Chemical composition and acetylcholinesterase inhibition of essential oil from leaves, flowers and fruits of Bidens segetum Mart. Ex Colla - Nascimento, Anderson Luis do; Silva, M. C.; Souza, Amanda de; Cardoso-Lopes, Elaine Monteiro; Moreno, Paulo Roberto Hrihorowitsch; Young, Maria Claudia Marx (Simpósio de Plantas Medicinais do Brasil, 2008)