Quantitative characterization of flavonoid compounds in rooibos tea (Aspalathus linearis) by LC-IV/DAD (original) (raw)
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Journal of Agricultural and Food Chemistry, 2002
Rooibos tea originates from the leaves and stems of the indigenous South African plant Aspalathus linearis. It has gained much attention for clinical purposes in the case of nervous tension, allergies (dermatitis), and various indigestive problems. Recently, antioxidative activity was also attributed to the tea on the basis of its flavonoid content. Therefore, an HPLC method using a C 18 reversed phase column was developed for the assay of 10 flavonoids in aqueous and methanolic infusions. Main compounds determined were the dihydrochalcone aspalthin, rutin, and orientin, and their content was in the range of 1.0 to 1.3 mg/g. The identity of detected flavonoids was confirmed by comparing their retention times and UV and MS spectra with those of corresponding standards. In addition, the MS analysis showed evidence of the presence of other compounds such as nothofagin, dihydroisoorientin, and dihydroorientin.
Journal of Agricultural and Food Chemistry, 2003
Unfermented rooibos originates from the leaves and the stems of the indigenous South African plant, Aspalathus linearis, and it has been reported to have a higher content of flavonoids compared to that of fermented rooibos. The HPLC/UV method developed in our laboratory for the analysis of the fermented rooibos was applied to the quantitative characterization of the major flavonoids present in the unfermented rooibos. Main compounds determined were aspalathin (49.92 (0.80 mg/g), isoorientin (3.57 (0.18 mg/g), orientin (2.336 (0. 049 mg/g), and rutin (1.69 (0.14 mg/g), followed in order by isovitexin, vitexin, isoquercitrin and hyperoside, quercetin, luteolin and chrysoeryol. The identity of detected flavonoids was confirmed by comparing their retention times and UV spectra with those of corresponding standards. The total antioxidant activity (TAA) of the tea infusions was measured by the ABTS •+ radical cation decolorization assay. The TAA of unfermented rooibos (0.8 Trolox meq/g) resulted 2-fold higher than that of the fermented rooibos. When compared with different water infusions of Camellia sinensis (green and black tea), this TAA value was about 50% lower.
Determination of flavonoids in tea and Rooibos extracts by TLC and HPLC
JPC - Journal of Planar Chromatography - Modern TLC, 2008
In this study thin-layer chromatography (TLC) was used for analysis of the constituents of extracts of tea (Camellia sinensis L.) and Rooibos (Aspalathus linearis) leaves. In particular, flavonoids, a group of phenolic compounds, for example myrecetin, rutin, catechin, quercetin, and kaempferol were analyzed. Extracts of various types of tea, for example black, green, and Rooibos herbal tea (called red tea) were analyzed. The efficiency of extraction of flavonoids from plant material by classical liquid extraction (LE) and supercritical-fluid extraction (SFE) was also compared. Recoveries of individual flavonoids were approximately ten times higher after use of solvent extraction. Separation of flavonoids from tea extracts on the basis of their polarities was optimized by selection of solvents, stationary phases, and chromatographic conditions. For final analyses glass-backed silica gel 60 F 254 plates and the mobile phase acetone-chloroform-water 80:20:10 (v/v) were used. UV detection of TLC chromatograms (254 and 366 nm) was used. Better detection of the flavonoids was achieved at 366 nm. The concentration of some important flavonoids in real tea samples was obtained by high-performance liquid chromatography (HPLC).
South African Journal of Botany, 2016
A large sample set (n = 209) of fermented, unpasteurised rooibos, spanning the production years 2011-2013, was collected from the two major production areas (Western Cape and Northern Cape, South Africa). Hot water infusions, as prepared for grading, were analysed to quantify the content of ten flavonoid glycosides, the enolic phenylpropenoic acid glucoside, phenylpyruvic acid-2-O-glucoside (PPAG) and the phenolic acid, ferulic acid (FA), using a previously validated reversed phase high performance liquid chromatography with diode array detection (RP-HPLC-DAD) method. Principal component analysis showed no clear grouping of samples according to production area and/or production year, based on the content of individual compounds or sub-classes, i.e. dihydrochalcone, flavonol, flavone and PPAG + FA. Discriminant analysis indicated grouping according to year, but not according to production area. ANOVA showed significant production area × year interactions (P b 0.05) for the flavonol and PPAG + FA sub-classes. The dihydrochalcone sub-class was only significantly (P b 0.05) affected by production area with samples from the Western Cape having significantly higher aspalathin and nothofagin contents than those from the Northern Cape. The flavone sub-class was not affected by production area or year. The major flavones, orientin and isoorientin, were the predominant constituents of the rooibos tea infusions, followed by quercetin-3-O-robinobioside, PPAG and aspalathin. These compounds were present at levels N 9 mg/L, while the other compounds were present at b5 mg/L.
South African Journal of Botany, 2015
Phenolic compounds have several biological effects such as anti-inflammatory, bactericidal and antioxidant properties due to their ability to neutralise free radicals. The aim of the study was to determine total phenolic content and antioxidant activities of Zimbabwean indigenous herbal teas and comparing them with Aspalathus linearis (Rooibos™), a commercial South African herbal tea. Plant leaves of Myrothamnus flabellifolius, Fadogia ancylantha, Lippia javanica, and Ficus sycamore and a concoction of Adansonia digitata fruit pulp, seed and fibre were analysed. Total phenolic content was determined using the Folin-Ciocalteau method. The butanol-HCl assay was used to determine condensed tannin content. Antioxidant properties were determined using 2,2-diphenyl-1picrylhydrazyl (DPPH), reducing power and inhibition of phospholipid peroxidation assays. F. sycamore had the highest total phenolic content (14.02 ± 0.01 g GAE/100 g) while A. digitata fruit pulp mixture had the lowest (0.79 ± 0.28 g GAE/100 g). The highest tannin content was found in F. sycamore (1.98 ± 0.12 g/100 g and the lowest was in L. javanica (0.1174 ± 0.01 g LE/100 g). Only F. sycamore exhibited higher antioxidant activity than A. linearis in all antioxidant assays whereas activity in other herbal teas was interchangeably higher or lower depending on antioxidant assay carried out.
Models to predict the total antioxidant capacity (TAC) of rooibos tea infusions from their chromatographic fingerprints and peak table data (content of individual phenolic compounds), obtained using HPLC with diode array detection, were developed in order to identify potential antioxidant markers. Peak table data included the content of 12 compounds, namely phenylpyruvic acid-2-O-glucoside, aspalathin, nothofa-gin, isoorientin, orientin, ferulic acid, quercetin-3-O-robinobioside, vitexin, hyperoside, rutin, isovitexin and isoquercitrin. The TAC values, measured using the oxygen radical absorbance capacity (ORAC) and DPPH radical scavenging assays, could be predicted from the peak table data or the chromatographic fingerprints (prediction errors 9–12%) using partial least squares (PLS) regression. Prediction models created from samples of only two production years could additionally be used to predict the TAC of samples from another production year (prediction errors < 13%) indicating the robustness of the models in a quality control environment. Furthermore, the uninformative variable elimination (UVE)-PLS method was used to identify potential antioxidant markers for rooibos infusions. All individual phenolic compounds that were quantified were selected as informative variables, except vitexin, while UVE-PLS models developed from chromatographic fingerprints indicated additional antioxidant markers, namely (S)-eriodictyol-6-C-glucoside, (R)-eriodictyol-6-C-glucoside, aspalalinin and two unidentified compounds. The potential antioxidant markers should be validated prior to use in quality control of rooibos tea.
Separations
Aspalathus linearis (Burm.f.) R. Dahlgren, commonly known as rooibos tea, was consumed traditionally by the indigenous South African inhabitants as an herbal remedy. Beside antioxidant properties, it displays antiallergic, antispasmodic, and hypoglycemic activities. An ultra-high-performance liquid chromatography method coupled with photodiode array and mass spectrometry detectors were developed for the determination of 14 phenolic constituents from leaves and stems of A. linearis. The efficient separation was performed within 30 min at a temperature of 30 °C by using C-18 column as the stationary phase and water/acetonitrile with 0.05% formic acid as the mobile phase. Method validation for linearity, repeatability, limits of detection, and limits of quantification was achieved. The limits of detection from 0.2–1 μg/mL were reported for the standard compounds. Their total content varied substantially (1.50–9.85 mg/100 mg sample) in 21 dietary supplements. The presence of regioisomer...
Analytical and Bioanalytical Chemistry, 2011
Rooibos (Aspalathus linearis) is a rich source of polyphenols and used to make a mild-tasting tea containing no caffeine, is low in tannins compared to green or black teas, and has antioxidant and antimutagenic/antitumoral properties. In vivo results show that rooibos has beneficial effects upon the lipid profile by decreasing serum triglycerides and cholesterol. In this sense, we have developed a simple and rapid method to separate and characterize simultaneously the polyphenolic compounds in aqueous and ethanolic rooibos extracts using high-performance liquid chromatography coupled to electrospray ionization time-of-flight mass spectrometry (HPLC-ESI-TOF-MS) and ion trap multiple mass spectrometry (HPLC-ESI-IT-MS 2 ). The phenolic compounds were separated on a C 18 column (4.6×150 mm, 1.8 μm) with 1% formic acid in water/acetonitrile 90:10 v/v and acetonitrile as mobile phases. The accuracy mass data generated by TOF-MS together with the fragmentation pattern obtained by IT-MS 2 experiments confirmed the presence of 25 and 30 phenolic compounds in the aqueous and ethanolic extracts, respectively.
Development and validation of HPLC method for determination of flavonoids in herbal preparations
2015
Introduction - Flavonoids are a large group of polyphenolic components possessing benzo-γ-pyronic structure and widely distributed in plants. The chemical nature and the biological activity of flavonoids depends on the structural class to which they belong, the degree of hydroxylation, the degree of polymerization, and the presence of other substituents and bonds. Today, there are large number of herbal preparations containing plant extracts rich in flavonoids used as OTC drugs, and therefore it is necessary to develop methods for controlling and monitoring their quality. Aim - Development and validation of HPLC method for determination of rutin and quercetin in tablets containing 1200 mg dry leaf of Ginkgo biloba. Method - Simple HPLC method with gradient elution (acetonitrile: 0.3% phosphoric acid), flow rate of 1,2 mL/min, column temperature of 25°C and UV detection (rutin at 255 nm, quercetin at 375 nm) of rutin and quercetin in herbal preparation containing dry leaf of Ginkgo b...
TOTAL FLAVONOID CONTENT OF COMMONLY CONSUMED TEAS IN INDIA
The flavonoids present in the tea are known to exhibit anticarcinogenic, antimicrobial, antiviral, antiarteriosclerosis, antihypertensive, antidiabetic, anti-inflammatory and antidiuretic activities and thus they are therapeutically important class of compounds. Therefore it is necessary to find out levels of bioactive compounds in various tea samples. In the present investigation six commercial varieties including black and green tea from Indian market were analyzed for their total flavonoid content using uv-visible spectrophotometer. The total amounts of flavonoid were determined by aluminium chloride method with some modifications and the total flavonoids were expressed as mg/g of quercetin equivalents. The results