Abstract Plant defensins are antimicrobial pep- tides that exhibit mainly antifungal activity against a broad range of plant fungal pathogens. However, their actions against Candida albicans have not been extensively studied. The mRNA for c-thionin, a defensin from Capsicum chinense, has been expressed in bovine endothelial cells. The conditioned medium of these cells showed antifungal activity on germ tube formation (60– 70% of inhibition) and on the viability of C. albicans (70–80% of inhibition). Additionally, C. albicans was not able to penetrate transfected cells. Conditioned medium from these cells also inhibited the viability (~80%) of the human tu- mor cell line, HeLa. Keywords Antimicrobial peptides Æ Candida albicans Æ Capsicum chinense Æ Cytotoxic Æ Defensin Æ Endothelial cells Introduction Innate immune response of plants, invertebrates and vertebrates shares conserved mechanisms, such as the production of cationic antimicrobial peptides (defensins), which were originally named c-thionins in plants. They are small basic peptides that have a characteristic three-dimen- sional folding pattern stabilized by eight disulfide- linked cysteines (Thomma et al. 2002). To date, most plant defensins studied exhibit antifungal activity against a broad range of fungi, mainly plant pathogens. Furthermore, cytotoxic activity of plant defensins against human tumor cell lines has been reported for sesquin from ground beans (Pellegrini and Franco 2005; Wong and Ng 2005). However, the effects of plant defensins on path- ogenic fungi of humans, such as Candida albicans, have been poorly studied (Pellegrini and Franco 2005). Candida albicans is an opportunistic fungal pathogen that may be present as a normal com- ponent of the human microflora. It is responsible for a variety of diseases in the immuno-compro- mised or immuno-suppressed hosts ranging from superficial to systemic mycoses (Cotter and Kavanagh 2000). During systemic infections, vascular endothelium plays a critical role, since C. albicans is able to adhere, penetrate and damage endothelial cells to gain access to other tissues (Filler et al. 1995). C. albicans can exist in two J. L. Anaya-Lo ´ pez Æ J. E. Lo ´ pez-Meza Æ V. M. Baizabal-Aguirre Æ H. Cano-Camacho Æ A. Ochoa-Zarzosa (&) Centro Multidisciplinario de Estudios en Biotecnologı´a, Facultad de Medicina Veterinaria y Zootecnia, Universidad Michoacana de San Nicola ´s de Hidalgo, Apdo. Postal 53, Administracio ´n Chapultepec, C.P. 58262 Morelia, Michoaca ´ n, Me ´ xico e-mail: ochoaz@zeus.umich.mx Biotechnol Lett (2006) 28:1101–1108 DOI 10.1007/s10529-006-9060-4 123 ORIGINAL PAPER Fungicidal and cytotoxic activity of a Capsicum chinense defensin expressed by endothelial cells Jose ´ L. Anaya-Lo ´ pez Æ Joel E. Lo ´ pez-Meza Æ Victor M. Baizabal-Aguirre Æ Horacio Cano-Camacho Æ Alejandra Ochoa-Zarzosa Received: 21 December 2005 / Accepted: 30 March 2006 / Published online: 23 June 2006 Ó Springer Science+Business Media B.V. 2006