Dietary astaxanthin exists predominantly as the all-E-isomer; however, certain amounts of theZ-isomers
are universally present in the skin, whose roles remain largely unknown.
The aim of this study was to investigate the effects of the astaxanthinE/Z-isomer ratio on skin-related physicochemical
properties and biological activities using human dermal fibroblasts
and B16 mouse melanoma cells. We revealed that astaxanthin enriched
inZ-isomers (totalZ-isomer ratio
= 86.6%) exhibited greater UV-light-shielding ability and skin antiaging
and skin-whitening activities, such as anti-elastase and anti-melanin
formation activities, than the all-E-isomer-rich
astaxanthin (totalZ-isomer ratio = 3.3%). On the
other hand, the all-E-isomer was superior to theZ-isomers in singlet oxygen scavenging/quenching activity,
and theZ-isomers inhibited type I collagen release
into the culture medium in a dose-dependent manner. Our findings help
clarify the roles of astaxanthinZ-isomers in the
skin and would help in the development of novel skin health-promoting
food ingredients.