乳酸菌生產血管收縮素 I 轉化酶抑制劑與 γ-胺基丁酸之最適培養條件探討與降血壓功效評估

Abstract

高血壓為心血管疾病危險因子之一，近年來許多研究指出，特定的乳酸菌於發酵過程中會產生血管收縮素轉換酶抑制劑 (angiotensin I converting enzyme inhibitor, ACEI)，或 γ-胺基丁酸 (γ-aminobutyric acid, GABA)，而具降血壓之功效。本研究以 Lactobacillus paracasei subsp. paracasei NTU 101 及 L. plantarum NTU 102 發酵脫脂牛奶製備 NTU 101 與 NTU 102 發酵乳，並藉由反應曲面法 (response surface methodology, RSM) 探討最適培養條件，以提高 ACEI 活性及 GABA 含量。利用自發性高血壓大鼠 (spontaneously hypertensive rats, SHR) 為動物模式，評估 NTU 101、NTU 102 發酵乳於短期及長期的血壓調節情形。 以 RSM 最適化條件培養 (20% 脫脂牛奶、起始 pH 9.0、15% 接菌量) L. paracasei subsp. paracaseiNTU 101，其發酵乳之 ACEI 活性從52 mU/mL 提升到 125 mU/mL；NTU 102 發酵乳可同時生產 ACEI 及 GABA，在 RSM 最適培養條件下 [10% 脫脂牛奶、添加 1% 麩胺酸鈉 (monosodium glutamate, MSG）、培養溫度 34oC]，可使 ACEI 活性從 33 mU/mL 提升到 93 mU/mL，GABA 含量從 1.58 mg/L 提升到 629 mg/L。以動物模式評估發酵乳降血壓功效，單次餵食 NTU 101 發酵乳八小時後可降低收縮壓 25 mmHg (p<0.001) 舒張壓 37 mmHg (p<0.01)，長期餵食八週後則可降低收縮壓 23 mmHg (p<0.001) 舒張壓 32 mmHg (p<0.001)。單次餵食 NTU 102 發酵乳八小時後可降低收縮壓 21 mmHg (p<0.01) 舒張壓 31 mmHg (p<0.05)，長期餵食八週後則可降低收縮壓 19 mmHg (p<0.001) 舒張壓 30 mmHg (p<0.01)。弓動脈切片鏡檢，乳酸菌發酵乳皆可恢復高血壓造成的彈性蛋白排列紊亂，安全性上並無任何疑慮，未來或許可提供作為產業化生產。

Hypertension is one critical factor of metabolic syndromes. Lactic acid bacteria fermented products show antihypertensive effects by angiotensin I converting enzyme inhibitor (ACEI) and/or γ-aminobutyric acid (GABA). In this study, we prepared NTU 101 fermented milk (101FM) and NTU 102 fermented milk (102FM) which fermented by Lactobacillus paracasei subsp. paracasei NTU 101 and L. plantarum NTU 102, respectively. To enhance the ACEI activity and GABA concentration in fermented milk, response surface methodology (RSM) was used to evaluate the optimal culture conditions. The ACEI activity of 101FM increased from 52 mU/mL to 125 mU/mL by following culture conditions: 20% skim milk, initial pH 9.0, and 15% inoculum density. On the other hand, the ACEI activity and GABA concentration of 102FM increased from 33 mU/mL to 93 mU/mL and from 1.58 mg/L to 629 mg/L under the follow conditions: 10% skim milk, 1% monosodium glutamate (MSG), and 34oC culture temperature. Next, 101FM and 102FM were used to investigate the effect on anti-hypertension in spontaneous hypertension rat (SHR). Eight hours after single oral administration of 101FM, the decreased of systolic blood pressure (SBP) and diastolic blood pressure (DBP) were 25 mmHg (p<0.001) and 37 mmHg (p<0.01), respectively. Eight weeks after chronic administration, the decreased of SBP and DBP were 23 mmHg (p<0.001) and 32 mmHg (p<0.001), respectively. Eight hours after single oral administration 102FM, the decreased of SBP and DBP were 21 mmHg (p<0.01) and 31 mmHg (p<0.05). Eight weeks after chronic administration, the decreased of SBP and DBP were 19 mmHg (p<0.001) and 30 mmHg (p<0.01) , respectively. By microscopic examination of arota biopsy, 101FM and 102FM both not only can reduce the disorganization of media layer but also is safety for organisms. It can provide the direction such as industrial production in the future study.