Carotenoids are reported to have immunological effects independent of vitamin A activity. Although antioxidant activity has been suggested as a basis of action, the ability of carotenoids to autoxidize to numerous non-vitamin A products with immunological activity is an alternative yet to be fully explored. We have undertaken a systematic study of β-carotene autoxidation and tested the product mixture for immunological activity. Autoxidation proceeds predominantly by oxygen copolymerization, leading to a defined, reproducible product corresponding to net uptake of almost 8 molar equivalents of oxygen. The product, termed OxC-beta, empirical formula C40H60O15versus C40H56for β-carotene, contains more than 30% oxygen (w/w) and 85% β-carotene oxygen copolymers (w/w) as well as minor amounts of many C8−C18 norisoprenoid compounds. No vitamin A or higher molecular weight norisoprenoids are present. The predominance of polymeric products has not been reported previously. The polymer appears to be a less polymerized form of sporopollenin, a biopolymer found in exines of spores and pollen. Autoxidations of lycopene and canthaxanthin show a similar predominance of polymeric products. OxC-beta exhibits immunological activity in a PCR gene expression array, indicating that carotenoid oxidation produces non-vitamin A products with immunomodulatory potential.
胡萝卜素据报道具有独立于维生素A活性的免疫效应。尽管抗氧化活性被认为是其作用的基础,但胡萝卜素能够自氧化为具有免疫活性的多种非维生素A产物的能力尚未被充分探索。我们进行了β-胡萝卜素自氧化的系统研究,并测试了产物混合物的免疫活性。自氧化主要通过氧共聚合进行,导致产生一个明确定义、可复制的产物,对应于几乎吸收了8摩尔当量的氧气。该产物被称为OxC-beta,经验式为C40H60O15>,与β-胡萝卜素的C40H56>相比,含氧量超过30%(重量百分比),β-胡萝卜素氧共聚物含量为85%(重量百分比),以及少量的许多C8-C18的非异戊二烯化合物。没有维生素A或更高分子量的异戊二烯化合物存在。以前尚未报道过聚合物的优势。这种聚合物似乎是孢子和花粉外壁中发现的生物聚合物孢粉素的较少聚合形式。番茄红素和辣胭脂素的自氧化显示出类似的聚合物优势。OxC-beta在PCR基因表达阵列中表现出免疫活性,表明胡萝卜素氧化产生了具有免疫调节潜力的非维生素A产物。