Protective and Regenerative Efficacy of a Plant Oil-Based Day and Night Cream: Investigated by a Novel Approach to Reveal the Impact of Blue Light Irradiation on Epidermal Barrier Integrity and Lipid Matrix

In recent years, the harmful effects of blue light (400 - 500 nm) as a component of visible light (400 - 700 nm) have increasingly gained attention of science, industry, and consumers. To date, only a few in vivo test methods for measuring the effects of blue light on the skin have been described. A direct measurement method that can detect the immediate effects of blue light on the epidermal permeability barrier (EPB) is still lacking. In this study, we present a new methodological approach that can be used to investigate both the protective and regenerative effects of cosmetic products on the EPB after blue light irradiation. In a study with 14 female volunteers, it was investigated whether the regular application of an O/W emulsion (day cream) can strengthen and protect the epidermal barrier against damaging blue light radiation of 60 J/cm2 (protective study design) and also whether a disruption of the epidermal barrier caused by blue light radiation is restored faster and better by the regular application of another O/W emulsion (night cream) than in product-untreated skin (regenerative study design). The two O/W emulsions are different in plant oil, active ingredient composition and texture. The seven-day treatment with the day cream initially led to a significant increase in the normalized lipid lamellae length in the intercellular space, whereas the irradiation with blue light after 24 hours led to a significant decrease in the lipid lamellae length in the untreated test area, but not in the area previously treated with the product. Regarding the regenerative study design, a two-day treatment with the night cream was able to restore a blue-light-induced decrease in lipid lamellae length in the intercellular space. In summary, with the study designs presented here, the protective and regenerative effect of two cosmetic products could be demonstrated for the first time on the integrity of the EPB after blue light irradiation and the data showed that the Lipbarvis® method is suitable for investigating the damaging effects of blue light on the EPB in vivo.

The HY5 transcription factor negatively regulates ethylene production by inhibiting ACS1 expression under blue light conditions in pear

Ethylene is the main factor controlling fruit ripening of pear(Pyrus ussuriensis).Ethylene production rate is negatively correlated with fruit shelf life;therefore,it is important to decrease the ethylene levels for optimal fruit storage.Here,we observed that blue light treatment could inhibit ethylene production and promote the expression of ELONGATED HYPOCOTYL 5(PuHY5),a basic leucine zipper domain(bZIP)transcription factor.The following studies showed that PuHY5 could bind to the promoter of ACC synthase 1(PuACS1),a rate-limiting enzyme in ethylene biosynthesis,and inhibit its expression.For pears in which Pu HY5 was silenced,the ethylene production and PuACS1 expression were much higher than those in the control fruit.These results demonstrated that blue light inhibited ethylene production through the induction of Pu HY5 in pear.Our finding provides a new method for prolonging fruit shelf life.

Blue light induces leaf color change by modulating carotenoid metabolites in orange-head Chinese cabbage(Brassica rapa L.ssp. pekinensis)

Carotenoids are involved in the formation of plant leaf color as well as photosystem photoprotection. This study showed that blue light significantly induced up-regulation of the total carotenoid content in the inner leaves of orange-head Chinese cabbage(OHCC). Furthermore, the transcriptomic analysis revealed that blue light treatment induced upregulation of genes in photosynthesis(BrHY5-2, BrCOP1 and BrDET1) and the methylerythritol 4-phosphate pathways(BrGGPS, BrDXS and BrHDR) upstream of the carotenoid metabolic pathway. Carotenoid metabolomic analysis revealed that the accumulation of several orange and red carotenoids(lycopene, zeaxanthin, β-carotene, lutein, and β-cryptoxanthin) after blue light treatment contributed to the deepening of the leaf coloration, suggesting that short-term blue light treatment could be used to boost nutritional quality. The light signal gene BrHY5-2 participated in the blue light-induced transcriptional regulation of carotenoid biosynthesis in OHCC. Overexpression of BrHY5-2 in Arabidopsis significantly increased the total carotenoid content and the sensitivity to blue light. The above findings revealed new insights about blue-light-induced carotenoid synthesis and accumulation in OHCC lines. They suggested a new engineering approach to increase the nutritional value of vegetables.

Supplemental blue light increases growth and quality of greenhouse pak choi depending on cultivar and supplemental light intensity

To evaluate the supplementary blue light intensity on growth and health-promoting compounds in pak choi（Brassica campestris ssp.chinensis var.communis）,four blue light intensity treatments（T0,T50,T100 and T150 indicate 0,50,100,and 150μmol m^（-2） s^（-1）,respectively）were applied 10 days before harvest under greenhouse conditions.Both of cultivars（greenand red-leaf pak choi）under T50 had the highest yield,content of chlorophyll and sugars.With light intensity increasing,antioxidant compounds（vitamin C and carotenoids）significantly increased,while nitrate content showed an opposite trend.The health-promoting compounds（phenolics,flavonoids,anthocyanins,and glucosinolates）were significantly higher under supplementary light treatment than T0,so as the antioxidant capacity（2,2-diphenyl-1-picrylhydrazyl and ferric-reducing antioxidant power）.The species-specific differences in photosynthetic pigment and health-promoting compounds was found in green-and red-leaf pak choi.T50 treatment could be used for yield improvement,whereas T100 treatment could be applied for quality improvement.Results showed that blue light intensity can regulate the accumulation of biomass,morphology and health-promoting compounds in pak choi under greenhouse conditions.

Research progress about the effect and prevention of blue light on eyes

In recent years, people have become increasingly attentive to light pollution influences on their eyes. In the visible spectrum, short-wave blue light with wavelength between 415 nm and 455 nm is closely related to eye light damage. This high energy blue light passes through the cornea and lens to the retina causing diseases such as dry eye, cataract, age-related macular degeneration, even stimulating the brain, inhibiting melatonin secretion, and enhancing adrenocortical hormone production, which will destroy the hormonal balance and directly affect sleep quality. Therefore, the effect of Blu-rays on ocular is becoming an important concern for the future. We describe blue light’s effects on eye tissues, summarize the research on eye injury and its physical prevention and medical treatment.

Effects of UV-B radiation on tetraspores of Chondrus ocellatus Holm(Rhodophyta),and effects of red and blue light on repair of UV-B-induced damage

We evaluated the effects of red and blue light on the repair of UV-B radiation-induced damage in tetraspores of Chondrus ocellatus Holm. Tetraspores of C. ocellatus were treated with different UV-B radiation levels(0,36,72,108,144 and 180 J/m2),and thereafter subjected to PAR,darkness,or red or blue light during a 2-h repair stage,each day for 48 days. The diameters and cellular contents of cyclobutane pyrimidine dimmers(CPDs),chlorophyll a(Chl a),phycoerythrin,and UV-B-absorbing mycosporinelike amino acids(MAAs) contents of the tetraspores were determined. Our results show that low doses of UV-B radiation(36 and 72 J/m 2) promoted the growth of C. ocellatus; however,increased UV-B radiation gradually reduced the C. ocellatus growth(greater than 72 J/m2). The MAAs(palythine and asterina-330) in C. ocellatus were detected and analyzed by LC/MS. Our results suggest that moderate red light could induce the growth of this alga in aquaculture. In addition,photorepair was inhibited by red light,so there may be some other DNA repair mechanism activated by red light. Blue light promoted the activity of DNA photolyase,greatly improving remediation efficiency. Red and blue lights were found to reduce the capacity of C. ocellatus to form MAAs. Therefore,PAR,red light,and blue light play different roles during the repair processes for damage induced by UV-B radiation.

Effects of blue light on gametophyte development of Laminaria japonica (Laminariales, Phaeophyta)

Laminaria gametophyte was greatly influenced by light in its growth and development. Using light-emitting diodes (LED) as blue and red light sources, we analyzed the light effect on gametophytes devel- opment of Laminaria japonica Aresch. The gametophytes were obtained from zoospores collected in April, May, July, 2003 and September, 2004. We found that the growth of gametophytes was stimulated by increasing inten- sity of blue light (BL) and red light (RL) illumination, of which BL was obviously stronger than that of RL. The fertilization of gametophytes depended largely on BL, and only sufficient BL illumination could take the repro- ductive effect. In addition, we noticed that there was a significant difference in light responses for gametophytes developed from zoospore collected in different times. For zoospores released in April, under BL1 (73.90 μmol photons/m·s), the unicellular female gametophytes and multi-cellular male gametophytes produced eggs and sperms respectively, and further developed towards sporophytes. However, for gametophytes developed in May, July or September, they became multi-cellular and never formed oogonia or antheridia. It is believed that the Laminaria sporangium maturation stage could affect the gametophytes reaction to BL under laboratory culture conditions. Therefore, cryptochrome- or phototropin-like BL photoreceptors is probably involved in BL-induced development of Laminaria gametophytes.

Effects of Different Combinations of Red and Blue Light on Morphology and Photosynthetic Characteristic of Tomato Seedlings

Blue and red light are spectral wavelengths more effective for plants. The effects of different ratios of red and blue light （R/B=2, R/B=4, R/B=8, R/B=12） provided by LEDs on morphology and photosynthetic characteristics of tomato seedlings were studied. The results showed that plant height, stem diameter, fresh weight, dry weight, seedling index and G value increased with the increase of R/B ratio until 8. On the contrary, SPDA value decreased with the increase of R/B ratio. Photosynthetic characteristics were measured by CO 2 assimilation （ Pn ）, stomatal conductance （ gs ） and intracellular CO 2 concentration （ Ci） . Pn and gs decreased with the increase of R/B ratio. Furthermore, similar trend was investigated in photochemical quenching （qP） and electron transport rate （ETR）. Results of this study suggest that compared with white LED, appropriate combination of red and blue light can enhance plant growth and photosynthetic characteristics, and the optimal blue/red ratio for tomato growth was R/B=8.

Efficiency droop alleviation in blue light emitting diodes using the InGaN/GaN triangular-shaped quantum well

The InGaN/GaN blue light emitting diode（LED） is numerically investigated using a triangular-shaped quantum well model,which involves analysis on its energy band,carrier concentration,overlap of electron and hole wave functions,radiative recombination rate,and internal quantum efficiency.The simulation results reveal that the InGaN/GaN blue light emitting diode with triangular quantum wells exhibits a higher radiative recombination rate than the conventional light emitting diode with rectangular quantum wells due to the enhanced overlap of electron and hole wave functions（above 90%） under the polarization field.Consequently,the efficiency droop is only 18% in the light emitting diode with triangular-shaped quantum wells,which is three times lower than that in a conventional LED.

Whole transcriptome analysis on blue light-induced eye damage

AIM:To analyze abnormal gene expressions of mice eyes exposed to blue light using RNA-seq and analyze the related signaling pathways.METHODS:Kunming mice were divided into an experimental group that was exposed to blue light and a control group that was exposed to natural light.After 14 d,the mice were euthanized and their eyeballs were collected.Whole transcriptome analysis was attempted to analyze the gene expression of the eyeballs using RNA-seq to reconstruct genetic networks.Gene Ontology(GO)and Kyoto Encyclopedia of Genes and Genomes(KEGG)analysis were used to reveal the related signaling pathways.RESULTS:The 737 differentially expressed genes were identified,including 430 up and 307 down regulated genes,by calculating the gene FPKM in each sample and conducting differential gene analysis.GO and KEGG pathway enrichment analysis showed that blue light damage may associated with the visual perception,sensory perception of light stimulus,phototransduction,and JAKSTAT signaling pathways.Differential lnc RNA,circ RNA and mi RNA analysis showed that blue light exposure affected pathways for retinal cone cell development and phototransduction,among others.CONCLUSION:Exposure to blue light can cause a certain degree of abnormal gene expression and modulate signaling pathways in the eye.

Oxidative stress and mitochondrial dysfunction of retinal ganglion cells injury exposures in long-term blue light

AIM:To investigate the phototoxic effect of long-term excessive narrow-band blue light in staurosporine-induced differentiated retinal ganglion cells-5(SSRGC-5).METHODS:SSRGC-5 cells were divided into two groups,blue light group(BL group)and control group.Cell viability was assessed by using CCK-8 assay.Metabolic profile analysis was performed by using Seahorse extracellular flux analyzer.Mitochondria ultrastructure were studied via transmission electron microscope(TEM).Mitochondria contents and oxidative stress was evaluated by flow cytometry.Western blotting was performed to monitor the changes in mitogen-activated protein kinases(MAPK)pathway and PI3 K/AKT pathway.RESULTS:Blue light caused morphological changes of SSRGC-5 cells.The cell viability was significantly decreased from 3 h in BL group.Intercellular ROS and mitochondrial superoxide levels were increased following blue light exposure.Metabolic profiling identified blue light induced SSRGC-5 cells to have severely compromised mitochondrial function.This was accompanied by impaired mitochondrial ultrastructure and remodeling,increased expression of the mitochondrial related proteins,and increased glycolysis as compensation.Moreover,the results showed that blue light induced higher expression of p-p38,p38,p-JNK,p-ERK,p-cJun,c-Jun,and p-AKT.CONCLUSION:These findings indicate that excessive narrow-band blue light induces oxidative stress and mitochondrial metabolic remodeling dysregulate in SSRGC-5 cells.Activated MAPK and AKT signaling pathways are involved in this process.

Carotenoids and Chlorophyll are not the Chromophores of Blue Light-Induced Prehaustoria in Dodder （Cuscuta campestris） Seedlings

Previous studies demonstrated that cryptochromes are involved in blue light-induced coiling and prehaustoria development in young de-etiolated dodder seedlings. In this study, we suggest that carotenoids and chlorophyll are not the blue light absorbing chromophores involved in the mediation of prehaustoria development to blue light. Norflurazon-bleached dodder segments coiled and formed prehaustoria under blue light. However, norflurazon significantly reduced prehaustoria number （62%） under a mixture of red and far-red light, suggesting that phytochromes could be altered by norflurazon.

Blue light induced retinal oxidative stress:Implications for macular degeneration

A number of studies have shown that oxidative stress can be harmful for the retina. The real causal circumstances that lead to degenerative diseases like age related macular degeneration remain obscure. Whether light induced radical stress is a direct interaction of light with photoreceptors or a secondary mechanism within the pigment epithelium or choroid is in discussion. Among the molecular mechanisms involved are production of reactive oxygen species(ROS), secondary lipid peroxidation, protein oxidation and DNA-damage. The initial trigger to write this review was first a recent finding of our group that the photoreceptor outer segments produce great amounts of ROS and second the detection of ectopic enzymes of the respiratory chainlocalized there- in addition to the hitherto known ROS sources like the visual pigments with their intermediates and the photoreceptor mitochondria harbouring the respiratory chain.

Effect of High-Order Aberrations and Satisfaction on Cataract Patients Implanted with Four Types of AcrySof Blue Light Filtering Intraocular Lens

Objective: The objective is to evaluate the visual acuity, high-order aberrations and satisfaction in the cataract patients with the implantation of different types of AcrySof blue light filtering intraocular lens, which would provide the clinical guidance for the selection of individualized intraocular lens. Methods: From January 2019 to December 2020, the patients with age-related cataract in Guangzhou Red Cross Hospital were equally randomized to be divided into four groups. 20 patients (20 eyes) were implanted with AcrySof (SN60WF), which was the blue light filtering single focus group;20 patients (20 eyes) were implanted with blue light filtering aspheric multifocal intraocular lens (AcrySof ReSTOR IOL +3.0D, SN6AD1), which was the multifocal intraocular lens group;20 patients (20 eyes) were implanted with aspheric astigmatism correction intraocular lens (Toric SN6AT), which was the astigmatism group;20 patients (20 eyes) were implanted with blue filtering aspheric multifocal astigmatism correction intraocular lens (AcrySof ReSTOR IOL +2.5D IQ, SV25T0), which was the ART group. Three months after the operation, the patients were followed up with slit lamp to check the visual acuity, including uncorrected distance visual acuity (UCDVA), uncorrected near visual acuity (UCNVA), best corrected distance visual acuity, (BCDVA);the questionnaire surveys on the satisfaction of different intraocular lens implantation (far and near vision, glare, halo and abnormal visual symptoms);the iTrace visual function analyzer was used to check the total high-order aberrations (spherical aberration, wisdom aberration and Clover aberration) in the 3 mm pupil diameter. Results: Three months after cataract surgery, American Simplified version of questionnaire survey showed that the scores of near removing glasses in the multifocal group and the ART group were significantly better than those in the single focus group and the astigmatism group (P < 0.05);there was no significant difference in the satisfaction of far removing glasses, glare and halo in each group (P > 0.05). Three months after cataract surgery, there were statistically significant differences about UCDVA, BCDVA and UCNVA among the four groups (F = 18.189, P < 0.001), the UCNVA in the multifocal group and ART group was significantly better than that in the single focus group and the astigmatism group (P < 0.01). The difference of higher-order aberrations (total higher-order aberrations, wisdom aberrations, spherical aberrations, clover aberrations) was no statistically significant among the four groups (P > 0.05). Conclusion: Different types of AcrySof blue light filtering intraocular lens implantation could improve the far vision and satisfaction of cataract patients, without different higher-order aberrations. Multifocal intraocular lens and ART intraocular lens could significantly improve the far vision of patients and reduce the dependence on near glasses.

AB044.Phototoxic stress induced in retinal pigmented epithelium cells by the synergy between polycyclic aromatic hydrocarbons and blue light

Background:Lesion to the retinal pigment epithelium(RPE)is a crucial event in age-related macular degeneration(AMD)development.Although the pathogenesis of this complex disease is poorly understood,sunlight exposure and smoking are major environmental risk factors associated with AMD.High-energy visible blue light(HEV;400-500 nm)is the most energetic and potentially harmful solar wavelengths reaching adults retina.On the other hand,RPE cells can be exposed to a large range of pollutants from cigarette smoke,with polycyclic aromatic hydrocarbons(PAH)being among the most toxic.Some PAH from cigarette smoke can absorb HEV light.This led us hypothesize that in RPE cells,the combination of PAH and HEV could synergize to exacerbate the stress caused by either factor alone.We thus investigate the combined effect of PAH and HEV light in RPE cells.Methods:Confluent RPE immortalized cells(ARPE19)were exposed to nanomolar concentrations of benzo[a]pyrene(BaP)or indeno[1,2,3-cd]pyrene(IcdP).While IcdP efficiently absorbs HEV wavelengths,BaP,the most studied PAH,does not significantly absorb HEV light and was used as a control.BaP or IcdP contaminated ARPE19 were then irradiated with increasing sub-lethal doses of HEV light(150-500 J/cm2)using a setup that mimics the light spectrum normally reaching the retina.Cytotoxicity,apoptosis and reactive oxygen species(ROS)generation were assessed in each condition.Results:In presence of low concentrations of IcdP,sub-lethal amounts of HEV light trigger,in a dose-dependent way,up to 70%of apoptotic cell death.Co-exposure to IcdP and HEV also leads to a synergistic ROS generation in ARPE19 cells,thus inducing oxidative stress.None of these effects were observed with BaP.Efficient inhibition of ROS production by specific antioxidants only decreases death by 20%in cells simultaneously exposed to both IcdP and HEV light.Conclusions:Low concentrations of IcdP synergize with HEV light to induce phototoxicity in ARPE19 cells.An increased oxidative stress results from the interaction between both agents and partially explains the enhanced HEV phototoxicity in IcdP contaminated ARPE19 cells.This suggests that another major mechanism is involved in the synergetic toxicity.For smokers,this synergy between HEV and PAH may accelerate RPE cells loss and contribute to their greater risk of developing AMD.

Effects of Adjunctive Daily Blue Light Toothbrushing on Dental Plaque and Gingival Inflammation—A Randomized Controlled Study

Phototherapy with blue light emitting diodes (LEDs) is gaining interest because of the efficient antimicrobial benefits reported in several studies in the last decade. The aim in this study was to investigate if a toothbrush with incorporated blue light used in daily oral care can reduce dental plaque and gingival inflammation. An 8-week single-blinded randomized controlled clinical study including 48 subjects compared effects of toothbrushes with/without 450 nm blue LED light emission, on clinical parameters (plaque index, gingival index, bleeding on probing), and on inflammatory markers in saliva and gingival crevicular fluid. Significant reductions in dental plaque and gingival inflammation (p < 0.001), and in some inflammatory markers (p ≤ 0.05), matrix metalloproteinase (MMP)-8, tissue inhibitor metalloproteinase inhibitor (TIMP)-1, interleukin (IL)-1β and interleukin (IL)-8, were detected within both groups from baseline to follow-up. For all subjects dental plaque was reduced with 57%, and a reduction in gingival inflammation was demonstrated by a decrease in gingival index (GI) with 46% and in bleeding on probing (BOP) with a decrease of 15%. No significant differences were found between the groups at a level of p = 0.05. However, the amount of plaque was reduced by 62% in the blue light group and 51% in the control group, a difference established at a level of p = 0.058. A toothbrush with a 450 nm LED did not show any statistical significant adjunctive effect of toothbrushing regarding reduction in measurements of dental plaque and gingival inflammation.

The effects of dark-broken by UV-B,UV-A,and blue light on fertility of PGMR Nongken 58s

PGMR ( Photoperiod sensitive Genic Male-sterile Rice) Nongken 58s was discovered in1973 by SHI Mingsong, with the characters ofpollen sterile under long daylength(LD) condi-tion but fertile under short daylength (SD)condition during its fertility change stage. LI

Transcriptome analysis of carotenoid biosynthesis in Dunaliella salina under red and blue light

The quality of light is an important abiotic factor that affects the growth and development of photosynthetic organisms.In this study,we exposed the unicellular green alga Dunaliella salina to red(660 nm)and blue(450 nm)light and analyzed the cell growth,total carotenoid content,and transcriptomes.The growth of D.salina was enhanced by illumination with red light,whereas blue light was not able to promote the algal growth.In contrast,the total carotenoid content increased under both red and blue light.The RNA of D.salina was sequenced and the transcriptomic response of algal cells to red and blue light was investigated.Six transcripts encoding for the blue light receptor cryptochrome were identified,and transcripts involved in the carotenoid metabolism were up-regulated under both red and blue light.Transcripts encoding for photoprotective enzymes related to the scavenging of reactive oxygen species were up-regulated under blue light.The present transcriptomic study provides a more comprehensive understanding of carotenoid biosynthesis in D.salina under different wavelengths of light.

Transcriptome analysis reveals effects of red and blue lightemitting diodes(LEDs)on the growth,chlorophyll fluorescence and endogenous plant hormones of potato(Solanum tuberosum L.)plantlets cultured in vitro

Red and blue light illumination has been reported to significantly affect plantlet growth.Potato is an important food and feed crop in the world and potato plantlet cultured in vitro plays an important role in potato production.However,few studies have documented the effects of red and blue light on the growth of potato plantlets revealed at the transcriptome level.The objective of this study was to determine the growth and physiological responses of potato plantlets cultured in vitro under monochromatic red(RR),monochromatic blue(BB)as well as combined red and blue(RB)LEDs using the RNA-Seq technique.In total,3150 and 814 differentially expressed genes(DEGs)were detected in potato plantlets under RR and BB,respectively,compared to RB(used as control).Compared to the control,the DEGs enriched in"photosynthesis"and"photosynthesis-antenna proteins"metabolic pathways were up-regulated and down-regulated by BB and RR,respectively,which might be responsible for the increases and decreases of maximum quantum yield(F_(v)/F_(m)),photochemical quantum yield(φ_(PSII)),photochemical quenching(q_(P))and electron transfer rate(ETR)in BB and RR,respectively.Potato plantlets exhibited dwarfed stems and extended leaves under BB,whereas elongated stems and small leaves were induced under RR.These dramatically altered plantlet phenotypes were associated with variable levels of endogenous plant hormones gibberellin(GAs),indoleacetic acid(IAA)and cytokinins(CKs),as assessed in stems and leaves of potato plantlets.In addition,monochromatic red and blue LEDs trigged the opposite expression profiles of DEGs identified in the"plant hormone signal transduction"metabolic pathway,which were closely related to the endogenous plant hormone levels in potato plantlets.Our results provide insights into the responses of potato plantlets cultured in vitro to red and blue LEDs at the transcriptomic level and may contribute to improvements in the micro-propagation of potato plantlets cultured in vitro from the light spectrum aspect.

Telomere Protective Effects of a Cyanobacteria Phycocyanin against Blue Light and UV Irradiations: A Skin Anti-Aging and Photo-Protective Agent

Background: Cyanobacteria phycocyanins (Cps) have already shown powerful antioxidant properties. In human cells submitted to oxidative stress the telomeres length decrease, the expression of progerin and the activity of mTOR are increased. At our knowledge, there is no published data on Cps correlated with ultraviolet radiation (UV) and blue light effects in human cells regarding telomeres’ length, progerin expression or mTOR1 complex activity. Objectives: In this study, we sought to assess 1) telomeres’ length in newborn human fibroblasts exposed to UV and blue light;2) progerin production in mature human normal fibroblasts exposed to UV;3) mTOR1 activation in adult human normal keratinocytes exposed to UV, analyzing the activity of a Cyanobacteria phycocyanin (Cp) in these in vitro models. Materials and Methods: Human skin fibroblasts or human normal keratinocytes were cultured—in the absence or in the presence of Cp and submitted to UVB + UVA and blue light irradiations. Telomeres’ length, progerin expression and mTOR1 activity were then assessed by molecular biology and immuno-enzymatic methods. Results: In cultured fibroblasts exposed to irradiations and treated by Cp, telomeres’ shortage and progerin expression were lower compared to irradiated untreated cells. In cultured keratinocytes treated by Cp and exposed to irradiations, the mTOR activity was lower compared to irradiated untreated cells. Conclusions: In these in vitro studies on human skin fibroblasts and on normal human keratinocytes, the cyanobacteria phycocyanin (Cp) showed a decrease of damages induced by UV and blue light expressed by telomeres preservation and downregulation of progerin expression and of mTOR activity, thus showing skin anti-aging and photo-protective potential.