Avaliação fitoquímica, físico-química e atividades antioxidante, hemotóxi-ca e antibacteriana do extrato de Protium spruceanum (Benth.) Engl

Protium spruceanum é uma das 146 espécies do gênero Protium, considerada como medicinal pela população do campo e no meio científico. O objetivo deste estudo foi avaliar a fitoquímica, físico-química e as atividades antioxidantes, hemotóxica e antibacteriana do extrato hidroetanólico da resina de P. spruceanum. Destaca-se que os resultados apresentados neste estudo apresentaram inúmeras classes fitoquímicas com resultados positivos, sólidos solúveis com 1,15%, índice de refração de 1,584, pH de 5,63, densidade relativa de 0,9517 g mL-1 20 °C, CI50 de 275,14 µg mL-1 de DPPH, fenólicos totais de 9,96 mg EAG 100 g-1, e rendimento de 6,61%. Atividade hemolítica positiva, em especial, eficiência na atividade antibacteriana com halos de inibição de 19,13 mm para Staphylococcus aureus, de 14,07 mm para Salmonella typhimurium, e de 17,51 mm para Salmonella enteritidis, e baixa inibição para Escherichia coli de 9,18 mm. O extrato hidroetanólico da resina de Protium spruceanum demonstrou resultados excepcionais como agente antioxidante e antibacteriano.

New Potential Use of Protium spruceanum in Hyperglycemia: α-Glucosidase Inhibition and Protection against Oxidative Stress

The high prevalence of diabetes and obesity encourages research for the development of α-glucosidase inhibitors from natural sources. This study evaluated the activity of fractions obtained from Protium spruceanum branches. Anti-α-glucosidase activity was investigated in vitro using 4-nitrophenyl-α-D-glucopyranoside as the substrate, while free-radical scavenging activity was evaluated by 2,2-diphenyl-1-picrylhydrazyl (DPPH) and 2,2’-azinobis-3-ethylbenzotiazoline-6-sulfonic acid (ABTS) assays. Furthermore, a model of oxidative stress promoted by H2O2 in fibroblasts was employed, and cell viability was determined by sulforhodamine B. Fractions inhibited α-glucosidase activity effectively, highlighting the hydromethanolic fraction (HMF). Quercitrin, isolated from the HMF, was identified by spectroscopy and quantified by a validated high performance liquid chromatography with diode array detector (HPLC-DAD) method and exhibited free radical scavenging activity comparable to the HMF. However, this flavonoid showed low anti-α-glucosidase effect, suggesting a synergism effect among several components of the HMF. This proposal is also supported by the docking results obtained by PyRx software. The compounds present in the HMF showed a noncompetitive inhibition at the in silico simulation. Finally, the HMF also protected fibroblasts against cell death induced by oxidative stress. This is the first evidence of the capacity of P. spruceanum branches to inhibit α-glucosidase activity and to counteract oxidative stress. These results encourage the use of this Brazilian plant against hyperglycemia-correlated diseases.

Effects of microbial conditioning and temperature on the leaf-litter shredding activity of Phylloicus sp.

Few studies try to explain the effects in tropical lotic ecosystems of an increase in water temperature on the shredding activity of invertebrate shredders, particularly in association with the quality of the leaf litter and the degree of litter conditioning. Therefore, the aims of this study were as follows: i) to better understand how this key invertebrate shredder group affects the decomposition of different species of leaf litter under gradual increases in temperature and microbial conditioning; and ii) to verify the possible consequences on leaf mass loss (LML). Three species of leaf litter were used in two experiments. In experiment I, the litters of three species (Protium spruceanum, Richeria grandis and Inga laurina) at three conditioning levels (1, 7, 14 days) were tested under five different temperatures (20, 22, 24, 26 and 28°C). In experiment II, the leaf litters of three species were used, without conditioning, under four temperatures (20, 22, 26 and 27°C). The shredding performed by Phylloicus sp. was largely dependent on the lignin and cellulose concentrations in each leaf species, independent of conditioning. The presence or absence of conditioning may cause the shredders to use different energy compensation strategies in response to the temperature increases.

PLANTAS MELÍFERAS DE RORAIMA - PARTE II

Das 31 plantas observadas, as que indicaram ter um potencial para produção de mel por Apis mellifera L foram: Acacia lorentensis Macbr. (Miguel Corrêa), Mimosa pudica L., Mimosa sp., Melochia hirsuta Cav. (vassoura), Waltheria americana L., Sida sp., Vochysia guianensis Aubl (guaruba), Bauhinia ungulata L. (mororó) e Peltogyne sp., Protium spruceanum Engl. (breu), Sesamum indicum DC (gergelim bravo). Em sedimentos das amostras de mel, os tipos polínicos encontrados foram: Mimosa sp., Acacia sp., Bauhinia ungulata L., Protium sp e Vochysia guianensis Aubl. As amostras com pólen de Protium sp. e Vochysia guianensis apresentaram sabor amargo.

Anthropic disturbances as the main driver of a semideciduous seasonal forest fragment in Minas Gerais

The new environmental conditions imposed by disturbance events often create a mosaic of spots in different successional stages. Our objective was to describe the temporal variation of a semideciduous seasonal forest based on its anthropic disturbance history, verifying possible changes in forest dynamics and structure. We sampled the arboreal vegetation with a diameter at breast height (1.3 m above the ground; DBH) ≥ 5 cm in 15 permanent plots of 20 × 20 m where we performed four inventories (2003, 2005, 2007 and 2015). We observed a density decrease and a basal area increase, which indicates the late successional stage of the analyzed tree community. The phytosociological structure, richness and species diversity of the tree community did not show changes throughout the monitoring. However, the Protium spruceanum predominance may be a response to the environmental changes caused by the mining occurred in the area 250 years ago. The anthropic disturbances enduring influences make this type of work indispensable because it allows the ecological processes understanding, allowing a factual management of the forests by the its effective management and conservation.