Antibacterial activities, proposed mode of action and cytotoxicity of leaf extracts from Triumfetta welwitschii against Pseudomonas aeruginosa.

BACKGROUND: Pseudomonas aeruginosa has become a main cause of Gram-negative infection, particularly in patients with compromised immunity. High rates of resistance to antibiotics are associated with nosocomial infections caused by P. aeruginosa strains. The search for novel antimicrobials has been necessitated by the emergence of antimicrobial resistance in some bacteria Plant-based antimicrobials has great potential to combat microbial infections using a variety of mechanisms. Triumfetta welwitschii plant roots are traditionally used to treat symptoms of diarrhoea and fever, suggesting that it possess antimicrobial and immunomodulatory effects. Since research investigating antimicrobial properties of the roots of Triumfetta welwitschii has been explored, there is need to investigate the antimicrobial activity of its leaf extracts in order to probe their prospective use as new antimicrobial agents that can be used to combat nosocomial infections. The objective of this study was to evaluate the antibacterial activities, the mode of action and cytotoxicity of T. welwitschii leaf extracts. METHOD: Extracts of T. welwitschii leaves were obtained using eight different solvents, the serial exhaustive extraction method and the cold maceration technique. In vitro antibacterial activity evaluation of the extracts was done on eight bacterial isolates using the broth microdilution method. The mode of action for the most potent extracts was investigated using the rhodamine 6G efflux assay and the propidium iodide-based membrane damage assay. Toxicity of the extracts was evaluated using the haemolytic and MTT (3-(4, 5-dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide) assays. RESULTS: The results showed that acetone, ethanol and dichlorometane: methanol extracts had the most potent antibacterial activities against Pseudomonas aeruginosa (ATCC 27853). All three extracts caused membrane disruption of P. aeruginosa as shown by nucleic acid leakage. All three extracts were unable to inhibit efflux pumps. CONCLUSION: The presence of antibacterial activities and low toxicity shown by the extracts indicates that the plant may be a source of effective antibacterial against some bacterial infections caused by P. aeruginosa. The disruption of membrane integrity is one possible mode of action of antibacterial activity of the potent extracts.

Nematicidal activities of 4-quinolone alkaloids isolated from the aerial part of Triumfetta grandidens against Meloidogyne incognita.

The methanol extract of the aerial part of Triumfetta grandidens (Tiliaceae) was highly active against Meloidogyne incognita, with second-stage juveniles (J2s) mortality of 100% at 500 µg/mL at 48 h post-exposure. Two 4-quinolone alkaloids, waltherione E (1), a new alkaloid, and waltherione A (2), were isolated and identified as nematicidal compounds through bioassay-guided fractionation and instrumental analysis. The nematicidal activities of the isolated compounds against M. incognita were evaluated on the basis of mortality and effect on egg hatching. Compounds 1 and 2 exhibited high mortalities against J2s of M. incognita, with EC50 values of 0.09 and 0.27 µg/mL at 48 h, respectively. Compounds 1 and 2 also exhibited a considerable inhibitory effect on egg hatching, which inhibited 91.9 and 87.4% of egg hatching, respectively, after 7 days of exposure at a concentration of 1.25 µg/mL. The biological activities of the two 4-quinolone alkaloids were comparable to those of abamectin. In addition, pot experiments using the crude extract of the aerial part of T. grandidens showed that it completely suppressed the formation of gall on roots of plants at a concentration of 1000 µg/mL. These results suggest that T. grandidens and its bioactive 4-quinolone alkaloids can be used as a potent botanical nematicide in organic agriculture.

Estudio fitoquímico, evaluación de la actividad antioxidante y antimicrobiana de la corteza de "triumfetta semitriloba" jacq (moteccepo) y análisis de parámetros reológicos del mucílago / Phytochemical study, evaluation of the antioxidant and antimicrobial activity of the bark of "triumfetta semitriloba" jacq (moteccepo) and analysis of rheological parameters of the mucilage

El género Triumfetta tiene varias especies tales como Triumfetta pilosa Poth, con actividad hipoglucemiante y antihelmíntica (Deepak, 2011); Triumfetta rhomboidea Jaqc, con actividad antibacterial (Devmurari, 2010). La especie Triumfetta semitriloba Jaqc ha sido muy poco estudiada. Sólo se conoce un estudio de sus hojas, las que presentaron actividad giardicida. (Barraza, 2011), sin embargo es muy utilizada en la medicina tradicional. En este trabajo de investigación se pretende contribuir al conocimiento fitoquímico de la corteza de Triumfetta semitriloba" Jaqc, puesto que los reportes de metabolitos de esta parte de la planta son escasos. Esta especie fue recolectada en la localidad de Generosa provincia de Chincheros departamento de Apurímac región quechua (entre 1900 y 2500 msnm), y fue clasificada en el Museo de Historia Natural como "Triumfetta semitriloba" Jacq, cuyo nombre vulgar es "Moteccepo". Se acondicionó la corteza y se determinó 70,00 % de humedad; 2,76 % de ceniza, y mediante el análisis de minerales se encontró que posee una alta cantidad de Ca (4007,16 ppm). Luego se realizó una comparación de técnicas de extracción, determinándose un mayor rendimiento en la maceración durante 2 semanas. Después se realizó la extracción sucesiva de la corteza con solventes de polaridad creciente encontrándose mayor extracción con agua (41,00 %) y menor extracción con acetato de etilo (0,37 %). En la marcha fitoquímica de la corteza se comprobó la presencia de saponinas esteroidales, taninos condensados, flavonoides y cumarinas. Al cuantificar polifenoles totales y taninos se encontró 1184,96 mgAG/100g y 751,20 mgAT/100g respectivamente. La evaluación de la actividad antioxidante por el método del radical DPPH del extracto metanólico y del extracto acuoso (mucílago liofilizado), reportó un CI50 de 21,08 g/mL y 169,90 g/mL respectivamente. Luego se analizó los posibles metabolitos responsables de esta actividad antioxidante, mediante el análisis de los extractos por CCF, espectroscopia UV-Vis, IR y CPG encontrándose presencia de flavanoles de las proantocianidinas. En la evaluación de la actividad antimicrobiana del extracto metanólico, se observó actividad frente a Staphylococcus aureus y Escherichia coli, mientras que frente a Bacillus subtilis no. Finalmente en la evaluación del mucílago liofilizado se encontró 12,55 g(Glucosa)/100g de carbohidratos totales y al analizar los parámetros reológicos del mucílago se determinó un comportamiento de fluido no Newtoniano, pseudoplástico. Así el mucílago de la corteza de "Triumfetta semitriloba" Jacq, resultó ser un fluido con un futuro promisorio para la elaboración de fitofármacos, en la industria de los alimentos, etc.

Chemical constituents of the leaves of Triumfetta semitriloba.

The new flavone glycoside 6-O-(6"-O-E-p-coumaroyl)-beta-D-galactoscutellarein (triumfettalarein, 1), along with indol-3-carboxylic acid (2), beta-sitosterol glycoside, and squalene were isolated from the methanol extract of leaves of Triumfetta semitriloba. The structure of the new isolate was established by spectral methods.

Triumfettoside, a new alkaloidal steroid glycoside and triumfettosterol, a new sterol from Triumfetta flavescens.

The aerial parts of Triumfetta flavescens H. (N. O. Tiliaceae) afforded a new alkaloidal steroid glycoside, characterized as stigma 5(6)-ene-7,22-dione-25-methylamino-3 beta,23 beta-diol-3-O-beta-D- glucoside and designated as triumfettoside (1); and a new sterol identified as stigma 5(6)-ene-7,22-dione-3 beta,23 beta-diol, designated as triumfettosterol (2). Their structures were elucidated on the basis of chemical and spectral analysis.