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.

This article describes the preparation of a graphene electrode modified with a new conjugate of peptide nanotubes and folic acid for the selective detection of human cervical cancer cells over-expressing folate receptors. The functionalization of peptide nanotubes with folic acid was confirmed by fluorescence microscopy and atomic force microscopy. The peptide nanotube–folic acid modified graphene electrode was characterized by scanning electron microscopy and cyclic voltammetry. The modification of the graphene electrode with peptide nanotube–folic acid led to an increase in the current signal. The human cervical cancer cells were bound to the modified electrode through the folic acid–folate receptor interaction. Cyclic voltammograms in the presence of [Fe(CN)₆]^3−/4− as a redox species demonstrated that the binding of the folate receptor from human cervical cancer cells to the peptide nanotube–folic acid modified electrode lowered the electron transfer resulting in a decrease in the measured current. A detection limit of 250 human cervical cancer cells per mL was obtained. Control experiments confirmed that the peptide nanotube–folic acid electrode specifically recognized folate receptors. The modified electrode described here opens up new possibilities for future applications in early stage diagnoses of diseases where cells over-express folate receptors, such as in cancer or leishmaniasis disease.

To evaluate the in vitro activity of anti-leishmanial drugs against intracellular Leishmania donovani amastigotes in different types of macrophages. Mouse peritoneal macrophages (PEMs), mouse bone marrow-derived macrophages (BMMΦ), human peripheral blood monocyte-derived macrophages (PBMΦ) and differentiated THP-1 cells were infected with L. donovani. Cultures were incubated with sodium stibogluconate, amphotericin B deoxycholate (Fungizone^®), miltefosine or paromomycin sulphate over six concentrations in 3-fold serial dilutions for 5 days. Analysis was based on percentage inhibition of infected macrophages and EC₅₀/EC₉₀ values estimated using sigmoidal curve-fitting. The rank order of drug activity was the same in the different macrophage populations: amphotericin B > miltefosine > sodium stibogluconate > paromomycin. However, significant (P < 0.05) differences were observed between populations. Amphotericin B was more active in PEMs and BMMΦ (EC₅₀ 0.02–0.06 µM) compared with PBMΦ and differentiated THP-1 cells (EC₅₀ 0.08–0.40 µM) and miltefosine was more active in PBMΦ (EC₅₀ 0.16–0.74 µM) compared with PEMs and BMMΦ (EC₅₀ 2.60–7.67 µM). Sodium stibogluconate displayed highest activity in PBMΦ (EC₅₀ 1.38–1.89 µg Sb^v/mL), followed by PEMs (EC₅₀ 21.75–27.79 µg Sb^v/mL) and BMMΦ and differentiated THP-1 cells (EC₅₀ 28.96–112.77 µg Sb^v/mL). Paromomycin showed highest activity in PBMΦ (EC₅₀ 80.03–104.38 µM) and PEMs (EC₅₀ 75.42–201.63 µM). In vitro activity of anti-leishmanial drugs is host cell dependent. This has implications for: (i) the evaluation of in vitro drug activity; (ii) the evaluation of drug susceptibility of clinical isolates; and (iii) the standardization of anti-leishmanial drug assays.

The Melan-A/MART-1 gene product is frequently recognized by tumor-specific HLA-A2-restricted CTL. An immunodominant nonapeptide has been localized to the region spanning residues 27-35. However, the decapeptide including residues 26-35 (the nonapeptide extended NH2 terminally by one residue) appeared to be recognized as efficiently as the nonapeptide. In this study, we show that the optimal length immunodominant peptide appears to correspond to the decapeptide 26-35, as assessed by quantitative analyses of both 4 polyclonal and 13 monoclonal populations of specific CTL. Functional assays of peptide binding to HLA-A2 indicate that the decapeptide is significantly a more efficient binder than the nonapeptide. Moreover, analogues of the decapeptide including substitutions at a secondary HLA-A2 peptide anchor further improve decapeptide binding. Finally, we show that the functional (9 CTL clones analyzed) and structural TCR repertoire (7 CTL clones) of a group of specific CTL clones is rather diverse. The findings reported here may have important implications for future peptide-based melanoma vaccination trials as well as for the monitoring of specific CTL responses in vivo.