Liliana Muschietti

Psilostachyin C: a natural compound with trypanocidal activity

In this study, the antiprotozoal activity of the sesquiterpene lactone psilostachyin C was investigated. This natural compound was isolated from Ambrosia scabra by bioassay-guided fractionation and was identified by spectroscopic techniques. Psilostachyin C exerted in vitro trypanocidal activity against Trypanosoma cruzi epimastigotes, trypomastigotes and amastigotes, with 50% inhibitory concentration (IC(50)) values of 0.6, 3.5 and 0.9 μg/mL, respectively, and displayed less cytotoxicity against mammalian cells, with a 50% cytotoxic concentration (CC(50)) of 87.5 μg/mL. Interestingly, this compound induced ultrastructural alterations, as seen by transmission electron microscopy, in which vacuolisation and a structural appearance resembling multivesicular bodies were observed even at a concentration as low as 0.2 μg/mL. In an in vivo assay, a significant reduction in the number of circulating parasites was found in T. cruzi-infected mice treated with psilostachyin C for 5 days compared with untreated mice (7.4 ± 1.2 × 10(5)parasites/mL vs. 12.8 ± 2.0 × 10(5)parasites/mL) at the peak of parasitaemia. According to these results, psilostachyin C may be considered a promising template for the design of novel trypanocidal agents. In addition, psilostachyin C inhibited the growth of Leishmania mexicana and Leishmania amazonensis promastigotes (IC(50)=1.2 μg/mL and 1.5 μg/mL, respectively).

Volatile constituents of leaves, roots and stems from Aristolochia elegans

The volatile oils from roots, stems and leaves of Aristolochia elegans Mast., collected at different stages of development, were obtained by hydrodistillation and analysed by GC and GC-mass spectrometry. All the samples of essential oils were found to be rich in sesquiterpenes. Sesquiterpene hydrocarbons, in particular β-caryophyllene, isocaryophyllene and bicyclogermacrene were the predominated components in the oil from the leaves, whereas their amounts were significantly decreased in the essential oils of the other plant parts. The oxygenated sesquiterpenes, mainly E-nerolidol, were the main constituents of the oils from stems and roots.

In vitro antiviral activity of plant extracts from Asteraceae medicinal plants

BackgroundDue to the high prevalence of viral infections having no specific treatment and the constant appearance of resistant viral strains, the development of novel antiviral agents is essential. The aim of this study was to evaluate the antiviral activity against bovine viral diarrhea virus, herpes simplex virus type 1 (HSV-1), poliovirus type 2 (PV-2) and vesicular stomatitis virus of organic (OE) and aqueous extracts (AE) from: Baccharis gaudichaudiana, B. spicata, Bidens subalternans, Pluchea sagittalis, Tagetes minuta and Tessaria absinthioides. A characterization of the antiviral activity of B. gaudichaudiana OE and AE and the bioassay-guided fractionation of the former and isolation of one active compound is also reported.MethodsThe antiviral activity of the OE and AE of the selected plants was evaluated by reduction of the viral cytopathic effect. Active extracts were then assessed by plaque reduction assays. The antiviral activity of the most active extracts was characterized by evaluating their effect on the pretreatment, the virucidal activity and the effect on the adsorption or post-adsorption period of the viral cycle. The bioassay-guided fractionation of B. gaudichaudiana OE was carried out by column chromatography followed by semipreparative high performance liquid chromatography fractionation of the most active fraction and isolation of an active compound. The antiviral activity of this compound was also evaluated by plaque assay.ResultsB. gaudichaudiana and B. spicata OE were active against PV-2 and VSV. T. absinthioides OE was only active against PV-2. The corresponding three AE were active against HSV-1. B. gaudichaudiana extracts (OE and AE) were the most selective ones with selectivity index (SI) values of 10.9 (PV-2) and >117 (HSV-1). For this reason, both extracts of B. gaudichaudiana were selected to characterize their antiviral effects. Further bioassay-guided fractionation of B. gaudichaudiana OE led to an active fraction, FC (EC50=3.1 μg/ml; SI= 37.9), which showed antiviral activity during the first 4 h of the viral replication cycle of PV-2 and from which the flavonoid apigenin (EC50 = 12.2 ± 3.3 μM) was isolated as a major compound.ConclusionsThe results showed that, among the species studied, B. gaudichaudiana seemed to be the most promising species as a source of antiviral agents.

Antiproliferative Effect and Ultrastructural Alterations Induced by Psilostachyin on Trypanosoma cruzi

The effect of psilostachyin, a natural sesquiterpene lactone, on the growth and viability of cultured epimastigotes of Trypanosoma cruzi (Tulahuen) is reported. The antiproliferative effect was evaluated by counting the parasites in a Neubauer chamber and measuring their viability by using the dye exclusion technique. The effect on parasite growth was irreversible at concentrations higher than 1.0 µg/mL and the addition of glutathione only partially blocked the effect of the compound. Moreover, we have studied the effects of this natural compound on parasite ultrastructure by transmission electron microscopy. Interestingly, psilostachyin induced ultrastructural alterations on the parasites at a concentration of 0.5 µg/mL, with important mitochondrial swelling and deformity of the kinetoplast.

Natural Terpenoids from Ambrosia Species Are Active In Vitro and In Vivo against Human Pathogenic Trypanosomatids

Among the natural compounds, terpenoids play an important role in the drug discovery process for tropical diseases. The aim of the present work was to isolate antiprotozoal compounds from Ambrosia elatior and A. scabra. The sesquiterpene lactone (STL) cumanin was isolated from A. elatior whereas two other STLs, psilostachyin and cordilin, and one sterol glycoside, daucosterol, were isolated from A. scabra. Cumanin and cordilin were active against Trypanosoma cruzi epimastigotes showing 50% inhibition concentrations (IC50) values of 12 µM and 26 µM, respectively. Moreover, these compounds are active against bloodstrean trypomastigotes, regardless of the T. cruzi strain tested. Psilostachyin and cumanin were also active against amastigote forms with IC50 values of 21 µM and 8 µM, respectively. By contrast, daucosterol showed moderate activity on epimastigotes and trypomastigotes and was inactive against amastigote forms. We also found that cumanin and psilostachyin exhibited an additive effect in their trypanocidal activity when these two drugs were tested together. Cumanin has leishmanicidal activity with growth inhibition values greater than 80% at a concentration of 5 µg/ml (19 µM), against both L. braziliensis and L. amazonensis promastigotes. In an in vivo model of T. cruzi infection, cumanin was more active than benznidazole, producing an 8-fold reduction in parasitemia levels during the acute phase of the infection compared with the control group, and more importantly, a reduction in mortality with 66% of the animals surviving, in comparison with 100% mortality in the control group. Cumanin also showed nontoxic effects at the doses assayed in vivo, as determined using markers of hepatic damage.

Chemical Composition of the Leaf Oil of Satureja odora and Satureja parvifolia

ABSTRACT The leaf oils of Satureja odora (Gris.) Epl. And S. parvifolia (Phil.) Epl. (Lamiaceae), two endemic species of Argentina, were investigated by GC and GC/MS. Both species showed great difference in their composition, the main compounds being pulegone (61.5%) in S. odora and carvacrol (34.0%), carvacryl acetate (14.7%), p-cymene (14.0%) and γ-terpinene (11.3%) in S. parvifolia.

5,7,5′-trihydroxy-3,6,2′,4′-tetramethoxyflavone from Eupatorium buniifolium

Abstract A new 2′-oxygenated flavonoid, 5,7,5′-trihydroxy-3,6,2′,4′-tetramethoxyflavone, and brickellin have been isolated from Eupatorium buniifolium. Their structures were established by spectroscopic methods.

Choleretic and antispasmodic effects of Lippia integrifolia aqueous extract

The aqueous extract of the aerial parts of Lippia integrifolia has been assayed for its choleretic and antispasmodic effects. Doses of 250, 500 and 750 mg/kg administered orally in rats significantly increased the bile flow and the bile acid output. The extract also showed a significant reduction of the contractions induced by acetylcholine, CaCl2 and KCl on isolated rat jejunum. The total caffeoyl quinic acids derivatives content, expressed as chlorogenic acid was 0.10% w/v by spectrophotometric determination.

In vitro antiplasmodial activity of extracts of Argentinian plants

Fifteen extracts from nine selected Argentine medicinal plants were tested for their antiplasmodial activity in vitro by assessing their ability to inhibit the uptake of [3H]-hypoxanthine into the Plasmodium falciparum K1 pyrimethamine/chloroquine resistant strain. The methanol extract of Satureja parvifolia showed good antiplasmodial activity (IC(50) 3 microg/ml). Inhibition of the growth of P. falciparum was also observed with aqueous extracts of Buddleja globosa and S. parvifolia.

Trypanocidal Activity of Smallanthus sonchifolius: Identification of Active Sesquiterpene Lactones by Bioassay-Guided Fractionation

In order to find novel plant-derived biologically active compounds against Trypanosoma cruzi, we isolated, from the organic extract of Smallanthus sonchifolius, the sesquiterpene lactones enhydrin (1), uvedalin (2), and polymatin B (3) by bioassay-guided fractionation technique. These compounds showed a significant trypanocidal activity against the epimastigote forms of the parasite with IC50 values of 0.84 μM (1), 1.09 μM (2), and 4.90 μM (3). After a 24 h treatment with 10 μg/mL of enhydrin or uvedalin, parasites were not able to recover their replication rate. Compounds 1 and 2 showed IC50 values of 33.4 μM and 25.0 μM against T. cruzi trypomastigotes, while polymatin B was not active. When the three compounds were tested against the intracellular forms of T. cruzi, they were able to inhibit the amastigote replication with IC50 of 5.17 μM, 3.34 μM, and 9.02 μM for 1, 2, and 3, respectively. The cytotoxicity of the compounds was evaluated in Vero cells obtaining CC50 values of 46.5 μM (1), 46.8 μM (2), and 147.3 μM (3) and the selectivity index calculated. According to these results, enhydrin and uvedalin might have potentials as agents against Chagas disease and could serve as lead molecules to develop new drugs.