• Proceedings of the Korean Society of Applied Pharmacology
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• 2007.11a
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• pp.79-92
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• 2007

Oxidative stress have known to be a risk factor for the degenerative processes and closely related to a lot of diseases. It is well established that antioxidants are good in protection and therapeutic means against oxidative damage. There is increasing interest in natural antioxidants and many natural antioxidants have been found and utilized as the possible protection for various diseases and skin aging. We have screened natural antioxidant agents for cosmeceuticals, nutraceuticals, and drugs as therapeutic and preventive means against oxidative stress, and have developed a number of novel antioxidants from various natural sources. A novel melanin synthesis inhibitor, Melanocin A, isolated from the metabolite of a fungal strain Eupenicillium shearii F80695 inhibited mushroom tyrosinase and melanin biosynthesis of B16 melanoma cells with $IC_{50}$ value of 9.0 nM and MIC value of $0.9\;{\mu}M$, respectively. Melanocin A also exhibited potent antioxidant activity by scavenging of DPPH and superoxide anion radicals. UV was found to increase the level of hydrogen peroxides and other reactive oxygen species (ROS) in skin tissues. This increase in ROS may not only alter the structure and function of many genes and proteins directly but may also modulate their expressions through signal transduction pathways and, ultimately, lead to skin damage. We investigated the effect of Melanocin A on UV-induced premature skin aging. Firstly, the effect of Melanocin A on UV-induced matrix metalloproteinase (MMP)-9 expression in an immortalized human keratinocyte cell line, HaCaT in vitro was investigated. Acute UV irradiation induced MMP-9 expression at both the mRNA and protein levels and Melanocin A suppressed this expression in a dose-dependent manner. We then investigated UV-induced skin changes in hairless mice in vivo by Melanocin A. Chronic exposure of hairless mouse dorsal skin to UV increased skin thickness and induced wrinkle formation and the gelatinase activities of MMP-2 and MMP-9. Moreover, Melanocin A significantly suppressed UV-induced morphologic skin changes and MMP-2 and MMP-9 expression. These results show that Melanocin A can prevent the harmful effects of UV that lead to skin aging. Therefore, we suggest that Melanocin A should be viewed as a potential therapeutic agent for preventing and/or treating premature skin aging. Terrein is a bioactive fungal metabolite isolated from Penicillium species. Terrein has a relatively simple structure and can be easily synthesized. However, the biologic effects of terrein are comparatively unknown. We found for the first time that terrein potently inhibit melanin production in melanocytes and has a strong hypopigmentary effect in a spontaneously immortalized mouse melanocyte cell line, Mel-Ab. Treatment of Mel-Ab cells with terrein (10-100 mM) for 4 days significantly reduced melanin levels in a dose-dependent manner. In addition, terrein at the same concentration also reduced tyrosinase activity. We then investigated whether terrein influences the extracellular signal-regulated protein kinase (ERK) pathway and the expression of microphthalmia-associated transcription factor (MITF), which is required for tyrosinase expression. Terrein was found to induce sustained ERK activation and MITF down-regulation, and luciferase assays showed that terrein inhibits MITF promoter activity in a dose-dependent manner. To elucidate the correlation between ERK pathway activation and a decreased MITF transcriptional level, PD98059, a specific inhibitor of the ERK pathway, was applied before terrain treatment and found to abrogate the terrein-induced MITF attenuation. Terrein also reduced the tyrosinase protein level for at least 72 h. These results suggest that terrain reduces melanin synthesis by reducing tyrosinase production via ERK activation, and that this is followed by MITF down-regulation.

• Journal of Life Science
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• v.31 no.8
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• pp.699-709
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• 2021

Muscle mass improvement through lifestyle modification has been shown to reduce the risk of metabolic syndrome. This study examined the capacity of ethanol extracts of Scytosiphon lomentaria (SLE) to suppress the bioactivity of myostatin, a potent negative regulator of skeletal muscle mass, as well as the effect of SLE treatment on metabolic homeostasis in obese zebrafish induced by high feeding. A total of 10 ㎍/ml SLE completely blocked myostatin (1 nM/ml) signaling in the pGL3-(CAGA)₁₂ luciferase assay and suppressed myostatin-induced Smad2 phosphorylation in the Western blot analysis. In the zebrafish larvae analysis, the whole body glucose concentration of the high feeding control (HFC) group was significantly higher than that of the normal feeding control (NFC) group. However, the glucose levels of the high feeding group treated with 12.5 ug SLE and of the high feeding group treated with 18.75 ug SLE were similar to those of the NFC group. The mRNA expression level of the GLUT2 gene of the HFC group was significantly lower than that of the NFC group. SLE treatment restored the expression of the GLUT2 gene to a level that was close to that of the NFC group, indicating that SLE is capable of regulating glucose levels in zebrafish larvae. The current results highlight the potential of SLE as a natural MSTN inhibitor and supplement that can be used to facilitate the treatment of metabolic syndrome.

• Journal of Life Science
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• v.32 no.11
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• pp.833-840
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• 2022

Chronic inflammation has been shown to be closely associated with tumor development and progression. Nuclear factor kappa B (NF-κB) is composed of a family of five transcription factors. NF-κB signaling plays a crucial role in the inflammatory response and is often found to be dysregulated in various types of cancer, making it an attractive target in cancer therapeutics. In this study, CDC-like kinase 3 (CLK3) was identified as a novel kinase that regulates the NF-κB signaling pathway. Our data demonstrate that CLK3 inhibits the canonical and non-canonical NF-κB pathways. Luciferase assays following the transient or stable expression of CLK3 indicated that this kinase inhibited NF-κB activation mediated by Tumor necrosis factor-alpha (TNFα) and Phorbol 12-myristate 13-acetate (PMA), which are known to activate NF-κB signaling via the canonical pathway. Consistent with data on the ectopic expression of CLK3, CLK3 knockdown using shRNA constructs increased NF-κB activity 1.5-fold upon stimulation with TNFα in HEK293 cells compared with the control cells. Additionally, overexpression of CLK3 suppressed the activation of this signaling pathway induced by NF-κB-inducing kinase (NIK) or CD40, which are well-established activators of the non-canonical pathway. To further examine the negative impact of CLK3 on NF-κB signaling, we performed Western blotting following the TNFα treatment to directly identify the molecular components of the NF-κB pathway that are affected by this kinase. Our results revealed that CLK3 mitigated the phosphorylation/activation of transforming growth factor-α-activated kinase 1 (TAK1), inhibitor of NF-κB kinase alpha/beta (IKKα/α), NF-κB p65 (RelA), NF-κB inhibitor alpha (IκBα), and Extracellular signal-regulated kinase 1/2-Mitogen-activated protein kinase (ERK1/2-MAPK), suggesting that CLK3 inhibits both the NF-κB and MAPK signaling activated by TNFα exposure. Further studies are required to elucidate the mechanism by which CLK3 inhibits the canonical and non-canonical NF-κB pathways. Collectively, these findings reveal CLK3 as a novel negative regulator of NF-κB signaling.

• Journal of Ginseng Research
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• v.47 no.3
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• pp.408-419
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• 2023

Background: Ginsenoside compound K (CK), the main active metabolite in Panax ginseng, has shown good safety and bioavailability in clinical trials and exerts neuroprotective effects in cerebral ischemic stroke. However, its potential role in the prevention of cerebral ischemia/reperfusion (I/R) injury remains unclear. Our study aimed to investigate the molecular mechanism of ginsenoside CK against cerebral I/R injury. Methods: We used a combination of in vitro and in vivo models, including oxygen and glucose deprivation/reperfusion induced PC12 cell model and middle cerebral artery occlusion/reperfusion induced rat model, to mimic I/R injury. Intracellular oxygen consumption and extracellular acidification rate were analyzed by Seahorse multifunctional energy metabolism system; ATP production was detected by luciferase method. The number and size of mitochondria were analyzed by transmission electron microscopy and MitoTracker probe combined with confocal laser microscopy. The potential mechanisms of ginsenoside CK on mitochondrial dynamics and bioenergy were evaluated by RNA interference, pharmacological antagonism combined with co-immunoprecipitation analysis and phenotypic analysis. Results: Ginsenoside CK pretreatment could attenuate mitochondrial translocation of DRP1, mitophagy, mitochondrial apoptosis, and neuronal bioenergy imbalance against cerebral I/R injury in both in vitro and in vivo models. Our data also confirmed that ginsenoside CK administration could reduce the binding affinity of Mul1 and Mfn2 to inhibit the ubiquitination and degradation of Mfn2, thereby elevating the protein level of Mfn2 in cerebral I/R injury. Conclusion: These data provide evidence that ginsenoside CK may be a promising therapeutic agent against cerebral I/R injury via Mul1/Mfn2 mediated mitochondrial dynamics and bioenergy.