Application of ATR-FTIR spectroscopy for profiling of non-structural carbohydrates in onion (Allium cepa L.) bulbs.

Qualitative and quantitative composition of non-structural carbohydrates comprising glucose, fructose, sucrose and fructooligosaccharides (FOS) is one of the key determinants of market suitability, storability and technological processability of onions. To develop a cost-effective and rapid tool for carbohydrate profiling, applicability of attenuated total reflectance Fourier-transform infrared (ATR-FTIR) spectroscopy of onion juice was investigated with special regard to FOS patterns. As reference, detailed carbohydrate profiles of onion juices were generated by high-performance liquid chromatography coupled with evaporative light scattering detection (HPLC-ELSD). Hierarchical cluster analysis (HCA) of ATR-FTIR spectra was successfully applied for classifying onions into fresh market, storage and dehydrator type according to HPLC-ELSD profiles. A bootstrapping method for automatized test-set validation by projection to latent structures (PLS) algorithms using HPLC and ATR-FTIR spectroscopy data was developed. Model statistics showed promising perspectives for reliable quantification of individual saccharides and sum parameters. The presented methodology allows estimating the nutritional and pre-biotic value directly during cultivation and processing.

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.

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/ß-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.

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.

Discrimination of fennel chemotypes applying IR and Raman spectroscopy: discovery of a new γ-asarone chemotype.

Various vibrational spectroscopy methods have been applied to classify different fennel chemotypes according to their individual profile of volatile substances. Intact fennel fruits of different chemotypes could be successfully discriminated by attenuated total reflectance Fourier transform infrared (ATR-FTIR) and near infrared (NIR) spectroscopy. Solvent extracts (CCl4) of the considered fennel fruits showed characteristic fingerprints with marker bands related to the individual volatile components (trans-anethole, fenchone, estragole, piperitenone oxide, γ-asarone, limonene) for ATR-FTIR and FT-Raman spectroscopy. Especially νC═C and νC═O absorption bands contribute to the different spectral profiles. On the basis of hierarchical cluster analysis, the considered fennel accessions were classified according to gas chromatographic (GC) and vibrational spectroscopic data. Furthermore, even a discrimination of "sweet" and "bitter" fennel fruits, both belonging to the trans-anethole chemotype, could be successfully performed. All vibrational spectroscopical techniques used in this study are rapid and easy to apply. Hence, they allow different fennel chemotypes to be reliably distinguished and can also be used for on-site measurement in free nature.

The gravitropic setpoint angle of dark-grown rye seedlings and the role of ethylene.

The orientation growth of coleoptiles of dark-grown seedlings of rye (Secale cereale L. cv. Marder II), when grown under various conditions, was analysed with respect to the gravivector ('gravitropic setpoint angle', GSA). Coleoptiles growing through moist vermiculite attain and maintain a GSA with an average of about 180 degrees, i.e. a vertical orientation. Seedlings growing uncovered either on the surface of vermiculite or positionally fixed on filter paper attain and maintain a GSA of 140-150 degrees (i.e. deviating from the vertical by an average of 30-40 degrees ). Changing the position of the embryo relative to the horizontally fixed seed kernel or of the angle of the seed with respect to gravity during germination (+/-40 degrees relative to the horizontal) had no significant effect on the subsequent GSA of both covered and uncovered seedlings. The GSA of uncovered coleoptiles could be restored close to 180 degrees by treatment of the seedlings with ethylene, either applied via ethephon or 1-aminocyclopropane-1-carboxylic acid (ACC) as well as by fruit-released ethylene. The results are discussed with respect to the mechanism of the regulation of gravitropic growth of grass seedlings.