Age‐dependent generation of reactive oxygen species in the skin of live hairless rats exposed to UVA light

Abstract

Aging proceeds by highly complicated biochemical processes, in which the involvement of the reactive oxygen species (ROS) and free radicals has been implicated. Although the relationship between UV-induced photoaging and ROS generation has been proposed, it has been difficult to establish direct proof of the generation of ROS in the skin under UV exposure. Recently, we reported finding endogenously generated ROS in the skin of live mice after UVA light exposure by a method of in vivo chemiluminescent detection, in which superoxide anion radical (*O2-) and singlet oxygen species (1O2) are contributed. In light of the results, we tried to understand the age-dependent changes in ROS generation in the skin of hairless rats under UVA exposure. Chemiluminescent levels due to ROS in the untreated and UVA-exposed skin decreased age dependently, and the signal intensities in old rats were significantly lower than those in young rats. However, the ratios of chemiluminescent intensities in the UVA-exposed skin to those in the untreated skin were significantly enhanced in an age-dependent manner. These results suggest that the antioxidative ability against ROS generation in the skin, possessed by antioxidant enzymes and low molecular weight antioxidants, is lowered age dependently.

<i>In vitro</i> inhibitory potential of methanolic extract of <i>Celosia argentea</i> var. <i>cristata</i> on tyrosinase, acetylcholinesterase and butyrylcholinesterase enzymes

“…The hyperpigmented skin is observed in various dermatological disorders namely melasoma, solar lentigines and ephelides (Maeda and Fukuda, 1991). The reactive oxygen species produced in the human body enhances the DNA damage, melanin biosynthesis and induces the proliferation of melanocytes (Yasui and Sakurai, 2003) which results in hyper pigmentation disorders. The production of melanin in the body can be reduced by several mechanisms including direct inhibition of tyrosinase enzyme, inhibiting the transport of melanosome to the stratum corneum, the supplementation of anti-oxidants (Pawelek and Kormer, 1982) as well.…”

Methanol Partition Fraction of Ethanol Extract of Discorea nipponica Makino Inhibits Melanogenesis

“…Antioxidants can interfere with oxidation processes by acting as free radical scavengers or ROS scavengers, and then down-regulate melanin production [12,[16][17]. For instance, vitamin C or vitamin E can reduce the photooxidation of preexisting melanin particles [18].…”

Novel Screening Method for Potential Skin-Whitening Compounds by a Luciferase Reporter Assay

“…Since the over-production and accumulation of melanin might occur in melasma, freckles, and other forms of melanin hyper-pigmentation, melanogenesis inhibitors have been developed as agents for use in medications and cosmetics; [1][2][3] for example, such tyrosinase inhibitors as arbutin, hydroquinone, and ellagic acid have been included in some cosmetic products. 14,15) Although we could also find sulforaphane with the usual method by measuring the melanin content using B16 melanoma cells, 5) this method took a long time and was troublesome for high-throughput screening.…”

“…[1][2][3] Over-production and accumulation of melanin, however, may cause various skin disorders. The use of skin-whitening agents, particularly by women, has been growing in recent years.…”