Cytotoxic Screening and In Vitro Evaluation of Pentadecane Against Leishmania infantum Promastigotes and Amastigotes.

Pentadecane is an organic compound that is made up of primarily carbon and hydrogen atoms. Pentadecane is a floral volatile found in many different plants and essential oils and also in crude extracts of some plants, and it shows antimicrobial activity. This study investigated in vitro effects of pentadecane in Leishmania infantum parasites and found that it decreases growth by 86 ± 2% both in promastigotes (half maximal inhibitory concentration [IC50] = 65.3 µM) and in amastigotes (IC50 = 60.5 µM), resulting in a reduction of macrophage infection; growth inhibition was 77% at 300 µM. Analysis of propidium iodide incorporation in L. infantum , treated with pentadecane at 48 hr, suggested that cells were arresting in the sub-G0/G1 and G1 phases of the cell cycle, whereas cytotoxicity assay of pentadecane in immortalized cells lines DH82 and U937 and in primary epithelial cells of Cercopiteco showed that it caused negligible cytotoxic effect. This study shows that pentadecane has antimicrobial activity against L. infantum parasites in in vitro culture.

Evaluation of two modified culture media for Leishmania infantum cultivation versus different culture media.

The aim of this study is to improve the cultivation of Leishmania promastigotes without the use of common, semisolid culture media such as Evans' modified Tobie's medium (EMTM), liquid RPMI 1640, and Peptone-yeast extract medium (P-Y). Although EMTM medium permits the growth of a high number of parasites, it is technically difficult to prepare as it requires the use of fresh rabbit blood from animals bred on farms, while RPMI 1640 and P-Y show lower growth rates than the EMTM. There is, therefore, a need to develop new blood-free and time-saving culture systems. The aim of this paper is to propose new modified microbiological media, named RPMI-PY and Tobie-PY, to isolate Leishmania and cultivate parasites for research and diagnostic purposes. This study compares classic culture media to the new media, RPMI-PY and Tobie-PY, and demonstrates that the new media have superior performance in terms of time and parasitic load. The growth rate of the parasite was significantly higher at 24, 48, and 72 hr cultivation, based on counts using Bürker's chambers, when compared to classic media. This study was carried out at the National References Centre for Leishmaniasis (C.Re.Na.L.) where the isolation procedures are conducted daily from a number of different biological matrices.