Essential oils from Alpinia purpurata (Zingiberaceae): Chemical composition, oviposition deterrence, larvicidal and antibacterial activity

Essential oils and aqueous extracts were obtained by hydrodistillation of flowers of red and pink variants of Alpinia purpurata (Zingiberaceae), a widely cultivated tropical ornamental plant. GC/MS analyses revealed the presence of 42 essential oil components with alpha-pinene, beta-pinene and beta-caryophyllene being the major constituents. Oils from the red and pink variants presented potent larvicidal activities against 4th instar Aedes aegypti with LC50 values of 80.7 and 71.5 ppm, respectively. Aqueous extracts of the two variants were also active against the dengue mosquito larvae (LC50 values of 18.3 and 12.6%. respectively). Oils and aqueous extracts of both variants showed significant oviposition deterrent effects at concentrations of 100 ppm and 20%, respectively. Oil from the red cultivar inhibited significantly the growth of gram-positive and gram-negative bacteria. The study demonstrates that products with valuable biological activities can be produced from flowers of A. purpurata that are not of commercial quality. (C) 2012 Elsevier B.V. All rights reserved.