Bioassay-guided in vitro study of the antileishmanial and cytotoxic properties of Bixa orellana seed extract

Leishmaniasis is a neglected tropical disease with important health consequences for millions of people worldwide[1]. Currently, there are no vaccines available and the treatment depends on a limited number of drugs, which are toxic, expensive, associated with resistance or require parenteral administration[2,3]. Therefore, there is a desperate need for safer and cheaper antileishmanials, which may be found in medicinal plants that are used as traditional remedies for various diseases[4]. Bixa orellana L. (Bixaceae) (B. orellana), a native plant of tropical America, can be found in divergent regions spanning the globe. It grows from seeds or cuttings, performs well in lowlands and mountainous regions and requires full sunlight and protection from the wind[5,6]. The plant is used in different countries for diverse purposes[7,8]. For example, the pulp from the seeds is used as a safe natural colorant in the food and cosmetic industry worldwide[9]. Furthermore, the effect of the plant against bacteria, yeasts and parasites has been evaluated[10-13]. Several reports indicate the use of B. orellana for the traditional treatment of leishmaniasis[14-16]. Previously, the laboratory investigated the in vitro and in vivo performance of the hydroalcoholic extract of B. orellana against Leishmania amazonensis (L. amazonensis). A significant activity against promastigotes (IC50=22 μg/ PEER REVIEW ABSTRACT