Liu Xinxin, Gu Yipeng, Zhou Yihao, Zhang Ruiqi, Koyama Tomoyuki
Graduate School of Marine Science and Technology, Tokyo University of Marine Science and Technology, 4-5-7 Konan, Tokyo 108-8477, Japan.
Guangxi Key Laboratory of Health Care Food Science and Technology, Institute of Food Science and Technology, Hezhou University, Hezhou 542899, China.
Molecules. 2024 Dec 19;29(24):6000. doi: 10.3390/molecules29246000.
The brown alga (SF) is historically consumed as a food material in Japan. A steaming process is often required for SF products on the market due to their moderate hardness and astringent taste. This investigation aimed to elucidate the effect of steaming on the anti-diabetic activity of SF and its related chemical components. Acetone extracts of SF were prepared after it were steamed for 0, 1, 2, or 4 h (SF-0h, SF-1h, SF-3h, and SF-4h, respectively). Alpha-glucosidase inhibitory profiles of each SF extract were made based on activity-guided separation. The active fractions were collected and NMR was applied for a further chemical composition analysis. Our results suggested that total polyphenol levels decreased drastically after steaming, which resulted in a drop in α-glucosidase inhibitory activity. The fatty acid, pheophytin a, and pyropheophytin a contents were elevated significantly after steaming, which contributed to the majority of the activity of steamed SF (SF-1h). However, prolonging the steaming time did not significantly affect the activity of SF further since the content of free fatty acids in steamed SF (SF-2h and SF-4h) almost did not change with a longer time of steaming. Moreover, palmitic acid, 8-octadecenoic acid, and tetradecanoic acid were identified as the top three important fatty acids for the inhibition of α-glucosidase by steamed SF. Further molecular docking results revealed that these fatty acids could interact with residues of α-glucosidase via hydrogen bonds, salt bridges, and hydrophobic interactions. In conclusion, steaming altered the α-glucosidase inhibitory properties of SF by changing the contents of polyphenols, fatty acids, and chlorophyll derivatives.
褐藻（SF）在日本一直被作为食品原料食用。由于市售SF产品硬度适中且有涩味，通常需要进行蒸煮处理。本研究旨在阐明蒸煮对SF及其相关化学成分的抗糖尿病活性的影响。将SF分别蒸煮0、1、2或4小时后制备丙酮提取物（分别为SF-0h、SF-1h、SF-3h和SF-4h）。基于活性导向分离对每种SF提取物的α-葡萄糖苷酶抑制谱进行分析。收集活性组分并应用核磁共振进行进一步的化学成分分析。我们的结果表明，蒸煮后总多酚水平急剧下降，导致α-葡萄糖苷酶抑制活性降低。蒸煮后脂肪酸、脱镁叶绿素a和焦脱镁叶绿素a的含量显著升高，这是蒸煮后SF（SF-1h）大部分活性的原因。然而，延长蒸煮时间对SF的活性没有进一步显著影响，因为蒸煮后SF（SF-2h和SF-4h）中游离脂肪酸的含量几乎不会随着蒸煮时间的延长而变化。此外，棕榈酸、8-十八碳烯酸和十四烷酸被确定为蒸煮后SF抑制α-葡萄糖苷酶的三大重要脂肪酸。进一步的分子对接结果表明，这些脂肪酸可通过氢键、盐桥和疏水相互作用与α-葡萄糖苷酶的残基相互作用。总之，蒸煮通过改变多酚、脂肪酸和叶绿素衍生物的含量改变了SF对α-葡萄糖苷酶的抑制特性。
