• Bulletin of the Korean Chemical Society
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• v.31 no.9
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• pp.2453-2458
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• 2010

Photochemical studies of N-[(trimethylsilyl)alkyl]saccharins were carried out to investigate their photochemical behavior. Depending on the nature of the substrate and the solvent system employed, reactions of these substances can take place by either SET-promoted silyl migration from carbon to either the amide carbonyl or sulfonyl oxygen or by a N-S homolysis route. The results of the current studies show that an azomethine ylide, arising from a SET-promoted silyl migration pathway, is generated in photoreactions of N-[(trimethylsilyl)methyl]saccharin and this intermediate reacts to give various photoproducts depending on the conditions employed. In addition, irradiation of N-[(trimethylsily)ethyl]saccharin produces an excited state that reacts through two pathways, the relative importance is governed by solvent polarity and protic nature. Finally, photoirradiation of N-[(trimethylsilyl)propyl]saccharin in a highly polar solvent system comprised of 35% aqueous MeOH gives rise to formation of a tricyclic pyrrolizidine and saccharin that generated via competitive SET-promoted silyl transfer and $\gamma$-hydrogen abstraction pathways.

• KSBB Journal
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• v.13 no.2
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• pp.155-161
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• 1998

The hairy roots of Crotalaria sessiliflora were induced from the tissue segments infected with Agrobacterium rhizogenes ATCC 15834. The induced hairy roots were subjected to paper electrophoresis fro the detection of opine-positive clones which were considered to have been transformed. Mannopine and agropine were presented in hairy root clones while mannopine was presented in two hairy root clones. Eight hairy root clones were selected and cultured in MS, B5 and WP media. Each of hairy root clones was showed a difference in branch pattern and growth rate. The best culture medium and culture conditions of hairy roots were in $\frac{1}{2}$MS(3% sucrose, pH 5.7) liquid medium at 25$^\circ C$, 70 rpm under dark, the growth rate in $\frac{1}{2}$MS liquid medium was increased with 210-fold more than that of inoculated hairy roots and with 2-fold more than that in MS liquid medium. Also, the adequate condition for hairy root growth was such that concentration of KH$_2PO$_4 was 1.25mM and the ratio of NH${_4}{^+}$ : NO${_3}{^-}$ was 1 to 3 in MS medium. The presence of pyrrolizidine alkaloids, monocrotaline, in the hairy roots was detected by TLC.

• Applied Microscopy
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• v.37 no.1
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• pp.1-10
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• 2007

Monocrotaline (MCT) is a pyrrolizidine alkaloid (PA) plant toxin that produces hapatotoxicity in humans and animals. To felt the hypothesis, we investigated the possible protective effects of Haedokjeongki-tang as an antioxidant against MCT-induced liver injury in rats. Cells with apoptotic morphology have been observed in the livers of animals exposed to Ph and Haedokjeongki-tang. Whether apoptosis occurs in the livers of MCT-treated animals and whether it is required for full manifestation of pathological changes is not known, To determine this, rats were treated with 100 mg MCT/kg, and apoptosis was detected by transmission electron microscopy and TUNEL assay. MCT produced apoptosis in the liver by 6 h after treatment and increased by 24 h. Administration of Haedokjeongki-tang did affect liver structure and inhibit apopotosis in MCT-induced liver injury. Upon light and electron microscopic examination, we observed that Haedokjeongki-tang improved the morphological and histopathological changes of the liver caused by MCT-induced injury. MCT caused a time-dependent release of GOT and GPT, a marker of liver injury. Furthermore, we observed with respect to antioxidants status, catalase and superoxide dismutase activity tended to be higher in the MCT-treated rats than in the Haedokjeongki-tang administered rats. Our finding showed that Haedokjeongki-tang administration partially reduced liver injury after MCT exposure.

• Applied Biological Chemistry
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• v.48 no.1
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• pp.1-15
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• 2005

Pathogens, insects and weeds have significantly reduced agricultural productivity. Thus, to increase the productivity, synthetic agricultural chemicals have been overused. However, these synthetic compounds that are different from natural products cannot be broken down easily in natural systems, causing the destruction of soil quality and agricultural environments and the gradually difficulty in continuous agriculture. Now agriculture is faced with the various problems of minimizing the damage in agricultural environments, securing the safety of human health, while simultaneously increasing agricultural productivity. Meanwhile, plants produce secondary metabolites to protect themselves from external invaders and to secure their region for survival. Plants infected with pathogens produce antibiotics phytoalexin; monocotyledonous plants produce flavonoids and diterpenoids phytoalexins, and dicotylodoneous plant, despite of infected pathogens, produce family-specific phytoalexin such as flavonoids in Leguminosae, indole derivatives in Cruciferae, sesquitepenoids in Solanaceae, coumarins in Umbelliferae, making the plant resistant to specific pathogen. Growth inhibitor or antifeedant substances to insects are terpenoids pyrethrin, azadirachtin, limonin, cedrelanoid, toosendanin and fraxinellone/dictamnine, and terpenoid-alkaloid mixed compounds sesquiterpene pyridine and norditerpenoids, and azepine-, amide-, loline-, stemofoline-, pyrrolizidine-alkaloids and so on. Also plants produces the substances to inhibit other plant growths to secure the regions for plant itself, which is including terpenoids essential oil and sesquiterpene lactone, and additionally, benzoxazinoids, glucosinolate, quassinoid, cyanogenic glycoside, saponin, sorgolennone, juglone and lots of other different of secondary metabolites. Hence, phytoalexin, an antibiotic compound produced by plants infected with pathogens, can be employed for pathogen control. Terpenoids and alkaloids inhibiting insect growth can be utilized for insect control. Allelochemicals, a compound released from a certain plant to hinder the growth of other plants for their survival, can be also used directly as a herbicides for weed control as well. Therefore, the use of the natural secondary metabolites for pest control might be one of the alternatives for environmentally friendly agriculture. However, the natural substances are destroyed easily causing low the pest-control efficacy, and also there is the limitation to producing the substances using plant cell. In the future, effects should be made to try to find the secondary metabolites with good pest-control effect and no harmful to human health. Also the biosynthetic pathways of secondary metabolites have to be elucidated continuously, and the metabolic engineering should be applied to improve transgenics having the resistance to specific pest.