title: In situ flavonoid analysis by FT-Raman spectroscopy: identification, distribution, and quantification of aspalathin in green rooibos (Aspalathus linearis).
abstract: FT-Raman spectroscopy was used for the first time for in situ identification of aspalathin and quantification of the dihyrochalcones in dried, green rooibos (Aspalathus linearis). With the support of two-dimensional correlation spectroscopy, characteristic key bands of aspalathin, the main flavonoid and antioxidant occurring in rooibos, were localized and identified in the spectra obtained from various plant samples. Application of Raman mapping revealed the spatial distribution of this valuable dihydrochalcone within the intact dried leaves. Based on the spectral data and reference HPLC values, reliable multivariate calibration models were developed for quantification of aspalathin, nothofagin, and the combined dihydrochalcone contents of dried, green rooibos.
authors.affiliation: Federal Centre for Breeding Research on Cultivated Plants, Institute of Plant Analysis, Neuer Weg 22-23, D-06484 Quedlinburg, Germany.
authors.forename: Malgorzata
authors.initials: M
authors.lastname: Baranska
authors.forename: Hartwig
authors.initials: H
authors.lastname: Schulz
authors.forename: Elizabeth
authors.initials: E
authors.lastname: Joubert
authors.forename: Marena
authors.initials: M
authors.lastname: Manley
mesh_terms: D000975:Antioxidants / Q000032:analysis*; D036903:Aspalathus / Q000737:chemistry*; D002138:Calibration; D002338:Carotenoids / Q000032:analysis; D047188:Chalcones / Q000032:analysis*; D002851:Chromatography, High Pressure Liquid / Q000379:methods; D005419:Flavonoids / Q000032:analysis*; D008031:Lignin / Q000032:analysis; D008954:Models, Biological; D018515:Plant Leaves / Q000737:chemistry; D013059:Spectrum Analysis, Raman / Q000379:methods*
chemical_list: D000975:Antioxidants; D047188:Chalcones; D005419:Flavonoids; C517016:aspalathin; D002338:Carotenoids; D008031:Lignin; C015812:dihydrochalcone