Extension of life-span using a RNAi model and in vivo antioxidant effect of Opuntia fruit extracts and pure betalains in Caenorhabditis elegans.

Betalains are nitrogenous plant pigments known for their high antioxidant capacity. For the first time, this antioxidant nature has been studied in an in vivo system using the model organism Caenorhabditis elegans. The oxidative stress caused in the fluorescent strain TJ375 (hsp-16.2::GFP) was reversed by the presence of both natural and semi-synthetic betalains, with an ED50 value around 25 µM for betacyanins and up to 10 µM for betaxanthins, with indicaxanthin, the major pigments in prickly pear fruits, as the most effective betalain. The effect of model betalains on the lifespan of the wild-type N2 strain was carefully studied using the automatic platform "Lifespan Machine". In a search for different approaches to suppress progeny, pop-1 RNAi was used to avoid FUdR use. The presence of betalains in the medium, both as pure compounds and as enriched Opuntia extracts significantly increased the lifespan of C. elegans.

The plasma bioavailability of nitrate and betanin from Beta vulgaris rubra in humans.

PURPOSE: To evaluate the plasma bioavailability of betanin and nitric oxide (NOx) after consuming beetroot juice (BTJ) and whole beetroot (BF). BTJ and BF were also analysed for antioxidant capacity, polyphenol content (TPC) and betalain content. METHODS: Ten healthy males consumed either 250 ml of BTJ, 300 g of BF or a placebo drink, in a randomised, crossover design. Venous plasma samples were collected pre (baseline), 1, 2, 3, 5 and 8 h post-ingestion. Betanin content in BTJ, BF and plasma was analysed with reverse-phase high-performance liquid chromatography (HPLC) and mass spectrometry detection (LCMS). Antioxidant capacity was estimated using the Trolox equivalent antioxidant capacity (TEAC) and polyphenol content using Folin-Ciocalteu colorimetric methods [gallic acid equivalents (GAE)] and betalain content spectrophotometrically. RESULTS: TEAC was 11.4 ± 0.2 mmol/L for BTJ and 3.4 ± 0.4 µmol/g for BF. Both BTJ and BF contained a number of polyphenols (1606.9 ± 151 mg/GAE/L and 1.67 ± 0.1 mg/GAE/g, respectively), betacyanins (68.2 ± 0.4 mg/betanin equivalents/L and 19.6 ± 0.6 mg/betanin equivalents/100 g, respectively) and betaxanthins (41.7 ± 0.7 mg/indicaxanthin equivalents/L and 7.5 ± 0.2 mg/indicaxanthin equivalents/100 g, respectively). Despite high betanin contents in both BTJ (~194 mg) and BF (~66 mg), betanin could not be detected in the plasma at any time point post-ingestion. Plasma NOx was elevated above baseline for 8 h after consuming BTJ and 5 h after BF (P < 0.05). CONCLUSIONS: These data reveal that BTJ and BF are rich in phytonutrients and may provide a useful means of increasing plasma NOx bioavailability. However, betanin, the major betalain in beetroot, showed poor bioavailability in plasma.