1,721,214 research outputs found
Phytotoxic activities of essential oils and hydrosols of Haplophyllum tuberculatum
No full textPhytotoxic properties of plants and their compounds against other plants or seeds are being increasingly reported. Moreover, essential oils may provide a new source of phytotoxic agents with possibly novel mechanisms of action. The aim of this study is to determine the chemical composition of the leaves, stems and leaves + stems essential oils by GC/MS and to assess their phytotoxic activities extracted from Haplophyllum tuberculatum A. Juss. (Forssk) as well as of the aromatic water obtained from these parts and of the roots. The phytotoxic activities of the essential oils and hydrosols were evaluated against Triticum aestivum L. and Raphanus sativus L. seeds. The GC–MS analysis revealed the presence of limonene, cis-p-menth-2-en-1-ol, trans-p-menth-2-en-1-ol, cis-piperitol, trans-piperitol, 1-octyl acetate, piperitone and isobornyl acetate as major compounds. Phytotoxic results showed that the assayed stems essential oils were active on the roots inhibition (IC50 = 1.09 mg/mL) for wheat. Leaves + stems essential oils had a significant activity against the tested seeds with IC50 ranged from 0.70 to 1.46 mg/mL for radical and epicotyls/coleoptiles percentage inhibition against T. aestivum L. and R. sativus L. While the hydrosols of leaves, stems and leaves + stems inhibited seeds germination at a higher concentration. The essential oils of this plants cannot be used as biologic herbicide with these cultivated plants
Kinetic study of niobium and tantalum hexameric forms and their substituted ions by capillary electrophoresis in alkaline medium
Full text linkIn this work a capillary electrophoretic (CE) method is used for the kinetic study of the intermetallic substitutions in hexameric ions of two strategic metals, tantalum and niobium in an alkaline medium. Recently proposed processes for the production and analytical separation of tantalum and niobium that are faster, more economical and environmental friendly are based on the use of highly alkaline media. It was previously established that in these media, tantalum and niobium exist as hexameric species, HxTa6O19X-8 (Ta6) and HxNb6019x-8 (Nb6), which can be analysed with a CE method using an alkaline electrolyte and UV detection. However, when using the above method on an industrial sample a minor species that should correspond to the substituted Ta1Nb5 form was observed. The purpose of the present study is to probe, by means of CE, the kinetic of the formation of substituted niobate-tantalate ions, Ta6-xNbx (1 ≤ x ≤ 5), starting from mixtures of pure hexaniobate and hexatantalate ions. This study required the development of a new CE method allowing the separation of all the five substituted ions and their two non-substituted hexameric parent ions in less than seven minutes. In details, a previously developed separation method was transferred to a Beckman instrument and the separation improved by adjusting the total length, the applied voltage, the injection volume, the rinsing steps and the internal standard. The kinetic study shows that samples initially containing non-substituted hexameric forms of tantalum and niobium in a 1:1M ratio naturally form the five possible substituted species Ta6-xNbx (1 ≤ x ≤ 5) after only a few hours which may represent an issue for future Nb-Ta separation processes operated in alkaline media. The developed method was also transferred to an Agilent instrument and the kinetic study repeated. Results obtained with the Agilent instrument corroborate those obtained with the Beckman instrument. The proposed electrophoretic separation method lays the ground for new analytical techniques that could help assessing the presence of substituted species that can be deleterious for Nb-Ta purification processes
In vitro antileishmanial and cytotoxicity activities of essential oils from Haplophyllum tuberculatum A. Juss leaves, stems and aerial parts
Full text linkBackground: Plants used for traditional medicine produce diverse and complex secondary metabolites exhibiting
various medicinal properties. The medicinal plant Haplophyllum tuberculatum is used by native people against
malaria and parasitic infections.
Methods: In this study and in order to contribute for the search of new natural drugs for leishmaniasis, the
essential oils of H. tuberculatum leaves, stems and aerial parts (leaves+stems) collected in two different periods,
2013 and 2015, and their components by GC/FID and GC/MS analyses were investigated. Those collected in 2013
were also re-analyzed two years later. The extracted oils were screened in vitro for anti-leishmanial activity on
Leishmania mexicana mexicana (L.m.m.) promastigotes and cytotoxicity on the Chinese Hamster Ovary (CHO) cell
line. Limonene (1.5 – 8%), its isomers (R- (+)-limonene and S-(-)-limonene), linalool and octanol were also tested.
Results: Results showed that the chemical composition varied according to the year of collection. Though major
compounds remain almost the same, qualitative and quantitative variations in the composition of the EOs can be
observed between the two years of collection, with some minor compounds identified only in one type of
samples. Variation in the composition were also observed in the re-analyzed volatile oils, showing stability
concerns. The essential oils and R-(+)-limonene showed moderate anti-leishmanial activity. Their IC50 range
from 6.48 to 50.28 μg/ml. Cytotoxicity assays for theses volatile extracts, R- (+)-limonene and S- (-)-limonene
on CHO cells showed relatively potent cytotoxicity with a selectivity index <10. Their CC50 range from 27.79
to 82.56 μg/ml.
Conclusions: The findings of the present study demonstrated that H. tuberculatum might not be considered
as a natural source for production of new anti-leishmanial agents without further analyzing its eventual in vivo toxicity
as well as that of major pure compounds
ORAL PRES. ON INVITATION :Experimental designs for the optimization of separation techniques
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Response surface designs: Part 2 - Data analysis and Multiresponse optimisation
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INTERNATIONAL LECTURE/COURSE/ORAL PRES. ON INVITATION: Six Sigma principle :Improving Method Capability of a Drug Substance HPLC Assay
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CHAPTER IN BOOK: Chromatographic development, validation, and data handling of tea fingerprints
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ORAL PRES. Data handling of chromatographic herbal fingerprints
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