Modified saponification and HPLC methods for analyzing carotenoids from the retina of quail: Implications for its use as a nonprimate model species

Matthew B. Toomey, Kevin McGraw

Research output: Contribution to journalArticle

27 Citations (Scopus)

Abstract

PURPOSE. To investigate carotenoid content in the retina of Japanese quail (Coturnix japonica), for comparison with carotenoids in human retina, and to assess the effects of different saponification procedures on the recovery of quail retinal carotenoids. METHODS. Extracted retinal carotenoids were saponified with methods adapted from recent studies, then identified and quantified with reverse-phase high-performance liquid chromatography (HPLC). To assess the effects of saponification conditions on carotenoid recovery from quail retina, we varied base concentration and the total time of saponification across a wide range and again used HPLC to compare carotenoid concentrations among conditions. RESULTS. Astaxanthin and galloxanthin were the dominant carotenoids recovered in the quail retina, along with smaller amounts of five other carotenoids (lutein, zeaxanthin, 3′-epilutein, ε-carotene, and an unidentified carotenoid). Astaxanthin was sensitive to saponification conditions; recovery was poor with strong bases (0.2 and 0.5 M KOH) and best with weak bases (0.01 and 0.2 M KOH). In contrast, xanthophyll carotenoids (galloxanthin, zeaxanthin, lutein, 3′-epilutein, and the unknown) were best recovered with strong base after 6 hours of saponification at room temperature. The recovery of ε-carotene was not affected by saponification conditions. CONCLUSIONS. Separate chemical hydrolysis procedures - using a strong base to recover xanthophylls and a weak base to recover astaxanthin - should be used for maximizing recovery of quail retinal carotenoids. Because the dominant carotenoids in quail retina are absent in human retina, and because of their different packaging (e.g., esterified in oil droplets) and light-absorbance properties compared with xanthophylls in the human eye, use of the quail as a model organism for studying human retinal carotenoids should be approached with caution.

Original languageEnglish (US)
Pages (from-to)3976-3982
Number of pages7
JournalInvestigative Ophthalmology and Visual Science
Volume48
Issue number9
DOIs
StatePublished - Sep 2007

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Quail
Carotenoids
Retina
High Pressure Liquid Chromatography
Xanthophylls
Lutein
Coturnix
Product Packaging
Reverse-Phase Chromatography
Oils
Hydrolysis

ASJC Scopus subject areas

  • Ophthalmology

Cite this

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title = "Modified saponification and HPLC methods for analyzing carotenoids from the retina of quail: Implications for its use as a nonprimate model species",
abstract = "PURPOSE. To investigate carotenoid content in the retina of Japanese quail (Coturnix japonica), for comparison with carotenoids in human retina, and to assess the effects of different saponification procedures on the recovery of quail retinal carotenoids. METHODS. Extracted retinal carotenoids were saponified with methods adapted from recent studies, then identified and quantified with reverse-phase high-performance liquid chromatography (HPLC). To assess the effects of saponification conditions on carotenoid recovery from quail retina, we varied base concentration and the total time of saponification across a wide range and again used HPLC to compare carotenoid concentrations among conditions. RESULTS. Astaxanthin and galloxanthin were the dominant carotenoids recovered in the quail retina, along with smaller amounts of five other carotenoids (lutein, zeaxanthin, 3′-epilutein, ε-carotene, and an unidentified carotenoid). Astaxanthin was sensitive to saponification conditions; recovery was poor with strong bases (0.2 and 0.5 M KOH) and best with weak bases (0.01 and 0.2 M KOH). In contrast, xanthophyll carotenoids (galloxanthin, zeaxanthin, lutein, 3′-epilutein, and the unknown) were best recovered with strong base after 6 hours of saponification at room temperature. The recovery of ε-carotene was not affected by saponification conditions. CONCLUSIONS. Separate chemical hydrolysis procedures - using a strong base to recover xanthophylls and a weak base to recover astaxanthin - should be used for maximizing recovery of quail retinal carotenoids. Because the dominant carotenoids in quail retina are absent in human retina, and because of their different packaging (e.g., esterified in oil droplets) and light-absorbance properties compared with xanthophylls in the human eye, use of the quail as a model organism for studying human retinal carotenoids should be approached with caution.",
author = "Toomey, {Matthew B.} and Kevin McGraw",
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T1 - Modified saponification and HPLC methods for analyzing carotenoids from the retina of quail

T2 - Implications for its use as a nonprimate model species

AU - Toomey, Matthew B.

AU - McGraw, Kevin

PY - 2007/9

Y1 - 2007/9

N2 - PURPOSE. To investigate carotenoid content in the retina of Japanese quail (Coturnix japonica), for comparison with carotenoids in human retina, and to assess the effects of different saponification procedures on the recovery of quail retinal carotenoids. METHODS. Extracted retinal carotenoids were saponified with methods adapted from recent studies, then identified and quantified with reverse-phase high-performance liquid chromatography (HPLC). To assess the effects of saponification conditions on carotenoid recovery from quail retina, we varied base concentration and the total time of saponification across a wide range and again used HPLC to compare carotenoid concentrations among conditions. RESULTS. Astaxanthin and galloxanthin were the dominant carotenoids recovered in the quail retina, along with smaller amounts of five other carotenoids (lutein, zeaxanthin, 3′-epilutein, ε-carotene, and an unidentified carotenoid). Astaxanthin was sensitive to saponification conditions; recovery was poor with strong bases (0.2 and 0.5 M KOH) and best with weak bases (0.01 and 0.2 M KOH). In contrast, xanthophyll carotenoids (galloxanthin, zeaxanthin, lutein, 3′-epilutein, and the unknown) were best recovered with strong base after 6 hours of saponification at room temperature. The recovery of ε-carotene was not affected by saponification conditions. CONCLUSIONS. Separate chemical hydrolysis procedures - using a strong base to recover xanthophylls and a weak base to recover astaxanthin - should be used for maximizing recovery of quail retinal carotenoids. Because the dominant carotenoids in quail retina are absent in human retina, and because of their different packaging (e.g., esterified in oil droplets) and light-absorbance properties compared with xanthophylls in the human eye, use of the quail as a model organism for studying human retinal carotenoids should be approached with caution.

AB - PURPOSE. To investigate carotenoid content in the retina of Japanese quail (Coturnix japonica), for comparison with carotenoids in human retina, and to assess the effects of different saponification procedures on the recovery of quail retinal carotenoids. METHODS. Extracted retinal carotenoids were saponified with methods adapted from recent studies, then identified and quantified with reverse-phase high-performance liquid chromatography (HPLC). To assess the effects of saponification conditions on carotenoid recovery from quail retina, we varied base concentration and the total time of saponification across a wide range and again used HPLC to compare carotenoid concentrations among conditions. RESULTS. Astaxanthin and galloxanthin were the dominant carotenoids recovered in the quail retina, along with smaller amounts of five other carotenoids (lutein, zeaxanthin, 3′-epilutein, ε-carotene, and an unidentified carotenoid). Astaxanthin was sensitive to saponification conditions; recovery was poor with strong bases (0.2 and 0.5 M KOH) and best with weak bases (0.01 and 0.2 M KOH). In contrast, xanthophyll carotenoids (galloxanthin, zeaxanthin, lutein, 3′-epilutein, and the unknown) were best recovered with strong base after 6 hours of saponification at room temperature. The recovery of ε-carotene was not affected by saponification conditions. CONCLUSIONS. Separate chemical hydrolysis procedures - using a strong base to recover xanthophylls and a weak base to recover astaxanthin - should be used for maximizing recovery of quail retinal carotenoids. Because the dominant carotenoids in quail retina are absent in human retina, and because of their different packaging (e.g., esterified in oil droplets) and light-absorbance properties compared with xanthophylls in the human eye, use of the quail as a model organism for studying human retinal carotenoids should be approached with caution.

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