Nitric oxide (NO) produced in large amounts by inducible nitric oxide synthase (iNOS) is known to be responsible for the vasodilation and hypotension observed during septic shock and inflammation. Thus, inhibitors of iNOS may be useful candidates for the treatment of inflammatory diseases accompanied by the overproduction of NO. In this study, we prepared alcoholic extracts of Jeju plants and screened them for their inhibitory activity against NO production in lipopolysaccharide (LPS)-activated macrophages. Among the 260 kinds of plant extract tested, 122 extracts showed potent inhibitory activity towards NO production by more than 25% at a concentration of 100 µg/mL. Plants such as Malus sieboldii, Vaccinium oldhamii, Corylus hallaisanensis, Carpinus laxiflora, Styrax obassia, and Securinega suffruticosa showed the most potent inhibition (above 70%) at a concentration of 100 µg/mL. The cytotoxic effects of the plant extracts were determined by colorimetric MTT assays and most plant extracts exhibited only moderate cytotoxicity at 100 µg/mL. Therefore, these plants should be considered promising candidates for the further purification of bioactive compounds and would be useful for the treatment of inflammatory diseases accompanying overproduction of NO.

Objective. Rheumatoid arthritis is a disease that, pathologically, is characterized by the progressive growth and invasion of the synovial pannus into the surrounding cartilage and bone. Many cytokines, including transforming growth factor ␤1 (TGF␤1), have been implicated in this process, but their mode of action is incompletely understood. The goal of the present study was to better understand the downstream signaling pathways of TGF␤ in fibroblasts.Methods. The role of phosphatidylinositol 3-kinase (PI 3-kinase) was determined by chemical inhibition with LY294002 or wortmannin. Activation of protein kinase B (Akt), c-Jun N-terminal kinases (JNKs), and extracellular signal-regulated kinases (ERKs) was evaluated by Western blot analysis using phospho-specific antibodies.Results. Exposure of fibroblasts to TGF␤ rapidly induced activation of a kinase, Akt, that is known to inhibit apoptosis by a variety of pathways. Activation of Akt was blocked by the specific PI 3-kinase inhibitor, LY294002, indicating that TGF␤-mediated phosphorylation of Akt was dependent on PI 3-kinase activation. This activation pathway was relatively selective for Akt, since inhibition of PI 3-kinase failed to substantially modify activation of ERKs or JNKs in synovial fibroblasts. Inhibition of the PI 3-kinase/Akt pathway resulted in impaired proliferation of synovial fibroblasts and partial attenuation of the protective effect of TGF␤ on Fas-mediated apoptosis.Conclusion. TGF␤ exerts its growth and antiapoptotic effects on fibroblasts, at least in part, by activation of the PI 3-kinase/Akt pathway.

Recent studies suggest that, in addition to activation and hypersecretion of matrix components, fibroblasts from patients with systemic sclerosis (SSc) are relatively resistant to apoptosis. Transforming growth factor-beta (TGF)-beta is strongly implicated in the pathogenesis of SSc and we and others have shown that TGF-beta can activate Akt, a kinase with potent anti-apoptotic effects. To determine whether Akt was activated in SSc, we quantified phospho-Akt expression in skin fibroblasts in vitro by western blot analysis and a functional kinase assay. In addition, the relative proportion of fibroblasts containing activated Akt in was quantified by immunohistochemistry on skin sections insitu. Analysis of Akt phosphorylation of skin fibroblasts in vitro suggested increased phosphorylation of Akt, and evaluation of skin sections by immunohistochemistry revealed significantly higher percentages of fibroblasts that stained for phospho-Akt compared with controls (78% +/- 14.0% vs 13% +/- 9%, p < 0.001). In addition, co-incident staining of phospho-Akt and alpha-smooth muscle actin was observed in some fibroblasts. These findings indicate that Akt is activated insitu in skin fibroblasts from patients with SSc. Akt activation may contribute to resistance to apoptosis, selection of disease-inducing fibroblasts, and, possibly, myofibroblasts.

Twenty compounds were isolated from the ethanol extract of Distylium racemosum branches and their inhibitory activities on tyrosinase, elastase and free radicals evaluated. The isolated compounds were identified as dibenzofurans (1-4), abscisic acid (5), 6'-O-galloylsalidroside (6), catechin derivatives (7-11), gallic acid derivatives (12-14), tyrosol (15), flavonoids (16-18), lupeol (19) and 1,2,3,6-tetragalloylglucose (20). For study of tyrosinase inhibition activities, when compared with arbutin (IC(50) 48.8 μg/mL), four compounds (8, 11, 13, 17) showed higher activities, with IC(50) values of 4.8, 30.2, 40.5 and 37.7 μg/mL, respectively. For the elastase inhibition test, dibenzofuran 1 showed greater activity than the positive control, oleanolic acid (IC(50) 9.7 μg/mL), with an IC(50) of 7.7 μg/mL. In the studies on DPPH radical scavenging activities, five compounds (11, 12, 13, 14, 15) showed higher activities than ascorbic acid (IC(50) 5.0 μg/mL), with IC(50) values of 4.6, 3.9, 2.9, 3.8 and 4.7 μg/mL, respectively.

Melanogenesis is a well-known physiological response of human skin that may occur because of exposure to ultraviolet light, for genetic reasons, or due to other causes. In our efforts to fi nd new skin lightening agents, palmitoleic acid was investigated for its ability to inhibit melanogenesis. In this study, palmitoleic acid s effect on melanin formation was assessed. Results indicated that palmitoleic acid was shown to down-regulate melanin content in a dose-dependent pattern. To clarify the target of palmitoleic acid action in melanogenesis, we performed Western blotting for tyrosinase, tyrosinase-related protein-1 (TRP-1), TRP-2, and microphthalmia-associated transcription factor (MITF), which are key melanogenic enzymes. Palmitoleic acid inhibited tyrosinase, TRP-2, and MITF expressions in a dose-dependent manner. However, it did not inhibit TRP-1 expression. In order to assess its usefulness in future cosmetic product applications, the cytotoxic effects of the palmitoleic acid were also determined by colourimetric MTT assays using human keratinocyte HaCaT cells. Palmitoleic acid exhibited no cytotoxicity at 500 μM in a human cell line. Therefore, this study suggests that palmitoleic acid is a candidate anti-melanogenic agent, and it might be effective in hyperpigmentation disorders.