Photolyase
Photolyase is found in plants, bacteria, reptiles,
amphibians, and marsupials, and even in the placenta of
mammals; it absorbs visible light and uses the energy to
disrupt the cyclobutane ring in a mechanism of action
called “photoreactivation.” In vivo and in vitro studies
of liposome-encapsulated photolyase derived from the
cyanobacteria Anacystis nidulans have demonstrated a
50% reduction in both apoptosis and the production of
cyclobutane pyrimidine dimers.64
Oxoguanine Glycosylase 1 Enzyme
The oxoguanine glycosylase 1 enzyme catalyzes the first
step in the process of base excision repair, the process
that removes guanine bases with oxidative damage—8-
hydroxy-2-deoxy guanosine—from DNA. The application of
this botanical enzyme encapsulated in liposomes following
exposure to UV-B radiation in mice chronically exposed to
such radiation reduced the size and progression of skin
cancers.65
Thymidine Oligonucleotides
Thymidine oligonucleotides are DNA fragments, specifically
thymidine dinucleotides homologous to the sequence that
repeats in one third of the telomere (TTAGGG), which is
the most common substrate for the photoproducts of UV
irradiation. Application of these oligonucleotides triggers
the SOS-like response normally initiated to rescue cells
exposed to UV radiation, involving processes such as
melanogenesis, but it does so without any irradiation taking
place, thereby improving the skin’s capacity to repair DNA
damage without prior UV exposure.66
These oligonucleotides have been shown to reduce the
development of squamous and basal cell carcinomas in
mice by decreasing cyclooxygenase-2 expression, inhibiting
cell proliferation, increasing apoptosis, and significantly
reducing cyclobutane pyrimidine dimers and the expression
of 8-hydroxy-2′-deoxyguanosine.67
In short, topical application of oligonucleotides and
DNA repair enzymes increases the body’s endogenous
capacity for DNA repair, thereby enhancing protection
against UV radiation and reducing photocarcinogenesis.
Cyclooxygenase-2 Inhibitors
In animal models, topical celecoxib reduces the
inflammation and acute oxidative damage produced by
UV-B radiation and inhibits the formation of carcinomas
induced by chronic exposure to such radiation.68 However,
these substances are not currently used in photoprotective
products.
PhotolyasePhotolyase is found in plants, bacteria, reptiles,amphibians, and marsupials, and even in the placenta ofmammals; it absorbs visible light and uses the energy todisrupt the cyclobutane ring in a mechanism of actioncalled “photoreactivation.” In vivo and in vitro studiesof liposome-encapsulated photolyase derived from thecyanobacteria Anacystis nidulans have demonstrated a50% reduction in both apoptosis and the production ofcyclobutane pyrimidine dimers.64Oxoguanine Glycosylase 1 EnzymeThe oxoguanine glycosylase 1 enzyme catalyzes the firststep in the process of base excision repair, the processthat removes guanine bases with oxidative damage—8-hydroxy-2-deoxy guanosine—from DNA. The application ofthis botanical enzyme encapsulated in liposomes followingexposure to UV-B radiation in mice chronically exposed tosuch radiation reduced the size and progression of skincancers.65Thymidine OligonucleotidesThymidine oligonucleotides are DNA fragments, specificallythymidine dinucleotides homologous to the sequence thatrepeats in one third of the telomere (TTAGGG), which isthe most common substrate for the photoproducts of UVirradiation. Application of these oligonucleotides triggersthe SOS-like response normally initiated to rescue cellsexposed to UV radiation, involving processes such asmelanogenesis, but it does so without any irradiation takingplace, thereby improving the skin’s capacity to repair DNAdamage without prior UV exposure.66These oligonucleotides have been shown to reduce thedevelopment of squamous and basal cell carcinomas inmice by decreasing cyclooxygenase-2 expression, inhibitingcell proliferation, increasing apoptosis, and significantlyreducing cyclobutane pyrimidine dimers and the expressionof 8-hydroxy-2′-deoxyguanosine.67In short, topical application of oligonucleotides andDNA repair enzymes increases the body’s endogenouscapacity for DNA repair, thereby enhancing protectionagainst UV radiation and reducing photocarcinogenesis.Cyclooxygenase-2 InhibitorsIn animal models, topical celecoxib reduces theinflammation and acute oxidative damage produced byUV-B radiation and inhibits the formation of carcinomasinduced by chronic exposure to such radiation.68 However,these substances are not currently used in photoprotectiveproducts.
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