Carotenoids are useful oral sun protectants, and supplementation with high doses of beta-carotene protects against UV-induced erythema formation. We compared the erythema-protective effect of beta-carotene (24 mg/d from an algal source) to that of 24 mg/d of a carotenoid mix consisting of the three main dietary carotenoids, beta-carotene, lutein and lycopene (8 mg/d each). In a placebo-controlled, parallel study design, volunteers with skin type II (n = 12 in each group) received beta-carotene, the carotenoid mix or placebo for 12 wk. Carotenoid levels in serum and skin (palm of the hand), as well as erythema intensity before and 24 h after irradiation with a solar light simulator were measured at baseline and after 6 and 12 wk of treatment. Serum beta-carotene concentration increased three- to fourfold (P < 0.001) in the beta-carotene group, whereas in the mixed carotenoid group, the serum concentration of each of the three carotenoids increased one- to threefold (P < 0.001). No changes occurred in the control group. The intake of either beta-carotene or a mixture of carotenoids similarly increased total carotenoids in skin from wk 0 to wk 12. No changes in total carotenoids in skin occurred in the control group. The intensity of erythema 24 h after irradiation was diminished in both groups that received carotenoids and was significantly lower than baseline after 12 wk of supplementation. Long-term supplementation for 12 wk with 24 mg/d of a carotenoid mix supplying similar amounts of beta-carotene, lutein and lycopene ameliorates UV-induced erythema in humans; the effect is comparable to daily treatment with 24 mg of beta-carotene alone.

Carotenoids are efficient antioxidants capable of scavenging reactive oxygen species generated under conditions of photooxidative stress. It has been shown that supplementation with high doses of beta-carotene protects skin against UV-induced erythema. This study was designed to investigate whether intervention with a natural dietary source rich in lycopene protects against UV-induced erythema in humans. Tomato paste (40 g), providing approximately 16 mg/d of lycopene, was ingested with 10 g of olive oil over a period of 10 wk by 9 volunteers. Controls (n = 10) received olive oil only. Erythema was induced by illumination of dorsal skin (scapular region) with a solar simulator at the beginning of the study, after 4 wk and after 10 wk. Intensity of erythema was measured by chromatometry; the a-value was determined directly before and 24 h after irradiation. Serum carotenoid levels were measured by HPLC. At the beginning of the study, carotenoid levels did not differ between the two groups. Serum levels of lycopene increased in supplemented subjects; the other carotenoids did not change significantly, and no change in serum carotenoids was observed in the control group. At wk 10, dorsal erythema formation was 40% lower in the group that consumed tomato paste compared with controls (P = 0.02; Wilcoxon-Mann-Whitney test). No significant difference between groups was found at wk 4 of treatment. The data demonstrate that it is feasible to achieve protection against UV light-induced erythema by ingestion of a commonly consumed dietary source of lycopene.

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In various cell types, the neuro-and endocrine peptide somatostatin induces inhibitory and anti-secretory effects. Since somatostatin receptors, especially of the subtype sst2A, are constantly over-expressed in gliomas, we investigated the influence of somatostatin and the receptor subtype-selective peptide/non-peptide agonists octreotide and L-054,522 on the secretion of the most important angiogenesis factor produced by gliomas, vascular endothelial growth factor (VEGF). Cultivated cells from solid human gliomas of different stages and glioma cell lines secreted variable amounts of VEGF, which could be lowered to 25% to 80% by co-incubation with somatostatin or sst2-selective agonists (octreotide and L-054,522). These effects were dose-dependent at nanomolar concentrations. Stimulation with different growth factors (EGF, bFGF) or hypoxia considerably increased VEGF production over basal levels. Growth factorinduced VEGF synthesis could be suppressed to <50% by co-incubation with somatostatin or an sst2-selective agonist; this was less pronounced in hypoxia-induced VEGF synthesis. The effects were detected at the protein and mRNA levels. These experiments indicate a potent anti-secretory action of somatostatin or sst2 agonists on human glioma cells that may be useful for inhibiting angiogenesis in these tumors.

Exposure of living organisms to UV light leads to photooxidative reactions. Peroxyl radicals are involved in the propagation of lipid peroxidation. Carotenoids are dietary antioxidants and show photoprotective effects in human skin, efficiently scavenging peroxyl radicals and inhibiting lipid peroxidation. Cultured human skin fibroblasts were used to examine the protective effects of the carotenoids, lycopene, beta-carotene and lutein on UVB-induced lipid peroxidation. The carotenoids were delivered to the cells using liposomes as the vehicle. The cells were exposed to UVB light for 20 min. Lycopene, beta-carotene and lutein were capable of decreasing UV-induced formation of thiobarbituric acid-reactive substances at 1 h to levels 40-50% of controls free of carotenoids. The amounts of carotenoid needed for optimal protection were divergent at 0.05, 0.40 and 0.30 nmol/mg protein for lycopene, beta-carotene and lutein, respectively. Beyond the optimum levels, further increases of carotenoid levels in cells led to prooxidant effects.