SHORT COMMUNICATION Acaricidal activity of the hyacinthacine analogues derived from pyrrolizidine alkaloids on Rhipicephalus (Boophilus) microplus Mônica Oliveira Duarte & Stela Regina Ferrarini & Mariane Pazinatto & Eduardo Rolim de Oliveira & Verônica Rolim & Vera Lucia Eifler-Lima & Vera Lucia Sardá Ribeiro & Gilsane von Poser Received: 22 January 2008 / Accepted: 30 April 2008 / Published online: 30 May 2008 # Springer-Verlag 2008 Abstract This study reports the effect of six hyacinthacine analogues derived from pyrrolizidine alkaloids on egg hatchability and mortality rates of newly hatched larvae of the cattle tick Rhipicephalus (Boophilus) microplus. All the compounds were toxic to the larvae of the ticks and inhibited the eggs hatchability in the higher concentration tested (5 μg/ml). Even in the lowest concentration (0.625 μg/ml), some effect in the eggs hatchability was observed. Introduction Pyrrolizidine alkaloids are toxic to some mammals, have anti-fungal activity and are mutagenic to Drosophila melanogaster . Pyrrolizidine alkaloids are known to deter generalist insect herbivores while specialist herbivores can detoxify and sequester these compounds (Macel et al. 2005). The effect of some pyrrolizidine alkaloids was investigated against the two-spotted spider mite (Tetranychus urticae) and it was demonstrated that mites treated with these compounds showed a high mortality of juveniles, a decrease in female fecundity and a shortened longevity (Pietrosiuk et al. 2003). Other interesting compounds from this class are the lolines, saturated pyrrolizidines with an exo-1-amine and an ether bridge between C-2 and C-7. Lolines with dimethylated or acylated 1-amines have insect anti-feedant and insecticidal activities comparable to nicotine, but little or no toxicity to mammals (Schardl et al. 2007). In the last years, the hyacinthacines, a group of pyrrolizidine alkaloid derivatives, have shown interesting biological properties. Some of these compounds demon- strated inhibitory activities against a variety of glycosidases (Asano et al. 2000). Recently, much attention has focused on the synthesis and development of glycosidase inhibitors because of an increasing awareness of the vital role played by carbohydrates in biological processes. The glycosidase inhibitors found utility as anti-diabetes, anti-fungals, anti- virals and anti-obesity drugs as well as insecticidal agents (Cardona et al. 2003; Desvergnes et al. 2005). Rhipicephalus (Boophilus) microplus (Canestrini 1887; the single host tick) constitutes a major problem for the cattle industry in tropical and subtropical regions of the world. It causes blood loss and reduction in weight gain. This tick is vector of several diseases such as bovine babesiosis (severe tick borne infectious blood disease of cattle caused by intraerythrocytic parasites of the genus Parasitol Res (2008) 103:723–726 DOI 10.1007/s00436-008-1022-4 DO01022; No of Pages M. O. Duarte : S. R. Ferrarini : V. L. Eifler-Lima : G. von Poser (*) Programa de Pós Graduação em Ciências Farmacêuticas, Universidade Federal do Rio Grande do Sul, Av. Ipiranga 2752, 90610-000 Porto Alegre, RS, Brazil e-mail: gilsane@farmacia.ufrgs.br M. Pazinatto : E. R. de Oliveira Instituto de Química, Universidade Federal do Rio Grande do Sul, Av. Bento Gonçalves 9500, 91509-900 Porto Alegre, RS, Brazil V. Rolim : V. L. S. Ribeiro Faculdade de Veterinária, Universidade Federal do Rio Grande do Sul, Av. Bento Gonçalves 9090, 90540-000 Porto Alegre, RS, Brazil