Virginia S. Martino

Antimicrobial activity of Argentine plants used in the treatment of infectious diseases. Isolation of active compounds from Sebastiania brasiliensis

Different extracts of Sebastiania brasiliensis, Sebastiania klotszchiana, Polygonum punctatum, Lithraea molleoides and Myrcianthes cisplatensis, all plants growing in Entre Ríos Province and traditionally used as antiseptics, were tested against a set of Gram positive and Gram negative bacteria and fungi. All the species, with the exception of M. cisplatensis, presented activity against some of the microorganisms tested. A 50% hydroalcoholic extract of S. brasiliensis was selected for bioguided fractionation. Two antimicrobial compounds identified as methylgallate (MIC 128 microg/ml) and protocatechuic acid (MIC 128 microg/ml) were isolated apart from quercetin, kaempferol, quercitrin and gallic acid.

Argentine plants as potential source of insecticidal compounds

CH2Cl2 and MeOH extracts of 15 Argentine plants used locally as insecticides, were evaluated for their insecticidal activity. Chenopodium multifidum L. (Chenopodiaceae); Flaveria bidentis (L.) O.K. (Compositae); Aristolochia argentina Gris. (Aristolochiaceae) and Tagetes erecta L. (Compositae) showed a significant activity against Sitophilus oryzae.

Antiviral activity in Argentine medicinal plants

In an ethnopharmacological screening of selected medicinal plants used in Argentina for the treatment of infectious diseases, aqueous extracts of five species were assayed in vitro to detect antiviral activity against herpes simplex virus type 1 (HSV-1), respiratory syncytial virus (RSV) and adenovirus serotype 7 (ADV-7). Polygonum punctatum, Lithraea molleoides, Sebastiania brasiliensis and Sebastiania klotzschiana but not Myrcianthes cisplatensis showed in vitro antiherpetic activity with 50% effective dose (ED50) ranging from 39 to 169 microg/ml. P. punctatum, L. molleoides and M. cisplatensis showed antiviral activity against RSV with ED50 ranging from 78 to 120 microg/ml. None of the extracts had antiviral activity against ADV-7. The differences between their maximal non cytotoxic concentration and their antiviral activity values were high enough to justify further analysis.

First cyclotide from Hybanthus (Violaceae)

Hypa A, a novel macrocyclic polypeptide containing 30 amino acid residues, has been isolated from the n-butanol extract of the Argentine plant Hybanthus parviflorus. The sequence, cyclo-(SCVYIPCTITALLGCSCKNKVCYNGIPCAE), was determined by automated Edman degradation, quantitative amino acid analysis and nanospray MS/MS(2). Three intramolecular disulfide bridges stabilize the cyclic peptide backbone of hypa A. Using these structural features to classify the peptide as a cyclotide, we extended the distribution of that substance class to a new genus, and now propose a uniform nomenclature for cyclotides.

Caffeoylquinic acids from Pterocaulon virgatum and Pluchea sagittalis

Pterocaulon virgatum (L.) DC. and Pluchea sagittalis (Lam.) Cabrera (common name ‘lucera’) are two Compositae widely distributed in the northeastern region of Argentina [l]. They are used in folk medicine due to their tonic, sour and digestive properties ([2, 31; Bowes, N., personal communication). Infusions of P. sugittalis have been described as colagogue and choleretic when given to patients with liver and gall-bladder problems [4]. In a previous paper we have reported the isolation of a flavone from P. sagittalis [S]. The present paper reports the isolation of 3,klicafieoylquinic acid (yield 1%) from P. uirgattun and isochlorogenic acid (yield 0.2 %) (a mixture of 3,4-; 4,5and 3,5&ATeoylquinic acid) from P. sagittalis. This is the first report of 3,4-dicaffeoylquinic acid as a single product; it always occurs in other sources with its isomers. Caffeic acid and its esters have proved to increase bile flow in rats [6, 71. The medicinal properties of these plants are presumably related to the high content of caffeic acid esters found in them.

Triterpenic Acids and Flavonoids from Satureja parvifolia. Evaluation of their Antiprotozoal Activity

Bioassay-guided fractionation of a Satureja parvifolia MeOH extract led to the isolation of eriodictyol, luteolin and ursolic and oleanolic acids as its active components against Plasmodium falciparum K1. This is the first time these compounds are reported as constituents of S. parvifolia. Ursolic acid showed an IC50 of 4.9 μg/ml, luteolin 6.4 μg/ml, oleanolic acid 9.3 μg/ml and eriodictyol 17.2 μg/ml. Antiplasmodial activity of eriodictyol and luteolin is reported here for the first time. Besides, the four compounds showed activity against P. falciparum 3D7 strain and Trypanosoma brucei rhodesiense. Eriodictyol showed moderate activity on all the parasites but was the most selective compound as a result of its rather low cytotoxicity (IC50 174.2 μg/ml) on the mammalian KB cell line.

Screening of Central and South American plant extracts for antimycobacterial activity by the Alamar Blue test

Forty eight ethanolic crude extracts and fractions (hexane, dichloromethane, ethyl acetate and n-butanol) from ten Brazilian plants (Leguminosae, Monimiaceae and Verbenaceae), 1 from Costa Rica (Verbenaceae) and 1 from Argentina (Verbenaceae) were screened for anti-mycobacterium activity against Mycobacterium tuberculosis (ATCC-27294H37Rv), by the Alamar Blue test, at a fixed concentration of 100 µg/mL. Out of the forty eight, seven were active at this concentration, corresponding to Lantana trifolia (hexane and dichloromethane extracts from leaves), Vitex cooperi (methanol:water, 1:1 extract from barks), Lippia lacunosa (hexane and dichloromethane extracts from leaves) and Lippia rotundifolia (hexane and dichloromethane extracts from leaves), all from the Verbenaceae family.

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).

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.

Immunomodulating properties of Argentine plants with ethnomedicinal use.

Five Argentine medicinal plants selected according to folk traditional or ethnomedical use, references and primary pharmacological screening; were chosen to elucidate their immunomodulating properties. Dichloromethane, methanolic and aqueous extracts of the aerial parts of Achyrocline flaccida (A. flaccida), Eupatorium arnottianum (E. arnottianum) and Eupatorioum buniifolium (E. buniifolium), leaves of Lithraea molleoides (L. molleoides) and leaves and stems of Phyllanthus sellowianus (P. sellowianus) were analyzed to disclose their effects on murine normal and tumor cell growth as well as on complement hemolytic activity. Modulation of cell growth was evaluated by tritiated thymidine incorporation while inhibition of complement activity was measured on both classical and alternative complement pathways (CP and AP respectively). The results obtained show that most of the extracts exerted inhibitory effect on tumor as well as on mitogen activated normal spleen cell growth. On tumor cells, IC50 ranged between 1-75 microg/ml for most of the extracts with the exception of dichloromethane of L. molleoides and P. sellowianus which required concentrations higher than 100 microg/ml to produce the effect. On mitogenic activated splenocytes, IC50 ranged between < 1 to 85 microg/ml with the exception of methanolic extract of E. buniifolium or P. sellowianus which were not effective on ConA or LPS stimulated splenocytes respectively. Only E. buniifolium was active on murine normal splenocytes proliferation (IC50 0.5-1.5 microg/ml). Finally, one (7%) of 15 extracts showed inhibition of complement activity on CP and 6 extracts (40%) presented moderate activity on CP. The dichloromethane extract of E. arnottianum was the most active (IC50 5 microg/ml), although remarkable effect was also obtained with dichloromethane and methanolic extracts of P. sellowianus (IC50 11.2 and 17.3 microg/ml respectively). Besides, 2 extracts (13%), dichloromethane extract of E. arnottianum and aqueous extract of P. sellowianus, showed moderate inhibition on AP.