꾸지뽕잎으로 제조한 덖음차(PM)와 발효차(FM)의 $alpha$-glucosidase 저해활성과 경구 내당성 및 stereptozotocin(STZ)으로 유발한 고혈당 쥐의 혈당, fructosamine 및 혈청 지질 함량에 미치는 영향을 조사하였다. 70% ethanol 추출물(20 mg/mL)의 $alpha$-glucosidase 저해 활성은 FM 92.5%, RM 54.6%, 건조꾸지뽕잎(RM) 69.1%였다. 경구 내당성을 조사한 결과, 고혈당 대조군은 360분까지 혈당의 감소가 없었으나 PM 및 FM을 투여한 군에서는 투여 후 60분부터 감소하여 120분 후에는 정상군 수준으로 회복되었다. 당뇨 유발 후 동결 건조한 차분말을 3% 혼합한 식이로 5주간 사육한 결과, PM 및 FM 투여군은 고혈당 대조군에 비하여 다음과 같은 효과가 있었다. 체중 증가량, 식이효율은 유의적으로 높았으며, 식이 및 음용수 섭취 량은 각각 $12.9{sim}16.9%$ 및 $6.8{sim}10.1%$가 감소하였다. 혈당과 fructosamine 함량은 각각 $27.3{sim}39.8%$ 및 $6.7{sim}20.0%$가 감소하였다. 혈청중성지질, total cholesterol 및 LDL-cholesterol 함량은 각각 $24.9{sim}27.1%$, $15.9{sim}17.4%$ 및 $33.8{sim}38.4%$ 감소하였다. HDL-cholesterol함량은 $20.5{sim}24.8%$가 증가하였다. 이러한 효과는 PM보다 FM이 다소 양호하였다. 이상의 결과, 꾸지뽕잎차의 항당뇨 효과는 $alpha$-glucosidase 저해 활성과 더불어 고혈당에 기인된 혈청 지질의 변화를 저해함으로써 나타난 것으로 생각되나 보다 구체적인 mechanism에 대하여 앞으로의 연구가 요망된다.
The effects of pan-fired (PM) and fermented (FM) Cudrania tricupidata tea leaves on $alpha$-glucosidase inhibitory activity, oral glucose tolerance, blood glucose levels and serum lipids profiles in streptozotocin (STZ)-induced hyperglycemic rats were investigated. The $alpha$-glucosidase inhibitory activity of FM ethanol extracts (20 mg/mL) was higher (92.5%) than that of raw dried leaves (RM) (69.1%) and PM (54.6%). In addition, the results of a glucose tolerance test revealed that the glucose levels of hyperglycemic rats that were fed PM and FM ethanol extracts and then orally administered glucose began to decrease after 60 minutes, but recovered after 120 minutes. However, the blood glucose levels in the hyperglycemic control group did not begin to decrease for 360 minutes. Additionally, the results of animal experiments that were conducted over five weeks to compare the dietary effects of PM and FM following hyperglycemic induction to the effects on the hyperglycemic control group (DM) were as follows: The body weight gain and FER of the treated rats were $12.9{sim}16.9%$ higher than those of the DM group, whereas the amounts of feed and water intake by the treated rats were $6.8{sim}10.1%$ lower. Additionally, the levels of blood glucose and serum fructosamine decreased by $27.3{sim}39.8%$ and $6.7{sim}20.0%$, respectively, in the treated rats. Moreover, the serum triglyceride, total cholesterol and LDL-cholesterol concentrations in the treated rats were $24.9{sim}27.1%$, $15.9{sim}17.4%$ and $33.8{sim}38.4%$ lower, respectively. Finally, the HDL-cholesterol contents were $20.5{sim}24.8%$ higher in the treated rats than in the control group. The above results suggest that PM and FM exerts an anti-hyperglycemic effect that occurs due to the inhibition of $alpha$-glucosidase activity as well as via prevention and/or inhibition of changes in the serum lipid profile. In addition, the results of this study revealed that the synthetic anti-hyperglycemic effect of FM was greater than that of PM. However, further detailed studies are needed to confirm these results.
