• Archives of Pharmacal Research
• /
• v.27 no.10
• /
• pp.985-989
• /
• 2004

A functional divergency oriented synthetic approach to the azoninone (9-membered lactams), key intermediate for the indolizidine alkaloids library, using amide enolate induced aza-Claisen rearrangement has been achieved.

• Bulletin of the Korean Chemical Society
• /
• v.24 no.12
• /
• pp.1832-1834
• /
• 2003

• Bulletin of the Korean Chemical Society
• /
• v.17 no.3
• /
• pp.212-214
• /
• 1996

• Bulletin of the Korean Chemical Society
• /
• v.32 no.spc8
• /
• pp.2867-2868
• /
• 2011

• Proceedings of the Korean Society of Life Science Conference
• /
• 2005.04a
• /
• pp.111-111
• /
• 2005

• Bulletin of the Korean Chemical Society
• /
• v.29 no.10
• /
• pp.1998-2004
• /
• 2008

Two synthetic pathways to substituted hexahydroimidazo[1,2-a]pyridines, which may serve as precursors of aza-alkaloids, were investigated. The first involves the condensation of a bisnucleophilic enediaminoester and a biselectrophile. The second involves attachment to nitrogen of the carbon chain skeleton required to form the six-memberd ring, before formation of the enediaminoester. Several substituted hexahydroimidazo[1,2- a]pyridines were synthesized via these two approaches.

• Proceedings of the Korean Society of Applied Pharmacology
• /
• 1998.11a
• /
• pp.167-168
• /
• 1998

Swainsonine is a toxic indolizidine alkaloid found in the plant, Swainsona species (Dorling, 1978; Colgate, 1979). It is a potent inhibitor of the glycoprotein processing pathway in the Golgi apparatus. Specifically, it inhibits mannosicase II resulting in abherrant high mannose glycans. Recent studies showed that swainsonine prevents metastasis of tumor cells and it inhibits solid growth tumor, at least partially (Goss et al., 1994; Baptista et al, 1994).

• Archives of Pharmacal Research
• /
• v.20 no.6
• /
• pp.545-549
• /
• 1997

Effects of swainsonine (SW;8${\alpha}$, ${\beta}$-indolizidine-${\alpha}$, $2{\alpha}$8-triol from Locoweed) on the humoral immune responses of lipopolysaccharide (LPS) wer studied in ICR mice. Mice were divided into 4 groups (10 mice/group), and LPS was given to each mouse 1 hr after i.p. injection with 3.7 mg/kg of swainsonine, by i.p. injection twice a week for 14 days at a dose of 2 mg/kg. Humoral immune responses were evaluated by hemagglutination (HA) titer and splenic plaque forming cells (PFC). The results of this study were summarized as follows: Mice administrated each of LPS and SW showed significant enhancement of the weight ratios of spleen to body, HA titer, 2-mercaptoethanol-resistant HA(MER-HA) titer and PFC compared with those in controls. However, the LPS plus SW treatment decreased HA titer, MER-HA titer and PFC corresponding to humoral immunity, as compared with those in the mice treated with LPS alone. These findings indicated that LPS significantly enhanced humoral immune responses, but their enhancement effects were lowered somewhat by SW.

• YAKHAK HOEJI
• /
• v.42 no.1
• /
• pp.75-81
• /
• 1998

Effects of swainsonine (SW: 8${\alpha}$, ${\beta}$-indolizidine-1alpha, 2${\alpha}$, 8${\beta}$-triol from Locoweed) on the cellular and nonspecific immune responses of lipopolysaccharide (LPS) wer e studied in ICR mice. Mice were divided into 4 groups (10mice/group), and LPS was given to each mouse 1 hr after i.p. injection with 3.7mg/kg of SW by i.p. injection twice a week for 14 days at a dose of 2mg/kg. Immune responses of the delayed-type hypersensitivity response (DTH) to sheep red blood cells (s-RBC), phagocytic activity and natural killer (NK) cell activity were evaluated. LPS treatment didn`t affect NK cell activity, phagocytic activity, DTH to s-RBC compared with those in controls, and phagocytic activity of sareoma 180 tumor bearing mice. However, circulating leukocytes were significantly decreased. Combinaton of LPS and SW increased circulating leukocytes significantly compared vath that in LPS alone, and DTH to s-RBC, NK cell activity and phagocytic activities of normal and sarcoma tumor bearing mice were not affected. These findings indicate that SW didn`t affected the cellular immune responses suppressed by LPS but significantly increased circulating leukocytes.

• Journal of the Korean Chemical Society
• /
• v.54 no.3
• /
• pp.261-268
• /
• 2010

In this account, three synthetic methodologies that serve as the basis for new strategies for the preparation of selected natural products are briefly introduced. One process, involving ruthenium carbene catalyzed ring rearrangement metathesis developed by Grubbs and his coworkers, transforms alkene-tethered cycloalkenes to thermodynamically more favored alkene-tethered cycloalkenes. Another ruthenium carbene promoted reaction, referred to as dienyne metathesis, was uncovered in early studies by Grubbs and his collaborators. This process converts dienynes to fused bicyclic conjugated dienes. Finally, a novel photo-electrocyclization reaction of pyridinium salts, which leads to the formation of 4-aminocyclopenten-3,5-diol derivatives, is discussed. Examples are provided to show the utility of these methodologies in natural product synthesis. Emphasis is given to studies in which pyridinium salt photochemistry is coupled with ring rearrangement and dienyne metathesis in routes for the synthesis of polyhydroxyalted indolizidine alkaloids and the construction of the tricyclic core of the lepadiformine and cylindricine alkaloids.