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Guohua Yang,Xavier N. Siwe,Alain S. Leutou,Zhile Feng,장대해,Hong Dae Choi,강정숙,손병화,Viviane N. Nenkep 한국생약학회 2009 Natural Product Sciences Vol.15 No.3
The crude extract of the mycelium of Cladosporium was found to exhibit antimicrobial activity against the Staphylococcus aureus, methicillin-resistant S. aureus, and multidrug-resistant S. aureus. Bioassayguided fractionation of an organic extract led to the isolation of an acetophenone derivative, clavatol (2',4'- dihydroxy-3',5'-dimethylacetophenone) (1), and a benzodiazepine alkaloid, circumdatin A (2). Compound 1 showed moderate antibacterial activity against S. aureus, methicillin-resistant S. aureus, and multidrug-resistant S. aureus with minimum inhibitory concentration (MIC) values of 62.5, 62.5, 31.0 µg/mL, respectively, but compound 2 was inactive. Compounds 1 and 2 exhibited UV-A protection activity with ED50 values of 227.0 and 82.0 µM, respectively, indicating that they were more potent than the positive control, oxybenzone (ED50 350 µM), a common sunscreen agent.
Bioactive Cyclopentenone Derivatives from Marine Isolates of Fungi
Feng, Zhile,Leutou, Alain S.,Yang, Guohua,Nenkep, Viviane N.,Siwe, Xavier N.,Choi, Hong-Dae,Kang, Jung-Sook,Son, Byeng-Wha Korean Chemical Society 2009 Bulletin of the Korean Chemical Society Vol.30 No.10
As part of an effort to discover bioactive natural products from marine sources, we investigated the bioactive secondary metabolites from two marine isolates of the fungi, Trichoderma viride and Rhizopus stolonifer. Three cyclopentenones, myrothenones A (1) and B (2) and trichodenone A (3), were isolated from T. viride and two cyclopentenones, 2-bromomyrothenone B (4) and botrytinone (5), were isolated from R. stolonifer. The molecular structures and absolute stereochemistries of the cyclopentenones were determined from chemical and physicochemical evidence, including quantum chemistry calculations, X-ray analysis, and the circular dichroism (CD) exciton chirality method. Myrothenone A (1) displays tyrosinase inhibitory activity, with an I$C_{50}$ value of 6.6 ${\mu}M$, and is therefore more active than the positive control, kojic acid.
Bioactive Cyclopentenone Derivatives from Marine Isolates of Fungi
Zhile Feng,Alain S. Leutou,Guohua Yang,Viviane N. Nenkep,Xavier N. Siwe,Byeng Wha Son,Hong Dae Choi,강정숙 대한화학회 2009 Bulletin of the Korean Chemical Society Vol.30 No.10
As part of an effort to discover bioactive natural products from marine sources, we investigated the bioactive secondary metabolites from two marine isolates of the fungi, Trichoderma viride and Rhizopus stolonifer. Three cyclopentenones, myrothenones A (1) and B (2) and trichodenone A (3), were isolated from T. viride and two cyclopentenones, 2-bromomyrothenone B (4) and botrytinone (5), were isolated from R. stolonifer. The molecular structures and absolute stereochemistries of the cyclopentenones were determined from chemical and physicochemical evidence, including quantum chemistry calculations, X-ray analysis, and the circular dichroism (CD) exciton chirality method. Myrothenone A (1) displays tyrosinase inhibitory activity, with an IC50 value of 6.6 μM,and is therefore more active than the positive control, kojic acid.
Encapsulation and physicochemical evaluation of efavirenz in liposomes
Nnamdi Ikemefuna Okafor,Christian Isalomboto Nkanga,Roderick Bryan Walker,Xavier Siwe Noundou,Rui Werner Marçedo Krause 한국약제학회 2020 Journal of Pharmaceutical Investigation Vol.50 No.2
Purpose Antiretroviral therapy remains the most effective means of managing the human immune deficiency virus/acquired immune deficiency syndrome (HIV/AIDS). Application of therapeutics has been hampered by factors including poor bioavailability of most anti-retroviral compounds (ARV), side effects and an alarming emergence of drug resistant strains of the virus. Methods Recent developments and use of drug delivery systems (DDS) has shown potential for improving the pharmacological profile of ARV. Amongst these complex DDS, liposomes have been explored for delivery of ARV. In this study, we have aimed at exploring efficient encapsulation of efavirenz (EFV), a potent ARV using different mass ratios of crude soybean lecithin and cholesterol. Results The EFV-loaded liposomes (EFL) were prepared using thin film hydration and evaluated for particle size, zeta potential (ZP), encapsulation efficiency (EE%), morphology and drug release studies. Differential scanning calorimetry (DSC), X-ray diffraction (XRD), energy dispersity spectroscopy (EDS) and Fourier transform infrared (FTIR) spectroscopy were used for comprehensive physicochemical characterization of EFL. EFL exhibited high encapsulation (99%) in 1:1 crude lecithin to cholesterol mass ratio. The average particle size and Zeta Potential of EFL were found to be 411.10 ± 7.40 nm and − 53.5.3 ± 0.06 mV, respectively. EFL showed a relatively controlled EFV release behaviour that was similar to the dissolution profile of un-encapsulated EFV. Conclusion This suggests that EFL represents a promising vehicle for effective EFV delivery while providing the advantages of a nano-scaled delivery system.
Microbial Transformation of a Monoterpene, Geraniol, by the Marine-derived Fungus Hypocrea sp.
Alain S. Leutou,Guo Hua Yang,Viviane N. Nenkep,Xavier N. Siwe,Zhi Le Feng,Thang T. Khong,Hong Dae Choi,Jung Sook Kang,Byeng Wha Son 한국미생물 · 생명공학회 2009 Journal of microbiology and biotechnology Vol.19 No.10