Biophysical evaluation of fertility islands in the Arid Chaco (Argentina)

Forests degradation in arid and semi-arid lands may conduct to the formation of “fertility islands” due to the accumulation of soil particles, water, nutrients and biomass under trees and shrubs. In the Arid Chaco fertility islands are characterised by the presence of Prosopis flexuosa and Larrea divaricata. The objective was to evaluate biophysical variables in soil, microclimate and the plant response under canopy and in intercanopy. Infiltrability, microtopography, soil bulk density, soil and air moisture and temperature, and light were measured under the canopy, at the limit of the canopy and in the intercanopy. These variables were correlated with the litter and plant frequencies associated with the fertility islands. P. flexuosa canopy and litter understorey tend to maintain more soil moisture compared with the intercanopy, by reducing soil and air temperature and by increasing air moisture. This increases the frequency of Dyksterhuis’ decreaser species. Under L. divaricata the canopy effect is not as effective as that of P. flexuosa and understorey plant response is not significative.

Aqueous and polyphenol-rich Larrea divaricata Cav. extracts as potential skin care agents

Skin cells are affected by UV-induced oxidative stress resulting in photoaging and diseases. The objective of this work was to assess the effect of an aqueous extract of Larrea divaricata(Aq) and a flavonoid rich fraction (EA), obtained by liquid/liquid fractionation, on the proliferation of keratinocytes and fibroblasts by the tritiated thymidine uptake assay and on cell viability by the trypan blue exclusion assay. The in vitro sun protection factor (SPF), peroxidase (Px)-like and superoxide dismutase (SOD)-like activities were determined by kinetic spectrophotometric assays, and the phytochemical composition was determined by HPLC-UV and HPLC MS/MS.Aq and EA induced keratinocytes and fibroblast proliferation, protected fibroblasts from H2O2-induced apoptosis and exerted SOD-like and Px-like activities. Aq and EA had a high sun UVB protection factor. So, L. divaricatacould be used in a future for the development of new dermocosmetic or phytotherapy adjuvant in skin oxidative damage.

UHPLC-ESI-OT-MS Phenolics Profiling, Free Radical Scavenging, Antibacterial and Nematicidal Activities of “Yellow-Brown Resins” from Larrea spp.

This research was designed to investigate the metabolite profiling, phenolics and flavonoids content and the potential antioxidant, antibacterial and nematicidal activities of “yellow-brown resins” from Larrea divaricata Cav (LdRe) and L. nitida Cav (LnRe). Metabolite profiling was obtained using an ultrahigh resolution liquid chromatography orbitrap MS analysis (UHPLC-ESI-OT-MS). The antioxidant properties were screened by four methods: 2,2-diphenyl-1-picrylhydrazyl assay (DPPH), trolox equivalent antioxidant activity assay (TEAC), ferric-reducing antioxidant power assay (FRAP) and lipid peroxidation in erythrocytes (LP). The antibacterial activity was evaluated according to the Clinical and Laboratory Standards Institute (CLSI) guidelines. In addition, the potential combinatory effect was analyzed with the fractional inhibitory concentration index (FICI) values using the checkerboard design. The nematicidal activity was carried out according to a standardized protocol. LdRe and LnRe showed a strong capture of the DPPH radical withvalues around 8.4 µg resin/mL; FRAP (1.69–1.94 mgTE/ g resin), TEAC (1.08–1.09 mgTE/g resin) and LP (81–82% at 100 µg of resin/mL) assays. A strong antimicrobial activity was displayed by both resins against methicillin-sensitive Staphylococcus aureus ATCC 25923(MSSA) and methicillin-resistant S. aureus ATCC 43300(MRSA) (MICs = 16–32 µg resin/mL). Additionally, the combination of LdRe or LnRe with the antibiotic cefotaxime showed an indifferent effect (FICI values = 1–1.25), however, this combinationcould be a potential strategy to reduce the drug doses, and in this way can be a potential alternative to reduce bacterial resistance. On the other hand, the resins showed a scarce nematicidal potential toward J2 Meloidogyne incognita; an important nematode infecting horticultural crops. Phenolics compounds were identified by UHPLC-PDA-OT-MS analysis, updating the knowledge on the chemical profile of these species. These results, together with the high content of quantified phenolics and flavonoids, allow the phenolics-enriched resins of these two Larrea species to be considered as a promising sustainable source of compounds of pharmacological interest.

Antracología de una unidad residencial de el Pichao (Tucumán-Argentina)

El sitio arqueológico El Pichao ha sido estudiado desde diversos aspectos, sin embargo, hasta la actualidad no se había llevado a cabo el análisis antracológico de las muestras recuperadas en unidades residenciales del período de Desarrollos Regionales (1000-535 AP). Este tema se aborda mediante el estudio de carbones obtenidos en la unidad STucTav5 - 100. La identificación taxonómica de los macro restos se realizó mediante la comparación de los carbones arqueológicos con una colección de referencia de cortes histológicos que incluye ejemplares de la flora del área de estudio; los carbones se examinaron observando las secciones transversal, longitudinal tangencial y longitudinal radial del leño bajo lupa binocular, microscopio óptico con luz incidente y se tomaron fotografías con microscopio electrónico de barrido. En el conjunto de carbones se identificaron a los siguientes taxa: Prosopis sp., P. torquata, Geoffroea decorticans, Acacia sp. Nicotiana glauca, Bulnesia schickendantzii, Larrea divaricata y un taxón quedó en la categoría de No Identificado. Los mismos forman parte de la flora local del área y habrían sido usados durante ocupaciones correspondientes al período de Desarrollos Regionales y posteriores. Los datos generados alientan al desarrollo de esta línea de trabajo en el área.