Flow dynamics and magnetic induction in the von-Karman plasma experiment

The von-Karman plasma experiment is a novel versatile experimental device designed to explore the dynamics of basic magnetic induction processes and the dynamics of flows driven in weakly magnetized plasmas. A high-density plasma column (10^16 - 10^19 particles.m^-3) is created by two radio-frequency plasma sources located at each end of a 1 m long linear device. Flows are driven through JxB azimuthal torques created from independently controlled emissive cathodes. The device has been designed such that magnetic induction processes and turbulent plasma dynamics can be studied from a variety of time-averaged axisymmetric flows in a cylinder. MHD simulations implementing volume-penalization support the experimental development to design the most efficient flow-driving schemes and understand the flow dynamics. Preliminary experimental results show that a rotating motion of up to nearly 1 km/s is controlled by the JxB azimuthal torque

Large-scale purification of pachydictyol A from the brown alga <i>Dictyota dichotoma</i> obtained from algal wash and evaluation of its antifouling activity against the freshwater mollusk <i>Limnoperna fortunei</i>

A scalable procedure was developed for the extraction and purification of pachydictyol A, the main diterpenoid isolated from the brown alga Dictyota dichotoma. The organic extract of this species is a complex mixture of a large variety of diterpenes, and in this work, the protocol was employed successfully for the purification of gram quantities of this compound from Patagonian D. dichotoma collected from algal wash. Pachydictyol A, together with other minor diterpenoids, was tested for antifouling activity against the invading freshwater mussel Limnoperna fortunei, using a byssal thread formation assay. The results obtained in the study showed a potent antifouling activity for pachydictyol A at 4.7 μg cm−2 disk load. As for the other diterpenoids, dictyoxide was also considerably active, while dictyol C and dictyotadiol had a considerably lower activity. Taking into account the large biomass of algal wash and the abundance of D. dichotoma, together with the effectiveness of the purification protocol, these results show that pachydictyol A and dictyoxide have a good chance to become natural, non-toxic, and ecologically friendly additives in antifouling paints for the protection of submersed structures against L. fortunei.Centro de Investigación y Desarrollo en Tecnología de PinturasFacultad de Ciencias Naturales y MuseoFacultad de Ciencias Agrarias y Forestale

Effect of secochiliolide acid isolated from the Patagonian shrub Nardophyllum bryoides as active component in antifouling paints

Environmental concerns about the use of toxic antifoulants have led to an increased interest in the development of new alternatives. So far, most of the antifouling natural products have been obtained from marine organisms. However, some secondary metabolites from terrestrial plants could be promising antifoulant candidates. The antifouling performance of secochiliolide acid, the main component isolated from Nardophyllum bryoides ethanolic extract, was evaluated for inclusion in rosin-based coatings. Field testing was conducted during the summer months at Mar del Plata harbor, Argentina. The results indicated that secochiliolide acid-based paints completely inhibited the settlement of Bugula neritina colonies, Polydora sp., Hydroides elegans, Corophium sp. and solitary ascidians, and also reduced the attachment of some algae as Enteromorpha intestinalis and Ectocarpus sp. In addition, a lower density and diversity of microfouling species was registered. These results highlighted the importance of terrestrial plants as a sustainable source of potential environmentally friendly antifoulants.Facultad de IngenieríaComisión de Investigaciones Científicas de la provincia de Buenos Aire

Alkaloids Analysis of Habranthus cardenasianus (Amaryllidaceae), Anti-Cholinesterase Activity and Biomass Production by Propagation Strategies

Plants in the Amaryllidaceae family synthesize a diversity of bioactive alkaloids. Some of these plant species are not abundant and have a low natural multiplication rate. The aims of this work were the alkaloids analysis of a Habranthus cardenasianus bulbs extract, the evaluation of its inhibitory activity against cholinesterases, and to test several propagation strategies for biomass production. Eleven compounds were characterized by GC-MS in the alkaloid extract, which showed a relatively high proportion of tazettine. The known alkaloids tazettine, haemanthamine, and the epimer mixture haemanthidine/6-epi-haemanthidine were isolated and identified by spectroscopic methods. Inhibitory cholinesterases activity was not detected. Three forms of propagation were performed: bulb propagation from seed, cut-induced bulb division, and micropropagated bulbs. Finally, different imbibition and post-collection times were evaluated in seed germination assays. The best propagation method was cut-induced bulb division with longitudinal cuts into quarters (T1) while the best conditions for seed germination were 0-day of post-collection and two days of imbibition. The alkaloids analyses of the H. cardenasianus bulbs showed that they are a source of anti-tumoral alkaloids, especially pretazettine (tazettine) and T1 is a sustainable strategy for its propagation and domestication to produce bioactive alkaloids. Keywords: Amaryllidaceae; bioactive alkaloids; GC-MS; propagation methods; biomass productio

ESTUDIOS QUÍMICOS DE AMBROSIA CUMANENSIS KUNTH EN PANAMÁ

Ambrosia cumanesis K (Asteraceae), known as Altamisa, is an aromatic species widely distributed throughout the country. Its use is associated with the treatment of kidney, anti-inflammatory, antiparasitic and laxative disorders. The chemical characterization of the aqueous and ethanolic extracts of the leaves of A. cumanesis K. was carried out, as well as of its essential oil, in order to evaluate its biological activity. Phytochemical screening tests were carried out to identify secondary metabolites, chromatographic methods were used for the purification of plant extracts and the identification of the main compounds was carried out by IR and NMR spectroscopy, and by CG-MS for the essential oil. The chemical analysis of the ethanolic extracts of the fresh leaves of Ambrosia cumanensis Kunth has led to the identification of alkaloids, terpenes and flavonoids as the major secondary metabolites. The extraction and purification of the extracts led to the isolation of three (3) known compounds, psilostachyn A, psilostachyn C and camphor. The analysis of the chemical composition of the essential oil of this plant has led to the identification of 25 compounds and the possible correlation between the composition variability and the seasonality. The microbiological activity of the ethanolic extracts and the essential oil was evaluated by inhibition halo, showing selective antimicrobial activity for the essential oil. This is the first report of chemical studies on Ambrosia cumanensis Kunth in Panama.Ambrosia cumanesis K (Asteraceae), conocida como Altamisa, es una especie aromática distribuida ampliamente en el país. Se ha asociado su uso al tratamiento de afecciones renales, como antiinflamatorio, antiparasitario y purgante, por lo que se realizó la caracterización química de los extractos acuosos y etanólicos de las hojas de A. cumanesis K., así como de su aceite esencial, con el fin de evaluar su actividad biológica. Se llevaron a cabo pruebas de tamizaje fitoquímico para identificación de metabolitos secundarios, se emplearon métodos cromatográficos para la purificación de los extractos vegetales y la identificación de los compuestos principales se realizó por espectroscopía IR y de RMN, y por CG-MS para el caso del aceite esencial. El análisis químico de los extractos etanólicos de las hojas frescas de A. cumanensis Kunth llevó a la identificación de alcaloides, terpenos y flavonoides como los metabolitos secundarios mayoritarios. La extracción y purificación de los extractos llevó al aislamiento de tres (3) compuestos conocidos, psilostachina A, psilostachina C y alcanfor. El análisis de la composición química del aceite esencial de esta planta ha producido la identificación de 25 compuestos, y mostró que la composición puede variar dependiendo de la estacionalidad. La actividad microbiológica de los extractos etanólicos y del aceite esencial fue evaluada por halo de inhibición, mostrando actividad antimicrobiana selectiva para el aceite esencial. Este es el primer reporte de estudios químicos sobre Ambrosia cumanensis Kunth en Panamá

Effect of secochiliolide acid isolated from the Patagonian shrub Nardophyllum bryoides as active component in antifouling paints

Environmental concerns about the use of toxic antifoulants have led to an increased interest in the development of new alternatives. So far, most of the antifouling natural products have been obtained from marine organisms. However, some secondary metabolites from terrestrial plants could be promising antifoulant candidates. The antifouling performance of secochiliolide acid, the main component isolated from Nardophyllum bryoides ethanolic extract, was evaluated for inclusion in rosin-based coatings. Field testing was conducted during the summer months at Mar del Plata harbor, Argentina. The results indicated that secochiliolide acid-based paints completely inhibited the settlement of Bugula neritina colonies, Polydora sp., Hydroides elegans, Corophium sp. and solitary ascidians, and also reduced the attachment of some algae as Enteromorpha intestinalis and Ectocarpus sp. In addition, a lower density and diversity of microfouling species was registered. These results highlighted the importance of terrestrial plants as a sustainable source of potential environmentally friendly antifoulants.Facultad de IngenieríaComisión de Investigaciones Científicas de la provincia de Buenos Aire

Antifouling Activity of Celastroids Isolated from Maytenus Species, Natural and Sustainable Alternatives for Marine Coatings

A group of celastroids, quinone-methide nortriterpenes isolated from Maytenus vitis-idaea and Maytenus spinosa were assayed for their antifouling activity. Toxicity assays were performed on Balanus amphitrite nauplii, and the most promising compounds were then incorporated in soluble-matrix antifouling paints, which were tested in the ocean. The results obtained after a 45 day-field trial of the paints indicated in all cases promising antifouling potencies. Although all compounds showed antifouling activity on a wide range of organisms, tingenone and celastrol were the most effective inhibitors of the settlement of fouling organisms. The effect of these substances on nauplii in laboratory tests was temporary instead of toxic, with a high recovery rate, which may avert a potentially adverse ecological damage on the benthic community. These results may provide a more environmentally friendly alternative for the control of biofouling, replacing toxic additives actually in use in marine paints.Centro de Investigación y Desarrollo en Tecnología de PinturasUniversidad de Buenos AiresUniversidad Nacional de Córdob