Argentine plant extracts active against polymerase and ribonuclease H activities of HIV-1 reverse transcriptase

Lipophilic and hydrophilic extracts of four Argentine plants (Gamochaeta simplicaulis Cabr. 1, Achyrocline flaccida Wein. D. C. 2, Eupatorium buniifolium H. et A. 3, and Phyllanthus sellowianus Muell. Arg. 4) were examined in vitro for their ability to inhibit the polymerase and ribonuclease H (RNase H) activities of human immunodeficiency virus type 1 (HIV-1) reverse transcriptase (RT) (wild and Y181C mutant types). The active extracts were also examined as inhibitors of viral replication in HLT4LacZ-1IIIB cell cultures, evaluating their cytotoxicity in parallel. Infusions 2I and 4I, among the crude extracts, showed the highest activity. These extracts were refractioned into four fractions; 2I4 and 4I4 were active as inhibitors of DNA-polymerase (wild and Y181C types) and RNase H activities. These fractions were potent as inhibitors of viral replication and were not cytotoxic. Refractionation of 2I4 yielded five new fractions, two of which, 2I4-4 and 2I4-5, showed notable activity. Refractionation of 4I4 yielded for new fractions; of these, 4I4-3 and 4I4-4 were active. The marked biological activity found in the infusion of A. flaccida and P. sellowianus makes them sufficiently attractive to be considered in the combined chemotherapy of the disease

EL SECRETO DETRÁS DE LOS SUPLEMENTOS DIETARIOS

Los suplementos dietarios, pensados como complementos de la dieta de personas sanas, son muy populares y se consumen en todo el mundo. A pesar de ser considerados por los consumidores como “naturales” e “inocuos”, estos deben ser consumidos con cuidado, en especial, teniendo en cuenta que existen numerosos informes de adulteraciones de este tipo de productos en todo el planeta

Germacranolide-type sesquiterpene lactones from Smallanthus sonchifolius with promising activity against Leishmania mexicana and Trypanosoma cruzi

Abstract Background Leishmaniasis and Chagas disease are life-threatening illnesses caused by the protozoan parasites Leishmania spp. and Trypanosoma cruzi, respectively. They are known as “neglected diseases” due to the lack of effective drug treatments and the scarcity of research work devoted to them. Therefore, the development of novel and effective drugs is an important and urgent need. Natural products are an important source of bioactive molecules for the development of new drugs. In this study, we evaluated the activity of enhydrin, uvedalin and polymatin B, three sesquiterpene lactones (STLs) isolated from Smallanthus sonchifolius, on Leishmania mexicana (MNYC/BZ/62/M) and Trypanosoma cruzi (Dm28c). In addition, the in vivo trypanocidal activity of enhydrin and uvedalin and the effects of these STLs on parasites’ ultrastructure were evaluated. Methods The inhibitory effect of the three STLs on the growth of L. mexicana amastigotes and promastigotes as well as T. cruzi epimastigotes was evaluated in vitro. The changes produced by the STLs on the ultrastructure of parasites were examined by transmission electron microscopy (TEM). Enhydrin and uvedalin were also studied in a murine model of acute T. cruzi infection (RA strain). Serum activities of the hepatic enzymes alanine aminotransferase, aspartate aminotransferase and lactate dehydrogenase were used as biochemical markers of hepatotoxicity. Results The three compounds exhibited leishmanicidal activity on both parasite forms with IC50 values of 0.42–0.54 μg/ml for promastigotes and 0.85–1.64 μg/ml for intracellular amastigotes. Similar results were observed on T. cruzi epimastigotes (IC50 0.35–0.60 μg/ml). The TEM evaluation showed marked ultrastructural alterations, such as an intense vacuolization and mitochondrial swelling in both L. mexicana promastigotes and T. cruzi epimastigotes exposed to the STLs. In the in vivo study, enhydrin and uvedalin displayed a significant decrease in circulating parasites (50–71%) and no signs of hepatotoxicity were detected. Conclusions Enhydrin, uvedalin and polymatin B possess significant leishmanicidal and trypanocidal activity on different parasite stages. These results show that these compounds may provide valuable leads for the development of new drugs against these neglected parasitic diseases

Trypanocidal and Leishmanicidal Activities of Sesquiterpene Lactones from Ambrosia tenuifolia Sprengel (Asteraceae) ▿

Bioassay-guided fractionation of the organic extract of Ambrosia tenuifolia Sprengel (Asteraceae) led to the isolation of two bioactive sesquiterpene lactones with significant trypanocidal and leishmanicidal activities. By spectroscopic methods (1H- and 13C-nuclear magnetic resonance, distortionless enhancement by polarization transfer, correlated spectroscopy, heteronuclear multiple-quantum coherence, electron impact-mass spectrometry, and infrared spectroscopy), these compounds were identified as psilostachyin and peruvin. Both compounds showed a marked in vitro trypanocidal activity against Trypanosoma cruzi epimastigotes with 50% inhibitory concentration (IC50) values of less than 2 μg/ml. Psilostachyin exerted a significant in vitro activity against the trypomastigote forms of T. cruzi (IC50, 0.76 μg/ml) and was selected for in vivo testing. Psilostachyin-treated mice had a survival of 100% and lower parasitemia values than control mice. Both compounds were also tested on Leishmania sp. promastigotes: psilostachyin (IC50, 0.12 μg/ml) and peruvin (IC50, 0.39 μg/ml) exerted significant leishmanicidal activities. This is the first time that the trypanocidal and leishmanicidal activities of these compounds have been reported. The selectivity index (SI) was employed to evaluate the cytotoxic effect of lactones on T lymphocytes. Although the SIs of both compounds were high for T. cruzi epimastigotes, psilostachyin was more selective against trypomastigotes (SI, 33.8) while peruvin showed no specificity for this parasite. Both compounds presented high selectivity for Leishmania spp. The results shown herein suggest that psilostachyin and peruvin could be considered potential candidates for the development of new antiprotozoal agents against Chagas' disease and leishmaniasis

Chemical structures of the sesquiterpene lactones cumanin, psilostachyin and cordilin and the sterol glycoside daucosterol.

<p>Chemical structures of the sesquiterpene lactones cumanin, psilostachyin and cordilin and the sterol glycoside daucosterol.</p

<i>In vivo</i> trypanocidal activity of cumanin: parasitemia levels (A) and survival curve (B) during the acute infection period.

<p>C3H/HeN female mice infected with 500 trypomastigotes were treated daily, by intraperitoneal route, with PBS, cumanin or benznidazole (1 mg/kg of body weight/day), starting on day 5 postinfection. Levels of parasitemia were monitored every 2 days in 5 µl of fresh blood from the tail vein, by counting parasites in a Neubauer chamber. The number of dead mice was recorded daily. Results are representative of three independent experiments.</p

Effect of cumanin, cordilin and daucosterol against <i>T. cruzi</i> trypomastigotes.

<p>Bloodstream trypomastigotes diluted at 1.5×10⁶/ml in complete liver infusion tryptose medium, were seeded by duplicate in the presence of different concentration of each compound (0–376 µM, 0–375 µM and 0–174 µM, for cumanin, cordilin and daucosterol, respectively) and incubated at 4°C for 24 h. The remaining live parasites of (<b>A</b>) RA strain, and (<b>B</b>) K98 strain, in each sample was determined in 5 µl of cell suspension diluted 1/5 in lysis buffer (0.75% NH4Cl, 0.2% Tris, pH 7.2) and counted in a Neubauer chamber. Values represent mean ± SEM from three independent experiments carried out in duplicate.</p

Isobologram describing the effect of the combination of (A) cumanin and psilostachyin and, (B) cumanine and benznidazole, on epimastigotes of <i>T. cruzi</i>.

<p>Growth inhibition of epimastigotes was evaluated by a [3H] thymidine uptake assay. RA epimastigotes were cultured for 72 h in the presence of different combinations of both compounds ranging from 0–5 µg/ml. The fractional inhibitory concentrations of drugs (FIC) were calculated for each point, and an isobologram was plotted. The fractional inhibitory concentration index (FICI) was interpreted as follows: FICI≤0.5 synergy, FICI>4.0 antagonism, FICI = 0.5–4 addition.</p

<i>In vitro</i> trypanocidal activity of organic extract and fractions of <i>Ambrosia elatior</i> on RA epimastigotes of <i>T. cruzi</i>.

<p>Results are expressed as mean ± S.E.M. (n = 3).</p