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A New Triterpene Saponin from Pittosporum viridiflorum from the Madagascar Rainforest
Seo, Youngwan,Berger, John M.,Hoch, Jeannine,Neddermann, Kim M.,Bursuker, Isia,Mamber, Steven W.,Kingston, David G. I. 韓國海洋大學校 附設 海洋科學技術硏究所 2002 硏究論文集 Vol.11 No.1
A novel triterpenoid saponin, pittoviridoside (1), which possesses an unusual 2,3,4-trisubstituted glycosidic linkage, has been isolated from Pittosporum viridiflorum using the engineered yeast strains 1138, 1140, 1353, and Sc-7 for bioactivity-guided fractionation. The structure of this compound was determined to be 3-O-[β-D-glucopyranosyl(1→2)]-[α-D-arabinopyranosyl(1→3)], [α-1-arabinofuranosyl(1→4)-β-D-glucuronopyranosyl-21-angeloyl-22-senecioylolean-12-en-3β,15α,16α,21β,22α,28-hexol by spectral, chemical, and GC analyses. This compound showed weak cytotoxicity against the A2780 human ovarian cancer cell line.
NEW FARNESYLHYDROQUINONE GLYCOSIDES FROM THE GORGONIAN EUPLEXAURA ANASTOMOSANS
SEO, YOUNGWAN,RHO, JUNG-RAE,CHO, KI WOONG,SHIN, JONGHEON 韓國海洋大學校 附設 海洋科學技術硏究所 2001 硏究論文集 Vol.10 No.2
Euplexides F(3) and G(4), novel farnesylhydroquinone glycosides, have been isolated as minor constituents of the gorgonian Euplexaura anastomosans. The structures of these compounds have been determined by combined spectroscopic methods. These compounds exhibited moderate cytotoxicity and inhibitory activity against PLA_2.
Solandelactones A-I, Lactonized Cyclopropyl Oxylipins Isolated from the Hydroid Solanderia secunda
Seo, Youngwan,Cho, Ki Woong,Rho, Jung-Rae,Shin, Jongheon,Kwon, Byoung-Mog,Bok, Song-Hae,Song, Jun-Im 이화여자대학교 생명과학연구소 1996 생명과학연구논문집 Vol.7 No.-
Solandelactones A-Ⅰ(1-9), cyclopropyl and lactone containing novel docosanoids have been isolated from the hydroid Solanderia secunda. The structures of these compounds have been elucidated by combined spectral and chemical studies. Configuration of the cyclopropyl ring has been assigned as the opposite of related oxylipins by NOESY experiments. Absolute stereochemistry has been determined on the basis of chemical transformations and CD measurements of synthetic derivatives. In addition, the biogenetic origin of solandelactones has been discussed. Solandelactones C,D and G exhibited moderate inhibitory activity against Farnesyl Protein Transferase.
Antioxidant Activity of the Chemical Constituents from the Flower Buds of Magnolia denudata
Youngwan Seo 한국생물공학회 2010 Biotechnology and Bioprocess Engineering Vol.15 No.3
The scavenging activity of the flower buds of Magnolia denudata Desrousseaux on reactive oxygen species (ROS) was evaluated using 2',7'-dichlorofluorescin diacetate (DCFH-DA) in HT 1080 cells. Methanol (MeOH)and dichloromethane (CH2Cl2) extracts inhibited dosedependently generation of ROS in the cellular system. MeOH and CH2Cl2 extracts were combined and fractionated with n-hexane, 85% aqueous MeOH, and n-butanol (n-BuOH). Both n-hexane-soluble and 85% aqueous-soluble fractions showing strong radical-scavenging activity in the cellular system were further separated by diverse chromatographic methods to give five known lignans (1-5). All these compounds exhibited significant radical-scavenging effect on intracellular ROS in a dose-dependent manner. Their scavenging activity on various reactive oxygen species (ROS) was also evaluated using electron spin resonance (ESR) spin-trap techniques.
Isolation of Tetraprenyltoluquinols from the Brown Alga <i>Sargassum thunbergii</i>
Seo, Youngwan,Park, Ki Eui,Kim, You Ah,Lee, Hee-Jung,Yoo, Jong-Su,Ahn, Jong-Woong,Lee, Burm-Jong The Pharmaceutical Society of Japan 2006 Chemical & pharmaceutical bulletin Vol.54 No.12
<P>Thunbergols A (4) and B (5), tetraprenyltoluquinols, along with three known compounds (1—3) have been isolated from the brown alga <I>Sargassum thunbergii</I>. The structures of these two new compounds were determined to be 9-(3,4-dihydro-2,8-dimethyl-6-hydroxy-2<I>H</I>-1-benzopyran-2-yl)-6-methyl-2-(4-methyl-3-pentenyl)-(2<I>E</I>,6<I>E</I>)-nonadienoic acid (4) and 10-(2,3-dihydro-5-hydroxy-7-methyl-1-benzofuran-2-yl)-10-hydroxy-6-methyl-2-(4-methyl-3-pentenyl)-(2<I>E</I>,6<I>E</I>)-undecadienoic acid (5), respectively, by combined spectroscopic methods. Both of them exhibited significant scavenging activities on radical and potently inhibited generation of ONOO<SUP>−</SUP> from morpholinosydnonimine (SIN-1).</P>
Building a HOG Descriptor Model of Pedestrian Images Using GA and GP Learning
Youngwan Cho,Kisung Seo 한국지능시스템학회 2018 INTERNATIONAL JOURNAL of FUZZY LOGIC and INTELLIGE Vol.18 No.2
For detecting a pedestrian by using features of images, it is generally needed to establish a reference model that is used to match with input images. The support vector machine (SVM) or AdaBoost Cascade method have been generally used to train the reference pedestrian model in the approaches using the histogram of oriented gradients (HOG) as features of the pedestrian model. In this paper, we propose a new approach to match HOG features of input images with reference model and to learn the structure and parameters of the reference model. The Gaussian scoring method proposed in this paper evaluates the degree of feature coincidence with HOG maps divided with angle of the HOG vector. We also propose two approaches for leaning of the reference model: genetic algorithm (GA) based learning and genetic programming (GP) based learning. The GA and GP are used to search the best parameters of the gene and nonlinear function representing feature map of pedestrian model, respectively. We performed experiments to verify the performance of proposed method in terms of accuracy and processing time with INRIA person dataset.
서영완,이희정,차효준,김유아,박기의 韓國海洋大學校 附設 海洋科學技術硏究所 2002 硏究論文集 Vol.11 No.2
The antioxidant activity of methanol and dichloromethane extracts of salt marsh plants was tested by using 1,1-Diphenyl-2-picryl-hydrazyl(DPPH). Three salt marsh plants (Erigeron annuus, Ixeris tamagawaensis kitamura, Portulaca oleracea) were found to be significantly effective in DPPH radical scavenging activity. The combined crude extracts of Portulaca oleracea were sequentially partitioned with n-hexane, 15% aq. MeOH, EtOAc, n-BuOH and H_2O. the antioxidative activities of several fractions were determined by evaluation the DPPH radical scavenging effect and by measuring lipid peroxide using 2-thiobarbituric acid (TBA). Among them, remarkable antioxidative effects were observed in the fractions of EtOAc and n-BuOH. The DPPH radical scavenging effect (IC_50=17.90㎍/ml) of the n-BuOH soluble fraction was comparable with that of natural antioxidant, a-tocopherol (IC_50=6.99㎍/ml).