Sandra Milena Leal

Chemical composition and antiprotozoal activities of Colombian Lippia spp essential oils and their major components

The chemical composition and biological activities of 19 essential oils and seven of their major components were tested against free and intracellular forms of Leishmania chagasi and Trypanosoma cruzi parasites as well as Vero and THP-1 mammalian cell lines. The essential oils were obtained from different species of Lippia, a widely distributed genus of Colombian plants. They were extracted by microwave radiation-assisted hydro-distillation and characterised by GC-FID and GC-MS. The major components were geranial, neral, limonene, nerol, carvacrol, p-cymene, gamma-terpinene, carvone and thymol. The essential oil of Lippia alba exhibited the highest activity against T. cruzi epimastigotes and intracellular amastigotes with an IC50 of 5.5 microg/mL and 12.2 microg/mL, respectively. The essential oil of Lippia origanoides had an IC50 of 4.4 microg/mL in L. chagasi promastigotes and exhibited no toxicity in mammalian cells. Thymol (IC50 3.2 +/- 0.4 microg/mL) and S-carvone (IC50 6.1 +/- 2.2 microg/mL), two of the major components of the active essential oils, were active on intracellular amastigotes of T. cruziinfected Vero cells, with a selective index greater than 10. None of the essential oils or major components tested in this study was active on amastigotes of L. chagasi infected THP-1 cells.

Vanadium polypyridyl compounds as potential antiparasitic and antitumoral agents: New achievements

In the search for new therapeutic tools against diseases produced by kinetoplastid parasites five vanadyl complexes, [V(IV)O(L-2H)(phen)], including 1,10-phenanthroline (phen) and tridentate salicylaldehyde semicarbazone derivatives as ligands have been synthesized and characterized in the solid state and in solution by using different techniques. EPR suggested a distorted octahedral geometry with the tridentate semicarbazone occupying three equatorial positions and phen coordinated in an equatorial/axial mode. The compounds were evaluated in vitro on epimastigotes of Trypanosoma cruzi, causative agent of Chagas disease, Leishmania panamensis and Leishmania chagasi and on tumor cells. The complexes showed higher in vitro anti-trypanosomal activities than the reference drug Nifurtimox (IC(50) values in the range 1.6-3.8 μM) and increased activities in respect to the free semicarbazone ligands. In vitro activity on promastigote and amastigote forms of Leishmania showed interesting results. The compounds [VO(L1-2H)(phen)] and [VO(L3-2H)(phen)], where L1 = 2-hydroxybenzaldehyde semicarbazone and L3 = 2-hydroxy-3-methoxybenzaldehyde semicarbazone, resulted active (IC(50) 2.74 and 2.75 μM, respectively, on promastigotes of L. panamensis; IC(50) 19.52 and 20.75 μM, respectively, on intracellular amastigotes of L. panamensis) and showed low toxicity on THP-1 mammalian cells (IC(50) 188.55 and 88.13 μM, respectively). In addition, the complexes showed cytotoxicity on human promyelocytic leukemia HL-60 cells with IC(50) values of the same order of magnitude as cisplatin. The interaction of the complexes with DNA was demonstrated by different techniques, suggesting that this biomolecule could be a potential target either in the parasites or in tumor cells.

Synthesis and in vitro activity of new tetrahydronaphtho[1,2-b]azepine derivatives against Trypanosoma cruzi and Leishmania chagasi parasites

Series of 2-exo-aryl-1,4-epoxy-2,3,4,5-tetrahydronaphtho[1,2-b]azepines 3a-k and cis-2-aryl-4-hydroxy-2,3,4,5-tetrahydronaphtho[1,2-b]azepines 4a-j were synthesized and evaluated against free and intracellular live forms of Trypanosoma cruzi and Leishmania chagasi parasites using in vitro assays. Cell toxicity was also analyzed on Vero and THP-1 mammalian cell lines. The compounds 3c, 3f, and 4d were the most active against both live forms of T. cruzi parasites with low mammalian cell toxicity. Some compounds were active on free live forms of L. chagasi parasites but none was active on intracellular amastigotes of L. chagasi infecting THP-1 macrophages.

Optimization of antitrypanosomatid agents: identification of nonmutagenic drug candidates with in vivo activity.

Chagas disease, caused by Trypanosoma cruzi parasite, was described thousands of years ago. Currently, it affects millions of people, mostly in Latin America, and there are not suitable drugs for treating it. As an attempt to find appropriate drugs to deal with this problem, we report here on the design, synthesis, and characterization of 82 new compounds. Trypanosomicidal behavior in vitro showed more than 20 outstanding derivatives with anti-Trypanosoma cruzi activity. Furthermore, we studied the nonspecific toxicity against mammalian cells determining their selectivity and also performed mutagenicity studies. Proof of concept, in vivo studies, was conducted with two of the most promising derivatives (77 and 80). They were identified as candidates because they have (i) very simple and cost-effective syntheses; (ii) activity against different stages and strains of the parasite showing excellent in vivo behavior during the acute phase of Chagas disease; and (iii) neither nonspecific toxicity nor mutagenic activity.

Antiprotozoal activity of essential oils derived from Piper spp. grown in Colombia

Plant species of the genus Piper are widely distributed throughout the Colombian territory. Eleven Piper spp. essential oils (EO1–EO11) were chemically characterized and tested against Trypanosoma cruzi, Leishmania (Leishmania) infantum and mammalian cells using standard in vitro assays. The selectivity index (SI) was calculated by the ratio of CC50 host cells to IC50 parasites. The EO from Piper var. brachypodom, obtained from two different locations (EO10 and EO11) in Chocó (Colombia), was active on the T. cruzi. It inhibited growth of epimastigotes (EO10: IC50 0.34 μg/mL; SI: 89.82) and amastigotes (EO11: IC50 22.72 μg/mL; SI: 2.31). EO11 was active against Leishmania (L.) infantum promastigotes (IC50 23.68 μg/mL; SI: 2.65), and less active on amastigotes (IC50 62.82 μg/mL). The EO10’s major component was trans-β-caryophyllene, which inhibited the T. cruzi (IC50 24.54 μg/mL) and L. the infantum (IC50 53.39 μg/mL), intracellular forms with some toxicity on Vero (CC50 12.93 μg/mL) and THP-1 (CC50 143.85 μg/mL). α-Pinene, the main constituent of Piper bredermeyeri, was active against the T. cruzi epimastigotes (IC50 2.74 μg/mL; SI: 4.22) and amastigotes (IC50 1.92 μg/mL; SI: 6.02). Linalool, limonene, 1,8-cineole and safrole were not active on intracellular parasites. The low SI obtained with both Piper brachypodon and trans-β-caryophyllene indicates a narrow window in their parasite-specific activity. Novel formulations contained active EOs or components could be designed in order to avoid toxicities and improve the cell internalization.

In vitro antileishmanial, trypanocidal, and Mammalian cell activities of diverse n,n' -dihetaryl substituted diamines and related compounds.

The leishmaniasis and Chagas diseases constitute a serious public health problem worldwide with few and ineffective treatment options. The search for new antiparasitic candidates at the initial steps of drug discovery and development is still necessary. The synthesis of 22 de novo synthetized N,N′-dihetaryl-alkyldiamine derivatives and in vitro antiparasitic activity were evaluated for the first time against intracellular and extracellular forms of Leishmania (Leishmania) infantum, L. (Viannia) panamensis, L. (Leishmania) amazonensis, and Trypanosoma cruzi. Additionally, the toxicity on mammalian cells was determined. Some of these substituted N,N′-diamines (25–35 % of the tested compounds) showed interesting results against free-living forms of parasites with activities at the inhibitory concentration (IC50) level of 1.96 to 28.83 μM for L. (L.) infantum promastigotes and IC50 of 0.02 to 5.31 μM for T. cruzi epimastigotes. No activity at the IC50 level on intracellular amastigotes of T. cruzi was observed. However, N1,N2-dibenzylethane-1,2-diamine 5a revealed an important activity against the intracellular amastigotes of L. infantum (IC50 25.42 μM ±0.33) and L. panamensis (IC50 58.20 μM ±3.23), while their analogue N1,N4-dibenzylbutane-1,4-diamine 5c resulted in activity only against L. panamensis (IC50 11.19 μM ±0.20) without toxicity on Vero and THP-1 mammalian cells. The active compounds against intracellular parasites with low toxicity in mammalian cells may be considered for future studies in experimental models.