紅麴二次代謝物 monascin 與 ankaflavin 對 3T3-L1脂肪細胞新生作用與脂解作用之探討

Abstract

本研究利用3T3-L1前脂肪細胞株探討紅麴二次代謝產物黃色素中的 monascin (MS) 與 ankaflavin (AK) 對於前脂肪細胞增生、脂肪新生之影響與分化路徑之探討，並分析成熟脂肪細胞脂解作用與脂蛋白脂解酶活性變化。結果顯示， MS 與 AK具有抑制前脂肪細胞增生之效果並呈劑量效應，處理濃度為 8 μg/mL 作用 48 hr 後，MS 與 AK 的抑制率分別為 80.5%、69.2%。在抑制分化之效果上，以 0.125 μg/mL MS處理後抑制三酸甘油酯 (triglyceride, TG) 累積達 37.1%，0.125 μg/mL AK 抑制率為 41.1%，抑制分化效果並無明顯劑量效應。分化路徑分別以轉錄、轉譯層次探討；轉錄層次以即時定量聚合酶鏈反應 (real-time polymerase chain reaction, real-time PCR) 分析之， MS 與 AK 於分化前期、中期皆可抑制CCAAT/enhancer-binding protein β (C/EBPβ)、C/EBPδ、peroxisome proliferator-activated receptor γ (PPARγ) 和 C/EBPα 之基因層次表現；後期 MS 與 AK 對PPARγ、C/EBPα 基因之表現影響並無統計上之差異。轉譯層次以西方點墨法分析，MS 與 AK 皆可抑制 C/EBPβ、PPARγ 與 C/EBPα 之蛋白質表現，且呈劑量效應，以 2 μg/mL MS 及 AK 處理六天後抑制率分別為 43.3%、33.7%、48.5% 及 76.1%、43.5%、63.3%。脂解作用方面，MS 與 AK 均可刺激成熟脂肪細胞釋放甘油，以 4 μg/mL MS及 AK 處理後釋放甘油比例分別增加 113.2%、278.3%，且能抑制脂肪細胞肝素釋放脂蛋白脂解酶 (heparin-releasable lipoprotein lipase, HR-LPL)，以 4 μg/mL MS及 AK 處理後抑制率分別為45.3%、58.1%。本研究證實紅麴二次代謝物除了monacolin K之外的活性物質黃色素 monascin及ankaflavin能夠抑制前脂肪細胞分化，並刺激成熟脂肪細胞進行脂解作用，減少胞內脂肪的累積。

The aim of the present work is to investigate the effects of Monascus secondary metabolites, monascin (MS) and ankaflavin (AK), on cell proliferation, adipogenesis, lipolysis and heparin-releasable lipoprotein lipase (HR-LPL) in 3T3-L1 preadipocyte. MS and AK inhibit the proliferation of 3T3-L1 cells in a dose-dependent fashion. At the 8 μg/mL concentration MS inhibits proliferation for 80.5% after 48 hr, where as AK for 69.2%. Adipogenesis is inhibited by MS and AK without dose-dependency. TG is decreased 37.1% and 41.1% by treating 0.125 μg/mL MS and AK. Adipocyte-specific transcription factors peroxisome proliferator-activated receptor γ (PPARγ), CCAAT/enhancer binding protein β (C/EBPβ), C/EBPδ and C/EBPα mRNA levels are measured by real-time polymerase chain reaction and protein levels by Western blot. The expression of the four transcriptional factors analysed (PPARγ, C/EBPβ, C/EBPδ and C/EBPα) is reduced at the initial and the middle period. At the later period, there is no effect on the expression of PPARγ and C/EBPα by treating MS and AK. The adipocyte-specific transcription factors PPARγ, C/EBPβ and C/EBPα are downregulated after the treatment with 2 μg/mL MS (43.3%, 33.7%, and 48.5% reduction) and 2 μg/mL AK (76.1%、43.5%、63.3%) in translational level by Westen blot. Furthermore, both MS and AK increase basal lipolysis of mature adipocytes by 113.2% and 278.3% up-regulation. And both MS and AK reduce the activity of heparin-releasable lipoprotein lipase by 45.3% and 58.1% reduction. This study reveals for the first time that Monascus secondary metabolites, MS and AK, can prevent the differentiatioin of preadipocyte and stimulate basal lipolysisi of mature adipocytes, avoiding the accumulation of lipid.