大蒜精油透過降低氧化型低密度脂蛋白與調節腸道菌相及其代謝產物改善肉鹼誘導運脂蛋白 E 全基因剔除小鼠模式之心血管疾病

Abstract

紅肉中豐富的肉鹼為攝取過量紅肉誘發心血管疾病之主要原因。肉鹼於腸道中會被腸道菌利用再透過肝臟酵素氧化形成氧化三甲胺 (trimethylamine N-oxide, TMAO)，為造成心血管疾病的主要原因之一，但不管是血液中 TMAO還是其他誘發心血管疾病之因子，皆會透過血液中氧化型低密度脂蛋白 (oxidized-low density lipoprotein, ox-LDL) 的形成和慢性發炎所致。因此血液中 ox-LDL 和促發炎細胞激素才是作為心血管疾病之重要生物標記。大蒜 (Allium sativum) 為常見的傳統藥食兩用之食療方食材，其加工品大蒜精油也可透過抗氧化和抗發炎並具有調節血脂之功效達到預防疾病之發生。本研究之目的為探討大蒜精油是否具有降低血液中 ox-LDL 之濃度和調節腸道菌相，達到預防和減緩心血管疾病之功效。大蒜精油為新鮮大蒜以水蒸餾蒸氣法萃取而得，其中最主要的成分為二烯丙基三硫。動物實驗以運脂蛋白E全基因剔除小鼠之模式，透過給予小鼠1.3%肉鹼飲食誘導血管斑塊之生成，並管餵小鼠25和50 mg/kg bw 兩種不同劑量之大蒜精油為期15週。結果顯示，不管是25還是50 mg/kg bw 之大蒜精油皆可顯著降低約50%血管斑塊之生成量 (p < 0.05)，同時可提升小鼠血液中高密度脂蛋白 (p < 0.001)、降低血液中ox-LDL之濃度 (p < 0.001)，並具有降低促發炎性細胞激素介白素-1β (p < 0.01) 和介白素-6。根據小鼠糞便之16S rDNA分析顯示，各組小鼠菌相組成具有差異 (p < 0.001)，且大蒜精油可提高腸道菌之豐富度、均勻度和富有度，且可顯著提升腸道中Alistipes、Roseburia 和Butyricicoccus 等產生丁酸之腸道菌，且腸道代謝產物丁酸也顯著提升。綜上所述，大蒜精油可透過改善血脂、降低血液中ox-LDL、抗發炎和調節腸道菌相及其代謝產物，達到心血管保護之作用。未來可將大蒜精油開發成保健食品，以預防因攝取過多肉品所誘發之心血管疾病。

High consumption of red meat can lead to cardiovascular diseases because of the high concentration of L-carnitine. L-carnitine can be utilized by gut microbiota before host hepatic enzyme to produce trimethylamine N-oxide (TMAO), which is the risk factor for cardiovascular disease. However, not only TMAO, but also all of the factors will cause cardiovascular diseasse through oxidized-low density lipoprotein (ox-LDL) production in the blood stream as well as chronic inflammation. Thus, increasing levels of ox-LDL and proinflammatory cytokine are the biomarker of cardiovascular diseases. Garlic (Allium sativum) is a traditional ingredient, and exhibiting Chinese dietary therapy against numerous diseases as well as garlic essential oil (GEO) possesses anti-oxidation, anti-inflammation effects, and modulates lipid profiles to prevent diseases. The aim of this study is to investigate the protective effects of GEO against cardiovascular diseases as well as explore the mechanisms through reduction the levels of ox-LDL and modulation of gut microbiota composition and its metabolites. GEO is extracted from fresh garlics by steam distillation and its major compound is diallyl trisulfide. In animal study, apoE-/- mice were fed with the 1.3% carnitine water to induce plaque formation and GEO (25 and 50 mg/kg bw) was orally administered for 15 weeks. The results showed that both of the 25 mg/kg bw and 50 mg/kg bw GEO reduced approximately 50% of aortic lesion (p < 0.05). GEO also elevated high density lipoprotein (p < 0.001) and lowering ox-LDL levels (p < 0.001). Furthermore, GEO exhibited the reduction of pro-inflammatory cytokines, including interleukin (IL)-1β (p < 0.01) and IL-6 levels. 16S ribosomal DNA sequencing analysis indicated that feces microbial composition was different (p < 0.001). GEO increased gut microbial abundance, evenness, and richness. Alistipes, Roseburia, and Butyricicoccus are elevated in the intestines with the GEO supplement, which is also the gut microbial metabolite butyrate-producing bacteria. GEO had also improved microbial metabolite butyrate in the intestines. In summary, GEO has cardio-protective effects through modulating gut microbiota and its metabolites. GEO can serve as a functional food to prevent CVDs risk from red meat consumption in the future.