Andrea Krähmer

Infrared and Raman spectroscopic methods for characterization of Taxus baccata L. – Improved taxane isolation by accelerated quality control and process surveillance

Different yew species contain poisonous taxane alkaloids which serve as resources for semi-synthesis of anticancer drugs. The highly variable amounts of taxanes demand new methods for fast characterization of the raw plant material and the isolation of the target structures during phyto extraction. For that purpose, applicability of different vibrational spectroscopy methods in goods receipt of raw plant material and in process control was investigated and demonstrated in online tracking isolation and purification of the target taxane 10-deacetylbaccatin III (10-DAB) during solvent extraction. Applying near (NIRS) and mid infrared spectroscopy (IRS) the amount of botanical impurities in mixed samples of two different yew species (R(2)=0.993), the leave-to-wood ratio for Taxus baccata material (R(2)=0.94) and moisture in dried yew needles (R(2)=0.997) can be quantified. By partial least square analysis (PCA) needles of different Coniferales species were successfully discriminated by Attenuated Total Reflectance-Fourier-Transform Infrared Spectroscopy (ATR-FT-IR). The analytical potential of ATR-FT-IR and Fourier Transform-Raman Spectroscopy (FT-RS) in process control of extraction and purification of taxanes is demonstrated for determination of the water content in methanolic yew extracts (R(2)=0.999) and for quantification of 10-DAB (R(2)=0.98) on a highly sophisticated level. The decrease of 10-DAB in the plant tissue during extraction was successfully visualized by FT-IR imaging of thin cross sections providing new perspectives for process control and design.

Attenuated Total Reflectance–Fourier Transform Infrared Spectroscopy on Intact Dried Leaves of Sage (Salvia officinalis L.): Accelerated Chemotaxonomic Discrimination and Analysis of Essential Oil Composition

Sage (Salvia officinalis L.) is cultivated worldwide for its aromatic leaves, which are used as herbal spice, and for phytopharmaceutical applications. Fast analytical strategies for essential oil analysis, performed directly on plant material, would reduce the delay between sampling and analytical results. This would enhance product quality by improving technical control of cultivation. The attenuated total reflectance-Fourier transform infrared spectroscopy (ATR-FTIR) method described here provides a reliable calibration model for quantification of essential oil components [EOCs; R(2) = 0.96; root-mean-square error of cross-validation (RMSECV) = 0.249 mL 100 g(-1) of dry matter (DM); and range = 1.115-5.280 mL 100 g(-1) of DM] and main constituents [e.g., α-thujone/β-thujone; R(2) = 0.97/0.86; RMSECV = 0.0581/0.0856 mL 100 g(-1) of DM; and range = 0.010-1.252/0.005-0.893 mL 100 g(-1) of DM] directly on dried intact leaves of sage. Except for drying, no further sample preparation is required for ATR-FTIR, and the measurement time of less than 5 min per sample contrasts with the most common alternative of hydrodistillation followed by gas chromatography analysis, which can take several hours per sample.

Quantifying biochemical quality parameters in carrots (Daucus carota L.) - FT-Raman spectroscopy as efficient tool for rapid metabolite profiling.

Application of FT-Raman spectroscopy for simultaneous quantification of carotenoids, carbohydrates, polyacetylenes and phenylpropanoids with high bioactive potential was investigated in storage roots of Daucus carota. Within single FT-Raman experiment carbohydrates, carotenoids, and polyacetylenes could be reliably quantified with high coefficients of determination of R(2)>0.91. The most abundant individual representatives of each compound class could be quantified with comparably high quality resulting in R(2)=0.97 and 0.96 for α-carotene and β-carotene, in R(2)=0.90 for falcarindiol (FaDOH), R(2)=0.99, 0.98 and 0.96 for fructose, glucose and sucrose. In contrast, application of FT-Raman spectroscopy for quantification of two laserine-type phenylpropanoids was investigated but failed due to low concentration and Raman response. Furthermore, evaluation of metabolic profiles by principle component analysis (PCA) revealed metabolic variety of carrot root composition depending on root color and botanical relationship.

NIR Spectroscopy of Actaea racemosa L. rhizome – En Route to Fast and Low-Cost Quality Assessment

Rhizomes of Actaea racemosa L. (formerly Cimicifuga racemosa) gained increasing interest as a plant-derived drug due to its hormone-like activity and the absence of estrogenic activity. According to the Current Good Manufacturing Practices guidelines and pharmacopeial standards, quality assessment of herbal starting materials includes tests on identity and substitution, as well as quantification of secondary metabolites, usually by HPTLC and LC methods. To reduce the laboratory effort, we investigated near-infrared spectroscopy for rapid species authentication and quantification of metabolites of interest.Near-infrared spectroscopy analysis is carried out directly on the milled raw plant material. Spectra were correlated with reference data of polyphenols and triterpene glycosides determined by LC/diode array detection and LC/evaporative light scattering detection, respectively. Quantification models were built and validated by cross-validation procedures. Clone plants, derived by vegetative propagation, and plants of a collection from different geographical origins cultivated in Berlin were analysed together with mixed batches from wild harvests purchased at wholesalers.Generally, good to excellent correlations were found for the overall content of polyphenols with coefficients of determination of R2 > 0.93. For individual polyphenols such as fukinolic acid, only models containing clone plants succeeded (R2 > 0.92). For the total content of triterpene glycosides, results were generally worse in comparison to polyphenols and were observed only for the mixed batches (R2 = 0.93).Next to quantitative analysis, near-infrared spectroscopy was proven as a rapid alternative to other, more laborious methods for species authentication. Near-infrared spectroscopy was able to distinguish different Actaea spp. such as the North American Actaea cordifolia and the Asian Actaea cimicifuga, Actaea dahurica, Actaea heracleifolia, and Actaea simplex.

Discrimination of Solanaceae Taxa and Quantification of Scopolamine and Hyoscyamine by ATR-FTIR Spectroscopy

Plant species of the Solanaceae family (nightshades) contain pharmacologically active anticholinergic tropane alkaloids, e.g., scopolamine and hyoscyamine. Tropane alkaloids are of special interest, either as active principles or as starting materials for semisynthetic production of other substances. For genetic evaluation, domestication, cultivation, harvest and post-harvest treatments, quantification of the individual active principles is necessary to monitor industrial processes and the resulting finished products. Up to now, frequently applied methods for quantification are based on high performance liquid chromatography and gas chromatography optionally combined with mass spectrometry. However, alternative analytical methods have the potential to replace the established standard methods partly. In this context, attenuated total reflection-Fourier transform infrared spectroscopy enabled chemotaxonomical classification of the Solanaceae Atropa belladonna, Datura stramonium, Hyoscyamus niger, Solanum dulcamara, and Duboisia in combination with cluster analysis. Also discrimination of genotypes within species was achieved to some extent. The most characteristic scopolamine bands could be identified in attenuated total reflection-Fourier transform infrared spectra of Solanaceae leaves, which allow a fast characterisation of plants with high scopolamine content. Applying a partial least square algorithm, very good calibration statistics were obtained for the prediction of the scopolamine content (residual prediction deviation = 7.67), and moderate prediction quality could be achieved for the hyoscyamine content (residual prediction deviation = 2.48).

Genetic Variation of the Host Plant Species Matters for Interactions with Above- and Belowground Herbivores

Plants are challenged by both above- and belowground herbivores which may indirectly interact with each other via herbivore-induced changes in plant traits; however, little is known about how genetic variation of the host plant shapes such interactions. We used two genotypes (M4 and E9) of Solanum dulcamara (Solanaceae) with or without previous experience of aboveground herbivory by Spodoptera exigua (Noctuidae) to quantify its effects on subsequent root herbivory by Agriotes spp. (Elateridae). In the genotype M4, due to the aboveground herbivory, shoot and root biomass was significantly decreased, roots had a lower C/N ratio and contained significantly higher levels of proteins, while the genotype E9 was not affected. However, aboveground herbivory had no effects on weight gain or mortality of the belowground herbivores. Root herbivory by Agriotes increased the nitrogen concentration in the roots of M4 plants leading to a higher weight gain of conspecific larvae. Also, in feeding bioassays, Agriotes larvae tended to prefer roots of M4 over E9, irrespective of the aboveground herbivore treatment. Fourier-Transform Infrared Spectroscopy (FT-IR) documented differences in metabolic profiles of the two plant genotypes and of the roots of M4 plants after aboveground herbivory. Together, these results demonstrate that previous aboveground herbivory can have genotype-specific effects on quantitative and qualitative root traits. This may have consequences for belowground interactions, although generalist root herbivores might not be affected when the root biomass offered is still sufficient for growth and survival.

Characterization of essential oil distribution in the root cross-section of Valeriana officinalis L. s.l. by using histological imaging techniques

BackgroundThe essential oil is an important compound of the root and rhizome of medicinally used valerian (Valeriana officinalis L. s.l.), with a stated minimum content in the European pharmacopoeia. The essential oil is located in droplets, of which the position and distribution in the total root cross-section of different valerian varieties, root thicknesses and root horizons are determined in this study using an adapted fluorescence-microscopy and automatic imaging analysis method. The study was initiated by the following facts:A probable negative correlation between essential oil content and root thickness in selected single plants (elites), observed during the breeding of coarsely rooted valerian with high oil content.Higher essential oil content after careful hand-harvest and processing of the roots.ResultsIn preliminary tests, the existence of oil containing droplets in the outer and inner regions of the valerian roots was confirmed by histological techniques and light-microscopy, as well as Fourier-transform infrared spectroscopy. Based on this, fluorescence-microscopy followed by image analysis of entire root cross-sections, showed that a large number of oil droplets (on average 43% of total oil droplets) are located close to the root surface. The remaining oil droplets are located in the inner regions (parenchyma) and showed varying density gradients from the inner to the outer regions depending on genotype, root thickness and harvesting depth.ConclusionsFluorescence-microscopy is suitable to evaluate prevalence and distribution of essential oil droplets of valerian in entire root cross-sections. The oil droplet density gradient varies among genotypes. Genotypes with a linear rather than an exponential increase of oil droplet density from the inner to the outer parenchyma can be chosen for better stability during post-harvest processing. The negative correlation of essential oil content and root thickness as observed in our breeding material can be counteracted through a selection towards generally high oil droplet density levels, and large oil droplet sizes independent of root thickness.

Züchterische Verbesserung der Silphie – erste Schritte

Eine zuchterische Bearbeitung der Silphie (Silphium perfoliatum L.) steht am Beginn. Mogliche Zuchtmerkmale, befruchtungsbiologische Grundlagen und mogliche Zuchtstrategien werden betrachtet. In den untersuchten Herkunften gibt es eine grose Ausgangsvariabilitat. Pflanzenbauliche und technologische Merkmale konnen effektiv bearbeitet werden. Fur die energetischen Merkmale fehlen schnelle und kostengunstige Methoden. Die Nahinfrarot-Spektroskopie (NIRS) wird fur die Bestimmung dieser Merkmale erprobt. Fur die schnelle Multiplikation zuchterisch wertvoller Einzelpflanzen wird ein In-vitro Vermehrungsverfahren entwickelt.