Comparison of the uptake and secretion of carotene and xanthophyll carotenoids by Caco-2 intestinal cells

Abstract

Carotenoids have been shown to have potential beneficial effects on human health which has led to an increasing interest in the study of their bioavailability. A Caco-2 cell model, as previously described, was employed to examine the percentage transfer of the carotenoids a-carotene, b-carotene, lycopene, astaxanthin, b-cryptoxanthin, lutein and zeaxanthin through an intact, highly differentiated Caco-2 cell monolayer at a range of different amounts. Our results show that astaxanthin, a carotenoid with powerful antioxidant capacity, had the highest percentage transfer overall. We examined the cellular uptake and secretion of lutein and zeaxanthin to compare two structurally similar carotenoids. Both were efficiently transported through the monolayer with a range between 5·1 (SEM 1·2) % to 20·2 (SEM 3·3) % and 5·5 (SEM 2·5) % to 13·4 (SEM 4) % for lutein and zeaxanthin, respectively. These carotenoids were compared to each other at each added amount and no significant difference was observed between the two xanthophylls. The carotene carotenoids a-carotene, b-carotene and lycopene and the xanthophyll b-cryptoxanthin were also examined and had lower uptake and secretion values when compared to lutein, zeaxanthin and astaxanthin. The xanthophyll b-cryptoxanthin was also not significantly different when compared to the carotene carotenoids. Data generated from this study compares well with in vivo bioavailability studies. Furthermore, the model provides comparative data on the relative absorption and transfer of seven different carotenoids. Our data indicate that lower amounts of carotenoids were absorbed and transferred more efficiently than higher amounts suggesting a saturation effect at higher exposure.

Cell Culture Model for Examining Fat-Soluble Nutrient Absorption <i>In Vitro</i>

“…The reported absorption rate of micellized lutein in Caco-2 cells on PS range from 7-41% [28,35,36,37]. In our experiments, the percentage of lutein dose in the cell lysates ranged from 18-36% and in the basolateral medium ranged from 0-10%, values that are similar to those previously reported.…”

Comparison of tetrahydrofuran, fetal calf serum, and Tween 40 for the delivery of astaxanthin and canthaxanthin to HepG2 cells

“…Lin et al (2007) reported a better uptake of lycopene into DU145 prostate cancer cells from FCS-compared to THF-supplemented media. Lipoproteins appear to play an important role in the cellular uptake of carotenoids (During and Harrison 2007;O'Sullivan et al 2007). The involvement of the scavenger receptor class B type I (SR-BI) in carotenoid uptake has been demonstrated (van Bennekum et al 2005;During and Harrison 2007).…”

“…For the FCS version, which was prepared according to Lin et al (2007) carotenoid stock aliquots were added to FCS in a tenfold higher concentration than desired, mixed and added to FCS free medium. As a third delivery vehicle, Tween 40 was used as described by O'Sullivan et al (2004O'Sullivan et al ( , 2007. Briefly, aliquots of the THF stock solution were concentrated at room temperature in a Jouan RC 10-10 centrifugal evaporator (Saint Herblain, France) and re-dissolved in identical volumes of Tween 40 (200 mL Tween 40 diluted in 1 L acetone).…”

“…Two hundred lL cell suspension or cell culture medium was extracted twice with 1 mL hexane-ethanol-acetone (50:25:25, by volume) (Olives Barba et al 2006;O'Sullivan et al 2007). To prevent oxidation of carotenoids during extraction, the antioxidants BHT and ascorbic acid (AA; 160 mg/mL), respectively, were added to n-hexane and acetone, respectively.…”

“…However, the delivery of carotenoids into cells in culture is impeded by the fact that they are, due to their sensitivity toward light and heat, instable as well as poorly soluble in aqueous solutions. Tetrahydrofuran (THF), a commonly used solvent for carotenoid delivery in cell culture, oxidizes readily in culture media, which may lead to instability of test compounds and result in cytotoxicity (Xu et al 1999;Williams et al 2000;Shahrzad et al 2002;Hurst et al 2004;O'Sullivan et al 2007). Therefore, attempts have been made to improve carotenoid delivery by using vehicles other than THF, including dimethyl sulfoxide, cyclodextrin, lipoproteins, micelles and beadlets (Martin et al 1996;Stivala et al 1996;Garrett et al 1999;Pfitzner et al 2000;Lancrajan et al 2001;Vertzoni et al 2006).…”