• Journal of the Society of Cosmetic Scientists of Korea
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• v.34 no.4
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• pp.287-301
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• 2008

In order to develop a new depigmenting agent, extracts were obtained from 60 native plants and their antimelanogenic activities were screened by evaluating the inhibitory effect on tyrosinase which is a major enzyme responsibles for the melanin synthesis. The extracts of Trichosanthes kirilowii fruits, Phyllostachys bambusoides inner films (BIF), Clerodendrum trichotomum leaves, and Acer okamotoanum leaves showed relatively high inhibitory effect on tyrosinase and their $IC_{50}$ values were $50{\sim}100{\mu}g/mL$. The extract of BIF inhibited melanin synthesis of B16F10 melanoma cells by 52%, which was the highest among those of various extracts. Furthermore, the effect of BIF extract is 10% higher than that of arbutin (42%), a popular depigmenting agent in Korea. Ten compounds having antimelanogenic activity were isolated from the BIF extract by solvent extraction and chromatography. These compounds were identified as phenolic derivatives: SM701, SM702, SM703, and BPR211 were hydroquinone derivatives; SM707 a gallic acid derivative; SM704, SM705, SM706, SM708 and SM709 ferulic acid derivatives. The free radical scavenging activities of these compounds were measured and compared to those of hydroquinone and vitamin C. The $SC_{50}$ values scavenging 50% DPPH of SM702 and SM709 were $60{\sim}70{\mu}M$ similar to that of hydroquinone and those of SM701 and SM708 were $30{\sim}40{\mu}M$ slightly lower than that of vitamin C. These results suggest the presence of components having high antioxidant activity in the BIF extract. The SM709, identified as 1,2-O-diferulylglycerol, inhibited the activities of tyrosine hydroxylase and dopa oxidase by 18 and 60%, respectively. The SM709 also inhibited the melanin synthesis of B16F10 melanoma cells by 62% and this was the highest antimelanogenic activity among those obtained from the various purified compounds. Therefore, antimelanogenic activity of the BIF extract was concluded to be due to both inhibition of DOPA oxidase and antioxidant activity.

• Nuclear Medicine and Molecular Imaging
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• v.43 no.5
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• pp.478-486
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• 2009

Purpose: 5-iododeoxyuridine analogues have been exclusively developed for the potential antiviral and antitumor therapeutic agents. In this study, we synthesized carbocyclic radioiododeoxyuridineanalogue (ddIVDU) and carbocyclic intermediate as efficient carbocyclic radiopharmaceuticals. Materials and Methods: The synthesis is LAH reduction, hetero Diels-Alder reaction as key reactions including Pd(0)-catalyzed coupling reaction together with organotin. MCA-RH7777 (MCA) and MCA-tk (HSV1-tk positive) cells were treated with various concentration of carbocyclic ddIVDU, and GCV. Cytotoxicity was measured by the MTS methods. For in vitro uptake study, MCA and MCA-tk cells were incubated with 1uCi of [$^{125}I$]carbocyclic ddIVDU. Accumulated radioactivity was measured after various incubation times. Results: The synthesis of ddIVDU and precursor for radioiodination were achieved from cyclopentadiene in good overall yield, respectively. The radioiododemetallation for radiolabeling gave more than 80% yield with > 95% radiochemical purity. GCV was more toxic than carbocyclic ddIVDU in MCA-tk cells. Accumulation of [$^{125}I$]carbocyclic ddIVDU was higher in MCA-tk cells than MCA cells. Conclusion: Biological data reveal that ddIVDU is stable in vitro, less toxic than ganciclovir (GCV), and selective in HSV1-tk expressed cells. Thus, this new carbocyclic nucleoside, referred to in this paper as carbocyclic 2',3'-didehydro-2',3'-dideoxy-5- iodovinyluridine (carbocyclic ddIVDU), is a potential imaging probe for HSV1-tk.

• Journal of Periodontal and Implant Science
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• v.35 no.4
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• pp.1019-1037
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• 2005

The major goals of periodontal therapy are the functional regeneration of periodontal supporting structures already destructed by periodontal disease as well as the reduction of signs and symptoms of progressive periodontal disease. There have been many efforts to develop materials and therapeutic methods to promote periodontal wound healing. There have been increasing interest on the chitosan made by chtin. Chitosan is a derivative of chitin made by deacetylation of side chains. Chitosan has been widely studied as bone substitution and membrane material in periodontology. Many experiments using chitosan in various animal models have proven its beneficial effects. Tetracycline has been considered for use in the treatment of chronic periodontal disease and gingivitis. The aim of this study is to evlauate the osteogenesis of tetracycline blended chitosan membranes on the calvarial critical size defect in Sprague Dawley rats. An 8mm surgical defect was produced with a trephine bur in the area of the midsagittal suture. The rats were divided into five groups: Untreated control group versus four experimental group. Four types of membranes were made and comparative study was been done. Two types of non-woven membranes were made by immersing non-woven chitosan into either the tetracycline solution or chitosan-tetracycline solution. Other two types of sponge membranes were fabricated by immersing chitosan sponge into the tetracycline solution, and subsequent freeze-drying. The animals were sacrificed at 2 and 8 weeks after surgical procedure. The specimens were examined by histologic analyses. The results are as follows: 1. Clinically the use of tetracycline blended chitosan membrane showed great healing capacity. 2. The new bone formations of all the experimental group, non-woven and sponge type membranes were greater than those of control group. But, there was no significant difference between the experimental groups. 3. Resorption of chitosan membranes were not shown in any groups at 2 weeks and 8 weeks. These results suggest that the use of tetracycline blended chitosan membrane on the calvarial defects in rats has significant effect on the regeneration of bone tissue in itself. And it implicate that tetracycline blended chitosan membrane might be useful for guided tissue regeneration.

• The Korean Journal of Nuclear Medicine
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• v.36 no.6
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• pp.333-343
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• 2002

Purpose: A new linker, hydrazino nicotinamide (HYNIC), was recently introduced for labelling of liposome with $^{99m}Tc$. In this study we synthesized HYNIC derivatized PEG (polyethylene glycol)-liposomes radiolabeled with $^{99m}Tc$. Materials and Methods: In order to synthesize HYNIC-DSPE (distearoyl phosphatidyl ethanolamine) which is a crucial component for $^{99m}Tc$ chelation, first of all succinimidyl 6-BOC-hydrazinopyridine-3-carboxylic acid was synthesized from 6-chloronicotinic acid by three sequential reactions. A DSPE derivative of succinimidyl 6-BOC-hydrazinopyridine-3-carboxylic acid was transformed into HYNIC-DSPE by HCI/dioxane. HYNIC-PEG-liposomes were prepared by hydration of the dried lipid mixture of EPC (egg phosphatidyl choline): PEG-DSPE : HYNIC-DSPE:cholesterol (1.85:0.15:0.07:1, molar ratio). The HYNIC-PEG-liposomes were labeled with $^{99m}Tc$ in the presence of $SnCl_2{\cdot}2H_2O$ (a reducing agent) and tricine (a coligand). To investigate the level of in vivo transchelation of $^{99m}Tc$ in the liposomes, the $^{99m}Tc$-HYNiC-PES-liposomes were incubated with a molar excess of DTPA, cysteine or glutathione solutions at $37^{\circ}C$ for 1 hour. The radiolabeled liposomes were also incubated in the presence of human serum at $37^{\circ}C$ for 24 hours. Results: 6-BOC-hydrazinopyridine-3-carboxylic acid was synthesized with 77.3% overall yield. The HYNIC concentration in the PEG-coated liposome dispersion was 1.08 mM. In condition of considering the measured liposomal size of 106 nm, the phospholipid concentration of $77.5\;{\mu}mol/m{\ell}$ and the liposomal particle number of $5.2{\times}10^{14}$ liposomes/ml, it is corresponded to approximate 1,250 nicotinyl hydrazine group per liposome in HYNIC-PEG-liposome. The removal of free $^{99m}Tc$ was not necessary because the labeling efficiency were above 99%. The radiolabeled liposomes maintained 98%, 96% and 99%, respectively, of radioactivity after incubation with transchelators. The radiolabeled liposomes possessed above 90% of the radioactivity in serum. Conclusion: These results suggest that the HYNIC can be synthesized easily and applied in labelling of PEG-liposomes with $^{99m}Tc$.

• New Physics: Sae Mulli
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• v.68 no.12
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• pp.1281-1287
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• 2018

In this study, $Al_xGa_{1-x}N$ films were grown on (0001) sapphire substrates by using metal-organic chemical vapor deposition (MOCVD). The crystallinity of the grown films was examined with X-ray diffraction (XRD) patterns. The surfaces and the chemical properties of the $Al_xGa_{1-x}N$ films were investigated using atomic force microscopy (AFM) and X-ray photoelectron spectroscopy (XPS), respectively. The optical properties of the $Al_xGa_{1-x}N$ film were studied in a wide photon energy range between 2.0 ~ 8.7 eV by using spectroscopic ellipsometry (SE) at room temperature. The data obtained by using SE were analyzed to find the critical points of the pseudodielectric function spectra, $<{\varepsilon}(E)>=<{\varepsilon}_1(E)>+i<{\varepsilon}_2(E)>$. In addition, the second derivative spectra, $d^2<{\varepsilon}(E)>/dE^2$, of the pseudodielectric function for the $Al_xGa_{1-x}N$ films were numerically calculated to determine the critical points (CPs), such as the $E_0$, $E_1$, and $E_2$ structure. For the four samples (x = 0.18, 0.21, 0.25, 0.29) between a composition of x = 0.18 and x = 0.29, changes in the critical points (blue-shifts) with increasing Al composition at 300 K for the $Al_xGa_{1-x}N$ film were observed via ellipsometric measurements for the first time.

• The Korean Journal of Nuclear Medicine Technology
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• v.28 no.1
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• pp.41-47
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• 2024

Purpose: ¹⁸F-FET, a radiopharmaceutical based on a Tyrosine amino acid derivative using the Sodium-Potassium Pump-independent Transporter (System L) for non-invasive evaluation of primary, recurrent, and metastatic brain tumors, exhibits distinct characteristics. Unlike the widely absorbed ¹⁸F-FDG in both tumor and normal brain tissues, ¹⁸F-FET demonstrates specific uptake only in tumor tissue while almost negligible uptake in normal brain tissue. This study aims to compare and evaluate the usefulness of ¹⁸F-FDG and ¹⁸F-FET Brain PET/CT quantitative analysis in brain tumor diagnosis. Materials and Methods: In 46 patients diagnosed with brain gliomas (High Grade: 34, Low Grade: 12), Brain PET/CT scans were performed at 40 minutes after ¹⁸F-FDG injection and at 20 minutes (early) and 80 minutes (delay) after ¹⁸F-FET injection. SUV_max and SUV_peak of tumor areas corresponding to MRI images were measured in each scan, and the SUV_max-to-SUV_peak ratio, an indicator of tumor prognosis, was calculated. Differences in SUV_max, SUV_peak, and SUV_max-to-SUV_peak ratio between ¹⁸F-FDG and ¹⁸F-FET early/delay scans were statistically verified using SPSS (ver.28) package program. Results: SUV_max values were 3.72±1.36 for ¹⁸F-FDG, 4.59±1.55 for ¹⁸F-FET early, and 4.12±1.36 for ¹⁸F-FET delay scans. The highest SUV_max was observed in ¹⁸F-FET early scans, particularly in HG tumors (4.85±1.44), showing a slightly more significant difference (P<0.0001). SUV_peak values were 3.33±1.13 for ¹⁸F-FDG, 3.04±1.11 for ¹⁸F-FET early, and 2.80±0.96 for ¹⁸F-FET delay scans. The highest SUV_peak was in ¹⁸F-FDG scans, while the lowest was in ¹⁸F-FET delay scans, with a more significant difference in HG tumors (P<0.001). SUV_max-to-SUV_peak ratio values were 1.11±0.09 for ¹⁸F-FDG, 1.54±0.22 for ¹⁸F-FET early, and 1.48±0.17 for ¹⁸F-FET delay scans. This ratio was higher in ¹⁸F-FET scans for both HG and LG tumors (P<0.0001), but there was no statistically significant difference between ¹⁸F-FET early and delay scans. Conclusion: This study confirms the usefulness of early and delay scans in ¹⁸F-FET Brain PET/CT examinations, particularly demonstrating the changes in objective quantitative metrics such as SUV_max, SUV_peak, and introducing the SUV_max-to-SUV_peak ratio as a new evaluation metric based on the degree of tumor malignancy. This is expected to further contributions to the quantitative analysis of Brain PET/CT images.