In vitro evaluation of trypanocidal activity in plants used in Argentine traditional medicine.

Thirty-two organic and aqueous extracts, belonging to 12 Argentine medicinal plants were tested for their in vitro trypanocidal activity on epimastigote forms of Trypanosoma cruzi. Among the selected species, the organic extracts of Ambrosia scabra, Ambrosia tenuifolia, Baccharis spicata, Eupatorium buniifolium, Lippia integrifolia, Mulinum spinosum and Satureja parvifolia, and the aqueous extracts of E. buniifolium, L. integrifolia, M. spinosum and S. parvifolia showed trypanocidal activity with a percentage of growth inhibition higher than 70% at a concentration of 100 microg/ml.

Two ellagitannins from the leaves of Terminalia triflora with inhibitory activity on HIV-1 reverse transcriptase.

The bioassay- guided fractionation of the aqueous extract of Terminalia triflora leaves afforded punicalin and 2-O-galloylpunicalin, isolated for the first time from this species. These compounds showed inhibitory activity on HIV-1 reverse transcriptase in a dose-dependent manner. Punicalin showed an IC(50) of 0.11 microg/ml (0.14 microM) and 2-O-galloylpunicalin an IC(50) of 0.10 microg/ml (0.11 microM).

Flavonoids from Achyrocline satureioides with relaxant effects on the smooth muscle of Guinea pig corpus cavernosum.

Ethanol extract of the aerial parts of Achyrocline satureioides (Lam.) DC. (Asteraceae) showed a significant, dose dependent, relaxant effect on the smooth muscle of corpus cavernosum strips, obtained from Guinea pig (65.5 +/- 4.1% of relaxation at the dose of 25.0 mg/ml). Bioassay guided fractionation of this extract furnished two flavonoids, quercetin and quercetin 3-methyl ether, with important vasorelaxing effects on the corpus cavernosum strips (79.8 +/- 8.4 and 66.0 +/- 4.8% of relaxation respectively at the dose of 0.075 mg/ml). Two methyl derivatives of quercetin obtained by synthesis, quercetin 3,7,3',4'-tetramethylether and quercetin 3,5,7,3',4'-pentamethylether, showed similar relaxant effects at the dose of 0.075 mg/ml (86.4 +/- 8.5 and 67.31 +/- 1.4% of relaxation respectively). The results show that the ethanol extract of A. satureioides and the assayed compounds exhibit significant vasorelaxing properties. Additionally, it is shown that the number of methyl groups in the quercetin nucleus has no significant influence on the effectiveness of these compounds.

Argentinian plant extracts with relaxant effect on the smooth muscle of the corpus cavernosum of guinea pig.

Extracts of different polarity from Baccharis trimera, Haplopappus rigidus Huperzia saururus, Maytenus ilicifolia, Satureja parvifolia and Senecio eriophyton were tested for their relaxant activity on smooth muscle using L-phenylephrine precontracted strips of corpus cavernosum obtained from Guinea pigs. Highly significant and dose dependent results were obtained with the dichloromethane extracts of H. saururus (87% of relaxation at the dose of 10 mg/ml), S. parvifolia (95% of relaxation at 2.5 mg/ml) and S. eriophyton (94% of relaxation at 5 mg/ml). Similar effects were observed with the methanol extracts of H. saururus (88% of relaxation at 10 mg/ml) and S. parvifolia (84% of relaxation at 10 mg/ml). These results were comparable to those obtained with the dichloromethane and methanol extracts of the well known Mexican species Turnera diffusa. Moreover, the aqueous extract of H. rigidus and the aqueous and methanol extracts of S. eriophyton were highly effective in a dose dependent manner (more than 90% of relaxation at the dose of 10 mg/ml). Significant results, but with a lower overall relaxant activity (about 70% of relaxation at 10 mg/ml), could also be obtained with the aqueous extract of S. parvifolia and with the dichlormethane and methanol extracts of B. trimera and M. ilicifolia. The positive controls with Sildenafil citrate at doses ranging from 0.35 to 35 microg/ml yielded moderate effects (up to 46% of relaxation at 35 microg/ml). The effects observed in the present study seem to validate the folk medicinal use of the tested plants and open new ways in the search for natural products with vasodilatory effects.

Volatile constituents of Aristolochia argentina.

The essential oils from leaves, aerial stems and underground organs of Aristolochia argentina Gris., a medicinal plant popularly known as "charrúa", were obtained by hydrodistillation and analyzed by GC and GC/MS. Forty-three components were identified in the oils. All parts of the plant afforded volatile oils characterized by high levels of argentilactone (57-89%) and the presence of undecatriene isomers (0.3-4.0%), these latter compounds providing the essential oils and extracts with an intense particular odor. Terpenes account for the remaining portion of the essential oils (5-29%). Bicyclogermacrene predominates in the aerial parts of the plant, whereas ishwarane is the main terpene of the subterranean organs. Argentilactone, a suspected carcinogenic compound, was also identified in a medicinal commercial tincture of A. argentina.

Inhibitory effect against polymerase and ribonuclease activities of HIV-reverse transcriptase of the aqueous leaf extract of Terminalia triflora.

Dichloromethane, methanol and aqueous extracts from the leaves of Terminalia triflora were investigated for their inhibitory effect on polymerase and ribonuclease activities of HIV reverse transcriptase.The most potent activity was found in the aqueous extract, which inhibited both polymerase and ribonuclease activities of the enzyme with an IC50 of 1.6 micro g/mL and 1.8 micro g/mL respectively. The antiinfective activity of the extract was demonstrated in HLT4LacZ-IIIB cell culture with an IC50 of 1.0 micro g/mL. The extract was submitted to a purification process by extractive and chromatographic methods. The activity remained in the hydrophillic fraction. Tannins present in this active purified fraction, as determined by TLC and HPLC methods, could account for the anti HIV-RT activity found in the aqueous extract.

Investigation of the larvicidal activity of Pothomorphe peltata and isolation of the active constituent.

The insecticidal activity of the leaves of Pothomorphe peltata (Piperaceae) was evaluated on Aedes aegypti larvae. The active methanol extract was subjected to a bioactivity-directed fractionation, monitored by the larvicidal assay, and led to the isolation of a catechol derivative, 4-nerolidylcatechol. This compound was quite potent against Aedes aegypti larvae (LC(50) = 9.1 microg/mL).

Phenolic compounds in seven South American Ilex species.

Ilex paraguariensis (common name: 'mate' or 'yerba mate') is used for the preparation of the most popular tea-like beverage of South America. Choleretic, hypocholesteremic, antioxidant, hepatoprotective and bitter taste properties of mate are attributed to the phenolic constituents of the leaves. I. paraguariensis has seven local congeneric substitutes or adulterants: I. brevicuspis; I. theezans; I. microdonta; I. dumosa var. dumosa; I. taubertiana; I. pseudobuxus; I. integerrima; and I. argentina. An HPLC method using UV with Photodiode Array Detector was developed for the identification and quantification of caffeoyl derivatives (caffeic acid, chlorogenic acid, 3,4-dicaffeoylquinic acid, 3,5-dicaffeoylquinic acid and 4,5-dicaffeoylquinic acid) and flavonoids (quercetin, rutin and kaempferol) in these species. I. paraguariensis showed a higher content of flavonoids and caffeoyl derivatives than the other assayed species.

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.

Profisetinidin type tannins responsible for antioxidant activity in Copaifera reticulata.

The in vitro antioxidant and free radical scavenging properties in bark extracts of South American tree Copaifera reticulata Ducke. (Caesalpinaceae) were studied using different bioassays. Lipid peroxidation was assessed by means of the production of thiobarbituric acid reactive substances (TBARS) in rat liver homogenate. All the extracts tested were effective in this method. The highest activity was observed in the aqueous extract, showing an IC50 of 30 micrograms/ml. DNA sugar damage induced by Fe (II) salts was also used to determine the capacity of the samples to suppress hydroxyl radical-mediated degradation of DNA. Although all the extracts tested were effective in reducing oxidation of DNA, the highest activity was observed in the methanol extract, showing an IC50 of 2 micrograms/ml. Bioassay-guided fractionation of a total methanol extract monitored by luminol-enhanced chemiluminescence, together with structural elucidation using 13C NMR and FABMS, led to the identification of profisetinidin type tannins in a semi-pure fraction. The fraction containing the active compounds also reduced the production of TBARS in rat liver homogenates (IC50 = 530 micrograms/ml) and DNA damage (IC50 = 1 microgram/ml), suggesting that profisetinidins could be responsible for the free radical scavenging and antioxidant activities observed in the extracts.

Human DNA topoisomerase I poisoning activity of bis-1-aminomethylnaphtalenes. A correlation with their cytotoxic activity.

Symmetrical bis-1-aminmoethylnaphtalenes, a group of compounds that demonstrated cytotoxicity towards human tumor cell lines, showed human topoisomerase I poisoning activity. The compounds tested were: N,N'-bis-1-naphthylmethyl-1,6-hexanediamine (1a), N,N'-bis-1-naphthylmethyl-1,8-octanediamine (1b), N,N'-bis-1-naphthylmethyl-1,12-dodecanediamine (1c), N,N'-bis-1-naphthylmethyl-4,4-bipiperidine (2) and N-(1-naphthylmethyl)-N'-dimethyl-1,3-diaminepropane dichlorhydrate (3). All showed human topoisomerase I inhibition by producing protein-linked DNA breaks. The most active were 1a, 1b, 1c with a percentage stimulation of DNA cleavage of 75, 84 and 70% at 100 micrograms/ml, respectively. Compounds 2 and 3 were moderately active as poisons of topoisomerase I activity, the former showing 58% stimulation of DNA cleavage at 100 micrograms/ml and the latter a 24% stimulation. The correlation observed between topoisomerase I poisoning and in vitro cytotoxic activity suggests that this could be a possible mechanism for the cytotoxicity observed in tumor cell lines.

Insecticidal activity against Aedes aegypti larvae of some medicinal South American plants.

The insecticidal activity of 11 extracts from nine South American medicinal plants has been studied using the Aedes aegypti larvicidal assay. Eight of the 11 plant extracts studied showed toxicity against the A. aegypti larvae (LC(50)<500 microg/ml). The dichloromethane extracts of Abuta grandifolia and Minthostachys setosa demonstrated high larvicidal activity, the most active being the dichloromethane extract of A. grandifolia, with an LC(50)=2.6 microg/ml (LC(100)= 8.1 microg/ml), indicating an activity 2-fold higher than beta-asarone, a natural botanical insecticide used as a positive control (LC(100)=16 microg/ml). On the other hand, the dichloromethane extract of M. setosa was quite potent against A. aegypti larvae showing an LC(50)=9.2 microg/ml (LC(100)=25.2 microg/ml). The results obtained suggest that the extracts of A. grandifolia and M. setosa are promising as larvicides against A. aegypti larvae and could be useful in the search for new larvicidal natural compounds.

Cytotoxic and DNA interaction activities of extracts from medicinal plants used in Argentina.

Eight crude extracts from seven Argentine plants with cancer-related ethnobotanical uses have been subjected to a bioscreening study to detect cytotoxic activity. The plants studied were: Aristolochia triangularis, Baccharis grisebachii, Bolax gummifera, Eupatorium hecatanthum, Erythrina crista-galli, Pterocaulon polystachium and Salpichroa origanifolia. Crown gall tumour inhibition, DNA interaction and cytotoxicity towards KB cells were assayed using the potato disc, the DNA-methyl green (DNA-MG) and the KB cells cytotoxicity bioassays respectively. The results obtained indicate that A. triangularis (ED50=47 microg/ml), B. gummifera (ED50=32 microg/ml) and E. hecatanthum (ED50=35 microg/ml) contained cytotoxic compounds against KB cells. All of the plants studied inhibited the growth of crown gall tumours, showing correlation between the experimental data and the uses reported for these plants. Moreover, the results obtained for the extracts of E. hecatanthum and P. polystachium indicate the presence of compounds that interact with DNA (48 and 22% of absorbance decrease, respectively). The results obtained suggest that cytotoxicity could play an important role in the activities claimed for the plants under study.

Diarylsemicarbazones: synthesis, antineoplastic activity and topoisomerase I inhibition assay.

A series of diarylsemicarbazones was synthesized and tested against human neoplastic cell lines. The more active members have a l-naphthyl ring at the carbamidic nitrogen, and chloro, dimethylamino or nitro group substituents at the benzylidene moiety. None of these showed affinity to DNA. One of the more active compounds was tested as a topoisomerase I inhibitor and showed a potent effect. SAR studies demonstrated linear correlation between lypophilicity and activity on the most sensitive lines and a definite conformational shape for antineoplastic action.

Diuretic activity of an aqueous extract of Phyllanthus sellowianus.

Phyllanthus sellowianus Muell. Arg. (Euphorbiaceae) is used widely as a hypoglycemic and diuretic agent in South American folk medicine. In order to assess the diuretic activity of this plant, test animals were treated with a single oral administration of an aqueous extract (5% w/v) of the stem bark of P. sellowianus (400 mg/kg body weight), which produced after 8 h a significant increase in the urinary excretion. In the studies on acute toxicity in mice neither mortality nor neurobehavioral or autonomic profile changes could be observed.

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.

Cytotoxic 4-nerolidylcatechol from Pothomorphe peltata inhibits topoisomerase I activity.

Bioactivity-guided fractionation of the leaf methanolic extract of P. peltata (Piperaceae), using the brine shrimp lethality test, led to the isolation of catechol derivative 4-nerolidylcatechol (4-NC). The methanolic extract was active against crown gall tumour in potato discs, showing a 22% crown gall tumour inhibition (SD = 4%), while 4-NC was cytotoxic against KB tumour cells growth (EC50 = 1.3 micrograms/ml). No interaction with DNA could be observed when tested using the methyl green-DNA (MG-DNA) bioassay. An inhibition in the activity of topoisomerase I using agarose gel electrophoresis was detected in the presence of the purified compound (IC50 = 20 micrograms/ml), suggesting that this could be a possible mechanism for the cytotoxicity observed in KB cells.

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.

Antioxidant and free radical scavenging activities in extracts from medicinal trees used in the 'Caatinga' region in northeastern Brazil.

The in vitro antioxidant and free radical scavenging properties of bark extracts of Anadenanthera macrocarpa Brenan (Fabaceae), Astronium urundeuva Engl. (Anacardiaceae), Mimosa verrucosa Benth. (Fabaceae) and Sideroxylon obtusifolium T.D. Penn. (Sapotaceae), four trees used as anti-inflammatory agents in the Brazilian state of Bahia, were studied using different bioassays. The total reactive antioxidant potential (TRAP) of the aqueous and methanolic extracts was determined by monitoring the intensity of luminol-enhanced chemiluminescence (CL), using 2,2'-azo-bis(2-amidinopropane) as a peroxyl radical source. All the extracts studied were active in this method. The highest activity, measured as equivalents of Trolox concentration, was observed in the methanolic extract of A. macrocarpa (TRAP = 3028 +/- 95 microM). Lipid peroxidation was assessed by means of the production of thiobarbituric acid reactive substances (TBARS) and hydroperoxide-initiated CL in rat liver homogenates. As in the case of luminol-enhanced CL, all the extracts tested were effective in reducing the production of TBARS. The highest activity was observed in the aqueous extract of A. macrocarpa (IC50 = 54 microg/ml). Extracts of A. macrocarpa and S. obtusifolium also reduced hydroperoxide-initiated CL, the methanolic extract of the former being the most active, showing an IC50 = 2.0 microg/ml. DNA-sugar damage induced by Fe(II) salts was also used to determine the capacity of the extracts to suppress hydroxyl radical-mediated degradation of DNA. All extracts tested were highly effective in reducing oxidation of DNA. The highest activity was observed in the methanolic extract of A. urundeuva, showing an IC50 = 37 microg/ml. The results obtained suggest that the antioxidant activity described could play an important role in the anti-inflammatory activity claimed for the plants under study.