No abstract

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.

Background/Aims: Besides antioxidant vitamins and minerals, fruits and vegetables contain flavonoids and related phenolics. The biological activities of these polyphenols have become well known in recent years evidencing their beneficial effects on human health. In this context, the characterization of the flavonoids present in tomatoes is of great interest. Thus the polyphenol pattern (including flavonols, flavanones and cinnamate derivatives), lycopene and β-carotene concentrations and the total antioxidant activity (TAA) of the phenolic fraction from different tomato lines and cultivars have been determined. Methods: The characterization was obtained by means of spectrophotometry and HPLC analyses. Results: Mean values for single flavonoids were 0.68 ± 0.16 for naringenin, 0.74 ± 0.12 for rutin and 0.32 ± 0.06 for a rutin-pentoside. Mean total polyphenol content was 13.15 ± 1.15 mg/100 g and mean TAA value was 1.3 ± 0.10 mmol/g. The obtained TAA values resulted in good accordance with the total polyphenol content (R² = 0.7928). The main phenolic acids were chlorogenic (mean ± SE 0.20 ± 0.03) and caffeic acid (mean ± SE 0.03 ± 0.01). Mean levels of lycopene and β-carotene were 5.38 ± 0.90 and 1.18 ± 0.40 mg/100 g, respectively. Conclusions: Almost all the lines characterised by low carotenoid content produce high levels of polyphenols, and consequently have the most powerful antioxidant potential.

Liquid chromatography/atmospheric pressure chemical ionization mass spectrometry (LC/APCI-ITMS) was applied to evaluate the levels of ginkgolides A and B and bilobalide in plasma of volunteers after administration of Ginkgo biloba extracts in free (Ginkgoselect) or phospholipid complex (Ginkgoselect Phytosome) forms, providing 9.6 mg of total terpene lactones. The maximum plasma concentrations, C(max), of total ginkgolides A, B and bilobalide were 85.0 and 181.8 microg/mL for Ginkgoselect and Ginkgoselect Phytosome, respectively. The C(max) values were reached at 120 min for the free form and at 180--240 min for the phospholipid complex form. In both cases, the mean elimination half-life of each terpene lactone was in the range 120--180 min. Due to its sensitivity (about 1 ng/mL) and specificity, LC/APCI-ITMS proved to be a very powerful tool for pharmacokinetic studies of these phytochemicals.