Recent epidemiological studies have suggested that the consumption of tomatoes and tomato-based food products reduce the risk of prostate cancer in humans. This protective effect has been attributed to carotenoids, which are one of the major classes of phytochemicals in this fruit. The most abundant carotenoid in tomato is lycopene, followed by phytoene, phytofluene, zeta-carotene, gamma-carotene, beta-carotene, neurosporene, and lutein. The distribution of lycopene and related carotenoids in tomatoes and tomato-based food products has been determined by extraction and high-performance liquid chromatography-UV/Visible photodiode array detection. Detailed qualitative and quantitative analysis of human serum, milk, and organs, particularly prostate, have revealed the presence of all the aforementioned carotenoids in biologically significant concentrations. Two oxidative metabolites of lycopene, 2,6-cyclolycopene-1,5-diols A and B, which are only present in tomatoes in extremely low concentrations, have been isolated and identified in human serum, milk, organs (liver, lung, breast, liver, prostate, colon) and skin. Carotenoids may also play an important role in the prevention of age-related macular degeneration, cataracts, and other blinding disorders. Among 25 dietary carotenoids and nine metabolites routinely found in human serum, mainly (3R,3'R,6'R)-lutein, (3R,3'R)-zeaxanthin, lycopene, and their metabolites were detected in ocular tissues. In this review we identified and quantified the complete spectrum of carotenoids from pooled human retinal pigment epithelium, ciliary body, iris, lens, and in the uveal tract and in other tissues of the human eye to gain a better insight into the metabolic pathways of ocular carotenoids. Although (3R,3'R,6'R)-lutein, (3R,3'R)-zeaxanthin, and their metabolites constitute the major carotenoids in human ocular tissues, lycopene and a wide range of dietary carotenoids have been detected in high concentrations in ciliary body and retinal pigment epithelium. The possible role of lycopene and other dietary carotenoids in the prevention of age-related macular degeneration and other eye diseases is discussed.

No abstract

Purpose-Dietary carotenoids lutein and zeaxanthin may play a protective role against visual loss from age-related macular degeneration (AMD) through antioxidant and light screening mechanisms. We used a novel noninvasive objective method to quantify lutein and zeaxanthin in the human macula using resonance Raman spectroscopy and compared macular pigment levels in AMD and normal subjects. Design-Observational study of an ophthalmology clinic-based population.Participants and Controls-Ninety-three AMD eyes from 63 patients and 220 normal eyes from 138 subjects.Methods-Macular carotenoid levels were quantified by illuminating the macula with a lowpower argon laser spot and measuring Raman backscattered light using a spectrograph. This technique is sensitive, specific, and repeatable even in subjects with significant macular pathologic features.Main Outcome Measure-Raman signal intensity at 1525 cm −1 generated by the carboncarbon double-bond vibrations of lutein and zeaxanthin.Results-Carotenoid Raman signal intensity declined with age in normal eyes (P < 0.001). Average levels of lutein and zeaxanthin were 32% lower in AMD eyes versus normal elderly control eyes as long as the subjects were not consuming high-dose lutein supplements (P = 0.001). Patients who had begun to consume supplements containing high doses of lutein (≥4 mg/day) regularly after their initial diagnosis of AMD had average macular pigment levels that were in the normal range (P = 0.829) and that were significantly higher than in AMD patients not consuming these supplements (P = 0.038).Conclusions-These findings are consistent with the hypothesis that low levels of lutein and zeaxanthin in the human macula may represent a pathogenic risk factor for the development of Correspondence and reprint requests to Paul S. Bernstein, MD, PhD, Moran Eye Center, University of Utah School of Medicine, 50 North Medical Drive, Salt Lake City, UT 84132. paul.bernstein@hsc.utah.edu. Three authors (PSB, RWM, and WG) and the University of Utah hold patent rights to the ocular Raman technology described in this article, and these authors and the university own significant equity interests in Spectrotek, LC, a company that has licensed the technology.Presented in part as a poster at the annual meeting of the American Academy of Ophthalmology, New Orleans, Louisiana, November 2001. A major epidemiologic study found that high dietary intakes and blood levels of these xanthophyll carotenoids are correlated with a significantly lower risk of AMD, 12,13 but another study did not reach the same conclusion. 14 These inconsistent findings derive in part from the fact that blood levels and dietary intakes of lutein and zeaxanthin are relatively poor markers of the actual amounts present in the macula. 15 Clearly, it is of utmost importance to know the levels of lutein and zeaxanthin at their relevant site of action, the human macula. Recently, an autopsy study has reported that eyes from donors with a history of AMD had lower levels of macular carotenoids than eyes wi...

We have used resonant Raman scattering spectroscopy as a novel, noninvasive, in vivo optical technique to measure the concentration of the macular carotenoid pigments lutein and zeaxanthin in the living human retina of young and elderly adults. Using a backscattering geometry and resonant molecular excitation in the visible wavelength range, we measure the Raman signals originating from the single- and double-bond stretch vibrations of the pi-conjugated molecule's carbon backbone. The Raman signals scale linearly with carotenoid content, and the required laser excitation is well below safety limits for macular exposure. Furthermore, the signals decline significantly with increasing age in normal eyes. The Raman technique is objective and quantitative and may lead to a new method for rapid screening of carotenoid pigment levels in large populations at risk for vision loss from age-related macular degeneration, the leading cause of blindness in the elderly in the United States.

No abstract

As in humans and monkeys, lutein [(3R,3′R,6′R)-βε, -carotene-3,3′-diol] and zeaxanthin [a mixture of (3R,3′R)-β,β-carotene-3,3′diol and (3R,3′S-meso)-β,β-carotene-3,3′-diol] are found in substantial amounts in the retina of the Japanese quail Coturnix japonica. This makes the quail retina an excellent non-primate small animal model for studying the metabolic transformations of these important macular carotenoids that are thought to play an integral role in protection against light-induced oxidative damage such as that found in age-related macular degeneration (AMD). In this study, we first identified the array of carotenoids present in the quail retina using C30-HPLC coupled with inline mass-spectral and photodiode-array detectors. In addition to dietary lutein (2.1%) and zeaxanthin (11.8%), we identified adonirubin (5.4%), 3′-oxolutein (3.8%), meso-zeaxanthin (3.0%), astaxanthin (28.2%), galloxanthin (12.2%), ε,ε-carotene (18.5%), and β-apo-2′-carotenol (9.5%) as major ocular carotenoids. We next used deuterium-labeled lutein and zeaxanthin as dietary supplements to study the pharmacokinetics and metabolic transformations of these two ocular pigments in serum and ocular tissues. We then detected and quantitated labeled carotenoids in ocular tissue using both HPLC-coupled mass spectrometry and non-invasive resonance Raman spectroscopy. Results indicated that dietary zeaxanthin is the precursor of 3′-oxolutein, β-apo-2′-carotenol, adonirubin, astaxanthin, galloxanthin, and ε, ε-carotene, whereas dietary lutein is the precursor for mesozeaxanthin. Studies also revealed that the pharmacokinetic patterns of uptake, carotenoid absorption, and transport from serum into ocular tissues were similar to results observed in most human clinical studies. KeywordsCarotenoid; Retina; Japanese quail; Lutein; Zeaxanthin; HPLC; APCI-MS Epidemiological and clinical studies in humans have generally demonstrated that there is an inverse relationship between nutritional consumption of antioxidants and prevalence of old age ocular disorders such as age-related macular degeneration (AMD) and cataract (1,2). The carotenoids lutein and zeaxanthin are notable examples because they are specifically concentrated in ocular tissues at high concentrations, and they are excellent absorbers of phototoxic blue light and reactive oxygen species (3,4). Studies using data from the Eye Disease Case Control (EDCC) Study Group have demonstrated that individuals with high blood levels of lutein and zeaxanthin and high consumption of foods rich in these same carotenoids had significantly lower risk of exudative AMD, and several follow up studies including the Age- † This work was supported by National Institute of Health Grant EY-11600 and by Research to Prevent Blindness, Inc. (New York, NY). In the human retina, dietary lutein [(3R,3′R,6′R)-β,ε-carotene-3,3′-diol] and zeaxanthin [(3R, 3′R)-β,β-carotene-3,3′-diol] are unevenly distributed in the retina, with millimolar concentrations found at the fovea with a lutein:zeaxanthin ratio of 1:2 and a...

The presence of unusually high levels of macular carotenoids in older donors who were regularly consuming high-dose lutein supplements supports the hypothesis that long-term lutein supplementation can raise levels of macular pigment. Elevated carotenoid levels in the peripheral retina and lens in these same donors could have important implications for understanding why some clinical methods of macular pigment measurement have had difficulty detecting robust and consistent responses in carotenoid supplementation trials.

We describe resonance Raman imaging (RRI) of macular pigment (MP) distributions in the living human eye. MP consists of the antioxidant carotenoid compounds lutein and zeaxanthin, is typically present in high concentrations in the healthy human macula relative to the peripheral retina, and is thought to protect this important central region from age-related macular degeneration. We demonstrate that RRI is capable of quantifying and imaging the spatially strongly varying MP distribution in the human retina. Using laser excitation of the MP molecules at 488 nm, and sequential camera detection of light emitted back from the retina at the MP's strongest Raman peak position and at an off-peak position, RRI maps of MP are obtained at a resolution below 50 μm within a fraction of a second per exposure. RRI imaging can be carried out with undilated pupils and provides a highly molecule-specific diagnostic imaging approach for MP distributions in human subjects.