• Proceedings of the Korean Society of Applied Pharmacology
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• 1996.04a
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• pp.252-252
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• 1996

We Investigated the peripheral excitatory effect of capsaicin and KR-25018, a newly synthesized capsaicin derivative which was demonstrated to have a potent analgesic activity. KR-25018 and capsaicin were found to be both potent efficacious contractors of isolated guinea pig bronchial smooth muscle. KR-25018 was equipotent with capsaicin and [Sar$\^$9/,Met(O$_2$)$\^$11/]-substance P, 10-fold more potent than histamine and 10-fold less potent than (${\beta}$ -Ala$\^$8/)-neurokinin A(4-10), and their -log(M)EC$\_$50/ values were 6.94${\pm}$0.08, 6.86${\pm}$0.05, 6.96${\pm}$0.07, 5.64${\pm}$0.04, 7.96${\pm}$0.02, respectively. Contractile responses to KR-25018 and capsaicin were potentiated by phosphoramidon (1 ${\mu}$M), an inhibitor of neuropeptide-inactivating endopeptidase, but completely abolished in a calcium-free medium. These responses to KR-25018 and capsaicin were unaffected by the NK-1 antagonist CP96345 (1${\mu}$M), partially inhibited by the NK-2 antagonist SR48968 (1 ${\mu}$M) but almost completely abolished by a combination of the antagonists. A vanilloid receptor antagonist capsazepine competitively antagonized the responses to both KR-25018 and capsaicin (pA$_2$: aganst KR-25018, 5.98${\pm}$0.47; against capsaicin, 5.80${\pm}$0.31), and a capsaicin-sensitive cation channel antagonist ruthenium red caused significant reduction in the maximum responses to KR-25018 and capsaicin (pD'$_2$: against KR-25018, 4.61${\pm}$0.33; against capsaicin 4.96${\pm}$0.21). In conclusion, the present results suggest that KR-25018 and cpasaicin act on the same vanilloid receptor inducing the influx of calcium through ruthenium red-sensitive cation channel and produce contractile responses via the release of tachykinins that act on both NK-1 and NK-2 receptor subtypes.

• Journal of Food Hygiene and Safety
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• v.9 no.3
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• pp.163-168
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• 1994

In the present study we investigated the peripheral function of capsaicin and KR-25018, a newly synthesized capsaicin derivative, which was demonstrated to have a potent analgesic activity through different mechanism from morphine and nonsteroidal antiinflammatory drugs. Capsaicin (10-8~10-5 M) and KR-25018 (10-8~10-5 M) produced concentration-dependent contractions of the isolated guinea pig bronchi. There were no significant differences in the maximum response and the EC50 values (EC50: 0.137$\pm$0.025 $\mu$M and 0.097$\pm$0.031 $\mu$M for capsaicin and KR-25018, respectively, P>0.05). Phosphoramidon (10 $\mu$M) and indomethacin (10 $\mu$M) had no significant effect on contractile response to the submaximal concentration range of capsaicin and KR-25018 (3$\times$10-9~3$\times$10-7 M). The response to KR-25018, like that to capsaicin, was significantly inhibited by ruthenium red with reduction in the maximum response, which is indicative of non-competitive antagonism. A further common feature of the responses to capsaicin and KR-25018 in the guinea pig bronchi was their sensitivity to capsazepine. Capsazepine caused a rightward parallel shift in concentration-response curves obtained by capsaicin and KR-25018. the pA2 values of capsazepine were 5.90 and 5.99 against capsaicin and KR-25018 response, respectively. In conclusion, KR-25018 and capsaicin exert their contractile effects in the isolated guinea pig bronchial muscle by common mechanisms, probably via the activation of a specific receptor.

• Proceedings of the Korean Society of Applied Pharmacology
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• 1996.04a
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• pp.253-253
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• 1996

KR-25018 과 capsaicin 모두 용량의존적으로 진통효과를 나타내었으며 효력은 KR-25018이 capsaicin 보다 약간 강하거나 비슷하였고, 두 약물 모두 10 mg/kg에서 최대 효과를 나타내었다. KR-25018 과 capsaicin의 투여 농도에 의존적으로 기관지의 substance P 양이 감소하였으며 두 약물 모두 5 mg/kg에서 최대효과를 나타내었다. Capsaicin 1 mg/kg 전처치에 의해 기니픽의 체온이 30 분부터 감소하였으나, KR-25018 1 mg/kg에 의해서는 체온변화가 훨씬 미약하였다. Capsazepine 의 병용투여에 의해 두 약물의 진통작용 및 substance P 감소작용은 모두 억제되었으나 체온 변화에 대해서는 capsazepine이 아무런 영향을 미치지 않았다.

• Archives of Pharmacal Research
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• v.17 no.5
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• pp.304-308
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• 1994

Among the new series of phenylacetamides, one of capsaicin derivatives, KR-25018 was found to have a very potent analgesic activity. Thus, the phamacological properties of KR-25018 were compared with those of morphine, capsaicin, and nonsteroidal antiinflammatory drugs (NSAIDs). The analgesic activities were evaluated in several animal models, using different stimuli, such as phenylbenzoquinone(PBQ)-induced weithing test, tail-filck test in mice and adjuvant arthritic flexion test in rat. The relationship of phamacological properties of KR-25018 to that of centrally acting opioids was assessed by the blocking test using naloxone. The analgesic potency of the KR-25018 $(MPED_{50}=0.89{\;}p.o.{\;}in{\;}PBQ-induced{\;}weithing{\;}test, {\;}MPED_{50}$=0.61$ s.c. in tail-flick test in mice0, with different action mechanism from morphine and NSAIDs, was comparable to that of morphine.

• Restorative Dentistry and Endodontics
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• v.20 no.2
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• pp.423-431
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• 1995

Trigeminal spinal sensory nucleus is a main relay site in transmission of orofacial pain. Glutamate and aspartate playa role in transmission of primary afferents. This experiment was performed to study the role of capsaicin, KR-25018 and shogaol on the release of glutamate and aspartate from trigeminal spinal sensory nucleus. Release of excitatory amino acids(EAAs) was induced by electrical stimulation of oral mucosa with innocuous or noxious stimuli. Capsaicin($10{\mu}M$), KR-25018($10{\mu}M$), shogaol($10{\mu}M$), ruthenium red and capsazapine were added to perfusion solution to observe the changes in EAA release, and glutamate and aspartate were determined by HPLC. Release of glutamate and aspartate from trigeminal sensory nucleus was increased by noxious stimulation of oral mucosa, but innocuous stimulation did not affect on the release of EAA Capsaicin and KR-25018 increased the release of glutamate and aspartate, and effect of KR-25018 on release of EAA was more potent than capsaicin. But shogaol had a weak effect on release of EAA. Effect of capsaicin and KR-25018 was partially blocked by capsaicin antagonists, ruthenium red and capsazepine.

• Biomolecules & Therapeutics
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• v.3 no.4
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• pp.256-259
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• 1995

Antinociceptive and desensitizing effects of systemically administered capsaicinoids (capsaicin and KR25018) were investigated in guinea pig. Nociceptive sensitivity to chemical stimulus was examined to test sensory function, and the content of substance P-like immunorractivity (SP-LI) in bronchi was determined as a peripheral marker of capsaicin-sensitive primary afferent neurons. Guinea pigs were pretreated s.c. with several doses of capsaicin (1,2.5,5, 10 mg/kg) or KR25018 (1, 2.5, 5, 10 mg/kg) one week prior to the experiments. Frequency of eye wiping was significantly decreased by capsaicin and KR25018 in a pretreatment dosedependent manner. In capsaicin- or KR25018-pretreated guinea pigs, there was a significant loss of SP-LI in bronchial tissue extracts. In summary, a newly synthesized capsaicin analogue H725018 exhibited antinociceptive effect against chemical stimulus in guinea pig, with comparable potency to capsaicin. This desensitizing activity of capsaicin or KR25018 might be related to the loss of SP-LI in peripheral afferent nerves.

• Biomolecules & Therapeutics
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• v.3 no.1
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• pp.54-57
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• 1995

The effect of Ruthenium Red on the antinociceptive action of capsaicinoids was investigated using tail-flick test in mice. Capsaicin and KR-25018, when administered subcutaneously, had a potent antinociceptive effect against noxious heat stimulus. Ruthenium Red which is known to block the calcium channel coupled to the capsaicin receptor, when injected intraperitoneally more than 5 mg/kg, showed severe sedation and apparent antinociceptive effect against noxious heat stimulus. The 2.5 mg/kg Ruthenium Red, at which dose any significant sedative effect was not shown, had no effect on the antinociceptive effects of capsaicin and KR-25018. Considering this result, the antinociceptive effect of capsaicinoid may not be related to the Ruthenium Red sensitive calcium channel which is activated by capsaicin.

• Proceedings of the Korean Society of Applied Pharmacology
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• 1993.04a
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• pp.147-147
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• 1993

신생쥐의 DRG 배양에서 접종후 1일째 neurite의 형성을 관찰할수 있었고 배양한 세포가 신경세포임을 확인하기 위하여 신경섬유에 대한 항체를 이용한 조직화학적 실험을 실시한 결과 붉게 염색된 세포를 볼 수 있었으므로 이 세포들이 DRG신경세포임을 확인할 수 있었다. 배양한 신경세포중 capsaicin에 대한 감수성을 갖는 신경세포군을 확인하기 위하여 cobalt stain 방법으로 실험한 결과 capsaicin에 대한 감수성율 갖는 신경세포룰 관찰할 수 있었고 비교를 위하여 함께 실험한 resiniferatoxin, KR 25018, 6-paradol, NE-19550, RDL-201등의 capsaicin 유사체들의 경우도 정도는 달리 하였으나 유사한 반응을 보였으므로 일차배양한 신경세포에 대한 작용이 capsaicin의 작용과 같을 가능성을 보여주었다. 진통효과 검정결과 진통효과가 있는 것으로 확인된 capsaicin 구조 유사체들인 resiniferatoxin, 6-paradol, NE-19550, RDL-201, KR-25018모두 농도 의존적인 반응을 보였다. 또한 칼슘 도입을 위해 요구되는 관능기로는 알킬측쇄와 P-위치의 수산기, 3-methoxy기 및 acyl amide 구조가 중요하였다. 알킬측쇄는 NVA의 경우처럼 탄소 8개 정도가 적당했으나 구조적으로 현저히 다른 치환기를 가진 resiniferatoxin이나 KR-25018의 경우에도 유효하였다. Vanillin환의 P-수산기도 필수적이었고 3-methoxy기의 존재시에는 칼슘 도입효과가 강하였다. Acyl amide 결합도 중요하나 필수적은 아니였다.

• Proceedings of the Korean Society of Applied Pharmacology
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• 1994.04a
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• pp.294-294
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• 1994

To investigate analgesic mechanism of capsaicin and its analogues (capsaicinoids), release of adenosine was measured by high performance liquid chromatography from dorsal spinal cord synaptosomes, Exposure of synaptosomes to K$\^$+/ and morphine produced a dose dependent release of adenosine in the presence of Ca$\^$++/. Capsaicin (0.1, 1, 10 M), and its analogues 6-paradol (1, 10 M), NE-19550 (1, 10, 100 M), DMNE (1, 10, 100 M) and KR 25018 (0.1, 1, 10 M) produced a dose dependent release of adenosine in the presence of Ca$\^$++/. Nifedipine, L-type voltage sensitive calcium channel blocker, inhibited K$\^$+/ (6, 12 mM)- and morphine (10 M)-evoked release of adenosine completely, but inhibited capsaicin, and capsaicinoids-evoked release of adenosine partially. Capsazepine, a novel capsaicin select ive antagonist, blocked only capsaicin and capsaicinoids induced release of adenosine. Therefore, the adenosine release by capsaicin and capsaicinoids having antinociceptive effects involve activation of capsaicin specific receptor and capsaicin sensitive Ca$\^$++/ channel.

• YAKHAK HOEJI
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• v.43 no.1
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• pp.55-60
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• 1999

To investigate analgesic mechanism of capsaicin and its analogues (capaicinoids) adenosine release was measured by high performance liquid chromatography from rat spinal cord synaptosomes. Exposure of synaptosomes to $K^+$ and morphine produced a dose dependent release of adenosine in the presence of $Ca^{++}$. Capsaicin (0.1, 1, $10{\;}{\mu}M$), and its analogues: NE-19550 (1, 10, $100{\;}{\mu}M$), DMNE (1, 10, $100{\;}{\mu}M$) and KR 25018 (0.1, 1, $10{\;}{\mu}M$) produced a concentration dependent release of adenosine in the presence of $Ca^{++}$. Nifedifine, L-type voltage sensitive calcium channel blocker, inhibited $K^+$ (6, 12 mM)-and morphine ($10{\;}{\mu}M$)-evoked release of adenosine partially. Capsazepine, a novel capsaicin selective antagonist, blocked only capsaicin and capsaicinoids induced release of adenoside. Therefore, it is suggested that the adenosine release by capsaicin and capsaicinoids having antinociceptive effects involves actvation of capsaicin specific receptor and capsaicin sensitive $Ca^{++}$. channel.