In vitro Anti-diabetic Effects of Crude Extracts of Platycodi Radix

In vitro에서 길경 추출 분획물의 항당뇨 효과 조사

  • 고병섭 (한의학 연구원 한약품질 검사팀) ;
  • 권대영 (한국식품연구원 기능성연구부) ;
  • 홍상미 (호서대학교 자연과학대학 식품영양학과) ;
  • 박선민 (기초과학연구소)
  • Published : 2007.12.01

Abstract

Anti-diabetic effect of Platycodi radix (PR) extract fractions was determined if vitro by investigating insulin-like action, insulin sensitizing action, glucose-stimulated insulin secretion, gene expression related to ${\beta}-cell$ function and mass, and ${\alpha}$-glucoamylase suppressing action. Insulin-like activity was not promoted by the treatment of PR methanol factions in 373-L1 fibroblast. However, treatment with 0, 20 and 100% PR methanol fractions along with 1 ng/mL insulin increased insulin-stimulated glucose uptake in 373-L1 adipocytes. In addition, the treatment of 0% and 100% methanol fractions along with differentiation inducers significantly increased the differentiation of 373-L1 fibroblasts to adipocytes. These fractions may contain insulin sensitizer. The 20%, 80% and 100% methanol fractions enhanced glucose-stimulated insulin secretion in Min6 cells, insulin secreting cell line. This was related to the mechanism to promote glucose sensing and ${\beta}-cell$ proliferation, which was regulated by the induction of IRS-2, glucokinase and PDX-1 genes. As expected, 20, 80 and 100% methanol fractions increased mRNA levels of IRS-2, glucokinase and PDX-1 genes. However, PR fractions did not affect the ${\alpha}-glucoamylase$ activity in vitro. These data suggested that PR extract fractions have anti-diabetic actions through improving insulin sensitization, glucose-stimulated insulin secretion, and ${\beta}-cell$ proliferation. Therefore, PR extracts can be beneficial for anti-diabetic treatment in lean diabetic patients.

민간요법에서 항당뇨 및 항비만 효과가 있는 것으로 알려진 길경의 항당뇨 효과가 있는 지 여부를 in vitro에서 조사하기 위해서 길경을 70% 에탄올로 추출한 후 메탄올과 물을 섞은 용액으로 단계별로 XAD-4 column으로 분획하였다. 본 연구에서는 1) 3T3-L1 섬유아세포와 지방세포에서 길경의 추출 분획물이 인슐린처럼 작용하는 인슐린성 물질이거나, 2) 인슐린 작용을 향상시키는 인슐린 민감성 물질이거나, 또는 3) 포도당 자극에 의한 인슐린 분비를 향상시키거나, 4) 베타세포의 기능과 양을 증가시키는데 관여하는 유전자인 IRS-2, glucokinase, PDX-1의 mRNA 발현을 향상시키거나, 5) $\alpha-glucoamylase$ 활성을 억제하는 물질로 작용하는 지 여부를 조사하였다. 길경 추출 분획물은 인슐린성 물질로 작용하지 않았다. 반면에 0, 20와 100%메탄올층은 3T3-L1 지방세포에서 인슐린 자극에 의한 포도당 흡수를 증가시켰다. 이 분획층 중에서 특히 0%과 100% 메탄올 분획층은 분화 유도물질의 작용을 향상시켜 3T3-L1 섬유아세포에서 지방세포로의 분화 및 중성 지방의 축적을 증가시켰다. 그러므로 이들은 $PPAR-{\gamma}$ agonist로 작용하는 물질을 함유할 가능성이 매우 높다. 인슐린을 분비하는 세포인 Min6 세포에서 포도당 자극에 의한 인슐린 분비를 향상시키는 지 여부를 조사하였는데 20, 80 그리고 100% 메탄올층은 포도당 자극에 의한 인슐린 분비를 증가시켰다. 그 기전은 인슐린 분비와 베타세포의 증식에 관여하는 유전자의 IRS-2, glucokinase 그리고 PDX-1의 mRNA의 양을 증가시키는 것과 관련이 있다. 결론적으로 길경은 지방 세포의 분화를 촉진하는 물질, 인슐린 민감성을 향상시키는 물질 그리고 베타세포의 기능과 증식을 촉진시키는 물질을 함유하고 있으므로 우리나라 및 아시아의 사람들에서 많이 유발되는 비만을 동반하지 않은 당뇨병 및 인슐린 저항성의 치료와 예방에 중요한 역할을 할 것으로 사료된다.

Keywords

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