Josean F. Tavares, Marianna V. B. Silva, Karine F. Queiroga, Rodrigo M. Martins, Tania M. S., Silva, Celso A. Camara, Maria de F. Agra, José M. Barbosa-Filho, Marcelo S. da Silva* and Márcia O.M. Marques

Abstract: The volatile fraction of Xylopia langsdorffiana leaves was analyzed by GC and GC/MS and tested for molluscicidal activity. With this methodology 19 different components were identified in the oil. Among them, germacrene D (22.9%), trans-β-guaiene (22.6%), β-caryophyllene (15.7%), and α-pinene (7.3%) were found to be the major constituents. The oil showed significant molluscicidal activity against Biomphalaria glabrata, with an LC90 value of 5.6 μg/mL, which falls below the threshold of 100 μg/mL, set for potential molluscicidal activity by the World Health Organization.

Human schistosomiasis is estimated to affect 200 million people around the world, causing high levels of morbidity and mortality in 74 countries in tropical and subtropical areas. Aquatic snails (the intermediate hosts in which asexual reproduction of the parasites occurs) play a major role in the transmission of the schistosomes that cause the disease. Snail control strategies are considered a priority in the reduction of such transmission (1). In Brazil, the worm Schistosoma mansoni is the etiological agent, and it requires the aquatic snail Biomphalaria glabrata as the major intermediate host for transmission (2). The use of molluscicidals, from plant extracts or through synthesis, can form a useful part of an integrated strategy for schistosomiasis control (3,4). In the search for molluscicidal natural products, Hostettmann identified several active saponins against the snails that carry schistosomes and other important parasites (5). In the current decade, several species of aromatic plants have been found to have significant and potentially useful molluscicidal activity (6–9). Apart from the molluscicidal activity of essential oils, several other biological activities have been reported, including antimicrobial activities (10–13). These properties are probably due to the multiple components of these complex mixtures which are facilitated by their prompt diffusion across cell membranes. Individual oils may have hundreds of constituents, with terpenes (monoterpenes and sesquiterpenes) and their oxygenated derivatives as major components. Other compounds include phenol ethers, phenylpropenes, etc., and specific compounds containing sulfur or nitrogen. Annonaceae is one of the largest Magnoliid families, with ca. 128 genera and 2300 species, mostly pantropical (14). In Brazil, the Annonaceae comprise 26 genera (seven endemic) and ca. 260 species (Mello-Silva, pers comm.), the majority occurring in forests, with few representatives in open areas. The members of this family play a significant role in the composition of Brazilian vegetation and represent a subject of great interest. The Annonaceae are known for their edible fruit and medicinal properties (15). The genus Xylopia contains approximately 150 species (16). The aim of the present study was to explore the molluscicidal activities of the essential oil from Xylopia langsdorffiana A. St. Hil.et Tul., using Biomphalaria glabrata as the target snail. This species grows abundantly in northeastern Brazil and the occurrences of bioactive compounds in the oil of other Xylopia spp encourage us to perform the present study.