Polyphenol pattern and antioxidant activity of different tomato lines and cultivars.

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 beta-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 (R(2) = 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 beta-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/electrospray ionization mass spectrometric characterization of flavonol glycosides in tomato extracts and human plasma.

Flavonoids continue to attract wide attention as possible very useful agents for combating free radical pathologies, i.e. the pathological states associated with free radical overproduction. Commonly used methods for the analysis of plant flavonoids include high performance liquid chromatography (HPLC) and capillary electrophoresis (CE). On the other hand, the soft-ionization approach based on electrospray ionization (ESI-MS) permits highly selective analysis of complex matrices. In this work, we examined firstly the ESI-MS behaviour of representative aglycones and glycosides of flavonols, flavones and isoflavones with the aim of suggesting a possible relationship between structure and mass spectra. Using HPLC coupled to a diode array detector (DAD) for on-line UV spectra acquisition, and in parallel to ESI-MS for mass spectra (LC/DAD-ESI-MS), we have developed methodology to observe flavonols directly in tomato puree extract. In this way, it has been possible to detect intact flavonol glycosides in tomato extracts and to characterize a flavonol trisaccharide. For the first time, using LC/ESI-MS, it has been possible to detect intact flavonol glycosides in plasma of healthy volunteers and to provide further evidence on the absorption of flavonoid glycosides after consumption of common vegetables like tomatoes.