A method is disclosed for treating or preventing macular degeneration, one of the leading causes of blindness and vision loss, by administering a preparation of zeaxanthin which contains the 3R-3'R stereoisomer as a sole or heavily dominant stereoisomer. Zeaxanthin, a yellowish pigment which is naturally present in macular cells in the center of the human retina, absorbs blue and near-ultraviolet light radiation, thereby protecting retinal cells against phototoxic damage. The purified R-R isomer of zeaxanthin can be taken orally as a prescription drug by patients suffering from macular degeneration, and it can also be used as a nutritional supplement, in forms such as a vitamin pills or food additives, by anyone who wants to reduce his or her risk of macular degeneration, which is widespread among people over the age of about 50 or 60. Zeaxanthin preparations which contain only the desired R-R isomer can be produced by fermentation of Flavobacterium multivorum cells (ATCC accession number 55238) or other host cells which contain genes isolated from this F. multivorum strain. These bacterial cells do not create any detectable quantities of the undesired S-S or S-R isomers of zeaxanthin, and they do not synthesize significant quantities of other carotenoids which might compete against zeaxanthin for alimentary uptake after oral ingestion.
The method of the invention uses raw corn, or a corn by-product as a source. The source is mixed with an alcohol to produce an alcohol-corn slurry. Centrifugation or filtration produces a clear filtrate from the alcohol-corn slurry. A membrane filtration step is then used to separate purified xanthophylls. Other steps may be combined with the basic process to produce additional corn products, such as oil and zein.
Trans-xanthophyll ester concentrates having a trans-xanthophyll ester content of at least four times greater and preferably at least nine times greater than the cis-xanthophyll ester content are obtained. Xanthophyll ester concentrates having a total xanthophyll ester content of at least 40 wt. % and preferably greater than about 55 wt. % are also obtained. A method of obtaining a trans-xanthophyll ester concentrate of high purity includes contacting plant material containing xanthophyll esters with a hydrocarbon solvent for a time sufficient to extract xanthophyll esters from the plant material, separating the hydrocarbon solvent and extract dissolved therein from the remaining plant material, evaporating the hydrocarbon solvent from the dissolved extract to obtain a crude xanthophyll ester concentrate, admixing the crude xanthophyll ester concentrate with an alcohol at approximately ambient temperature to dissolve non-xanthophyll impurities and cis-xanthophyll esters from the concentrate and removing the alcohol containing impurities and cis-xanthophyll esters from the crude trans-xanthophyll concentrate to obtain a purified trans-xanthophyll ester concentrate. By using only the corollas of marigold flowers, lutein ester concentrates of high purity are obtained with pesticide residues absent from the concentrate at parts per billion detection levels.
A marigold plant, a regenerable portion thereof and seed are disclosed whose flower petals, leaves or flower petals and leaves contain one or more of an enhanced zeaxanthin ratio, an enhanced neoxanthin plus violaxanthin ratio, an enhanced .beta.-carotene ratio, an enhanced .alpha.-cryptoxanthin ratio, an enhanced phytoene ratio or an enhanced phytofluene ratio relative to that ratio in a non-mutant marigold. The flower petals of such a plant also typically contain zeta-carotene that is not normally found in such petals. Also disclosed are methods of preparing such plants, oleoresins and comestible materials that have such carotenoid ratios.
