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196 result(s) for "selectivity index"
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Changes on the Climatic Edge: Adaptation of and Challenges to Pastoralism in Montesinho (Northern Portugal)
Mountain areas are sensitive to changes in precipitation and temperature, which significantly impact traditional pastoralist communities, their economy, and their lifestyle. Alarming climate change scenarios justify the investigation of the ecological and socioeconomic vulnerabilities that characterize Portugal's mountain regions. This work explores how the traditional production systems of small ruminants—sheep and goats—could adapt in the Montesinho mountain range as it changes over the next 2 decades. Land use–land cover maps from 1995 and 2018 show how the pastoral landscape has changed and indicate trends for a future scenario. Documented landscape grazing patterns are used to determine sheep and goat landscape preferences under different climatic conditions. Finally, we identify the near-future constraints on traditional sheep and goat systems, contrasting landscape changes with sheep and goat preferences. Over coming decades, the balance between rangelands and cultivated lands will persist in the Montesinho mountain landscape, despite some trade-offs between both. Woodlands could emerge from scrublands colonizing rangelands, and permanent crops could significantly replace arable lands in agricultural areas. Therefore, it is likely that the agricultural areas preferred for sheep, and rangelands preferred for goats, may not be affected by the forecast landscape changes, but rather be favored by the expansion of permanent crops. However, pasture areas must expand, as they are key to pastoral landscape function in a warming climate scenario. Landscape decision makers and managers should implement a landscape-monitoring system to inform policies and strategies aimed at protecting and safeguarding mountain pastoralism and its vital ecosystem services.
Effective Drug Concentration and Selectivity Depends on Fraction of Primitive Cells
Poor efficiency of chemotherapeutics in the eradication of Cancer Stem Cells (CSCs) has been driving the search for more active and specific compounds. In this work, we show how cell density-dependent stage culture profiles can be used in drug development workflows to achieve more robust drug activity (IC50 and EC50) results. Using flow cytometry and light microscopy, we characterized the cytological stage profiles of the HL-60-, A-549-, and HEK-293-derived sublines with a focus on their primitive cell content. We then used a range of cytotoxic substances—C-123, bortezomib, idarubicin, C-1305, doxorubicin, DMSO, and ethanol—to highlight typical density-related issues accompanying drug activity determination. We also showed that drug EC50 and selectivity indices normalized to primitive cell content are more accurate activity measurements. We tested our approach by calculating the corrected selectivity index of a novel chemotherapeutic candidate, C-123. Overall, our study highlights the usefulness of accounting for primitive cell fractions in the assessment of drug efficiency.
Antioxidant and Anti-Proliferative Activity of Essential Oil and Main Components from Leaves of Aloysia polystachya Harvested in Central Chile
The aim of this study was to determine, first, the chemical composition of Aloysia polystachya (Griseb) Moldenke essential oil, from leaves harvested in central Chile; and second, its antioxidant and cytotoxic activity. Eight compounds were identified via gas chromatography–mass spectrometry (GC–MS) analyses, with the most representative being R-carvone (91.03%), R-limonene (4.10%), and dihydrocarvone (1.07%). For Aloysia polystachya essential oil, antioxidant assays (2,2-diphenyl-1-picrylhydrazyl (DPPH), H2O2, ferric reducing antioxidant power (FRAP), and total reactive antioxidant potential (TRAP)) showed good antioxidant activity compared to commercial antioxidant controls; and anti-proliferative assays against three human cancer cell lines (colon, HT-29; prostate, PC-3; and breast, MCF-7) determined an IC50 of 5.85, 6.74, and 9.53 µg/mL, and selectivity indices of 4.75, 4.12, and 2.92 for HT-29, PC-3, and MCF-7, respectively. We also report on assays with CCD 841 CoN (colon epithelial). Overall, results from this study may represent, in the near future, developments for natural-based cancer treatments.
Thiazole as a Promising Scaffold for the Treatment of Schistosomiasis: In Vitro and In Vivo Activity Against Different Developmental Stages of Schistosoma mansoni
Background: Schistosomiasis affects more than 250 million people, and praziquantel remains the only drug available for treatment; however, its activity is restricted to adult worms. Previously, our group evaluated six thiazole derivatives (PBT1–PBT6) in vitro against adult Schistosoma mansoni, identifying PBT2, PBT5, and PBT6 as the most active compounds. The present study aimed to evaluate the in vitro activity of PBT2, PBT5, and PBT6 against schistosomula and juvenile worms, as well as their in vivo efficacy against adult S. mansoni. Methods: Mechanically transformed schistosomula and juvenile worms recovered from mice (21 days post-infection) were incubated with the compounds (12.5–200 μM). Cytotoxicity was assessed using murine splenocytes and peritoneal macrophages exposed to the same concentration range. For in vivo evaluation, infected mice were orally treated with compounds (50, 100, or 200 mg/kg) for five consecutive days. Results: All compounds induced 100% mortality in schistosomula and juvenile worms within 3 h of exposure at 100 and 200 μM. Parasite cell viability was markedly reduced (>90%) at concentrations between 50 and 200 μM. The LC50 values ranged from 15.3 to 30.9 μM for schistosomula and from 27.8 to 34.9 μM for juvenile worms, with low cytotoxicity observed in mammalian cells (CC50 ≥ 193.9 μM). In vivo treatment resulted in significant reductions in fecal egg counts (~80% at 200 mg/kg), total worm burden (~60%), and egg loads in liver and intestinal tissues, in addition to an increased proportion of dead eggs in the intestine. Conclusions: The evaluated thiazole derivatives demonstrated potent in vitro activity against immature stages of S. mansoni and significant in vivo efficacy against adult parasites, accompanied by favorable changes in key parasitological parameters. These findings reinforce the potential of thiazole-based compounds as promising multistage schistosomicidal candidates.
Clinical Potential of Essential Oils: Cytotoxicity, Selectivity Index, and Efficacy for Combating Gram-Positive ESKAPE Pathogens
(1) Background: Essential oils (EOs) have emerged as promising antibacterial agents due to their broad-spectrum activity and low risk of resistance development. Therefore, this review aimed to assess the effectiveness of EOs against Gram-positive ESKAPE pathogens, and to evaluate their safety and toxicity in mammalian cells. (2) Methods: A comprehensive search was conducted in PubMed, Scopus, and Web of Science. (3) Results: Heracleum pyrenaicum exhibited the most potent effect, with a MIC of 0.02–0.04 µg/mL and a selectivity index ranging from 251.3 to 2006.5, indicating high selective toxicity toward bacterial cells over mammalian cells. In contrast, certain species such as Cannabis sp. and Citrus sp. had selectivity indices of <1, indicating toxicity to mammalian cells. Ocimum basilicum showed good efficacy against methicillin-resistant S. aureus (MRSA), with a selectivity index of 23.4–34.9, while Satureja nabateorum demonstrated potent activity against E. faecium, with a selectivity index of 65.6–87.2. (4) Conclusions: EOs from Heracleum, Eucalyptus, Cinnamomum, Mentha, Thymus, and Syzygium aromaticum had good efficacy and high safety margins and show a potential for development for treating Gram-positive ESKAPE pathogen infections. However, EOs with a narrow safety margin (selectivity index < 10) raise concerns and warrant further in vivo and clinical trials to better understand their therapeutic windows and potential adverse effects.
Distribution, movement, and microhabitat use of the introduced predatory snail Euglandina rosea in Hawaii: implications for management
The purposeful introduction of the land snail Euglandina rosea, which feeds exclusively on snails and slugs, has been implicated as a major factor in the decline of diverse Pacific island land snail faunas. We report on the distribution, movement patterns, and microhabitat preferences of E. rosea in a gulch in the Waianae Mountains, Oahu, Hawaii, because such data will help focus management actions at a local scale to protect native snail populations in areas where E. rosea is established. The Waianae Mountains harbor many endangered or threatened snails, most currently found in isolated habitat patches near the ridges. Conversely, most living individuals (28/29) and shells (46/56) of E. rosea were collected within the gulch, which supported higher densities of other native and non‐native snails, and was cooler and more moist than the ridges. Thirteen individuals of E. rosea were tracked (eight directly using a bobbin and thread method, and five indirectly by mark–recapture); most (10/13) moved on average <2.5 m per week (range 0.1–25.21 m), and all stayed within the gulch. Members of E. rosea preferred leaf litter over open, fern/shrub, or wood microhabitats. There were large differences in the population density of E. rosea over small spatial scales, indicating that there may be places where native snail populations could persist even in areas where populations of E. rosea are established. Identifying areas with differing population densities of E. rosea is critical for not only understanding why some native snail species may be more vulnerable to extinction, but also to locate areas where predation pressure is low and conservation efforts will be most likely to succeed.
Opportunistic or Non-Random Wildlife Crime? Attractiveness Rather Than Abundance in the Wild Leads to Selective Parrot Poaching
Illegal wildlife trade, which mostly focuses on high-demand species, constitutes a major threat to biodiversity. However, whether poaching is an opportunistic crime within high-demand taxa such as parrots (i.e., harvesting proportional to species availability in the wild), or is selectively focused on particular, more desirable species, is still under debate. Answering this question has important conservation implications because selective poaching can lead to the extinction of some species through overharvesting. However, the challenges of estimating species abundances in the wild have hampered studies on this subject. We conducted a large-scale survey in Colombia to simultaneously estimate the relative abundance of wild parrots through roadside surveys (recording 10,811 individuals from 25 species across 2221 km surveyed) and as household, illegally trapped pets in 282 sampled villages (1179 individuals from 21 species). We used for the first time a selectivity index to test selection on poaching. Results demonstrated that poaching is not opportunistic, but positively selects species based on their attractiveness, defined as a function of species size, coloration, and ability to talk, which is also reflected in their local prices. Our methodological approach, which shows how selection increases the conservation impacts of poaching for parrots, can be applied to other taxa also impacted by harvesting for trade or other purposes.
Synthesis and Evaluation of the Antiproliferative Activity of the Derivatives of 3,5-Diaryl-3,4-dihydro-2H-pyrrole-2-carboxylic Acids
The metabolic cycle of L-proline plays a crucial role in cancer cell survival, proliferation, and metastasis. A key intermediate in the biosynthesis and degradation of proline is 3,4-dihydro-2H-pyrrole-2-carboxylic acid. A direct route for synthesizing substituted derivatives of this acid involves the cyclization of 2-amino-5-oxonitriles. Michael additions of [(diphenylmethylene)amino]acetonitrile to enones in a basic medium—either with aqueous sodium hydroxide or under solid–liquid phase-transfer catalysis conditions using CaO as a base—enable the synthesis of substituted 2-amino-5-oxonitriles as single diastereoisomers or as diastereoisomeric mixtures. Selective removal of the diphenylmethylene-protecting group, followed by in situ cyclization in acidic conditions, yields trans- and cis-3,5-diaryl-3,4-dihydro-2H-pyrrole-2-carbonitriles. The reaction of nitriles with HCl/dioxane/methanol followed by treatment with water produces esters and amides as by-products. In vitro screening of the synthesized compounds against multiple human cancer cell lines revealed that some compounds exhibit a good or high selectivity index. In conclusion, the synthetic schemes presented offer simple and efficient routes for the preparation of the derivatives of substituted 3,4-dihydro-2H-pyrrole-2-carboxylic acids, with some compounds exhibiting promising antiproliferative activity.
Cytotoxic effects of extracts obtained from plants of the Oleaceae family: bio-guided isolation and molecular docking of new secoiridoids from Jasminum humile
Traditionally, Oleaceae plants are used to treat many diseases, such as rheumatism, hypercholesterolaemia, or ulcers. To investigate the cytotoxic potential of Jasminum humile L., Jasminum grandiflorum L., and Olea europaea L. (Oleaceae) extracts against selected human cancer cells lines, followed by a phytochemical investigation of the most potent one. The 95% ethanol extracts of aerial parts of three oleaceous plants were examined for their cytotoxicity against HepG-2, MCF-7, and THP-1 cell lines using MTT assay and doxorubicin (positive control). J. humile was bio-selected and submitted to bio-guided fractionation. Chromatographic workup of ethyl acetate and n-butanol fractions afforded two new compounds; 1-methoxyjasmigenin (1) and 1-methyl-9-aldojasmigenin (2), along with five known ones (3-7). Structures were unambiguously elucidated using 1D/2D NMR and ESI-HRMS. Isolated compounds were assessed for their anti-proliferative potential, and both selectivity index and statistical significance were determined. Molecular docking was conducted against the Mcl-1 receptor using (AZD5991) as a standard. Jasmoside (5) was the most potent anticancer compound showing IC 50 values of 66.47, 41.32, and 27.59 µg/mL against HepG-2, MCF-7, and THP-1 cell lines, respectively. Moreover, isojasminin (4) exhibited IC 50 values of 33.49, 43.12, and 51.07 µg/mL against the same cell lines, respectively. Interestingly, 5 exhibited the highest selectivity index towards MCF-7 and THP-1, even greater than doxorubicin. Molecular docking results were in full agreement with the MTT assay and the proposed SAR. In this study, two new compounds were purified. The biological activity highlighted jasmoside (5) as a lead anticancer drug for further future investigation.
Anti-malarial activity of the alkaloid, heptaphylline, and the furanocoumarin, imperatorin, from Clausena anisata against human Plasmodium falciparum malaria parasites: ex vivo trophozoitocidal, schizonticidal and gametocytocidal approach
Background The erythrocytic stage of the life cycle of the malaria parasite, Plasmodium falciparum , consists of trophozoite, schizont and gametocyte stages in humans. Various anti-malarial agents target different stages of the parasite to produce treatment outcomes. This study reports on the stage-specific anti-malarial activity of heptaphylline and imperatorin against human P. falciparum in addition to their cytotoxicity and selectivity indices (SI). Methods The compounds were isolated from Clausena anisata using column chromatography and their structures elucidated using NMR spectroscopy. The anti-malarial activity was determined by measuring the trophozoitocidal, schizonticidal and gametocytocidal activities of the compounds using the SYBR green assay. Cytotoxicity was evaluated using the tetrazolium-based colorimetric assay. Results Heptaphylline and imperatorin produced trophozoitocidal, schizonticidal and gametocytocidal activities with IC 50 s of 1.57 (0.2317)–26.92 (0.3144) µM with those of artesunate (the standard drug) being 0.00024 (0.0036)–0.0070 (0.0013) µM. In the cytotoxicity assay, the compounds produced CC 50S greater than 350 µM and SI of 13.76–235.90. Also, the trophozoitocidal and schizonticidal activities of the compounds were more pronounced than their gametocytocidal activity. Imperatorin was 42.04% more trophozoitocidal than hepthaphyline. However, hepthaphyline has more schizonticidal and gametocytocidal properties than imperatorin. Conclusion Heptaphylline and imperatorin are promising anti-malarial agents, since they possess potent anti-malarial activity with weak cytotoxicity on RBCs. However, imperatorin is a better anti-malarial prophylactic agent whereas heptaphylline is a better malaria treatment agent.