... Zoologisches Institut der JW Goethe Universit/it Frankfurt, Siesmayerstraf3e 70, D-6000 Frank... more ... Zoologisches Institut der JW Goethe Universit/it Frankfurt, Siesmayerstraf3e 70, D-6000 Frankfurt, Federal Republic of Germany 1 University of London, Chelsea College, Department of ... J Neural Transm 58:281-289 Semm P, Schneider T, Vollrath L, Wiltschko W (1982) Magnet-...
Catechins in testa and bioactive compounds in testa-free and testa-containing kernels of cashew n... more Catechins in testa and bioactive compounds in testa-free and testa-containing kernels of cashew nuts were analysed. The cashew nut testa contained (+)-catechin and (À)-epicatechin with concentrations of 5.70 and 4.46 g per kg DM, respectively. Testa-containing kernels revealed significantly higher levels of b-carotene (218 vs. 89.6 lg/kg DM), lutein (525 vs. 292 lg/kg DM), and a-tocopherol (10.1 vs. 2.4 mg/kg DM), similar amounts of zeaxanthin (7.0 vs. 7.1 lg/kg DM), c-tocopherol (10.6 vs. 10.1 mg/kg DM), stearic acid (41 vs.
PURPOSE. Vitamin A is essential for vision. The key step in the vitamin A biosynthetic pathway is... more PURPOSE. Vitamin A is essential for vision. The key step in the vitamin A biosynthetic pathway is the oxidative cleavage of -carotene into retinal by the enzyme ,-carotene-15,15Јmonooxygenase (BCO). The purpose of the study was to investigate -carotene metabolism and its effects on BCO expression in the human retinal pigment epithelial (RPE) cell line D407. METHODS. BCO mRNA and protein expression were analyzed by real-time quantitative PCR and Western blot analysis, respectively. BCO activity was assayed in protein extracts isolated from D407 cells. The conversion of -carotene to retinoids was determined by measuring retinol levels in D407 cells on -carotene supplementation. RESULTS. By RT-PCR, BCO mRNA was detected in D407 cells, bovine RPE, and retina. Western blot analyses revealed the presence of BCO at the protein level in D407 cells. Exogenous -carotene application to D407 cells resulted in a concentration (75% at 0.5 M and 96% at 5 M; P Ͻ 0.05)-and time (127% at 2 hours and 97% at 4 hours in 5 M -carotene, P Ͻ 0.05)-dependent upregulation of BCO mRNA expression. Application of exogenous retinoic acid downregulated BCO mRNA levels at higher concentrations (1 M; Ϫ96%, P Ͻ 0.0005) and upregulated it at a lower concentration (0.01 M; 399%, P Ͻ 0.005). The RAR-a-specific antagonist upregulated BCO expression by sixfold (P Ͻ 0.005). Tests for enzymatic activity demonstrated that the mRNA upregulation resulted in enzymatically active BCO protein (7.3 ng all-trans-retinal/h per milligram of protein). Furthermore, D407 cells took up -carotene in a time-dependent manner and converted it to retinol. CONCLUSIONS. The results suggest that BCO is expressed in the RPE and that -carotene can be metabolized into retinol. -Carotene cleavage in the RPE may be an alternative pathway that would ensure the retinoid supply of photoreceptor cells. (Invest Ophthalmol Vis Sci. 2005;46:3562-3569) essential role in the retinoid metabolism of the eyes. We demonstrated BCO mRNA, protein, and enzyme activity in the human RPE cell line D407. Application of exogenous -carotene to D407 cells resulted in an upregulation of BCO mRNA and protein levels, accompanied by a conversion of -carotene to retinoids. Together, our analyses suggest that -carotene cleavage, via BCO in the RPE, contributes to the function and survival of the adjacent photoreceptor cells.
This study aimed to investigate the effect of air drying parameters such as temperature, specific... more This study aimed to investigate the effect of air drying parameters such as temperature, specific humidity and velocity, on non-enzymatic browning behaviour and on bio-active compounds and antioxidant properties of osmotically pretreated papayas. Convection drying was conducted under through-flow mode at four temperatures (50, 60, 70, 80 C), three air velocities (0.2, 0.5, 0.7 m/s) and two specific humidity levels (10, 25 g/kg dry air). Higher drying temperatures resulted in a significant decrease in moisture content and polyphenol oxidase activity, while degree of browning and 5-hydroxymethylfurfural increased. The antioxidant activity and total phenolic compounds increased with temperature and as well with decreasing air velocity. In contrast, specific humidity did not have a major effect on quality attributes of dried samples, except for carotenoid contents. This study has shown that drying parameters can decompose and/or enhance carotenoids contents in dried papayas. To obtain the product with highest level of bio-active compounds and lowest possible melanoid formation, treatment with temperature of 70 C, specific humidity of 10 g/kg dry air and velocity of 0.2 m/s proved to be the most suitable option. Based on these results, optimization of the process, particularly drying temperature, should be considered with respect to preserving product colour and biochemical properties.
... Zoologisches Institut der JW Goethe Universit/it Frankfurt, Siesmayerstraf3e 70, D-6000 Frank... more ... Zoologisches Institut der JW Goethe Universit/it Frankfurt, Siesmayerstraf3e 70, D-6000 Frankfurt, Federal Republic of Germany 1 University of London, Chelsea College, Department of ... J Neural Transm 58:281-289 Semm P, Schneider T, Vollrath L, Wiltschko W (1982) Magnet-...
Catechins in testa and bioactive compounds in testa-free and testa-containing kernels of cashew n... more Catechins in testa and bioactive compounds in testa-free and testa-containing kernels of cashew nuts were analysed. The cashew nut testa contained (+)-catechin and (À)-epicatechin with concentrations of 5.70 and 4.46 g per kg DM, respectively. Testa-containing kernels revealed significantly higher levels of b-carotene (218 vs. 89.6 lg/kg DM), lutein (525 vs. 292 lg/kg DM), and a-tocopherol (10.1 vs. 2.4 mg/kg DM), similar amounts of zeaxanthin (7.0 vs. 7.1 lg/kg DM), c-tocopherol (10.6 vs. 10.1 mg/kg DM), stearic acid (41 vs.
PURPOSE. Vitamin A is essential for vision. The key step in the vitamin A biosynthetic pathway is... more PURPOSE. Vitamin A is essential for vision. The key step in the vitamin A biosynthetic pathway is the oxidative cleavage of -carotene into retinal by the enzyme ,-carotene-15,15Јmonooxygenase (BCO). The purpose of the study was to investigate -carotene metabolism and its effects on BCO expression in the human retinal pigment epithelial (RPE) cell line D407. METHODS. BCO mRNA and protein expression were analyzed by real-time quantitative PCR and Western blot analysis, respectively. BCO activity was assayed in protein extracts isolated from D407 cells. The conversion of -carotene to retinoids was determined by measuring retinol levels in D407 cells on -carotene supplementation. RESULTS. By RT-PCR, BCO mRNA was detected in D407 cells, bovine RPE, and retina. Western blot analyses revealed the presence of BCO at the protein level in D407 cells. Exogenous -carotene application to D407 cells resulted in a concentration (75% at 0.5 M and 96% at 5 M; P Ͻ 0.05)-and time (127% at 2 hours and 97% at 4 hours in 5 M -carotene, P Ͻ 0.05)-dependent upregulation of BCO mRNA expression. Application of exogenous retinoic acid downregulated BCO mRNA levels at higher concentrations (1 M; Ϫ96%, P Ͻ 0.0005) and upregulated it at a lower concentration (0.01 M; 399%, P Ͻ 0.005). The RAR-a-specific antagonist upregulated BCO expression by sixfold (P Ͻ 0.005). Tests for enzymatic activity demonstrated that the mRNA upregulation resulted in enzymatically active BCO protein (7.3 ng all-trans-retinal/h per milligram of protein). Furthermore, D407 cells took up -carotene in a time-dependent manner and converted it to retinol. CONCLUSIONS. The results suggest that BCO is expressed in the RPE and that -carotene can be metabolized into retinol. -Carotene cleavage in the RPE may be an alternative pathway that would ensure the retinoid supply of photoreceptor cells. (Invest Ophthalmol Vis Sci. 2005;46:3562-3569) essential role in the retinoid metabolism of the eyes. We demonstrated BCO mRNA, protein, and enzyme activity in the human RPE cell line D407. Application of exogenous -carotene to D407 cells resulted in an upregulation of BCO mRNA and protein levels, accompanied by a conversion of -carotene to retinoids. Together, our analyses suggest that -carotene cleavage, via BCO in the RPE, contributes to the function and survival of the adjacent photoreceptor cells.
This study aimed to investigate the effect of air drying parameters such as temperature, specific... more This study aimed to investigate the effect of air drying parameters such as temperature, specific humidity and velocity, on non-enzymatic browning behaviour and on bio-active compounds and antioxidant properties of osmotically pretreated papayas. Convection drying was conducted under through-flow mode at four temperatures (50, 60, 70, 80 C), three air velocities (0.2, 0.5, 0.7 m/s) and two specific humidity levels (10, 25 g/kg dry air). Higher drying temperatures resulted in a significant decrease in moisture content and polyphenol oxidase activity, while degree of browning and 5-hydroxymethylfurfural increased. The antioxidant activity and total phenolic compounds increased with temperature and as well with decreasing air velocity. In contrast, specific humidity did not have a major effect on quality attributes of dried samples, except for carotenoid contents. This study has shown that drying parameters can decompose and/or enhance carotenoids contents in dried papayas. To obtain the product with highest level of bio-active compounds and lowest possible melanoid formation, treatment with temperature of 70 C, specific humidity of 10 g/kg dry air and velocity of 0.2 m/s proved to be the most suitable option. Based on these results, optimization of the process, particularly drying temperature, should be considered with respect to preserving product colour and biochemical properties.
Uploads
Papers by Donatus Nohr