Crotofolane Diterpenoids and Other Constituents Isolated from Croton kilwae.

Six new crotofolane diterpenoids (1-6) and 13 known compounds (7-19) were isolated from the MeOH-CH2Cl2 (1:1, v/v) extracts of the leaves and stem bark of Croton kilwae. The structures of the new compounds were elucidated by extensive analysis of spectroscopic and mass spectrometric data. The structure of crotokilwaepoxide A (1) was confirmed by single-crystal X-ray diffraction, allowing for the determination of its absolute configuration. The crude extracts and the isolated compounds were investigated for antiviral activity against respiratory syncytial virus (RSV) and human rhinovirus type-2 (HRV-2) in HEp-2 and HeLa cells, respectively, for antibacterial activity against the Gram-positive Bacillus subtilis and the Gram-negative Escherichia coli, and for antimalarial activity against the Plasmodium falciparum Dd2 strain. ent-3ß,19-Dihydroxykaur-16-ene (7) and ayanin (16) displayed anti-RSV activities with IC50 values of 10.2 and 6.1 µM, respectively, while exhibiting only modest cytotoxic effects on HEp-2 cells that resulted in selectivity indices of 4.9 and 16.4. Compounds 2 and 5 exhibited modest anti-HRV-2 activity (IC50 of 44.6 µM for both compounds), while compound 16 inhibited HRV-2 with an IC50 value of 1.8 µM. Compounds 1-3 showed promising antiplasmodial activities (80-100% inhibition) at a 50 µM concentration.

Novel Selective and Low-Toxic Inhibitor of LmCPB2.8ΔCTE (CPB) One Important Cysteine Protease for Leishmania Virulence.

Leishmaniasis is a highly prevalent, yet neglected disease caused by protozoan parasites of the genus Leishmania. In the search for newer, safer, and more effective antileishmanial compounds, we herein present a study of the mode of action in addition to a detailed structural and biological characterization of LQOF-G6 [N-benzoyl-N'-benzyl-N″-(4-tertbutylphenyl)guanidine]. X-ray crystallography and extensive NMR experiments revealed that LQOF-G6 nearly exclusively adopts the Z conformation stabilized by an intramolecular hydrogen bond. The investigated guanidine showed selective inhibitory activity on Leishmania major cysteine protease LmCPB2.8ΔCTE (CPB) with ~73% inhibition and an IC50-CPB of 6.0 µM. This compound did not show any activity against the mammalian homologues cathepsin L and B. LQOF-G6 has been found to be nontoxic toward both organs and several cell lines, and no signs of hepatotoxicity or nephrotoxicity were observed from the analysis of biochemical clinical plasma markers in the treated mice. Docking simulations and experimental NMR measurements showed a clear contribution of the conformational parameters to the strength of the binding in the active site of the enzyme, and thus fit the differences in the inhibition values of LQOF-G6 compared to the other guanidines. Furthermore, the resulting data render LQOF-G6 suitable for further development as an antileishmanial drug.

Growth Curve, Morphological and Molecular Characterization of Two Strains of Trypanosoma cruzi (Kinetoplastida, Trypanosomatidae) isolated from Triatoma sherlocki (Hemiptera, Reduviidae, Triatominae).

BACKGROUND: Trypanosoma cruzi presents great variability in morphology, virulence, pathogenicity, avoidance of the host immune system, and antigenic constitution, associated with different clinical manifestations of the disease. METHODS: Two strains of T. cruzi were cultivated in liver infusion tryptose to determine growth kinetics, morphometry and molecular characterization using restriction fragment length polymorphism polymerase chain reaction. RESULTS: The biological parameters showed sharp growth by the 7th day. Morphologically, both strains showed short and thin forms and were classified as Group I. CONCLUSION: Group TcI presents cardiac manifestations and T. sherlocki is adapting to the home environment, requiring attention to future problems.

Baccharis trimera (Less.) DC leaf derivatives and eupatorin activities against Leishmania amazonensis.

Natural products have been largely explored as treatments for leishmaniasis, neglected diseases with few toxic therapeutic options, as scaffolds for the development of new drugs. Herein, derivatives from the aerial parts of Baccharis trimera (Less.) DC (extract and its fractions) were evaluated against Leishmania amazonensis and macrophage cells. The ethyl acetate extract was fractionated by solid-phase extraction, resulting in eight fractions (F1-F8). Fractions F3-4 were further separated into 149 subfractions; subfraction 148 (IC50-PRO = 1.56 ± 0.1 µg mL-1) was selected for purification and constituent(s) characterization by high-performance liquid chromatography, as well as 1H and 13C nuclear magnetic resonance spectroscopy. The flavonoid eupatorin (3',5-dihydroxy-4',6,7-trimethoxyflavone) was identified. This compound was 3.7 times more effective against intracellular amastigotes (IC50-AMA = 1.6 ± 0.1 µM) than amphotericin B and presented low cytotoxicity (CC50 > 100 µM), being almost 62 times more selective for the parasite, showing great potential in drug development for cutaneous leishmaniasis treatment.

Design, synthesis and biological evaluation of N-oxide derivatives with potent in vivo antileishmanial activity.

Leishmaniasis is a neglected disease that affects 12 million people living mainly in developing countries. Herein, 24 new N-oxide-containing compounds were synthesized followed by in vitro and in vivo evaluation of their antileishmanial activity. Compound 4f, a furoxan derivative, was particularly remarkable in this regard, with EC50 value of 3.6 µM against L. infantum amastigote forms and CC50 value superior to 500 µM against murine peritoneal macrophages. In vitro studies suggested that 4f may act by a dual effect, by releasing nitric oxide after biotransformation and by inhibiting cysteine protease CPB (IC50: 4.5 µM). In vivo studies using an acute model of infection showed that compound 4f at 7.7 mg/Kg reduced ~90% of parasite burden in the liver and spleen of L. infantum-infected BALB/c mice. Altogether, these outcomes highlight furoxan 4f as a promising compound for further evaluation as an antileishmanial agent.

The antileishmanial activity of the antarctic brown alga Ascoseira mirabilis Skottsberg.

Leishmaniasis is a group of diseases that have limited and high toxic therapeutic options. Herein, we evaluated the antileishmanial potential and cytotoxicity of hexanic extract obtained from the Antarctic brown alga Ascoseira mirabilis using bioguided fractionation against Leishmania amazonensis and murine macrophages, which was fractionated by SPE, yielding seven fractions (F1-F7). The fraction F6 showed good anti-amastigote activity (IC50 = 73.4 ± 0.4 µg mL-1) and low cytotoxicity (CC50 > 100 µg mL-1). Thus, in order to identify the bioactive constituent(s) of F6, the fraction was separated in a semipreparative HPLC, yielding four fractions (F6.1-F6.4). F6.2 was the most bioactive fraction (IC50 = 66.5 ± 4.5 µg mL-1) and GC-MS analyses revealed that the compounds octadecane, propanoic acid, 1-monomyristin and azelaic acid correspond to 61% of its composition. These data show for the first time the antileishmanial potential of the Antarctic alga A. mirabilis.

In vitro activities of glycoalkaloids from the Solanum lycocarpum against Leishmania infantum

ABSTRACT Leishmania infantum is an etiologic agent of visceral leishmaniasis. This disease is a neglected disease that can be fatal if not treated and additionally, the few therapeutic option present several drawbacks, including difficult route of administration and toxicity, which turn the search for new therapeutic alternatives necessary. Herein, we evaluated the leishmanicidal in vitro activity of the solanum extract from Solanum lycocarpum A. St.-Hil., Solanaceae, and the isolated alkaloids solasodine, solamargine and solasonine against promastigotes and intracellular amastigotes of L. infantum. Solasodine (IC50-pro = 4.7 µg/ml; IC50-ama = 10.8 µg/ml) and solamargine (IC50-pro = 8.1 µg/ml; IC50-ama = 3.0 µg/ml) exhibited interesting leishmanicidal ativity. Solasonine was approximately four-times (Selective Index 3.7) more selective to the parasite than to the host cells. This data suggest that solasonine might be considered as a potential drug candidate for leishmaniasis treatment.