Taek Hwan Lee

Inhibitory effects of resveratrol on melanin synthesis in ultraviolet B-induced pigmentation in Guinea pig skin.

Resveratrol is a polyphenolic compound found in various natural products such as grapes and berries and possesses anti-cancer, anti-hyperlipidemia, and anti-aging properties. Recently, it has been reported that resveratrol inhibits α-melanocyte-stimulating hormone signaling, viability, and migration in melanoma cells. However, these effects have not been confirmed in vivo, specifically brownish guinea pigs. To evaluate the potential of resveratrol as a regulator of melanin for hyperpigmentation therapy, the influence of resveratrol on pigmentation was investigated by ultraviolet B-induced hyperpigmentation in brownish guinea pig skin. We found that resveratrol reduced the expression of melanogenesis-related proteins tyrosinase, tyrosinase-related proteins 1 and 2, and microphthalmia-associated transcription factor in melanoma cells. Furthermore, topical application of resveratrol was demonstrated to significantly decrease hyperpigmentation on ultraviolet B-stimulated guinea pig skin in vivo. Based on our histological data, resveratrol inhibits melanin synthesis via a reduction in tyrosinase-related protein 2 among the melanogenic enzymes. This study is the first to provide evidence supporting resveratrol as a depigmentation agent, along with further clinical investigation of resveratrol in ultraviolet B-induced skin disorders such as hyperpigmentation and skin photoaging.

Enzyme-processed Korean Red Ginseng extracts protects against skin damage induced by UVB irradiation in hairless mice

UV irradiation is the main factor contributing to skin damages that are associated with an excessive production of matrix-degrading metalloproteinase (MMP)-1 and a deficient expression of collagens. To date, red ginseng has been revealed to possess many biomedical effects, such as anti-aging, anti-oxidation, and anti-inflammatory. In this study, we prepared the Korean Red Ginseng extracts treated with enzyme (KRGE) and investigated the effects of dietary KRGE on the formation of wrinkles generated by UVB irradiation in hairless mice. It was found that KRGE inhibited the UVB-induced formation of wrinkles, epidermal thickness, and skin dryness in hairless mice. Further results also showed that KRGE attenuated UVB-induced MMP-1 level, while accelerated procollagen type I, transforming growth factor-β1 secretion. Interestingly, the expression of profilaggrin and filaggrin in both the epidermis and dermis were decreased due to UVB exposure and reversed by KRGE. The KRGE 0.06% was prior to KRGE 0.24%. In view of these results, which indicated that KRGE protected skin from UVB-induced photodamages, which may not only mediated by regulating of MMP-1 and procollagen type I, but also by increasing the production of profilaggrin and filaggrin. In conclusion, our results suggest that KRGE may be a promising agent for the treatment of skin photodamages. The challenge of KRGE will be expected as cosmeceuticals and nutraceuticals in order to intervene in aging-related degenerative skin changes.

Dietary fermented soybean suppresses UVB-induced skin inflammation in hairless mice via regulation of the MAPK signaling pathway.

Soybean may be a promising ingredient for regulating UVB-induced inflammatory damage to the skin. We investigated the anti-inflammatory effects of diets supplemented with fermented soybean on UVB-induced skin photodamage and the effectiveness of soybean (S) and fermented soybean (FS) dietary supplementation. To investigate the effects of two major isoflavones-daidzein and genistein-from FS, we used cocultures with keratinocytes and fibroblasts. Genistein treatment strongly inhibited the production of IL-6 and MAPK signaling. Forty hairless male mice divided into four groups were fed with a control diet (group N: normal, group C; +UVB) or diets with 2.5% S+UVB or 2.5% FS+UVB (group S, group FS) for 8 weeks. Macrophage infiltration to the dermis was reduced more in groups S and FS than in group C. The expression levels of iNOS and COX-2 were significantly decreased in group FS (by 7.7% ± 0.4% and 21.2% ± 0.3%, respectively [p < 0.05]).

Anti-neuroinflammatory and neuroprotective effects of the Lindera neesiana fruit in vitro

BACKGROUND Lindera neesiana Kurz (Lauraceae), popularly known as Siltimur in Nepal, is an aromatic and spicy plant with edible fruits. It is a traditional herbal medicine widely used for the treatment of diarrhea, tooth pain, headache, and gastric disorders and is also used as a stimulant. PURPOSE The aim of the present study was to examine in vitro cytoprotective, anti-neuroinflammatory and neuroprotective potential of an aqueous extract of L. neesiana (LNE) fruit using different central nervous system (CNS) cell lines. METHODS In order to study the neuroprotective potential of LNE, we used three different types of CNS cell lines: murine microglia (BV2), rat glioma (C6), and mouse neuroblastoma (N2a). Cell viability was assessed using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) reagent, and prostaglandin E2 (PGE2), tumor necrosis factor alpha (TNF-α), interleukin (IL)-6, and nerve growth factor (NGF) release in the culture media was determined using enzyme linked immunosorbent assay (ELISA) kits. Western blot analysis was performed to determine the protein expression of inducible nitric oxide synthase (iNOS), cyclooxygenase 2 (COX2), mitogen activated protein kinase (MAPK) family proteins, Bax, B cell lymphoma (BCL)-2, and cleaved caspase 3. Neurite outgrowth was determined using the IncuCyte imaging system. RESULTS LNE treatment not only reduced nitric oxide (NO) production in a dose-dependent manner, but also significantly reduced proinflammatory cytokines, iNOS and COX-2 production by lipopolysaccharide (LPS) stimulated BV-2 cells. LNE increased the expression of phosphorylated (p)-extracellular signal-regulated kinase (ERK), whereas p-p38 and p- janus kinase (JNK) expression was significantly decreased in activated microglia. Furthermore, LNE increased cell viability of N2a cells, which was accompanied by decreased caspase-3 expression and the ratio of Bax/Bcl2 protein expression as well as increased NGF and neurite outgrowth, suggesting its neuroprotective potential against LPS-induced effects. Additionally, LNE substantially increased nuclear factor erythroid 2-related factor 2 (Nrf2) secretion in N2a cells and inhibited lipid dehydrogenase (LDH) release in H2O2-stimulated BV2 cells demonstrating the strong anti-inflammatory and antioxidant effects of LNE in CNS cell lines. CONCLUSION Here we found that water the soluble extract of LNE has promising anti-neuroinflammation and anti-apoptotic properties and identify LNE as a potential natural candidate for neuroprotection.

Resveratrol-Enriched Rice Down-Regulates Melanin Synthesis in UVB-Induced Guinea Pigs Epidermal Skin Tissue.

Synthetic compounds that are used in the clinic to regulate skin hyperpigmentation, such as arbutin, hydroquinone, and kojic acid, are only moderately effective. But, their use is limited by side effects. As part of an effort to overcome the limitations, we developed resveratrol-enriched rice (RR) using genetic engineering technique. Each of resveratrol and rice has been reported to produce anti-melanogenic effects. Therefore, we hypothesized that RR would show more anti-melanogenic effects than those of resveratrol or rice alone. Anti-melanogenic effect of RR was done by using melan-a mouse melanocytes. The depigmenting efficacy was then observed following topical application of the RR to UVB-stimulated hyperpigmented dorsal skin of guinea pigs. Treatment with RR extract resulted a 21.4 ± 0.7% decrease in tyrosinase expression at melan-a cells. Colorimetric analysis showed a significantly lower depigmenting value by day 9 following treatment with RR in UVB-irradiated guinea pigs the dorsal skin (p<0.01), indicating that RR produced a depigmentation effect. By staining with Fontana-Masson stain, we found that the RR-treated group had more effect histopathologically in epidermal melanin production than resveratrol or rice alone-treated group. RR was associated with reduction in the levels of microphthalmia-associated transcription factor (MITF), and downregulation of tyrosinase and tyrosinase-related protein (TRP-2) expression, leading to inhibit epidermal melanin production by western blot analysis. This study suggests that the resveratrol-enriched rice may be a promising candidate in regulating skin pigmentation with UVB exposure.

A novel synthetic Piper amide derivative NED-180 inhibits hyperpigmentation by activating the PI3K and ERK pathways and by regulating Ca2+ influx via TRPM1 channels.

Piper amides have a characteristic, unsaturated amide group and exhibit diverse biological activities, including proliferation and differentiation of melanocytes, although the molecular mechanisms underlying its antimelanogenesis effect remain unknown. We screened a selected chemical library of newly synthesized Piper amide derivatives and identified (E)‐3‐(4‐(tert‐butyl)phenyl)‐N‐(2,3‐dihydrobenzo[b][1,4]dioxin‐6‐yl)acrylamide (NED‐180) as one of the most potent compounds in suppressing melanogenesis. In murine melan‐a melanocytes, NED‐180 downregulated the expression of melanogenic regulatory proteins including tyrosinase, Tyrp1, Dct, and MITF. PI3K/Akt‐dependent phosphorylation of GSK3β by NED‐180 decreases MITF phosphorylation and inhibits melanogenesis without any effects on cytotoxicity and proliferation. Furthermore, topical application of NED‐180 significantly ameliorated UVB‐induced skin hyperpigmentation in guinea pigs. Interestingly, data obtained using calcium imaging techniques suggested that NED‐180 reduced the TPA‐induced activation of TRPM1 (melastatin), which could explain the NED‐180‐induced inhibition of melanogenesis. All things taken together, NED‐180 triggers activation of multiple pathways, such as PI3K and ERK, and inhibits TRPM1/TRPV1, leading to inhibition of melanogenesis.

Flavonoids isolated from Lespedeza cuneata G. Don and their inhibitory effects on nitric oxide production in lipopolysaccharide-stimulated BV-2 microglia cells.

Background: Lespedeza cuneata (Dum. Cours.) G. Don, a perennial legume native to Eastern Asia, has been used therapeutically in traditional Asian medicine to protect the function of liver, kidneys and lungs. However, its effect on inflammatory nitric oxide (NO) production and the active constituents have not yet been explored. Objective: In this study, we investigated the phytochemical constituents of L. cuneata and evaluated their effect on NO production using lipopolysaccharide (LPS)-stimulated BV2 cells. Materials and Methods: The 80% methanol extract of the aerial part of L. cuneata were used for the isolation of flavonoids. The isolated compounds were elucidated by various spectroscopic methods including nuclear magnetic resonance and mass spectrometry spectrometry. To evaluate the effect on inflammatory NO production, LPS-stimulated murine microglia BV-2 cells were used as a screening system. Results: Nine flavonoids were isolated from the aerial parts of L. cuneata. Among the isolated flavonoids, compounds 4, 5, 7 and 9 are reported from the genus Lespedeza for the first time. Moreover, compounds 1 and 6 showed significant inhibitory effects on NO production in LPS-stimulated BV2 cells without cell toxicity. Conclusion: In this study, nine flavonoids were isolated from L. cuneata. Among the compounds, only 1 and 6, which have free hydroxyl groups at both C3 and C7 showed significant inhibitory activity on NO production in LPS-stimulated BV2 cells. These results suggested L. cuneata and its flavonoid constituents as possible candidate for the treatment of various inflammatory diseases.

Resveratrol-Enriched Rice Attenuates UVB-ROS-Induced Skin Aging via Downregulation of Inflammatory Cascades

The skin is the outermost protective barrier between the internal and external environments in humans. Chronic exposure to ultraviolet (UV) radiation is a major cause of skin aging. UVB radiation penetrates the skin and induces ROS production that activates three major skin aging cascades: matrix metalloproteinase- (MMP-) 1-mediated aging; MAPK-AP-1/NF-κB-TNF-α/IL-6, iNOS, and COX-2-mediated inflammation-induced aging; and p53-Bax-cleaved caspase-3-cytochrome C-mediated apoptosis-induced aging. These mechanisms are collectively responsible for the wrinkling and photoaging characteristic of UVB-induced skin aging. There is an urgent requirement for a treatment that not only controls these pathways to prevent skin aging but also avoids the adverse effects often encountered when applying bioactive compounds in concentrated doses. In this study, we investigated the efficacy of genetically modified normal edible rice (NR) that produces the antiaging compound resveratrol (R) as a treatment for skin aging. This resveratrol-enriched rice (RR) overcomes the drawbacks of R and enhances its antiaging potential by controlling the abovementioned three major pathways of skin aging. RR does not exhibit the toxicity of R alone and promisingly downregulates the pathways underlying UVB-ROS-induced skin aging. These findings advocate the use of RR as a nutraceutical for antiaging purposes.

Vaccinium bracteatum Thunb. Exerts Anti-Inflammatory Activity by Inhibiting NF-κB Activation in BV-2 Microglial Cells

This study was designed to evaluate the pharmacological effects of Vaccinium bracteatum Thunb. methanol extract (VBME) on microglial activation and to identify the underlying mechanisms of action of these effects. The anti-inflammatory properties of VBME were studied using lipopolysaccharide (LPS)-stimulated BV-2 microglial cells. We measured the production of nitric oxide (NO), inducible NO synthase (iNOS), cyclooxygenase (COX)-2, prostaglandin E2 (PGE2), tumor necrosis factor-alpha (TNF-α), interleukin-1 beta (IL-1β), and interleukin-6 (IL-6) as inflammatory parameters. We also examined the effect of VBME on intracellular reactive oxygen species (ROS) production and the activity of nuclear factor-kappa B p65 (NF-κB p65). VBME significantly inhibited LPS-induced production of NO and PGE2 and LPS-mediated upregulation of iNOS and COX-2 expression in a dose-dependent manner; importantly, VBME was not cytotoxic. VBME also significantly reduced the generation of the pro-inflammatory cytokines TNF-α, IL-1β, and IL-6. In addition, VBME significantly dampened intracellular ROS production and suppressed NF-κB p65 translocation by blocking IκB-α phosphorylation and degradation in LPS-stimulated BV2 cells. Our findings indicate that VBME inhibits the production of inflammatory mediators in BV-2 microglial cells by suppressing NF-κB signaling. Thus, VBME may be useful in the treatment of neurodegenerative diseases due to its ability to inhibit inflammatory mediator production in activated BV-2 microglial cells.

Juglone up-regulates sirt1 in skin cells under normal and UVB irradiated conditions.

Sirtuin 1 (Sirt1) is a member of the sirtuin family of proteins in mammals. Sirt1 is the most widely studied of the seven sirtuin family members because it is the closest homologue to yeast Sir2 [1]. Sirt1 regulates several genes with a very general and widely used regulatory mechanism, and is involved in various disorders. Recently, regulators and expressional alterations of Sirt1 have been reported to be related with processes like inflammation [2], oxidative damage [3], apoptosis [4], diabetes [5], and aging [6]. However, the changes in Sirt1 expression under UVB conditions have not been extensively studied. Juglone; a naturally occurring Pin1 inhibitor found inwalnuts is known to possess anti-cancer [7] and anti-proliferative [8] effects. However, role of juglone in Sirt1 regulation has never been reported. We sought to demonstrate the relationship between Pin1 and Sirt1 expression in skin cells under normal and UVB irradiated conditions by using juglone, along with resveratrol which is a well-known Sirt1 activator [9]. HaCaT and NHDF cells obtained from the Korean Cell Line Bank (Seoul National University, Seoul, Korea) were cultured in high