Low Sun Exposure Is Associated with Both Progressive-Onset and Relapse-Onset Multiple Sclerosis Risk: A Case-Control Study.

BACKGROUND: Sun exposure has consistently been associated with multiple sclerosis (MS) onset, but case samples are predominantly relapse-onset MS (ROMS), and risk estimates have rarely been reported separately for ROMS and progressive-onset MS (POMS). We aimed to determine whether sun exposure prior to disease onset was associated with POMS and whether the effect differed between POMS and ROMS. METHODS: This nationwide case-control study included 153 POMS cases, 204 incident ROMS cases, and 558 community controls with data from two separate datasets: the PPMS Study (2015-2021) and the Ausimmune Study (2003-2006). Information on time spent in the sun before the first MS symptom, skin phenotype, and sun protection behavior was collected. Satellite data on ambient ultraviolet radiation (UVR) were used to calculate cumulative UVR dose. Unconditional logistic regression was used with adjustment for covariates. RESULTS: There were consistent dose-response associations, with higher levels of UVR exposure associated with a reduced risk of POMS, both for leisure-time and occupational UVR from age 6 to symptom onset. Associations were overall stronger for POMS than ROMS. For example, cumulative leisure-time UVR dose (per 100 kJ/m2 increment) was associated with POMS (aOR 0.93, 95% CI: 0.91-0.95) and the association was slightly weaker for ROMS (aOR 0.96, 95% CI: 0.94-0.99) for age 6 to symptom onset (test for interaction p < 0.001). CONCLUSIONS: Low levels of sun exposure, throughout the whole lifespan, are associated with an increased risk of POMS and ROMS onset. The sun effects are usually stronger for POMS than ROMS.

Finite element analysis of non-ultraviolet and ultraviolet-irradiated titanium implants.

AIM: The purpose of this study is to calculate von Mises stresses, von Mises strains, deformation, principal stresses and principal elastic strains of non-UV and UV-irradiated hybrid SLA (sandblasted, large-grit, acid-etched)-coated titanium implants. MATERIALS AND METHODS: A cross-sectional analytical study was conducted at the Institute of Dentistry, CMH Lahore Medical College. Cone beam computed tomography (CBCT) data of One Hundred and Thirty Eight Dio Hybrid sandblasted and acid-etched implants of identical dimensions (10 mm in length and 4.5 mm in diameter) were allocated in the three groups. Control group A samples were not given UV irradiation, while groups B and C were given UVA (382 nm, 25 mWcm-2) and UVC (260 nm, 15 mWcm-2) irradiation, respectively. The CBCT data were analyzed using FEA (ANSYS software). CBCT images were taken before functional loading (8th week) and after functional loading (26th week). A 3-way ANOVA test was employed to see the difference between the three groups. Tukey test was utilized for multiple comparisons. p ≤ 0.05 was considered significant. RESULTS: The control group exhibited the highest average values for maximum von Mises stress, von Mises strain, deformation, principal stress, and principal elastic strain in both the maxilla and mandible compared to the UV-irradiated groups. Additionally, these measures consistently displayed higher averages in the maxilla across all groups compared to the mandible. Particularly, the UVC-irradiated group demonstrated the lowest von Mises stresses around the implants compared to the UVA group. CONCLUSION: Insignificant differences were observed between UVA- and UVC-irradiated implants in terms of principal stress, deformation, von Mises strain, and principal elastic strain. The only notable distinction was in von Mises stress, where the UVC-irradiated group exhibited lower von Mises stress around SLA-coated titanium implants.

Is ultraviolet light disinfection fit to be the future standard for the disinfection of flexible endoscopes without a working channel?

OBJECTIVE: To investigate colony-forming unit (CFU) reduction on contaminated flexible endoscopes (FEs) without a working channel after UV-C light disinfection, compared to the current disinfection method with the endoscope washer disinfector (EWD). DESIGN, SETTING AND PARTICIPANTS: After pharyngolaryngoscopy, a manual pre-cleaning with tap water was performed. A culture was then collected by rolling the distal 8-10 cm of the FE over an Agar plate. The FE was disinfected using the D60 (60-s disinfection process with UV-C light) or the EWD (gold standard reprocessing process with water and chemicals). Another culture was then taken. After incubation, a CFU count was performed. RESULTS: A total of 200 FEs without a working channel were divided equally between the two disinfection groups. After clinical use and manual pre-cleaning, 84 of the 100 (84.0%) (UV-C light group) and 79 of the 100 (79.0%) (EWD) FEs were contaminated with at least 1 CFU. FEs that showed no contamination after use were excluded from further analysis. After disinfection with UV-C light, 72 (85.7%) FEs showed no contamination (i.e., 0 CFUs) versus 66 (83.5%) FEs after reprocessing with the EWD. CONCLUSION: There is no difference in CFUs reduction on contaminated FEs without a working channel between UV-C light disinfection and the current gold standard, the EWD.

Effect of Ultraviolet-C Light Exposure Time on the Dimensional Stability of Addition Silicone Dental Impressions: An In Vitro Study.

AIM: To compare the effect of different ultraviolet-C (UV-C) light exposure times on the dimensional stability of addition silicone dental impressions. MATERIALS AND METHODS: The dimensional stability of the addition silicone dental impressions was assessed by measuring specific dimensions on dental casts that were recovered from an upper acrylic resin model of dental implants. The impressions were reproduced using a customized tray adapted in a three-point simplex dental articulator permitting only opening and closing movements. Addition silicone dental impressions were divided into five groups (N = 12) according to the UV-C light exposure time. Group A was untreated; group B received 10 minutes; group C, 20 minutes; group D, 30 minutes; and group E, 40 minutes. All the impressions were poured with type IV dental stone and the internal edges of the upper silicone retainers of impression copings were used as five reference points (E, D, C, B, and A) to determine six linear measurements between ED, CB, EA, AD, EB, and CD points using a traveling microscope of 0.001 mm accuracy. One-way analysis of variance (ANOVA) was used for the statistical analysis (p < 0.05). RESULTS: Expansion and contraction were noted among ED, CB, EA, and EB measurements, whereas only expansion was noted among AD and CD measurements. The ANOVA analysis showed there was no significant difference in the arithmetic means for the measurements between and within group A and the other groups (p > 0.05). CONCLUSION: The UV-C light exposure time of 10, 20, 30, and 40 minutes did not have any negative effect on the dimensional stability of the addition silicone dental impressions evaluated. CLINICAL SIGNIFICANCE: In the daily routine dental practice, dental impressions need to be washed and disinfected immediately after making to prevent cross-infections. The UV-C light has been proposed as a promising method for disinfection, but only a few studies have been published about its effect on the dimensional stability of dental silicones. How to cite this article: Bravo-Cueto AG, Tinedo-López PL, Malpartida-Carrillo V. Effect of Ultraviolet-C Light Exposure Time on the Dimensional Stability of Addition Silicone Dental Impressions: An In Vitro Study. J Contemp Dent Pract 2024;25(6):507-513.

Skin lightness affects ultraviolet A-induced oxidative stress: Evaluation using ultraweak photon emission measurement.

The human skin is usually exposed to ultraviolet A (UVA) in the sunlight and experiences oxidative stress associated with skin disorders and aging. Although oxidative stress caused by UVA exposure is assumed to be dependent on skin colour, few studies have demonstrated this dependency. We investigated the effects of skin colour on UVA-induced oxidative stress using ultraweak photon emission (UPE) generated from the skin during oxidation processes. The UPE intensities of skin samples were detected using a photomultiplier tube every second without any labelling. We irradiated skin tissue of different colours with UVA and measured UPE over time. UVA-induced UPE could be detected from immediately after irradiation to 2 h after irradiation, indicating persistent oxidative stress. Skin lightness (L*) positively correlates with UPE intensity. Lighter-coloured skin exhibited more UVA-induced UPE, indicating higher oxidative stress. Additionally, oxidative stress persisted significantly more in lighter skin compared with darker skin. Skin tissues exhibited pigment darkening after UVA irradiation. Our results suggest that skin lightness affects oxidative stress induced by UV irradiation. Our study demonstrated the relationship between skin lightness and UVA-induced oxidative stress for the first time and offers new photodermatological insights into the human skin.

No seasonality in the risk of multiple sclerosis in an equatorial country: A case-control ecological study.

BACKGROUND: Multiple sclerosis risk has been shown to have seasonal variations that are more pronounced in higher latitudes. However, this phenomenon has not been adequately studied near the Equator. OBJECTIVE: To explore the risk of multiple sclerosis associated with month, season of birth, and sunlight exposure variables in Colombia. METHODS: In this case-control study, 668 multiple sclerosis cases were matched to 2672 controls by sex and age. Association of multiple sclerosis with each month/season of birth and sunlight exposure variables was estimated with multilevel mixed-effects logistic regression and ecological regression models, respectively. Seasonality in the births of multiple sclerosis was assessed with a non-parametric seasonality test. RESULTS: We found a higher probability of multiple sclerosis in September (0.25; 95% confidence interval (CI) = 0.21-0.31) and lower in March (0.15; 95% CI = 0.10-0.18), which turned non-significant after a multiple comparisons test. Sunlight exposure variables had no significant effect on the risk of MS, and the tests of seasonality in the births of MS did not show significant results. CONCLUSION: Our results show no seasonality in the risk of multiple sclerosis near the Equator, supporting the hypothesis that this phenomenon is latitude dependent.

State of the science on prevention and screening to reduce melanoma incidence and mortality: The time is now.

Answer questions and earn CME/CNE Although overall cancer incidence rates are decreasing, melanoma incidence rates continue to increase about 3% annually. Melanoma is a significant public health problem that exacts a substantial financial burden. Years of potential life lost from melanoma deaths contribute to the social, economic, and human toll of this disease. However, most cases are potentially preventable. Research has clearly established that exposure to ultraviolet radiation increases melanoma risk. Unprecedented antitumor activity and evolving survival benefit from novel targeted therapies and immunotherapies are now available for patients with unresectable and/or metastatic melanoma. Still, prevention (minimizing sun exposure that may result in tanned or sunburned skin and avoiding indoor tanning) and early detection (identifying lesions before they become invasive or at an earlier stage) have significant potential to reduce melanoma incidence and melanoma-associated deaths. This article reviews the state of the science on prevention and early detection of melanoma and current areas of scientific uncertainty and ongoing debate. The US Surgeon General's Call to Action to Prevent Skin Cancer and US Preventive Services Task Force reviews on skin cancer have propelled a national discussion on melanoma prevention and screening that makes this an extraordinary and exciting time for diverse disciplines in multiple sectors-health care, government, education, business, advocacy, and community-to coordinate efforts and leverage existing knowledge to make major strides in reducing the public health burden of melanoma in the United States. CA Cancer J Clin 2016;66:460-480. © 2016 American Cancer Society.

Educational interventions to promote sun-protection behaviors in adolescents in the United States: A systematic review.

The most prevalent modifiable risk factor for skin cancer is cumulative lifetime exposure to ultraviolet (UV) radiation, supporting the development of interventions promoting the early adoption of sun-protection behaviors. This systematic review summarizes behavioral interventions designed to promote sun-protection behaviors and reduce harmful UV exposure among U.S. adolescents. Ten studies describing 15 intervention arms were ultimately included in this review and comprised seven cross-sectional studies, a cohort study, a quasi-experimental study, and a randomized controlled trial. Most interventions included in this review were effective in increasing awareness of skin cancer and knowledge of the risk factors for skin cancer, but knowledge did not correlate with self-reported frequency of sun-protection behaviors in this population.

Chinese women with melasma exhibit a low minimal erythema dose to both UVA and UVB.

BACKGROUND: Melasma is a common disorder manifested by symmetric hyperpigmentation of sun-exposed skin. Although ultraviolet (UV) radiation is a known risk factor of melasma, whether skin sensitivities to UVA and/or UVB differ between healthy controls and female patients with melasma is unknown. METHODS: Minimal erythema dose (MED)-UVA and MED-UVB results were compared between female patients with melasma and healthy controls. Additionally, relationships between MED values and Melasma Area and Severity Index (MASI) scores, and skin color were assessed. RESULTS: The melasma and control groups included 142 and 137 subjects, respectively. Compared with healthy control group, our melasma group had lower MED-UVA (P < .001) and MED-UVB (P < .05). MASI scores were negatively correlated with MED-UVA and MED-UVB (P < .001). Additionally, Skin a* values in melasma-involved skin were negatively correlated with MED-UVA (P < .05). Skin b* values in melasma-involved skin were negatively correlated with MED-UVB and MED-UVA (P < .05). CONCLUSIONS: Patients with melasma exhibit a low MED to both UVA and UVB, rendering them have a predisposition to an increased UV sensitivity. Because of the association between melasma and UV sensitivity, sun exposure should be avoided to alleviate or prevent melasma.

Sun protection behaviour in organ transplant recipients and non-transplant patients attending a dermatology outpatient clinic in Sweden: A questionnaire survey.

BACKGROUND/PURPOSE: Organ transplant recipients (OTRs) are at high risk of developing skin cancer and are therefore advised to protect their skin against ultraviolet radiation from the sun. Specialized OTR clinics with dermatological follow-up may improve sun habits among OTRs. In this study, we compared self-reported sun exposure and sun protection behaviour between OTRs and non-transplant patients (non-TPs) and between OTRs with and without special dermatological follow-up. METHODS: Patients from Sahlgrenska University Hospital, Gothenburg, Sweden, completed a sun exposure questionnaire. Between 2011 and 2015, 282 OTRs transplanted in the period 1976-2014 and 414 non-TPs were recruited among dermatological outpatients. Participants were stratified into five groups by their status as OTRs or non-TPs and by attendance to dermatological follow-up. RESULTS: More non-TPs than OTRs reported one or more sunburns in the past year, 46% vs. 20%, P < .0001). More OTRs with than OTRs without dermatological follow-up reported frequent use of sunscreens (63% vs 44%, P = .006). More OTRs with follow-up used one or more sun protection measure such as covering clothes, than other OTRs (54% vs 34%, P = .016). CONCLUSION: In this study, OTRs reported less sun exposure than non-TPs. Specialized dermatological follow-up seems to improve sun protection behaviour among OTRs. We suggest that specialized OTR clinics should be more broadly implemented.

Cosmeceutical Therapy: Engaging the Repercussions of UVR Photoaging on the Skin's Circadian Rhythm.

Sunlight is an important factor in regulating the central circadian rhythm, including the modulation of our sleep/wake cycles. Sunlight had also been discovered to have a prominent influence on our skin's circadian rhythm. Overexposure or prolonged exposure to the sun can cause skin photodamage, such as the formation of irregular pigmentation, collagen degradation, DNA damage, and even skin cancer. Hence, this review will be looking into the detrimental effects of sunlight on our skin, not only at the aspect of photoaging but also at its impact on the skin's circadian rhythm. The growing market trend of natural-product-based cosmeceuticals as also caused us to question their potential to modulate the skin's circadian rhythm. Questions about how the skin's circadian rhythm could counteract photodamage and how best to maximize its biopotential will be discussed in this article. These discoveries regarding the skin's circadian rhythm have opened up a completely new level of understanding of our skin's molecular mechanism and may very well aid cosmeceutical companies, in the near future, to develop better products that not only suppress photoaging but remain effective and relevant throughout the day.

[Progress in health effects and measurement standards of ultraviolet radiation in the workplace].

Ultraviolet radiation affects human health. On the one hand, moderate amounts of UV radiation can promote human health and have the effect of promoting vitamin D production; but on the other hand, excessive UV radiation can also cause adverse effects on human skin and eyes, such as causing skin photoaging, skin cancer, electrophthalmia and cataracts to occur. Therefore, the measurement of ultraviolet radiation is extremely important. This paper mainly reviews the health effects of ultraviolet radiation and the progress of measurement standards in the workplace, and puts forward suggestions on the revision of the existing standards from five aspects including use new measuring instruments and methods, improve the existing measuring instruments, specify the number of measurements, expand the scope of application of the standards and consider the influence of the sun on the measurement of artificial ultraviolet radiation, so as to provide reference for the revision of new standards.

An Ecological Study Indicates the Importance of Ultraviolet A Protection in Sunscreens.

The use of sunscreens is recommended to limit the impact of sun exposure on the skin. The objective of this study was to examine the relationship between sunscreen sales and melanoma in 4 different countries with diverse sunscreen regulations. Data from publicly avail-able databases were examined for Sweden, England, Australia, and the USA from 1999 to 2018. The association between incidence of melanoma and sunscreen sales was estimated using a generalized estimating equation, and modelling was used to predict melanoma cases. Incidence of melanoma was positively associated with sunscreen sales in England, Australia, and the USA, and negatively associated with sunscreen sales in Sweden. Growth rates in melanoma cases of 0.42%, 16.7%, 19.1% and 12.2% were predicted for Sweden, England, Australia, and the USA, respectively. The differences observed between England, Australia, and the USA, on the one hand, and Sweden, on the other hand, are consistent with the adoption of strong regulations requiring the use of ultraviolet A blocking agents in sunscreens.

Patient and Tumour Characteristics of Keratoacanthoma in a Large, Community-based Cohort Study from Queensland, Australia.

Keratoacanthomas are common keratinocyte skin tumours. However, there is little community-based data published on the clinical features of keratoacanthoma. The aim of this study was to describe the patient and tumour characteristics of keratoacanthomas, as well as their treatment patterns. Data were obtained from the QSkin Sun and Health study, a prospective cohort of 40,438 randomly sampled and consented participants aged 40-69 years in Queensland, Australia. In 2010, a baseline survey collected data, including demography, phenotype, ultraviolet radiation exposure, medical history and lifestyle. Histopathological reports of keratoacanthomas arising until 30 June 2014 were reviewed. In total, 584 participants developed 738 keratoacanthomas; 18% of participants developed multiple tumours. Common patient characteristics were male sex (58%), age ≥60 years (76%), fair skin (80%), and previous history of actinic keratoses/keratinocyte cancers (89%). Keratoacanthomas were commonly located on the legs/feet (48%), and rarely on the the head/neck (7%). Excision was the most frequently used surgical method (71%) Evidence of histopathological regression was reported in 67% of keratoacanthomas, suggesting a potential for spontan-eous resolution in a significant proportion of keratoacanthomas.

Surface Activation of Titanium Dental Implants by Using UVC-LED Irradiation.

Organic contaminants significantly limit the bioactivity of titanium implants, resulting in the degradation known as the ageing of titanium. To reactivate the surfaces, they can be photofunctionalized, i.e., irradiated with C-range ultraviolet (UVC) light. This descriptive in vitro study compares the effectiveness of novel light-emitting diode (LED) technology to remove contaminant hydrocarbons from three different commercially available titanium dental implants: THD, TiUnite, and SLA. The surface topography and morphology were characterized by scanning electron microscopy (SEM). The chemical compositions were analyzed by X-ray photoelectron spectroscopy (XPS), before and after the lighting treatment, by a pair of closely placed UVC (λ = 278 nm) and LED devices for 24 h. SEM analysis showed morphological differences at the macro- and micro-scopic level. XPS analysis showed a remarkable reduction in the carbon contents after the UVC treatment: from 25.6 to 19.5 C at. % (carbon atomic concentration) in the THD; from 30.2 to 20.2 C at. % in the TiUnite; from 26.1 to 19.2 C at. % in the SLA surface. Simultaneously, the concentration of oxygen and titanium increased. Therefore, LED-based UVC irradiation decontaminated titanium surfaces and improved the chemical features of them, regardless of the kind of surface.

Controversies on the Use of Ultraviolet Rays for Disinfection During the COVID-19 Pandemic.

During the coronavirus disease 2019 (COVID-19) pandemic, the use of ultraviolet (UV) rays to disinfect skin areas, clothes and other objects at the entry/exit points of public spaces has been widely discussed by stakeholders. While ultraviolet germicidal irradiation (UVGI) has been shown to effectively inactivate coronaviruses, including severe acute respiratory syndrome coronavirus (SARS-CoV)-1 and Middle East respiratory syndrome coronavirus (MERS-CoV), no specific evidence proves that it effectively inactivates the new SARS-CoV-2 virus that causes COVID-19. Because UV rays damage human tissue, UVGI should be used with caution and not directly on human skin. Various guidelines recommend that UVGI should not be used as a sole agent for disinfecting surfaces or objects but as an adjunct to the latest standard disinfecting procedures.

Quick assessment of influenza a virus infectivity with a long-range reverse-transcription quantitative polymerase chain reaction assay.

BACKGROUND: The polymerase chain reaction (PCR) is commonly used to detect viral pathogens because of its high sensitivity and specificity. However, conventional PCR methods cannot determine virus infectivity. Virus infectivity is conventionally examined with methods such as the plaque assay, even though such assays require several days. Long-range reverse-transcription quantitative PCR (RT-qPCR) has previously been suggested for the rapid assessment of RNA virus infectivity where the loss of infectivity is attributable to genomic fragmentation. METHODS: IAV was irradiated with 253.7 nm ultraviolet (UV) rays to induce genomic strand breaks that were confirmed by a full-length RT-PCR assay. The IAV was then subjected to plaque assay, conventional RT-qPCR and long-range RT-qPCR to examine the relationship between infectious titer and copy number. A simple linear regression analysis was performed to examine the correlation between the results of these assays. RESULTS: A long-range RT-qPCR assay was developed and validated for influenza A virus (IAV). Although only a few minutes of UV irradiation was required to completely inactivate IAV, genomic RNA remained detectable by the conventional RT-qPCR and the full-length RT-PCR for NS of viral genome following inactivation. A long-range RT-qPCR assay was then designed using RT-priming at the 3' termini of each genomic segment and subsequent qPCR of the 5' regions. UV-mediated IAV inactivation was successfully analyzed by the long-range RT-qPCR assay especially when targeting PA of the viral genome. This was also supported by the regression analysis that the long-range RT-qPCR is highly correlated with plaque assay (Adjusted R2 = 0.931, P = 0.000066). CONCLUSIONS: This study suggests that IAV infectivity can be predicted without the infectivity assays. The rapid detection of pathogenic IAV has, therefore, been achieved with this sensing technology.

Photofunctionalization as a suitable approach to improve the osseointegration of implants in animal models-A systematic review and meta-analysis.

OBJECTIVES: To determine whether photofunctionalization influences dental implant osseointegration. MATERIAL AND METHODS: Data on osseointegration rates were extracted from 8 databases, based on bone-to-implant contact (BIC) and pushout tests. Internal validity was accessed through the SYRCLE risk of bias tool for animal experimental studies. Meta-analyses were performed for investigation of the influence of photofunctionalization on implant osseointegration, with a random effect and a confidence interval of 95%. The certainty of evidence was accessed through the GRADE approach. RESULTS: Thirty-four records were identified, and 10 were included in the meta-analysis. Photofunctionalized implants showed higher mean values for BIC in rabbits (MD 6.92 [1.01, 12.82], p = .02), dogs (MD 23.70 [10.23, 37.16], p = .001), rats (MD 20.93 [12.91, 28.95], p < .0001), and in the pooled BIC analyses (MD 14.23 [7.80, 20.66], p < .0001) compared to those in control implants in the overall assay. Conversely, at late healing periods, the pooled BIC meta-analyses showed no statistically significant differences (p > .05) for photofunctionalized and control implants at 12 weeks of follow-up. For pushout analysis, photofunctionalized implants presented greater bone strength integration (MD 19.92 [13.88, 25.96], p < .0001) compared to that of control implants. The heterogeneity between studies ranged from "not important" to "moderate" for rabbits I2  = 24%, dogs I2  = 0%, rats I2  = 0%, and pooled BIC (I2  = 49%), while considerable heterogeneity was observed for pushouts (I2  = 90%). CONCLUSION: Photofunctionalization improves osseointegration in the initial healing period of implants, as summarized from available data from rabbit, dog, and rat in vivo models.

42 °C heat stress pretreatment protects human melanocytes against 308-nm laser-induced DNA damage in vitro.

Vitiligo is a common depigment of skin disorder due to loss of functional melanocytes. Recently, the phototherapy with a 308-nm xenon-chloride excimer laser (UVB laser) is wildly used in vitiligo treatment. However, excessive UVB will induce photo-damage and photo-carcinogenesis in melanocytes. Previous studies revealed a protective effect of heat on UVB-induced melanocyte damage. In this study, we combined heat stress pretreatment with UVB to evaluate whether heat stress pretreatment has an ameliorative effect on UVB-induced damage. Human primary melanocytes (HMCs) were cultured and irradiated with a 308-nm laser with/without heat treatment. MTT assay, apoptosis analysis, and comet assay were conducted to monitor the damage of HMCs. Western blot and immunofluorescence staining were performed to assess the expression and subcellular localization of HSP70. HMCs heated at 42 °C for 1 h exhibit no cytotoxicity. Furthermore, preheat treatment attenuated the UVB laser-induced injury, reduced the DNA damage, and attenuated the cell apoptosis. The level and the localization of HSP70 determined the protective effects against UVB-induced DNA damage. Combining preheat treatment with a 308-nm xenon-chloride excimer laser would be a potential therapeutic method not only promotes the repigment of vitiligo but also reduces the UVB-induced photo-damage.

Interactive Effect of Melatonin and UV-C on Phenylpropanoid Metabolite Production and Antioxidant Potential in Callus Cultures of Purple Basil (Ocimum basilicum L. var.s purpurascens).

The present study evaluated the interactive effect of melatonin and UV-C on phenylpropanoid metabolites profile and antioxidant potential of Ocimum basilicum L. Callus was treated with varying concentrations of melatonin and UV-C radiations for different time durations, either alone and/or in combination. Individual treatments of both UV-C and melatonin proved to be more effective than combine treatments. Results indicated that UV-C (10 min) exposure increased rosmarinic acid (134.5 mg/g dry weight (DW)), which was 2.3-fold greater than control. Chichoric acid (51.52 mg/g DW) and anthocyanin (cyanide 0.50 mg/g DW) were almost 4.1-fold, while peonidin was found 2.7-fold higher in UV-C (50 min) exposure. In the case of melatonin, 1.0 mg/L concentrations showed maximum rosmarinic acid (79.4 mg/g DW) accumulation; i.e., 1.4-fold more, as compared to the control. However, 2 mg/L melatonin accumulate chichoric acid (39.99 mg/g DW) and anthocyanin (cyanide: 0.45 mg/g DW and peonidin: 0.22 mg/g DW); i.e., 3.2, 3.7 and 2.0-fold increase, as compared to the control, respectively. On the other hand, melatonin-combined treatment (melatonin (Mel) (4 mg/L) + UV-C (20 min)) was proved to be effective in caffeic acid elicitation, which was 1.9-fold greater than the control. Furthermore, antioxidant potential was evaluated by both in vitro (DPPH, ABTS and FRAP assays) and in cellulo methods. Maximum in vitro antioxidant activity (DPPH: 90.6% and ABTS: 1909.5 µM) was observed for UV-C (50 min)-treated cultures. The highest in vitro antioxidant activity measured with the ABTS assay as compared to the FRAP assay, suggesting the main contribution of antioxidants from basil callus extracts acting through a hydrogen atom transfer (HAT) over an electron transfer (ET)-based mechanism. Cellular antioxidant assay was evaluated by production of ROS/RNS species using yeast cell cultures and further confirmed the protective action of the corresponding callus extracts against oxidative stress. Overall, both melatonin and UV-C are here proved to be effective elicitors since a positive correlation between the induced production of phenolic compounds, and in cellulo antioxidant action of basil callus extracts were observed.