Epidemiological evidence suggests that dietary intake of carotenoids and tocopherols may influence the risk of certain chronic diseases, such as cancer and CVD. In vitro studies investigating the synergistic effects of mixtures of carotenoids and tocopherols have been hindered due to the difficulty of solubilising these lipophilic compounds. The objective of the present study was to develop a system for delivering tocopherols and carotenoids simultaneously to cells in culture. Differentiated human colonic adenocarcinoma cells (CaCo-2) were incubated with a mixture of these phytochemicals for 24 h. The phytochemical mixture included carotenoids (astaxanthin, canthaxanthin, lutein, lycopene, α-carotene, β-carotene) and tocopherols (α-tocopherol and γ-tocopherol). The emulsifiers polyoxyethylene sorbitan monopalmitate (Tween 40) and polyoxyethylene sorbitan monooleate (Tween 80) were employed as the delivery vehicles, and were compared with tetrahydrofuran (THF). Each vehicle was added at a maximum concentration of 1 ml/l. No toxic effects to the CaCo-2 cells were noted when Tween 40 or Tween 80 were used. Both Tween 40 and Tween 80 resulted in greater solubility of the mixture and delivered substantially more carotenoids and tocopherols to the cells than THF. In particular, lycopene was detected within the cells when Tween 40 and Tween 80 were employed, whereas it was below the limits of detection by HPLC when THF was used as the delivery vehicle. The phytochemicals were retained within the cells for 24 h after supplementation. Tween 40 and Tween 80 have potential as simple, rapid and non-toxic methods for delivering mixtures of carotenoids and tocopherols to cells in culture.

Limonoids such as deoxylimonin, obacunone and pedoniti are known to have antifeedant effects against some lepidopteran pests. However, there is no electrophysiological data showing the effect these compounds have on taste receptor cells. This information gap is due to the fact that limonoids are insoluble in water and this makes it difficult to apply the tip-recording technique in an electrophysiological bioassay of limonoids. This problem was solved by dissolving the limonoids in a mixture of 50 % tetrahydrof uran and 50 % aqueous NaCl. Limonoids and sucrose so dissolved were used to investigate responses of Eldana saccharina maxillary styloconic sensilla. The solvent mixture did not appear to damage the taste receptor cells and the taste receptor responses to solutes dissolved in that solvent were reproducible. Sucrose stimulated a cell in the medial as well as in the lateral styloconic sensilla. Deoxylimonin alone stimulated a cell in the medial sensillum but not in the lateral sensillum. When presented with sucrose, deoxylimonin inhibited the sugar receptor cell and this was also true for obacunone.