Prediction of essential oil content of oregano by hand-held and Fourier transform NIR spectroscopy.

BACKGROUND: In the framework of a breeding programme, the analysis of hundreds of oregano samples to determine their essential oil content (EOC) is time-consuming and expensive in terms of labour. Therefore developing a new method that is rapid, accurate and less expensive to use would be an asset to breeders. The aim of the present study was to develop a method based on near-inrared (NIR) spectroscopy to determine the EOC of oregano dried powder. Two spectroscopic approaches were compared, the first using a hand-held NIR device and the second a Fourier transform (FT) NIR spectrometer. RESULTS: Hand-held NIR (1000-1800 nm) measurements and partial least squares regression allowed the determination of EOC with R² and SEP values of 0.58 and 0.81 mL per 100 g dry matter (DM) respectively. Measurements with FT-NIR (1000-2500 nm) allowed the determination of EOC with R² and SEP values of 0.91 and 0.68 mL per 100 g DM respectively. RPD, RER and RPIQ values for the model implemented with FT-NIR data were satisfactory for screening application, while those obtained with hand-held NIR data were below the level required to consider the model as enough accurate for screening application. CONCLUSION: The FT-NIR approach allowed the development of an accurate model for EOC prediction. Although the hand-held NIR approach is promising, it needs additional development before it can be used in practice.

Molecular characterization of artemisia virus A, a new sobemovirus isolated from Artemisia annua.

A distinct sobemovirus was isolated from diseased Artemisia annua plants grown in experimental culture plots in Switzerland. Electron microscopy performed on extracts of leaf and root samples of a diseased A. annua plant revealed icosahedral-30 nm viral particles. The complete nucleotide sequence of the viral genome was determined. The single positive-strand RNA of 4138 nt encodes four open reading frames with an organization similar to that described for sobemoviruses. Phylogenetic analysis revealed a close relationship to ryegrass mottle virus. The virus was efficiently acquired by healthy A. annua from contaminated soil samples. "Artemisia virus A" is tentatively proposed as a name for this new candidate member of the unassigned genus Sobemovirus.

Quantification of the total amount of artemisinin in leaf samples by thin layer chromatography.

Artemisinin is a natural molecule highly active against malaria. At present, the extraction of this molecule from the leaves of Artemisia annua L. remains the only viable method to produce cheaply large quantities of artemisinin. Agronomic research on this plant species aims to improve agricultural yields, to decrease production costs and to ensure a steady global supply of artemisinin. These research activities require an easy, rapid, low cost, and reliable analytical technique to quantify the artemisinin content in the leaves. Thin layer chromatography (TLC) methods to quantify this molecule have already been published. However, this method does not allow the quantification of the total artemisinin content in the leaves. In order to validate the TLC method, results obtained with this method were related to results for the same samples obtained by accelerated solvent extraction and high pressure liquid chromatography with an evaporative light scattering detector (ASE-HPLC-ELSD). Using the Nernst partition law, a corrective factor of 1.21 is suggested to enable information about the true total amount of artemisinin in leaf samples to be obtained within a range of 0.25 to 3%. In conclusion, this study proposes for the first time a corrective factor in order to quantify the total artemisinin content of A. annua leaves with TLC.

Si-Accumulation In Artemisia annua Glandular Trichomes Increases Artemisinin Concentration, but Does Not Interfere In the Impairment of Toxoplasma gondii Growth.

Artemisia annua is used as a source of artemisinin, a potent therapeutic agent used for the treatment of infectious diseases, chiefly malaria. However, the low concentration (from 0.01 to 1.4% of dried leaf matter) of artemisinin in the plant obtained with the traditional cropping system makes it a relatively expensive drug, especially in developing countries. Considering that artemisinin and silicon (Si) are both stored in A. annua glandular trichomes, and that Si accumulation has never been investigated, this study aimed to look into Si effects on A. annua trichome artemisinin concentration, and whether leaf infusion from Si-treated A. annua plants is able to control Toxoplasma gondii growth. T. gondii is the etiologic agent of toxoplasmosis, a zoonotic parasitic disease whose traditional treatment shows significant side effects. The experimental design consisted of A. annua seedlings randomly planted in soil treated with different doses of calcium/magnesium silicate (0, 200, 400, 800, and 1600 kg ha-1). Analysis of foliar macronutrients showed significant increases of nitrogen content only at the highest dose of silicate. Foliar micronutrients, Si concentrations, and plant height were not affected by any of the silicate doses. However, the dose of 400 kg ha-1 of silicate increased the trichome size, which in turn raised artemisinin concentration in leaves and the infusion. In contrast, the 800 and 1600 kg ha-1 doses dramatically decreased artemisinin concentration. HeLa cell treatment with the infusion of A. annua grown in soil treated with 400 kg ha-1 of silicate decreased parasite proliferation in a dose-dependent manner when the treatment was carried out after or along with T. gondii infection. However, this effect was similar to A. annua grown in soil without silicate treatment. Thus, it can be concluded that, even though Si applied to the soil at 400 kg ha-1 has a positive effect on the A. annua glandular trichome size and the artemisinin concentration, this outcome cannot be directly associated with the efficiency of A. annua infusion on T. gondii growth, suggesting that other components from A. annua leaves could be acting in synergy with artemisinin.