Acetylcholinesterase inhibition by somes promising Brazilian medicinal plants

A microplate assay and a thin-layer chromatography (TLC) "in situ" assay based on the Ellman assay was used to screen for acetylcholinesterase inhibitors from ethyl acetate and methanol extracts of Brazilian medicinal plants of families that, according to the literature, have traditional uses that might be connected with acetylcholinesterase inhibition. Eighteen species belonging to Convolvulaceae, Crassulaceae, Euphorbiaceae, Leguminosae, Malvaceae, Moraceae, Nyctaginaceae and Rutaceae families were tested. The most active plants were Ipomoea asarifolia (IC50 = 0.12 mg/mL), Jatropha curcas (IC50 = 0.25 mg/mL), Jatropha gossypiifolia (IC50 = 0.05 mg/mL), Kalanchoe brasiliensis (IC50 = 0.16 mg/mL) and Senna alata (IC50 = 0.08 mg/mL). The most promising extracts were the Jatropha gossypiifolia and Senna alata species assuming there were compounds with a similar activity to galanthamine, which should contain about 1% of an active compound, or if present at lower levels even more active compounds than galanthamine (IC50 = 0.37 x 10-3 mg/mL) should be present

Superação da dormência de sementes de capim-carrapicho Dormancy overcoming in southern sandbur seeds

O objetivo desta pesquisa foi o de identificar tratamentos que, capazes de superar a dormência das sementes de Cenchrus echinatus, fossem favorá veis à germinação e passíveis de serem aplicados visando semeadura à campo. Para tanto, 4 lotes de sementes foram submetidos a tratamentos de escarificação mecânica, de retirada do invólucro de brácteas espinhosas e das glumas para a separa ção da cariopse , de imer são em KNO3 (1%) por 5 e 20 minuto s, imer sã o em KNO3 (1, 3 e 5%) por 5 minutos, de imersão em H2O por 5 minutos, de armazenamento a 5°C/ 7 dias, de exposição à 40, 55 e 70°C/ 8h em estufa com circulação forçada de ar e de imersão em H2SO4 (98%, 36N) por 1; 5 e 15 minutos seguida por lavagem em água co rren te. As sementes tratadas foram avaliadas por meio dos testes de germinação e de emergência de plântulas; de primeira contagem de germinação e de emergência de plântulas, de velocidade germinação e de emergência. Os tratamentos de escarificação mecânic a, da cariopse nua e de imersão das sementes em KNO3 (1 a 3%) por 5 minutos são técnicas de superação da dormência capazes de implementar a emergência em condições de campo.<br>The main goal of this research was to identify those treatments that besides being capable of overcoming dormancy in Cenchrus echinatus seeds were favorable to germination and liable to field use. Four seed lots were submitted to mechanical escarafication, cariopse excised, KNO3 (1%) immers ion fo r 5 and 20 minutes, KNO3 (1, 3 e 5%) immersion for 5 minutes, H2O immers ion for 5 minute s, 5°C/7 days storage, thermal treatments at 40, 55,and 70°C/8h in air circulating oven, H2SO4 (98%, 36N) immersion fo r 1, 5, and 15 minutes. Treated seeds were evaluated by means of the standard germination test and emerging seedlings, first germination and emergence count, germination and emergence speed. The use of mechanical escarafication, cariopse excised, KNO3 (1 - 3%) immersion for 5 minutes are dormancy overcoming techniques able to promote field emergence

Drought sensitivity of Amazonian carbon balance revealed by atmospheric measurements

Feedbacks between land carbon pools and climate provide one of the largest sources of uncertainty in our predictions of global climate(1,2). Estimates of the sensitivity of the terrestrial carbon budget to climate anomalies in the tropics and the identification of the mechanisms responsible for feedback effects remain uncertain(3,4). The Amazon basin stores a vast amount of carbon(5), and has experienced increasingly higher temperatures and more frequent floods and droughts over the past two decades(6). Here we report seasonal and annual carbon balances across the Amazon basin, based on carbon dioxide and carbon monoxide measurements for the anomalously dry and wet years 2010 and 2011, respectively. We find that the Amazon basin lost 0.48 +/- 0.18 petagrams of carbon per year (Pg C yr(-1)) during the dry year but was carbon neutral (0.06 +/- 0.1 Pg C yr(-1)) during the wet year. Taking into account carbon losses from fire by using carbon monoxide measurements, we derived the basin net biome exchange (that is, the carbon flux between the non-burned forest and the atmosphere) revealing that during the dry year, vegetation was carbon neutral. During the wet year, vegetation was a net carbon sink of 0.25 +/- 0.14 Pg C yr(-1), which is roughly consistent with the mean long-term intact-forest biomass sink of 0.39 +/- 0.10 Pg C yr(-1) previously estimated from forest censuses(7). Observations from Amazonian forest plots suggest the suppression of photosynthesis during drought as the primary cause for the 2010 sink neutralization. Overall, our results suggest that moisture has an important role in determining the Amazonian carbon balance. If the recent trend of increasing precipitation extremes persists(6), the Amazon may become an increasing carbon source as a result of both emissions from fires and the suppression of net biome exchange by drought