Thai herbal antipyretic 22 formula (APF22) inhibits UVA-mediated melanogenesis through activation of Nrf2-regulated antioxidant defense.

Thai herbal antipyretic 22 formula (APF22), a polyherbal formula, has been traditionally used to treat dermatologic problems including hyperpigmentation. Exposure of the skin to ultraviolet A (UVA) causes abnormal melanin production induced by photooxidative stress. This study thus aimed to investigate the protective effects of APF22 extracts and phenolic compounds, ferulic acid (FA), and gallic acid (GA; used as positive control and reference compounds), on melanogenesis through modulation of nuclear factor E2-related factor 2 (Nrf2) signaling and antioxidant defenses in mouse melanoma (B16F10) cells exposed to UVA. Our results revealed that the APF22 extracts, FA, and GA reduced melanin synthesis as well as activity and protein levels of tyrosinase in UVA-irradiated B16F10 cells. Moreover, APF22 extracts and both FA and GA were able to activate Nrf2-antioxidant response element signaling and promote antioxidant defenses including glutathione, catalase, glutathione peroxidase, and the glutathione-S-transferase at both mRNA and enzyme activity levels in irradiated cells. In conclusion, APF22 extracts suppressed UVA-mediated melanogenesis in B16F10 cells possibly via redox mechanisms involving activation of Nrf2 signaling and upregulation of antioxidant defenses. Moreover, pharmacological action of the APF22 extracts may be attributed to the phenolic compounds, FA, and GA, probably serving as the APF22's active compounds.

The effect of botulinum toxin type A in different dilution on the contraction of fibroblast-In vitro study.

BACKGROUND: Botulinum toxin type A (BoNT-A) may directly remodel dermal tissues or induce a loss of normal morphology and cytoplasmic retraction and spread. Intradermal injection was claimed to produce a dermo-lifting effect, including midface lifting by using low concentration with variable dilution. OBJECTIVE: To understand how intradermal BoNT-A achieves tissue lifting, we examined different type of BoNT-A and their effects on dermal fibroblast contraction. METHODS: Normal human dermal fibroblasts were treated with onabotulinumtoxin (ONA), abobotulinumtoxin (ABO), prabotulinumtoxinA (PRABO), incobotulinumtoxinA (INCO), and letibotulinumtoxin A (LETI) in dilutions used in real-world practice. Fifty fibroblasts per dilution were photographed and measured the length to demonstrate their contraction every 2 hours from baseline (0 hours) to 12 hours post-treatment. RESULTS: ONA did not significantly decrease fibroblast lengths, at any timepoint or dilution. At 1:7 dilution ratios, ABO decreased fibroblast lengths after 2 hours and significantly after 10-12 hours. At 1:7, 1:8, 1:9, and 1:10 dilution, PRABO decreased length, and most rapidly at 1:7 and 1:8. At 1:6, 1:8, 1:9, and 1:10 dilution, INCO decreased lengths almost immediately. At 1:6 dilution, INCO decreased lengths almost immediately. At 1:7 dilution, INCO decreased lengths after 2-4 hours, while at 1:8, 1:9, and 1:10 dilution, INCO decreased lenghts nearly imediately. LETI decreased lengths at all dilutions except 1:9, with near-immediate effects at 1:6, 1:7, 1:8, and 1:10. At 1:4 dilution, LETI decreased lengths from 1 hour. CONCLUSIONS: Different commercial preparations of BoNT-A toxins cause different fibroblast contractions in vitro. Product selection and dilution used may affect the clinical outcome of intradermal injection of BoNT-A for face lifting.

Photoprotection by dietary phenolics against melanogenesis induced by UVA through Nrf2-dependent antioxidant responses.

Dietary phenolics may play a protective role in UV-mediated skin pigmentation through their antioxidant and UV-absorbing actions. In this study, we investigated whether genetic silencing of Nrf2, regulating the transcription of antioxidant genes, affected melanogenesis in primary human epidermal melanocytes (HEMn) and B16F10 melanoma cells subjected to UVA (8J/cm(2)) exposure. Then, we explored the antimelanogenic actions of phenolics; caffeic acid (CA) and ferulic acid (FA) providing partial UVA protection; quercetin (QU) and rutin (RU) providing strong UVA protection and; avobenzone (AV), an efficient UVA filter, in association with modulation of Nrf2-mediated antioxidant defenses in response to UVA insults in B16F10 cells. Upon oxidative insults, Nrf2 silencing promoted melanogenesis in both HEMn and B16F10 cells irradiated with UVA. Stimulation of melanogenesis by UVA correlated with increased ROS and oxidative DNA damage (8-OHdG), GSH depletion as well as a transient downregulation of Nrf2 nuclear translocation and of Nrf2-ARE signaling in B16F10 cells. All test compounds exerted antimelanogenic effects with respect to their abilities to reverse UVA-mediated oxidative damage as well as downregulation of Nrf2 activity and its target antioxidants (GCLC, GST and NQO1) in B16F10 cells. In conclusion, defective Nrf2 may promote melanogenesis under UVA irradiation through oxidative stress mechanisms. Compounds with antioxidant and/or UVA absorption properties could protect against UVA-induced melanogenesis through indirect regulatory effect on Nrf2-ARE pathway.

UVA-induced melanogenesis and modulation of glutathione redox system in different melanoma cell lines: the protective effect of gallic acid.

Oxidative stress has been suggested to play a role in ultraviolet A (UVA)-mediated melanogenesis. Glutathione (GSH) and GSH-related enzymes including γ-glutamate cysteine ligase (γ-GCL) and glutathione S-transferase (GST) are important antioxidant defenses responsible for maintaining cellular redox balance. Hence, improving GSH redox system to cope with oxidative insults may be essential for attenuation of abnormal melanin production. Gallic acid (GA), a dietary phenolic, has been shown to provide beneficial effects against hyperpigmentation possibly through its antioxidant properties. This study thus aimed to assess the antimelanogenic action of GA with regard to modulation of GSH-GCL system and GST in two melanoma cell lines, lightly pigmented G361 human melanoma and more pigmented B16F10 mouse melanoma cells, irradiated with UVA. G361 cells were shown to have lower basal GSH content and GST activity than B16F10 cells. Moreover, GA provided antimelanogenic effects in correlation with promotion of GSH levels, GST activity as well as γ-GCL and GST mRNA in both G361 and B16F10 cells at 2-h post-irradiation. In summary, GA exhibits protective effects on UVA-mediated melanogenesis possibly through improvement of GSH-related antioxidant defenses. Furthermore, different redox state in G361 and B16F10 cells may affect the responses of melanoma cells to GA.