Melina A. Sgariglia

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.

Propolis from the northwest of Argentina as a source of antifungal principles

Aims:  To determine the antimycotic and cytotoxic activities of partially purified propolis extract on yeasts, xylophagous and phytopathogenic fungi.

Free radical scavenging activities and inhibition of inflammatory enzymes of phenolics isolated from Tripodanthus acutifolius

ETHNOPHARMACOLOGICAL RELEVANCE Leaf extracts from Tripodanthus acutifolius (Ruiz and Pavón) Van Tieghem have long been used in Argentinean traditional medicine as anti-inflammatory, however, there is no scientific evidence which supports this use in the literature. AIM OF THE STUDY The present study was conducted to evaluate the ability of five phenolic compounds purified from infusion prepared from Tripodanthus acutifolius leaves to inhibit key enzymes in inflammatory processes. As anti-inflammatory compounds frequently possess free radical scavenging activities, purified substances were comparatively evaluated to asses their free radical scavenging properties. Genotoxic effects were also evaluated. MATERIALS AND METHODS Compounds were evaluated on their ability to inhibit hyaluronidase and cyclooxygenase-2 (COX-2) activities to assess their anti-inflammatory capacities. Free radical scavenging activity was assessed by: 1,1-diphenyl-2-picryl-hydrazyl radical (DPPH), superoxide anion assay and the inhibition on lipid peroxidation. Genotoxicity was evaluated by Bacillus subtilis rec assay. RESULTS Fractionation of Tripodanthus acutifolius infusion yielded a novel phenylbutanoid derivative (tripodantoside) and four known flavonoid glycosides (rutin, nicotiflorin, hyperoside and isoquercitrin). Flavonoids produced higher inhibition on hyluronidase activity (IC(50) approximately 1.7 mM) than tripodantoside (IC(50)=27.90 mM). A similar COX-2 inhibition activity was exerted by tripodantoside and monoglycosilated flavonoids (IC(50) approximately 50 microM). Compounds were strong radical scavengers, with effective concentration 50 (EC(50)) values for DPPH in the range of 2.7-6.3 microg/mL, and for superoxide anion in the range of 3.9-8.7 microg/mL. All compounds scavenged peroxyl radicals in the lipid peroxidation assay. The substances showed no genotoxic effects. CONCLUSIONS The anti-inflammatory effects, free radical scavenging activities and lack of genotoxicity of purified compounds may support the folk use of infusion from Tripodanthus acutifolius leaves as anti-inflammatory.

Properties of honey from Tetragonisca angustula fiebrigi and Plebeia wittmanni of Argentina.

The composition of honey samples of Plebeia wittmanni (n = 10) and Tetragonisca angustula fiebrigi (n = 12) was analysed. The colours of all collected honeys were amber to dark amber and the pH varied. Moisture was lower than reported for other stingless bee honeys. Conductivity and ash content of P. wittmanni honey were higher than for T. angustula fiebrigi. Acidity of P. wittmanni honey was the highest ever mentioned for all other Plebeia species. Total sugars and sucrose were higher in T. angustula fiebrigi than in P. wittmanni honey. T. angustula fiebrigi honey showed the highest sucrose content ever mentioned and was rich in oligosaccharides. Both honeys split off sucrose, α-glucosides, trehalose, and amylose. The strongest hydrolytic activity was on sucrose, with high activity for T. angustula fiebrigi honey. Raffinose was also hydrolyzed. The honey of both bees inhibited bacterial growth. These properties support, at least in part, the medicinal use of the stingless bee honey by native people.ZusammenfassungStachellose Bienen sind einheimische Bienen der tropischen und subtropischen Zonen Amerikas und wurden von Einheimischen als Honigquelle und als Medizin benutzt. Von Zentralamerika bis ins tropische und subtropische Südamerika fanden ihre Honige Verwendung in der Behandlung von Infektionen der Augen, Wunden und des oberen Atmungstrakts, sowie als Abführmittel. Die Quechua-Sprache unterscheidet verschiedene Stachellose Bienen-Arten Nordwest-Argentiniens als tiusimi, yana, kayasan, kella und pusquillo. Die physikalischen Parameter und die Zusammensetzung von Honig der Arten Trigona (Tetragonisca) angustula fiebrigi und Plebeia wittmanni, die alle in der Provinz Tucumán, Argentinien gewonnen wurden, sind in Tabelle I zusammengestellt. Die Analyse der Zucker zeigte, dass Glukose und Sacharose die Hauptkomponenten bilden. Hinsichtlich der enzymatischen Aktivität dieser Honie konnten wir zeigen, dass sie in der Lage sind, Sacharose, α-Glykoside, Trehalose und Amylose aufzuspalten. Die stärkste hydrolytische Aktivität fanden wir bei zwei T. angustula fiebrigi-Honigen, wobei diese gegen Sacharose gerichtet war. Raffinose, ein Sacharose-ähnliches Oligosacharid wurde ebenfalls hydrolisiert (Tab. II). Verdünnte Honige von T. angustula fiebrigi (> 30 μL; 30 % w/v) und P. wittmanni (> 20 μL; 20 % w/v) zeigten anitbiotische Eigenschaften gegen verschiedene pathogene Bakterien (Escherichia coli, Pseudomonas aeruginosa, Enterococcus faecalis und Staphylococcus aureus) mit einer Konzentration von 108 CFU/mL (Tab. III). Diese Eigenschaften erklären die medizinische Verwendung der Honige Stachelloser Bienen in ihren Ursprungsländern, v.a durch die einheimische Bevölkerung.

Purification and identification of antibacterial phenolics from Tripodanthus acutifolius leaves.

Aims:  To perform an activity‐guided purification, identification and quantification of antibacterial compounds from Tripodanthus acutifolius infusion. To validate the antibacterial activity of purified substances.

Purification and characterization of an exo-polygalacturonase from Pycnoporus sanguineus.

The present work describes the purification and characterization of a novel extracellular polygalacturonase, PGase I, produced by Pycnoporus sanguineus when grown on citrus fruit pectin. This substrate gave enhanced enzyme production as compared to sucrose and lactose. PGase I is an exocellular enzyme releasing galacturonic acid as its principal hydrolysis product as determined by TLC and orcinol-sulphuric acid staining. Its capacity to hydrolyze digalacturonate identified PGase I as an exo-polygalacturonase. SDS-PAGE showed that PGase I is an N-glycosidated monomer. The enzyme has a molecular mass of 42kDa, optimum pH 4.8 and stability between pH 3.8 and 8.0. A temperature optimum was observed at 50-60 degrees C, with some enzyme activity retained up to 80 degrees C. Its activation energy was 5.352calmol(-1). PGase I showed a higher affinity towards PGA than citric pectin (Km=0.55+/-0.02 and 0.72+/-0.02mgml(-1), respectively). Consequently, PGase I is an exo-PGase, EC 3.2.1.82.

Antifungal activity and cytotoxicity of extracts and triterpenoid saponins obtained from the aerial parts of Anagallis arvensis L.

ETHNOPHARMACOLOGICAL RELEVANCE Anagallis arvensis L. (Primulaceae) is used in argentinean northwestern traditional medicine to treat fungal infections. We are reporting the isolation and identification of compounds with antifungal activity against human pathogenic yeast Candida albicans, and toxicity evaluation. AIM OF THE STUDY to study the antifungal activity of extracts and purified compounds obtained form A. arvensis aerial parts, alone and in combinations with fluconazole (FLU), and to study the toxicity of the active compounds. MATERIALS AND METHODS Disk diffusion assays were used to perform an activity-guided isolation of antifungal compounds from the aerial parts of A. arvensis. Broth dilution checkerboard and viable cell count assays were employed to determine the effects of samples and combinations of FLU + samples against Candida albicans. The chemical structures of active compounds were elucidated by spectroscopic analysis. Genotoxic and haemolytic effects of the isolated compounds were determined. RESULTS Four triterpenoid saponins (1-4) were identified. Anagallisin C (AnC), exerted the highest inhibitory activity among the assayed compounds against C. albicans reference strain (ATCC 10231), with MIC-0 =1µg/mL. The Fractional Inhibitory Concentration Index (FICI=0.129) indicated a synergistic effect between AnC (0.125µg/mL) and FLU (0.031µg/mL) against C. albicans ATCC 10231. AnC inhibited C. albicans 12-99 FLU resistant strain (MIC-0 =1µg/mL), and the FICI=0.188 indicated a synergistic effect between AnC (0.125µg/mL) and fluconazole (16µg/mL). The combination AnC+ FLU exerted fungicidal activity against both C. albicans strains. AnC exerted inhibitory activity against C. albicans ATCC 10231 sessile cells (MIC50=0.5µg/mL and MIC80=1µg/mL) and against C. albicans 12-99 sessile cells (MIC50=0.75µg/mL and MIC80=1.25µg/mL). AnC exerted haemolytic effect against human red blood cells at 15µg/mL and did not exerted genotoxic effect on Bacillus subtilis rec strains. CONCLUSIONS The antifungal activity and lack of genotoxic effects of AnC give support to the traditional use of A. arvensis as antifungal and makes AnC a compound of interest to expand the available antifungal drugs.