Comparison of antimicrobial activity in the epidermal mucus extracts of fish

The mucus layer on the surface of fish consists of several antimicrobial agents that provide a first line of defense against invading pathogens. To date, little is known about the antimicrobial properties of the mucus of Arctic char (Salvelinus alpinus), brook trout (S. fontinalis), koi carp (Cyprinus carpio sub sp. koi), striped bass (Morone saxatilis), haddock (Melanogrammus aeglefinus) and hagfish (Myxine glutinosa). The epidermal mucus samples from these fish were extracted with acidic, organic and aqueous solvents to identify potential antimicrobial agents including basic peptides, secondary metabolites, aqueous and acid soluble compounds. Initial screening of the mucus extracts against a susceptible strain of Salmonella enterica C610, showed a significant variation in antimicrobial activity among the fish species examined. The acidic mucus extracts of brook trout, haddock and hagfish exhibited bactericidal activity. The organic mucus extracts of brook trout, striped bass and koi carp showed bacteriostatic activity. There was no detectable activity in the aqueous mucus extracts. Further investigations of the activity of the acidic mucus extracts of brook trout, haddock and hagfish showed that these fish species had specific activity for fish and human pathogens, demonstrating the role of fish mucus in antimicrobial protection. In comparison to brook trout and haddock, the minimum bactericidal concentrations of hagfish acidic mucus extracts were found to be approximately 1.5 to 3.0 times lower against fish pathogens and approximately 1.6 to 6.6 folds lower for human pathogens. This preliminary information suggests that the mucus from these fish species may be a source of novel antimicrobial agents for fish and human health related applications.     

Identification of vibriocidal compounds from medicinal plants using chromatographic fingerprinting

The aim of the present study was to investigate the vibriocidal activity of bark of Syzygium cumini, leaves of Lawsonia inermis, fruits of Terminalia bellerica and identify the bioactive compounds. The vibriocidal activity of plant extracts was determined in aqueous and organic solvents, and the minimum inhibitory concentration (MIC) against Vibrio spp. using the disk diffusion method was established. The chemical constituents of the plant extracts were analysed by thin layer chromatography (TLC), the vibriocidal compounds were determined by TLC-bioautography and were further confirmed by high performance liquid chromatography (HPLC). Significant inhibitory activity was observed with ethanol extract of plants against the test bacteria while less antibacterial activity was observed in acetone, methanol and aqueous extracts. The MIC of the plant extracts ranged between 2.5 and 20 mg/ml. The TLC, TLC-bioautography and HPLC analysis showed that gallic acid and tannin present in ethanol extracts of S. cumini, tannin present in L. inermis and gallic acid present in T. bellerica may be responsible for the vibriocidal activity. S. cumini, L. inermis and T. bellerica can be used for the treatment of gastroenteritis, diarrhoea and cholera diseases after detailed investigations. We also conclude that the plants rich in gallic acid and tannin can be used as an alternative to search for new vibriocidal drugs.     

Strobilols A-D: four cadinane-type sesquiterpenes from the edible mushroom Strobilurus ohshimae

Four sesquiterpenoids--strobilols A (1), B (2), C (3), and D (4)--were isolated from the organic extracts of fruiting bodies of the edible mushroom Strobilurus ohshimae. Their structures were determined by spectroscopic methods. Compound 1 exhibited moderate activity against the brine shrimp Artemia salina. This paper is the first report on isolation of cadinane-type sesquiterpenoids from S. ohshimae.     

Antibacterial activities in various tissues of the horse mussel, Modiolus modiolus

A search for antibacterial activity in different organs/tissues of the horse mussel, Modiolus modiolus, was conducted. Dried samples were extracted with 60% (v/v) acetonitrile, containing 0.1% (v/v) trifluoroacetic acid. Due to high salt content, two liquid phases were obtained; an acetonitrile-rich phase (ACN extract) and an aqueous phase. The aqueous phase was further subjected to solid phase extraction (SPE). Eluates from SPE and ACN extracts were tested for antibacterial, lysozyme, and toxic activity. Antibacterial activity was demonstrated in extracts from several tissues, including plasma, haemocytes, labial palps, byssus, mantle, and gills. Some of the extracts were sensitive to proteinase K treatment, indicating antibacterial peptides and/or proteins. Lysozyme-like activity and toxic activity against Artemia salina nauplii was detected in fractions from the gills, mantle, muscle, and haemocytes. Results from this study indicate that M. modiolus is a promising source for identifying novel drug lead compounds.     

Biological screening of Brazilian medicinal plants

In this study, we screened sixty medicinal plant species from the Brazilian savanna ("cerrado") that could contain useful compounds for the control of tropical diseases. The plant selection was based on existing ethnobotanic information and interviews with local healers. Plant extracts were screened for: (a) molluscicidal activity against Biomphalaria glabrata, (b) toxicity to brine shrimp (Artemia salina L.), (c) antifungal activity in the bioautographic assay with Cladosporium sphaerospermum and (d) antibacterial activity in the agar diffusion assay against Staphylococcus aureus, Escherichia coli, Bacillus cereus and Pseudomonas aeruginosa. Forty-two species afforded extracts that showed some degree of activity in one or more of these bioassays.     

Biological activities of extracts from Chenopodium ambrosioides Lineu and Kielmeyera neglecta Saddi

ABSTRACT: BACKGROUND: Chenopodium ambrosioides and Kielmeyera neglecta are plants traditionally used in Brazil to treat various infectious diseases. The study of the biological activities of these plants is of great importance for the detection of biologically active compounds. METHODS: Extracts from these plants were extracted with hexane (Hex), dichloromethane (DCM), ethyl acetate (EtOAc) and ethanol (EtOH) and assessed for their antimicrobial properties, bioactivity against Artemia salina Leach and antifungal action on the cell wall of Neurospora crassa. RESULTS: Extracts from C. ambrosioides (Hex, DCM and EtOH) and K. neglecta (EtOAc and EtOH) showed high bioactivity against A. salina (LD50 < 1000 ug/mL), which might be associated with cytotoxic activity against cancer cells. C. ambrosioides Hex and DCM showed specific activity against yeasts, highlighting the activity of hexanic extract against Candida krusei (MIC = 100 ug/mL). By comparing the inhibitory concentration of 50% growth (IC 50%) with the growth control, extracts from K. neglecta EtOAc and EtOH have shown activities against multidrug-resistant bacteria (Enterococcus faecalis ATCC 51299 and Staphylococcus aureus ATCC 43300), with IC 50% of 12.5 ug/mL The assay carried out on N. crassa allowed defining that extracts with antifungal activity do not have action through inhibition of cell wall synthesis. CONCLUSIONS: Generally speaking, extracts from C. ambrosioides and K. neglecta showed biological activities that have made the search for bioactive substances in these plants more attractive, illustrating the success of their use in the Brazilian folk medicine.     

Identification of disulfides from the biodegradation of dibenzothiophene.

Several investigations have identified benzothiophene-2,3-dione in the organic solvent extracts of acidified cultures degrading dibenzothiophene via the Kodama pathway. In solution at neutral pH, the 2,3-dione exists as 2-mercaptophenylglyoxylate, which cyclizes upon acidification and is extracted as the 2,3-dione. The fate of these compounds in microbial cultures has never been determined. This study investigated the abiotic reactions of 2-mercaptophenylglyoxylate incubated aerobically in mineral salts medium at neutral pH. Oxidation led to the formation of 2-oxo-2-(2-thiophenyl)ethanoic acid disulfide, formed from two molecules of 2-mercaptophenylglyoxylate. Two sequential abiotic, net losses of both a carbon and an oxygen atom produced two additional disulfides, 2-oxo-2-(2-thiophenyl)ethanoic acid 2-benzoic acid disulfide and 2,2'-dithiosalicylic acid. The methods developed to extract and detect these three disulfides were then used for the analysis of a culture of Pseudomonas sp. strain BT1d grown on dibenzothiophene as its sole carbon and energy source. All three of the disulfides were detected, indicating that 2-mercaptophenylglyoxylate is an important, short-lived intermediate in the breakdown of dibenzothiophene via the Kodama pathway. The disulfides eluded previous investigations because of (i) their high polarity, being dicarboxylic acids; (ii) the need to lower the pH of the aqueous medium to <1 to extract them into an organic solvent such as dichloromethane; (iii) their poor solubility in organic solvents, (iv) their removal from organic extracts of cultures during filtration through the commonly used drying agent anhydrous sodium sulfate; and (v) their high molecular masses (362, 334, and 306 Da) compared to that of dibenzothiophene (184 Da).     

Identification of Disulfides from the Biodegradation of Dibenzothiophene

Several investigations have identified benzothiophene-2,3-dione in the organic solvent extracts of acidified cultures degrading dibenzothiophene via the Kodama pathway. In solution at neutral pH, the 2,3-dione exists as 2-mercaptophenylglyoxylate, which cyclizes upon acidification and is extracted as the 2,3-dione. The fate of these compounds in microbial cultures has never been determined. This study investigated the abiotic reactions of 2-mercaptophenylglyoxylate incubated aerobically in mineral salts medium at neutral pH. Oxidation led to the formation of 2-oxo-2-(2-thiophenyl)ethanoic acid disulfide, formed from two molecules of 2-mercaptophenylglyoxylate. Two sequential abiotic, net losses of both a carbon and an oxygen atom produced two additional disulfides, 2-oxo-2-(2-thiophenyl)ethanoic acid 2-benzoic acid disulfide and 2,2′-dithiosalicylic acid. The methods developed to extract and detect these three disulfides were then used for the analysis of a culture of Pseudomonas sp. strain BT1d grown on dibenzothiophene as its sole carbon and energy source. All three of the disulfides were detected, indicating that 2-mercaptophenylglyoxylate is an important, short-lived intermediate in the breakdown of dibenzothiophene via the Kodama pathway. The disulfides eluded previous investigations because of (i) their high polarity, being dicarboxylic acids; (ii) the need to lower the pH of the aqueous medium to <1 to extract them into an organic solvent such as dichloromethane; (iii) their poor solubility in organic solvents, (iv) their removal from organic extracts of cultures during filtration through the commonly used drying agent anhydrous sodium sulfate; and (v) their high molecular masses (362, 334, and 306 Da) compared to that of dibenzothiophene (184 Da).     

Antibacterial efficacy of Withania somnifera (ashwagandha) an indigenous medicinal plant against experimental murine salmonellosis

In the present study, we evaluated the antibacterial activity of ashwagandha [Withania somnifera L. Dunal (Solanaceae; root and leaves)], an Indian traditional medicinal plant against pathogenic bacteria. Both aqueous as well as alcoholic extracts of the plant (root as well as leaves) were found to possess strong antibacterial activity against a range of bacteria, as revealed by in vitro Agar Well Diffusion Method. The methanolic extract was further subfractionated using various solvents and the butanolic sub-fraction was found to possess maximum inhibitory activity against a spectrum of bacteria including Salmonella typhimurium. Moreover, in contrast to the synthetic antibiotic (viz. chloramphenicol), these extracts did not induce lysis on incubation with human erythrocytes, advocating their safety to the living cells. Finally, the antibacterial efficacy of the extracts isolated from plant (both root and leaves) was determined against experimental salmonellosis in Balb/C mice. Oral administration of the aqueous extracts successfully obliterated salmonella infection in Balb/C mice as revealed by increased survival rate as well as less bacterial load in various vital organs of the treated animals.     

The effect of Smallanthus sonchifolius leaf extracts on rat hepatic metabolism

Smallanthus sonchifolius (yacon), originating from South America, has become popular in Japan and in New Zealand for its tubers which contain beta-1,2-oligofructans as the main saccharides. The plant is also successfully cultivated in Central Europe in the Czech Republic in particular. Its aerial part is used in Japan and in Brazil as a component in medicinal teas; while aqueous leaf extracts have been studied for their hypoglycemic activity in normal and diabetic rats. We have already demonstrated the high content of phenolic compounds in yacon leaf extracts and their in vitro antioxidant activity. In this paper, we present the effects of two organic fractions and two aqueous extracts from the leaves of S. sonchifolius on rat hepatocyte viability, on oxidative damage induced by tert-butyl hydroperoxide (t-BH) and allyl alcohol (AA), and on glucose metabolism and their insulin-like effect on the expression of cytochrome P450 (CYP) mRNA. All the extracts tested exhibited strong protective effect against oxidative damage to rat hepatocyte primary cultures in concentrations ranging from 1 to 1000 microg/ml, reduced hepatic glucose production via gluconeogenesis and glycogenolysis at 1000 microg/ml. Moreover, the effects of the organic fractions (200 and 250 microg/ml) and to a lesser extent, the tea infusion (500 microg/ml) on rat CYP2B and CYP2E mRNA expression, were comparable to those observed with insulin. The combination of radical scavenging, cytoprotective and anti-hyperglycemic activity predetermine S. sonchifolius leaves for use in prevention and treatment of chronic diseases involving oxidative stress, particularly diabetes.     

SOS-red fluorescent protein (RFP) bioassay system for monitoring of antigenotoxic activity in plant extracts

An optical antigenotoxicity assay using genetically engineered red fluorescent bacteria is presented. Exposure of Escherichia coli RS4U to genotoxicants [mitomycin C (MMC), nalidixic acid (NA) and hydrogen peroxide (HP)] resulted in phenotypic red fluorescence proportional to the concentration of the inducer. Except for tannic acid (TA), co-treatment of the genotoxicant-activated bacteria with ascorbic acid (AA) and aqueous plant extracts (Mangifera indica, Psidium guajava and Syzygium cumini) afforded protection against all three genotoxicants. TA was effective in suppressing the genotoxic effect of MMC and HP. The antigenotoxic effect is seen as inhibition of the genotoxicant-triggered red fluorescence. The IC50 of the plant extracts and AA varied with the genotoxicant used. Rec assay verified the antigenotoxic activity of the plant extracts. Folin-Ciocalteu test, FeCl3 test and DPPH assay confirmed the presence of polyphenolic compounds and hydrolyzable tannins in the plant extracts and the antioxidant capacity of the plant samples.     

Antioxidant activity of leaf extracts from Bauhinia monandra

Bauhinia monandra Kurz. is used in Brazil for the treatment of diabetes. Since this activity may be correlated with the presence of antioxidant compounds, leaf extracts of B. monandra were evaluated for their radical scavenging capacity (RSC). An ethanolic extract was taken up in aqueous methanol and partitioned with hexane, chloroform, ethyl acetate to yield three organic extracts together with remaining aqueous extract. The RSC was determined spectrophotometrically using 1,1-diphenylpicrylhydrazyl free radical (DPPH). The chloroform and ethyl acetate extracts were the most appropriate as sources of antioxidant compounds as shown by their inhibition concentration (IC50) and inhibition percentage (IP) values. The antioxidant activity of such extracts was attributed to the presence of three compounds of different polarities (flavonoids and steroids). The chloroform and ethyl acetate extracts exhibited an IC50 of approximately 2 mg/g DPPH and IP values in the range of 60-65%. The results indicate that the extracts of B. monandra have a very potent antioxidant activity, compared with the pure catechins used as positive controls and with other plant extracts.     

Molluscicidal activity of various solvent extracts from Solanum nigrum var. villosum L. aerial parts against Galba truncatula

Molluscicidal activity of Solanum nigrum var. villosum (morelle velue) extracts and their fractions were tested against the mollusca gastropoda Galba truncatula intermediate host of Fasciola hepatica. The results indicated that the hydro-methanol (MeOH-H2O) immature fruit extract possess the highest molluscicidal activity (LC50 = 3.96 mg/L) against Galba truncatula compared with other tested compounds. After acido-basic treatment, the methanolic extract fraction isolated from the immature fruits and the richest in alkaloids was the most toxic (LC50 = 1.65 mg/L). The fractions richest in saponosides obtained from the hydromethanolic and methanolic extracts of immature fruits showed interesting molluscicidal activities (LC50 = 6.15 mg/L and LC50 = 7.91 mg/L, respectively). The observed molluscicide activity could be attributed to the presence of alkaloids or saponosides. So, the immature fruits of Solanum nigrum var. villosum could be substrates of choice for molluscicide activity. In addition, total alkaloids and saponosides present in this plant deserve further investigations in order to identify the active principles and demonstrate their activities on mollusks in their natural habitat. According to the World Health Organization's guidelines on screening for plant molluscicides, use of these fractions may add to the arsenal of methods to control snail transmitting fasciolosis in tropical and Third World countries where fasciolosis is a common disease.     

Antifouling activity of sessile bacilli derived from marine surfaces

Marine biofilms are a virtually untapped source of bioactive molecules that may find application as novel antifoulants in the marine paint industry. This study aimed at determining the potential of marine biofilm bacteria to produce novel biomolecules with potential application as natural antifoulants. Nine representative strains were isolated from a range of surfaces and were grown in YEB medium and harvested during the late exponential growth phase. Bacterial biomass and spent culture medium were extracted with ethanol and ethyl acetate, respectively. Extracts were assayed for their antifouling activity using two tests: (1) antimicrobial well diffusion test against a common fouling bacterium, Halomonas marina, and (2) anti-crustacean activity test using Artemia salina. Our results showed that none of the ethanolic extracts (bacterial biomass) were active in either test. In contrast, most of the organic extracts had antimicrobial activity (88%) and were toxic towards A. salina (67%). Sequencing of full 16 S ribosomal DNA analysis showed that the isolates were related to Bacillus mojavensis and Bacillus firmus. Matrix-assisted laser desorption ionization-time-of-flight mass spectrometry (MALDI-TOF-MS) profiling of ethyl acetate extracts of culture supernatants showed that these species produce the bioactive lipopeptides surfactin A, mycosubtilin and bacillomycin D.     

Antimicrobial activity of fractions and compounds from Calophyllumbrasiliense (Clusiaceae/Guttiferae)

Calophyllum brasiliense (Clusiaceae/Guttiferae) is a native Brazilian medicinal plant traditionally used against several diseases, including infectious pathologies. Crude methanolic extracts (CME) and two fractions, denoted non-polar (soluble in chloroform) and polar (nonsoluble in chloroform), were prepared from different parts of the plant (roots, stems, leaves, flowers and fruits) and studied. The following compounds were isolated and tested against pathogenic bacteria and yeasts by determination of the minimal inhibitory concentration (MIC): brasiliensic acid (1), gallic acid (2), epicatechin (3), protocatechuic acid (4), friedelin (5) and 1,5-dihydroxyxanthone (6). The results indicated that all the parts of the plant exhibited antimicrobial activity against Gram-positive bacteria, which are selectively inhibited by components of C. brasiliense. No activity was observed against Gram-negative bacteria and yeasts tested. Regarding the isolated compounds, substance 4 showed antimicrobial activity against all the tested microorganisms, whereas compound 6 exhibited antimicrobial activity only against Gram-positive bacteria. The results from the current study confirm and justify the popular use of this plant to treat infectious processes.     

In vitro evaluation of Datura innoxia (thorn-apple) for potential antibacterial activity

Various parts of Datura innoxia were examined for potential antibacterial activity by preparing their crude aqueous and organic extracts against Gram-negative bacteria (Escherichia coli and Salmonella typhi) and Gram-positive bacteria (Bacillus cereus, Bacillus subtilis and Staphylococcus aureus). The results of agar well diffusion assay indicated that the pattern of inhibition depends largely upon the plant part, solvent used for extraction and the organism tested. Extracts prepared from leaves were shown to have better efficacy than stem and root extracts. Organic extracts provided potent antibacterial activity as compared to aqueous extracts. Among all the extracts, methanolic extract was found most active against almost all the bacterial species tested. Gram-positive bacteria were found most sensitive as compared to Gram-negative bacteria. Staphylococcus aureus was signifi cantly inhibited by almost all the extracts even at very low MIC followed by other Gram-positives. For Escherichia coli (a Gram-negative bacterium), the end point was not reached for ethyl acetate extract while it was very high for other extracts. The study promises an interesting future for designing a potentially active antibacterial agent from Datura innoxia.     

Qualitative HPLC‐DAD/ESI‐TOF‐MS Analysis,Cytotoxic, and Apoptotic Effects of Croatian Endemic Centaurea ragusina L. Aqueous Extracts

Centaurea ragusina L., an endemic Croatian plant species, revealed a good cytotoxic activity of aqueous extracts (AE) on human bladder (T24) and human glioblastoma (A1235) cancer cell lines. The chemical constituents were tentatively identified using high performance liquid chromatography HPLC‐DAD/ESI‐TOF‐MS in negative ionization mode. The main compounds of herba extract were sesquiterpene lactones: solstitialin A 3,13‐diacetate and epoxyrepdiolide; organic acid: quinic acid. The main compounds of flower extract were organic acids: quinic acid, citric acid, and malic acid; sesquiterpene lactone: cynaropicrin; phenolic compounds: chlorogenic acid and phenylpropanoid: syringin. The AE of C. ragusina were investigated for correlation of their effects on human bladder (T24) and human glioblastoma (A1235) cancer cell lines using the MTT assay. Although both extracts showed significant dose‐ and time‐dependent cytotoxic activity against both cancer cell lines, the flower extract exhibited slightly higher activity. In order to determine type of cell death induced by treatment, cell lines were exposed subsequently to a treatment with both flower and herba AE. The majority of the cells died by induced apoptosis treatment. Flower AE (26.25%), compared to a leaf AE (22.15%) showed slightly higher percentage of an apoptosis in T24 cells, when compared to a non‐treated cells (0.04%).     

Evaluation of the antifungal activity of Rumex vesicarius L. and Ziziphus spina-christi (L) Desf. Aqueous extracts and assessment of the morphological changes induced to certain myco-phytopathogens

Many Plant extracts had proved a potential antifungal activity against a wide range of phytopathogenic fungi. The aim of this study was to evaluate the antifungal activity of the aqueous extracts of Rumex vesicarius L. and Ziziphus spina-christi (L) Desf. against some fungal species. The effect on growth inhibition, conidia germination, sporogenesis, morphological, and ultrastructural characterizations of fungal growth by scanning and transmission electron microscopes, have been investigated. Both plant extracts exhibited an antifungal activity against Fusarium, Helminthosporium, Alternaria, and Rhizoctonia species, besides, the sporogenesis of Alternaria and Fusarium species was suppressed. Both plants induced severe morphological changes in the hyphal shape and surface. We concluded that the aqueous extracts of these plants had strong antifungal activities. More investigations should be performed to evaluate the possible applications in agriculture and in vivo.     

Solanum paniculatum L. (Jurubeba): potent inhibitor of gastric acid secretion in mice.

Solanum paniculatum L. is used commonly in Brazilian folk medicine for the treatment of liver and gastrointestinal disorders. The freeze-dried aqueous extracts (WEs) obtained from distinct parts of the plant (flowers, fruits, leaves, stems and roots) were tested to determine their antiulcer and antisecretory gastric acid activities using mice. The aqueous extracts of roots, stems and flowers inhibited gastric acid secretion in pylorus-ligated mice with ED50 values of 418, 777 and 820 mg/kg body wt. (i.d.), respectively. Extracts of leaves (0.5-2 g/kg body wt., i.d.) did not affect gastric secretion, whereas fruit extracts (0.5-2 g/kg body wt., i.d.) stimulated gastric acid secretion. The stimulatory effect of the fruit extract was inhibited by pretreatment with atropine (5 mg/kg body wt., i.m.) but not with ranitidine (80 mg/kg body wt., i.p.) suggesting that the fruit extract activates the muscarinic pathway of gastric acid secretion. In contrast, administration of the root extract into the duodenal lumen inhibited histamine- and bethanechol-induced gastric secretion in pylorus-ligated mice. In addition, the aqueous extract of roots (ED50 value, 1.2 g/kg body wt., p.o.) protected the animals against production of gastric lesions subsequent to the hypersecretion induced in mice by stress following cold restraint. This effect was not reproduced when the lesions were induced by blockade of prostaglandins synthesis via subcutaneous injection of indomethacin. Thus, antiulcer activity of the plant extracts appears to be related directly to a potent anti-secretory activity. No toxic signs were observed following administration of different extracts up to 2 g/kg body wt., p.o. Collectively, the results validate folk use of Solanum paniculatum L. plant to treat gastric disorders.     

Antibacterial activity of plant extracts from northwestern Argentina

AIMS: To determine the antibacterial and cytotoxic activities of aqueous and ethanolic extracts of northwestern Argentinian plants used in folk medicine. To compare the mentioned activities with those of five commercial antibiotics. To identify the compounds responsible for the antibacterial activity. METHODS AND RESULTS: Plant extracts were prepared according to traditional uses in northwestern Argentina. Antibacterial activity was assayed by agar dilution in Petri dishes and broth dilution in 96-well plates. Lethal dose 50 (LD(50)) was determined by the Artemia salina assay. Phytochemical analysis was performed by sample adsorption on silica gel, thin-layer chromatography (TLC), bioautography and UV-visible spectra. The results showed that Tripodanthus acutifolius aqueous extracts have lower minimal inhibitory concentrations (MIC) (502 and 506 microg of extracted material (EM) per ml for infusion and decoction, respectively) than cefotaxim MIC (640 microg ml(-1)) against Acinetobacterfreundii (303). These data were lower than their LD(50). Tripodanthus acutifolius tincture showed lower MIC (110 microg of EM per ml) and minimal bactericidal concentration (MBC) (220 microg of EM per ml) than cefotaxim (MIC and MBC of 320 microg ml(-1)) for Pseudomonasaeruginosa. This extract also showed a MIC/MBC of 110/220 microg of EM per ml, lower than oxacillin (MIC/MBC of 160/220 microg ml(-1)) for Staphylococcus aureus (ATCC 25923). The cytotoxicity of all extracts were compared with that of commercial antibiotics. Rutin (3,3',4',5,7-pentahydroxyflavone 3-beta-rhamnosilglucoside), iso-quercitrin (3,3',4',5,7-pentahydroxyflavone 3-beta-glucoside) and a terpene would be partially responsible for the antibacterial activity of T. acutifolius infusion. CONCLUSIONS: Tripodanthus acutifolius extracts had the ability to inhibit bacterial growth. The antibacterial activity differs with the applied extractive method, and it could be partially attributed to glycoflavonoids. This paper contributes to the knowledge of antibacterial capacity of plants from northwestern Argentina. SIGNIFICANCE AND IMPACT OF THE STUDY: These antibacterial activities support further studies to discover new chemical structures that can contribute to alleviate or cure some illnesses.