Abstract
Recently, many pharmaceutical activities in carotenoids are reported. Since carotenoids that possess novel chemical structures can be new candidates for pharmaceuticals, we have found or generated novel carotenoids (and rare carotenoids in nature) by following two approaches. Approach A: Screening of such carotenoids from novel or rare carotenogenic bacteria Approach B: Production of such carotenoids using Escherichia coli cells that express various crt genes As results of Approach A, we isolated novel carotenoids diapolycopenedioicacid xylosyl esters A, B, C from Rubritalea squalenifaciens sp. nov., and methyl 5-glucosyl-5,6-dihydro-apo-4,4'-lycopenoate, 5-hydroxy-5,6-dihydro-apo-4,4' -lycopene, and methyl 5-hydro-apo-4,4'-lycopenoate from Planococcus maritinus. As results of Approach B, we succeeded in producing 2,2'-dihydroxycanthaxanthin (novel carotenoid) and 2-hydroxycanthaxanthin (rare carotenoid) using E. coli that expressed the crtE, crtB, crtl, crtY, crtW, and crtG genes. We also produced caloxanthin-3'-β-D-glucoside (novel carotenoid), zeaxanthi-3,3'-β-u-diglucoside (rare carotenoid), and nostoxanthin (rare carotenoid) using E. coli that expressed the crtE, crtB, crtl, crtY, crtZ, crtX, and crtG genes. The novel or carotenoids isolated or prepared in these studies were examined to possess ^1O_2 quenching activity using methylene blue. As the results, some of them proved potent ^1O_2 quenching activities.
