ABSTRACT Detecting trends in streamflow and rainfall series can have great significance for proper water resource management. Thus, the objective of this study was to analyze the trends of historical streamflow and rainfall series using nonparametric statistical tests. A historical series of pluviometric and fluviometric gauges, which belong to the hydrometeorological network of the Brazilian Water National Agency in the Santo Antônio River Basin, Brazil, from 1985 to 2014 were used. By applying statistical tests, it was found that the time series are independent and random, and from the total 24 rainfall gauges evaluated, 12 presented nonstationary behavior, exhibiting mostly decreasing trends. Based on the six fluviometric gauges used for the annual streamflow series, only the annual data of one gauge tended to decrease to the minimum streamflow. However, for the monthly series, three gauges showed decreasing trends between July and September. This decrease in streamflow may be a consequence of rainfall reductions, high water demand, and changes in land use and cover.

Abstract We evaluated the structural and floristic characteristics of a Brazilian savanna fragment occupied by cerradão (CD) and cerrado sensu stricto (CS) in response to the influence of rainfall and long-term fire suppression. We carried out floristic, phytosociological and remote sensing studies in a cerrado fragment located in Corumbataí (SP, Brazil) after 43 years of complete fire suppression. We surveyed 43 plots of 200 m2 each (17 plots in CS and 26 plots in CD) and all individuals ≥ 0.32 cm diameter measured at 30 cm from the ground were included in the sample. We calculated phytosociological parameters for each species and classified them in three ecological groups, namely savanna, generalist and forest species. The remote sensing analysis used aerial photographs and satellite images from 1962 to 2019 (i.e. 59 years). The structural study of community revealed high predominance of forest and generalist species when compared to savanna species. Non-linear correlation between CD expansion rates and total rainfall within the study period indicated a positive influence of the rainfall (R2 = 0.42). Thus, our analysis indicated a tendency of a continuous and fast expansion of CD over areas of CS in the long-term absence of fire combined with periods of heavy rain.

The new triterpene friedelan-1,3,21-trione, the known compounds friedelan-3-one, 3β-friedelinol, 3,4-seco-friedelan-3-oic acid, 28-hydroxyfriedelan-3-one, friedelan-3-oxo-28-al, friedelan-3,21-dione, 30-hydroxyfriedelan-3-one, a mixture of 30-hydroxyfriedelan-3-one/21α-hydroxyfriedelan-3-one, 21β-hydroxyfriedelan-3-one, gutta-percha, squalene, and a mixture of palmitic/stearic/oleic acids were isolated from the hexane extracts of leaves and branches of T. micrantha. Their chemical structures were established by Fourier transform infrared spectroscopy (FTIR), gas chromatography (GC), 1D/2D nuclear magnetic resonance (NMR) and comparison with the literature data. All compounds were described for T. micrantha and the genus Tontelea for the first time. The branch and leaf extracts displayed anti-Zika virus activity at the lowest tested concentration of 15.6 µg mL-1, mainly virucidal effect, and presented no cytotoxicity to Vero cells. Furthermore, the ethyl acetate and methanolic leaf extracts demonstrated the best activities at the concentration of 31.2 and 15.6 µg mL-1 at the viral adsorption and penetration stages, respectively. These results showed that these extracts may be promising candidates for the Zika virus treatment.

ABSTRACT The phytochemical study of the extract leaves from Maytenus distichophylla Mart. and Salacia crassifolia (Mart. ex Schult.) G. Don, Celastraceae, resulted in the isolation of 3-oxofriedelane, 3β-hydroxyfriedelane, 3β,24-dihydroxyfriedelane, 3-oxo-28,29-dihydroxyfriedelane, two mixtures of pentacyclic triterpenes (α-amyrin with β-amyrin and 3β-stearyloxy-urs-12-ene with 3β-stearyloxy-olean-12-ene), 3β-palmityloxy-urs-12-ene, the steroid β-sitosterol and its glycosylated derivative β-glucosyl-β-sitosterol, tritriacontanoic acid and the natural polymer gutta percha. The chemical structures of these constituents were established by IR, 1H and 13C NMR spectral data. Crude extracts, the mixtures of triterpenes and the isolated constituents were subjected to in vitro acetylcholinesterase inhibitory evaluation. Acetylcholinesterase inhibitory effect was observed for crude chloroform extract leaves from M. distichophylla (100%) and S. crassifolia (97.93 ± 5.63%) and for the triterpenes 3β,24-dihydroxyfriedelane (99.05 ± 1.12%), 3-oxo-28,29-dihydroxyfriedelane (90.59 ± 3.76%) and 3β-palmityloxy-urs-12-ene (97.93 ± 1.47%). The percent inhibitions induced by these natural products were very similar to those produced by physostigmine (93.94 ± 2.10%) a standard acetylcholinesterase inhibitor. Therefore, these results open perspectives for the use of these species as source of compounds with similar physostigmine pharmacological effect.