Department of Chemistry, University of Connecticut, 55 North Eagleville Road, Storrs, CT 06269-3060, USA.
Arch Biochem Biophys. 2010 Dec 1;504(1):142-53. doi: 10.1016/j.abb.2010.08.006. Epub 2010 Aug 13.
Recent advances in the fields of chromatography, mass spectrometry, and chemical analysis have greatly improved the efficiency with which carotenoids can be extracted and analyzed from avian plumage. Prior to these technological developments, Brush (1968) concluded that the burgundy-colored plumage of the male pompadour Cotinga Xipholena punicea is produced by a combination of blue structural color and red carotenoids, including astaxanthin, canthaxanthin, isozeaxanthin, and a fourth unidentified, polar carotenoid. However, X. punicea does not in fact exhibit any structural coloration. This work aims to elucidate the carotenoid pigments of the burgundy color of X. punicea plumage using advanced analytical methodology. Feathers were collected from two burgundy male specimens and from a third aberrant orange-colored specimen. Pigments were extracted using a previously published technique (McGraw et al. (2005)), separated by high-performance liquid chromatography (HPLC), and analyzed by UV/Vis absorption spectroscopy, chemical analysis, mass spectrometry, nuclear magnetic resonance (NMR), and comparison with direct synthetic products. Our investigation revealed the presence of eight ketocarotenoids, including astaxanthin and canthaxanthin as reported previously by Brush (1968). Six of the ketocarotenoids contained methoxyl groups, which is rare for naturally-occurring carotenoids and a novel finding in birds. Interestingly, the carotenoid composition was the same in both the burgundy and orange feathers, indicating that feather coloration in X. punicea is determined not only by the presence of carotenoids, but also by interactions between the bound carotenoid pigments and their protein environment in the barb rami and barbules. This paper presents the first evidence of metabolically-derived methoxy-carotenoids in birds.
近年来，色谱、质谱和化学分析领域的进展极大地提高了从鸟类羽毛中提取和分析类胡萝卜素的效率。在这些技术发展之前，Brush（1968）得出结论，雄性凤头犀鸟 Xipholena punicea 的酒红色羽毛是由蓝色结构色和红色类胡萝卜素（包括虾青素、角黄素、异叶黄素和第四种未鉴定的极性类胡萝卜素）的组合产生的。然而，X. punicea 实际上并不表现出任何结构色。这项工作旨在使用先进的分析方法阐明 X. punicea 羽毛中酒红色的类胡萝卜素色素。从两只酒红色雄性标本和第三只异常橙色标本中收集羽毛。使用先前发表的技术（McGraw 等人，2005 年）提取色素，通过高效液相色谱（HPLC）分离，并通过紫外/可见吸收光谱、化学分析、质谱、核磁共振（NMR）和与直接合成产物的比较进行分析。我们的研究表明存在八种酮类胡萝卜素，包括虾青素和角黄素，如 Brush（1968）先前报道的那样。六种酮类胡萝卜素含有甲氧基，这在天然存在的类胡萝卜素中很少见，也是鸟类中的一个新发现。有趣的是，两种酒红色和橙色羽毛中的类胡萝卜素组成相同，表明 X. punicea 的羽毛颜色不仅由类胡萝卜素的存在决定，还由结合在羽枝和羽小枝中的类胡萝卜素色素与其蛋白质环境之间的相互作用决定。本文首次证明了鸟类中代谢衍生的甲氧基类胡萝卜素的存在。
