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Stilbenes and Oligostilbenes from Leaf and Stem of Vitis amurensis and Their Cytotoxic Activity
Do Thi Ha,Quan Cheng Chen,Tran Manh Hung,Tran Minh Ngoc,Phuong Thien Thuong,김홍진,성연희,민병선,배기환,윤의중 대한약학회 2009 Archives of Pharmacal Research Vol.32 No.2
Chromatographic separation of the EtOAc fraction from the leaf and stem of Vitis amurensis led to the isolation of six oligostilbenoids (i.e., r-2-viniferin (1), trans-amurensin B (2), trans-ε -viniferin (3), gnetinH (4), amurensin G (5), (+)-ampelopsin A (8)) and four stilbenoids (i.e., trans-resveratrol (6), (+)- ampelopsin F (7), piceatannol (9), and trans-piceid (10)). The structures have been identified on the basis of spectroscopic evidence and physicochemical properties. The isolates were investigated for cytotoxic activity against three cancer cell lines in vitro using the MTT assay method. Amurensin G (5) and trans-resveratrol (6) showed significant cytotoxic activity against L1210, K562 and HTC116 cancer cell lines with IC50 values ranging from 15.7 ± 2.1 to 30.9 ± 1.8 μM. (+)-Ampelopsin A (8) and trans-piceid (10) exhibited considerable cytotoxic activity against L1210 (IC50 values of 30.6 ± 4.1 and 28.7 ± 2.81μM, respectively) and K562 (IC50 values of 38.6 ± 0.82 and 24.6 ± 0.76 μM, respectively). Gnetin H (4)showed only weak cytotoxic activity against L1210 with an IC50 value of 40.1 ± 4.23 μM. On the other hand, r-2-viniverin (1), trans-amurensin B (2), trans-ε -viniferin (3), (+)-ampelopsin F (7), and piceatannol(9) exhibited no activity on three cancer cell lines.
To Dao Cuong,Hoang Thi Ngoc Anh,Tran Thu Huong,Pham Ngoc Khanh,Vu Thi Ha,Tran Manh Hung,김영호,Nguyen Manh Cuong 한국생약학회 2019 Natural Product Sciences Vol.25 No.4
Soluble epoxide hydrolases (sEH) are enzymes present in all living organisms, metabolize epoxy fatty acids to 1,2-diols. sEH in the metabolism of polyunsaturated fatty acids plays a key role in inflammation. In addition, the endogenous lipid mediators in cardiovascular disease are also broken down to diols by the action of sEH that enhanced cardiovascular protection. In this study, sEH inhibitory guided fractionation led to the isolation of five phenolic compounds trans-resveratrol (1), trans-piceatannol (2), sulfuretin (3), (+)-balanophonin (4), and cassigarol E (5) from the ethanol extract of the seeds of Passiflora edulis Sims cultivated in Vietnam. The chemical structures of isolated compounds were determined by the interpretation of NMR spectral data, mass spectra, and comparison with data from the literature. The soluble epoxide hydrolase (sEH) inhibitory activity of isolated compounds was evaluated. Among them, trans-piceatannol (2) showed the most potent inhibitory activity on sEH with an IC50 value of 3.4 mM. This study marks the first time that sulfuretin (3) was isolated from Passiflora edulis as well as (+)-balanophonin (4), and cassigarol E (5) were isolated from Passiflora genus.
Mapless Navigation with Distributional Reinforcement Learning
TRAN VAN MANH,김곤우 한국로봇학회 2024 로봇학회 논문지 Vol.19 No.1
This paper provides a study of distributional perspective on reinforcement learning for application in mobile robot navigation. Mapless navigation algorithms based on deep reinforcement learning are proven to promising performance and high applicability. The trial-and-error simulations in virtual environments are encouraged to implement autonomous navigation due to expensive real-life interactions. Nevertheless, applying the deep reinforcement learning model in real tasks is challenging due to dissimilar data collection between virtual simulation and the physical world, leading to high-risk manners and high collision rate. In this paper, we present distributional reinforcement learning architecture for mapless navigation of mobile robot that adapt the uncertainty of environmental change. The experimental results indicate the superior performance of distributional soft actor critic compared to conventional methods.
iCaMs: 안티 콜 피싱 및 메시지 사기를 위한 지능형 시스템
( Manh-hung Tran ),양희규,( Thien-binh Dang ),추현승 ( Hyun-seung Choo ) 한국정보처리학회 2019 한국정보처리학회 학술대회논문집 Vol.26 No.2
The damage from voice phishing reaches one trillion won in the past 5 years following report of Business Korea on August 28, 2018. Voice phishing and mobile phone scams are recognized as a top concern not only in Korea but also in over the world in recent years. In this paper, we propose an efficient system to identify the caller and alert or prevent of dangerous to users. Our system includes a mobile application and web server using client and server architecture. The main purpose of this system is to automatically display the information of unidentified callers when a user receives a call or message. A mobile application installs on a mobile phone to automatically get the caller phone number and send it to the server through web services to verify. The web server applies a machine learning to a global phone book with Blacklist and Whitelist to verify the phone number getting from the mobile application and returns the result.
A Novel Two-Stage Power Conversion Method suitable for LDCs of the Electric Vehicles
Tran Manh Tuan,Woojin Choi 전력전자학회 2019 ICPE(ISPE)논문집 Vol.2019 No.5
The Low Voltage DC-DC converters (LDCs) of the Electric Vehicles require high power density and high efficiency operation over the wide range of load and input voltage variations. This paper introduces a novel topology which combines three 1 MHz Half-Bridge (HB) LLC resonant converters and an Inverting Buck-Boost (IBB) converter to adjust the output voltage without frequency modulation. The switching frequency of the proposed converter is fixed at 1MHz to achieve a constant frequency operation for the resonant converter to achieve a maximum efficiency. In the proposed topology GaN FETs and planar transformers are employed to optimize the converter operation at high frequency. A 1 MHz/1.8 kW prototype converter is built to verify the feasibility and the validity of the proposed LDC topology.
Tran Manh Tuan,Woojin Choi 전력전자학회 2019 ICPE(ISPE)논문집 Vol.2019 No.5
Recently wireless Power Transfer (WPT) has received a great interest due to its advantages such as better user convenience and better safety as compared to the conventional charger with cord. In a WPT charging system operating at MHz range, a DC/DC converter to provide the accurate voltage and current to the battery for its safety. This paper presents about the design and implementation of a high frequency class D Wireless Power Transfer system which makes it possible to charge the Lithium Batteries by the Constant Current (CC) and Constant Voltage (CV) Charge with a pair of coil. Since the charger can provide automatic transfer from CC to CV charge, the battery can be fully charged without the help of an additional DC/DC converter. The simulation and 50W-6.78-MHz hardware experimental results are presented to verify the feasibility of the proposed method and to evaluate the performance of the proposed wireless battery charger.
Lipoxygenase Inhibitory Constituents from Rhubarb
Tran Minh Ngoc,Pham Thi Hong Minh,Tran Manh Hung,IkSoo Lee,민병선,Phuong Thien Thuong,배기환 대한약학회 2008 Archives of Pharmacal Research Vol.31 No.5
Phytochemical study on the ethanol extract of rhubarb led to the isolation of fifteen compounds, including five anthraquinones: chrysophanol (1), physcion (2), emodin (7), chrysophanol- 8-O-β-D-glucopyranoside (9) and emodin-8-O-β-D-glucopyranoside (15), and ten stilbenes: desoxyrhaponticin (3), rhaponticin (4), resveratrol (5), desoxyrhapotigenin (6), rhapontigenin (8), piceatannol-3'-O-β-D-glucopyranoside (10), piceid (11), ε -viniferin (12), ampelopsin B (13) and isorhaponticin (14). Their structures were identified by comparing the physicochemical data with those of published papers. Among the isolated compounds, stilbene derivatives (3-6, 8 and 10-14) showed remarkable inhibitory effect on lipoxygenase with IC50 values ranging from 6.7 to 74.1 μM. The inhibition kinetics analyzed by Lineweaver-Burk plots found that they were competitive inhibitors with the linoleic acid at the active site of lipoxygenase. In addition, stilbenes exhibited significantly free radical scavenging activity against ABTS•+ with trolox equivalent activity capacity (TEAC) values ranging from 1.16 to 4.64. Whereas, anthraquinone derivatives (1-2, 7, 9 and 15) neither inhibited lipoxygenase nor scavenged free radical ABTS•+. These results indicated that stilbene derivatives were considerate to be mainly lipoxygenase inhibitor and free radical scavenger constituents of rhubarb.