances produced by onion (Allium cepa L.). Thus, the methanolic extract of onion bulbs was concentrated under reduced pressure and submitted to a purification process guided by in vitro assays with second-stage juveniles (J2) of M. exigua. After several steps, two nematicidal substances that seemed to be interconverting when in solution were isolated. When exposed to 500 ppm aqueous solutions of substances 1 and 2, 55 and 38% of the J2, respectively, were dead after 24 h. Very preliminary nuclear magnetic resonance spectroscopy studies suggested that these substances correspond to a pair of carbohydrates.