Gas exchange and osmotic adjustment in cotton cultivars subjected to severe salt stress.

Salinity is harmful to crops when the concentration of soluble salts overcomes the salinity threshold of the crop, causing osmotic stress and limitations in plant growth. In this scenario, adopting tolerant cultivars is the most adequate strategy to minimize agricultural losses. However, the inheritance of tolerance depends on the genotype. From this perspective, this study assessed the tolerance to severe salt stress in 11 cotton cultivars based on gas exchange parameters and the free proline content. The cultivars were grown in a greenhouse and subjected to 34 days of saline irrigation (10 dS m-1), starting 45 days after seedling emergence (B1 phase). Plant growth was monitored weekly until the end of the salt stress period. The treatments consisted of a combination of two factors: eleven cultivars associated with two electrical conductivity levels of irrigation water (ECw: 0.3 and 10.0 dS m-1). The experimental design was in randomized blocks in a 11 × 2 factorial arrangement with three replications (66 plots), with the experimental unit consisting of one plant per plot. Salinity impacted plant growth, being reflected on the gas exchange and free proline data of most cultivars. However, BRS 286, FMT 705, BRS 416, and BRS Acácia, and CNPA 7MH withstood the effects of stress and osmotically adjusted to the salt stress conditions, thus minimizing the damage to growth. Those cultivars are the most indicated for improvement programs aiming at tolerance to salt stress based on the results found in this research.

Salicylic acid does not relieve salt stress on gas exchange, chlorophyll fluorescence, and hydroponic melon growth.

The objective of this study was to evaluate the salicylic acid applications in attenuating the harmful effects of saline nutrient solution on the physiology and growth of 'Gaúcho' melon cultivated in the NFT hydroponic system. The experiment was conducted in a greenhouse, in Pombal-PB, Brazil. The cultivation system used was the Nutrient Film Technique - NFT hydroponics. A completely randomized split-plot design was used, with the plot referring to four levels of salinity in the nutrient solution - ECns (2.1 control, 3.2, 4.3, and 5.4 dS m-1) and the sub-plot four concentrations of salicylic acid (SA) (0, 1.5, 3.0, and 4.5 mM), applied via foliar spray, with six replications. Nutrient solution of 4.3 and 5.4 dS m-1 electrical conductivity promotes higher maximum and variable fluorescence, respectively. The stomatal conductance, transpiration, stem diameter, main branch length, leaf dry mass, and stem dry mass of 'Gaúcho' melon plants decrease with the increase in salinity of the nutrient solution. Salicylic acid increases the initial fluorescence and the main branch length of 'Gaúcho' melon plants in hydroponic cultivation. Salicylic acid at a concentration of 1.5 to 4.5 mM did not attenuate the effects of salt stress on the internal CO2 concentration, CO2 assimilation rate, and root dry mass of 'Gaúcho' melon plants.

ADME studies and preliminary safety pharmacology of LDT5, a lead compound for the treatment of benign prostatic hyperplasia.

This study aimed to estimate the absorption, distribution, metabolism and excretion (ADME) properties and safety of LDT5, a lead compound for oral treatment of benign prostatic hyperplasia that has previously been characterized as a multi-target antagonist of α1A-, α1D-adrenoceptors and 5-HT1A receptors. The preclinical characterization of this compound comprised the evaluation of its in vitro properties, including plasma, microsomal and hepatocytes stability, cytochrome P450 metabolism and inhibition, plasma protein binding, and permeability using MDCK-MDR1 cells. De-risking and preliminary safety pharmacology assays were performed through screening of 44 off-target receptors and in vivo tests in mice (rota-rod and single dose toxicity). LDT5 is stable in rat and human plasma, human liver microsomes and hepatocytes, but unstable in rat liver microsomes and hepatocytes (half-life of 11 min). LDT5 is highly permeable across the MDCK-MDR1 monolayer (Papp ∼32×10-6 cm/s), indicating good intestinal absorption and putative brain penetration. LDT5 is not extensively protein-bound and is a substrate of human CYP2D6 and CYP2C19 but not of CYP3A4 (half-life >60 min), and did not significantly influence the activities of any of the human cytochrome P450 isoforms screened. LDT5 was considered safe albeit new studies are necessary to rule out putative central adverse effects through D2, 5-HT1A and 5-HT2B receptors, after chronic use. This work highlights the drug-likeness properties of LDT5 and supports its further preclinical development.

ADME studies and preliminary safety pharmacology of LDT5, a lead compound for the treatment of benign prostatic hyperplasia

This study aimed to estimate the absorption, distribution, metabolism and excretion (ADME) properties and safety of LDT5, a lead compound for oral treatment of benign prostatic hyperplasia that has previously been characterized as a multi-target antagonist of α1A-, α1D-adrenoceptors and 5-HT1A receptors. The preclinical characterization of this compound comprised the evaluation of its in vitro properties, including plasma, microsomal and hepatocytes stability, cytochrome P450 metabolism and inhibition, plasma protein binding, and permeability using MDCK-MDR1 cells. De-risking and preliminary safety pharmacology assays were performed through screening of 44 off-target receptors and in vivo tests in mice (rota-rod and single dose toxicity). LDT5 is stable in rat and human plasma, human liver microsomes and hepatocytes, but unstable in rat liver microsomes and hepatocytes (half-life of 11 min). LDT5 is highly permeable across the MDCK-MDR1 monolayer (Papp ∼32×10-6 cm/s), indicating good intestinal absorption and putative brain penetration. LDT5 is not extensively protein-bound and is a substrate of human CYP2D6 and CYP2C19 but not of CYP3A4 (half-life >60 min), and did not significantly influence the activities of any of the human cytochrome P450 isoforms screened. LDT5 was considered safe albeit new studies are necessary to rule out putative central adverse effects through D2, 5-HT1A and 5-HT2B receptors, after chronic use. This work highlights the drug-likeness properties of LDT5 and supports its further preclinical development.

Atividade analgésica e antiedematogênica de Polygala paniculata L. (Polygalaceae) selvagem e obtida por micropropagação / Analgesic and antiedematogenic activities of wild and micropropagated Polygala paniculata L (Polygalaceae)

Polygala paniculata L. (Polygalaceae) é uma erva que ocorre em todas as regiões do Brasil. No presente trabalho, foram avaliadas as atividades analgésica, através do teste da placa quente, da retirada de cauda e da formalina, e antiedematogênica, através do teste do edema de orelha induzido por óleo de cróton, dos extratos etanólicos obtidos das partes aéreas de Polygala paniculata selvagem e cultivadas por micropropagação. A aplicação oral do extrato etanólico de Polygala paniculata apresentou atividade analgésica, em ratos, tanto em testes de dor induzida por agentes térmicos (testes da placa quente e de retirada da cauda) quanto por agentes químicos (teste da formalina), de modo que os melhores resultados foram obtidos na dose de 400 mg/kg. Também foi observada redução na formação de edema de orelha induzida pela aplicação de óleo de cróton. Os efeitos provocados pelos extratos obtidos a partir das plantas cultivadas in vitro foram menos pronunciados que aqueles produzidos pelos extratos das plantas selvagens, embora ambos tenham sido significativos. Estes resultados sugerem que o extrato etanólico de Polygala paniculata possui atividades analgésica e antiedematogênica.

The ethanolic extracts of Polygala paniculata L. (Polygalaceae), wich is a herbaceous plant widely distributed all over Brazil, were tested for their analgesic effects using hot plate, tail flick and formalin test models, and for their antiedematogenic effects using croton oil induced ear oedema. The ethanolic extracts obtained from wild and micropropagated plants produced analgesic effects against thermal and chemical induced pain. The highest results were observed at the dose of 400 mg/kg. The inhibition of ear oedema in mice was also observed after treatment with ethanolic extract of Polygala paniculata. The effects produced by micropropagated plants were lower than wild plants, whereas both had produced significant effects. These results suggest that the ethanolic extracts from wild and micropropagated Polygala paniculata possess analgesic and antiedematogenic effects.

Ação de extratos do açaí (Euterpe oleracea Mart. ) sobre a produção de óxido nítrico em células RAW 264.7

Açaí (Euterpe oleracea Mart.), é uma palmeira tropical muito apreciada por sua beleza e valor nutricional. Estudos químicos revelaram a presença de ácidos graxos e esteróides. No presente trabalho foi avaliada a ação de extratos obtidos dos frutos e flores sobre a produção de óxido nítrico (ON), molécula que apresenta várias atividades fisiológicas, tais como vasodilatação, neurotransmissão, além de atividades tumoricidas e citotóxicas. Células Raw 264,7 estimuladas com lipopolissacarídeo bacteriano (LPS, 100 ng/ml) e interferon-alfa (IFN-alfa, 10 U/ml) produziram grande quantidade de óxido nítrico (35 μM) quando comparadas com as células não estimuladas (3 μM). Os extratos com hexano, diclorometano, acetato de etila e n-butanol apresentaram alta capacidade de inibição em células ativadas com LPS e IFN-alfa, de acordo com a concentração, sendo que na concentração mais alta ocorreu uma inibição de quase 100 por cento. Também avaliamos se o efeito inibitório seria devido a seqüestro do radical livre (ON), através do uso do SNAP (um doador de ON). Somente o extrato em acetato de etila mostrou atividade sequestrante. Esforços estão sendo empregados na tentativa de compreender os possíveis mecanismos associados ao efeito inibitório destes extratos.

Açaí (Euterpe oleracea Mart.) is a tropical palm tree appreciated for its attractive beauty and for nutritional purposes. Chemical studies have revealed the presence of fatty acids and steroids. In the present work, it has been tested the action of the extracts obtained from the fruits and flowers on the nitric oxide (NO) production, a very important molecule with a lot of physiological rules such as vasodilatation, neurotransmission, tumoricidal and cytotoxic activity. Cells RAW 264.7 stimulated with bacterial lipopolysaccharide (LPS, 100 ng/ml) and interferonalpha (IFN-alpha, 10 U/ml) produce large amounts of nitric oxide (35 μM) when compared with non-stimulated cells (3μM). The hexane, dichloromethane, ethyl acetate and n-butanol extracts have shown high inhibition capacity, concentration-dependent in the cells activated with LPS and IFN-alpha, and the highest concentration has promoted almost 100 percent of inhibition. We also have tested if the inhibitory effect was due to a scavenger action using a NO donor, the SNAP. Only the ethyl acetate extract has shown significant scavenger action. At this moment an effort is going on to try to understand the possible mechanisms associated to the inhibition of those extracts.

Role of nitric oxide and superoxide in Giardia lamblia killing.

Giardia lamblia trophozoites were incubated for 2 h with activated murine macrophages, nitric oxide (NO) donors or a superoxide anion generator (20 mU/ml xanthine oxidase plus 1 mM xanthine). Activated macrophages were cytotoxic to Giardia trophozoites (approximately 60% dead trophozoites). The effect was inhibited (> 90%) by an NO synthase inhibitor (200 microM) and unaffected by superoxide dismutase (SOD, 300 U/ml). Giardia trophozoites were killed by the NO donors, S-nitroso-acetyl-penicillamine (SNAP) and sodium nitroprusside (SNP) in a dose-dependent manner (LD50 300 and 50 microM, respectively). A dual NO-superoxide anion donor, 3-morpholino-sydnonimine hydrochloride (SIN-1), did not have a killing effect in concentrations up to 1 mM. However, when SOD (300 U/ml) was added simultaneously with SIN-1 to Giardia, a significant trophozoite-killing effect was observed (approximately 35% dead trophozoites at 1 mM). The mixtures of SNAP or SNP with superoxide anion, which yields peroxynitrite, abolished the trophozoite killing induced by NO donors. Authentic peroxynitrite only killed trophozoites at very high concentrations (3 mM). These results indicate that NO accounts for Giardia trophozoites killing and this effect is not mediated by peroxynitrite.

Role of nitric oxide and superoxide in Giardia lamblia killing

Giardia lamblia trophozoites were incubated for 2 h with activated murine macrophages, nitric oxide (NO) donors or a superoxide anion generator (20 mU/ml xanthine oxidase plus 1 mM xanthine). Activated macrophages were cytotoxic to Giardia trophozoites (~60 per cent dead trophozoites). This effect was inhibited (>90 per cent) by an NO synthase inhibitor (200 muM) and unaffected by superoxide dismutase (SOD, 300 U/ml). Giardia trophozoites were killed by the NO donors S-nitroso-acetyl-penicillamine(SNAP)and sodium nitroprusside (SNP) in a dose-dependent manner (LD50 300 and 50 muM, respectively). A dual NO-superoxide anion donor, 3-morpholino-sydnonimine hydrochloride (SIN-1), did not have a killing effect in concentration up to 1 mM. However, when SOD (300 U/ml) was added simultaneously with SIN-1 to Giardia, a significant trophozoite-killing effect was observed (~35 per cent dead trophozoites at 1 mM). The mixture of SNAP or SNP with superoxide anion, which yields peroxynitrite, abolished the trophozoite killing induced by NO donors. Authentic peroxynitrite only killed trophozoites at very high concentrations (3 mM). These results indicate that NO accounts for Giardia trophozoite killing and this effect is not mediated by peroxynitrite.