• YAKHAK HOEJI
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• v.40 no.2
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• pp.163-169
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• 1996

Glycosidation of 20(S)-protopanaxadiol obtained by the alkaline hydrolysis of total ginsenosides with 2,3,4,6-tetra-O-acetyl-${\alpha$-D-glucopyranosyl bromide in the presence of $CdCO_3$ in benzene-dioxane gave a mixture of acetylated monoglucosides and diglucosides in a total yield of 68%. Under the same condenstion condition, 20-dehydroxyglucosides were formed by dehydration of 12-O-glucosides. The structures of produced glycosides were elucidated as 3-O-${\beta$-D-glucopyranosyl-20(S)-protopanaxadiol, 12-O-${\beta$-D-glucopyranosyl-dammar-20(22), 24-dien-$3{\beta},12{\beta}$-diol, 3,12-di-O-${\beta}$-D-glucopyranosyl-dammar-20(22), 24-dien-$3{\beta},\;12{\beta}$-diol, respectively.

• Applied Chemistry for Engineering
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• v.9 no.1
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• pp.155-157
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• 1998

Dinitramide salts may be useful as effective solid oxidizers because of higher oxygen content than nitrate salts. 3-Nitramino-propanoate was given by base treatement in the retro-Michael reaction of N-nitro-4-azaheptanedioate, which was prepared by nitration of 4-azaheptanedioate using $HNO_3$-TFAA(trifiluoroacetic anhydride)-$Br_2$. The nitramino compound was treated wile $NO_2BF_4$ to give dinitramino compound which was subsequently reacted with bases to give dinitramide salts.

• Bulletin of the Korean Chemical Society
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• v.31 no.4
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• pp.874-880
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• 2010

A series of 13- and 14-membered cyclic enkephalin analogs based on the moderately $\mu$ selective prototype compound Tyr-C[D-$A_2bu$-Gly-Phe-Leu] 8a were synthesized to investigate the structure-activity relationship. The modifications of sequence were mainly focused on two positions 3 and 5, critical for the selective recognition for $\mu$ and $\delta$ opioid receptors. The substitution of hydrophobic $Leu^5$ with hydrophilic $Asp^5$ derivatives led to Tyr-C[D-$A_2bu$-Gly-Phe-Asp(N-Me)] 7 and Tyr-C[D-Glu-Phe-gPhe-rAsp(O-Me)] 5, the peptides with a large affinity losses at both $\mu$ and $\delta$ receptors. The substitution of $Phe^3$ with $Gly^3$ led to Tyr-C[D-Glu-Gly-gPhe-rLeu] 3 and Tyr-C[D-Glu-Gly-gPhe-D-rLeu] 4, the peptides with large affinity losses at $\mu$ receptors, indicating the critical role of phenyl ring of $Phe^3$ for $\mu$ receptor affinities. One atom reduction of the ring size from 14-membered analogs Tyr-C[D-Glu-Phe-gPhe-(L and D)-rLeu] 6a, 6b to 13-membered analogs Tyr-C[D-Asp-Phe-gPhe-(L and D)-rLeu] 1, 2 reduced the affinity at both $\mu$ and $\delta$ receptors, but increased the potency in the nociceptive assay, indicating the ring constrain is attributed to high nociceptive potency of the analogs. For the influence of D- or L-chirality of $Leu^5$ on the receptor selectivity, regardless of chirality and ring size, all cyclic diastereomers displayed marked $\mu$ selectivity with low potencies at the $\delta$ receptor. The retro-inverso analogs display similar or more active at $\mu$ receptor, but less active at $\delta$ receptor than the parent analogs.

• Clean Technology
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• v.21 no.2
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• pp.102-107
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• 2015

Rhodamine dyes are widely used as fluorescent probes because of their excellent photophysical properties, such as high extinction coefficients, excellent quantum yields, great photostability, relatively long emission wavelengths. A great synthetic effort has been focused on developing efficient and practical procedures to prepare rhodamine derivatives, because for most applications the probe must be covalently linked to another (bio)molecule or surface. Sulforhodamine B is one of the most used rhodamine dyes for this purpose, because it carries two sulfoxy functions which can be easily utilized for binding with other molecules. Recently, we needed an expedient, practical synthesis of sulforhodamine derivatives. We found the existing procedure for obtaining those compounds unsatisfactory, particularly, with the cyclization process of the dihydroxytriarylmethane (1) to produce the corresponding xanthene derivative (2). We report here our findings, which represent modification of the existing literature procedure and provide access to the corresponding xanthene derivative (2) in a high yield. Use of methanol as a co-solvent was found quite effective to prohibit the water molecule produced during the cyclization reaction from retro-cyclizing back to the starting dihydroxytriarylmethane and the yield of the cyclization was increased (up to 84% from less than 20%). The reaction temperature was significantly lowered (80 vs. 135 ℃). Thus, the reaction proceeds in a higher yield and energy-saving manner where the use of reactants and the production of chemical wastes is minimized.

• Reproductive and Developmental Biology
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• v.30 no.3
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• pp.181-187
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• 2006

In recent years the number of patients waiting for organ transplantation has greatly outpaced the supply of human organs available, which leads to a renewed interest in pig-to-human xenotransplantation as an alternative. However, one of the biggest barriers in the xenotransplantation is presence of porcine endogenous retroviruses(PERV) that can infect human cells. In this study, to present a possible solution for this problem we tried to inhibit expression of PERVs using shRNAs(short hairpin RNA) at the level of RNA synthesis and virus release. The shRNA targeting the sequence of PERV A, B type was cloned into pSIREN-RetroQ vector under the control of polymerase-III U6-RNA gene promoter. Quantitative real-time PCR was performed to detect my alterations in mRNA production of PERV A, B targeted by the shRNA in each done. Depending on the target sequence of the shRNA, the transcription of PERV was decreased to as much as 4% and the number of progeny viruses was reduced to less than 1/200,000. Transgenic pigs producing such shRNAs may result in a highly reduced PERV expression in cells and organs, which is a prerequisite for safe xenotransplantations.