Search

The current study aimed to characterize the transport kinetics of retinol in fully differentiated human immortalized keratinocyte cells (HaCaT) cultured in trans-well with high-calcium media by measuring the cell integrity of skin barriers, time and concentration dependent transport of retinol, and its metabolites. 25 to 200 µg/mL retinol treatment did not show any significant cytotoxicity in HaCaT. The expression of epidermal differentiation related genes including Keratin 1 (KRT1), Keratin 10 (KRT10), and Involucrin (IVL) significantly increased in HaCaT cells cultured with high-calcium media (2.8 mM) compared to low calcium (0.03 mM). There was no significant decrease in TEER value after incubating retinol (10 to 100 µg/mL) compared to control (p > 0.05), indicating that retinol tends to maintain strength and integrity of the epidermal barrier. The maximum epidermal migration of retinol from apical to basal media occurred from incubation of 75 µg/mL retinol, indicating that it was not concentration dependent. The area under the curve (AUC) of mAU*min for the unknown peak found in basal media for 600 min increased in a concentration dependent pattern, showing 10.23 ± 0.16 and 72.73 ± 30.86 at 10 and 100 µg/mL of retinol treated in apical, respectively. The metabolite having a precursor ion (m/z 325.83 [M + H + Na]+) in the spectrum was identified as a retinoic acid (m/z 301.3 [M + H]+) with sodium adduct. Results from the current study suggest that optimal concentration of retinol and treatment time in human keratinocytes could enhance the conversion of retinol to retinoic acid, promoting dermatological use of retinol.

Previous reports on phytochemicals in green tea (GT) and processed teas mainly focused on more representative compounds such as catechins. Here, we focus on the insignificantly studied non-catechin components in tea extracts, and explore the multivariate correlation between diverse phenolic compounds in tea and the in vitro antioxidant and anticancer effects. Extracts from GT and four types of processed teas were further divided into hydrophilic and hydrophobic fractions, whose phenolic compositions and antioxidant capacities were quantified using HPLC-MS and three antioxidant assays, respectively. For three types of teas, the anticancer effects of their extracts and fractions were assessed using cancer cell lines. The hydrophobic fractions had lower antioxidant capacities than the corresponding hydrophilic fractions, but exhibited superior antiproliferative effects on cancer cells compared with the whole extract and the hydrophilic fraction. Partial least squares-discriminant analysis revealed a strong correlation between the anticancer effects and the theaflavins and flavonols. Therefore, in addition to catechins, the hydrophobic fraction of tea extracts may have beneficial health effects.