Bioactive chromenes from Rhyncholacis penicillata.

Investigation of the aerial parts of Rhyncholacis penicillata afforded the new chromenes, 7-hydroxy-6-(3-methylbutyryl)-5-oxymethyl-chromene (rhynchonin A) and 7-hydroxy-6-(2-methylbutyryl)-6-oxymethylchromene (rhynchonin B). Structures were elucidated by spectroscopic methods and independent synthesis. Rhynchonin A showed broad insecticidal, acaricidal and nematicidal potency including strong biological activity against Heliothis zea.