Cichorium glandulosum Boiss. et Huet (CGB) extract has an α-glucosidase inhibitory effect (IC₅₀ = 59.34 ± 0.07 μg/mL, positive control drug acarbose IC₅₀ = 126.1 ± 0.02 μg/mL), but the precise enzyme inhibitors implicated in this process are not known. The screening of α-glucosidase inhibitors in CGB extracts was conducted by bioaffinity ultrafiltration, and six potential inhibitors (quercetin, lactucin, 3-O-methylquercetin, hyperoside, lactucopicrin, and isochlorogenic acid B) were screened as the precise inhibitors. The binding rate calculations and evaluation of enzyme inhibitory effects showed that lactucin and lactucopicrin exhibited the greatest inhibitory activities. Next, the inhibiting effects of the active components of CGB, lactucin and lactucopicrin, on α-glucosidase and their mechanisms were investigated through α-glucosidase activity assay, enzyme kinetics, multispectral analysis, and molecular docking simulation. The findings demonstrated that lactucin (IC₅₀ = 52.76 ± 0.21 μM) and lactucopicrin (IC₅₀ = 17.71 ± 0.64 μM) exhibited more inhibitory effects on α-glucosidase in comparison to acarbose (positive drug, IC₅₀ = 195.2 ± 0.30 μM). Enzyme kinetic research revealed that lactucin inhibits α-glucosidase through a noncompetitive inhibition mechanism, while lactucopicrin inhibits it through a competitive inhibition mechanism. The fluorescence results suggested that lactucin and lactucopicrin effectively reduce the fluorescence of α-glucosidase by creating lactucin-α-glucosidase and lactucopicrin-α-glucosidase complexes through static quenching. Furthermore, the circular dichroism (CD) and Fourier transform infrared spectroscopy (FT-IR) analyses revealed that the interaction between lactucin or lactucopicrin and α-glucosidase resulted in a modification of the α-glucosidase’s conformation. The findings from molecular docking and molecular dynamics simulations offer further confirmation that lactucopicrin has a robust binding affinity for certain residues located within the active cavity of α-glucosidase. Furthermore, it has a greater affinity for α-glucosidase compared to lactucin. The results validate the suppressive impact of lactucin and lactucopicrin on α-glucosidase and elucidate their underlying processes. Additionally, they serve as a foundation for the structural alteration of sesquiterpene derived from CGB, with the intention of using it for the management of diabetic mellitus.

中文翻译：

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菊苣中α-葡萄糖苷酶抑制剂的筛选。 et Huet 提取物及其相互作用机制的研究

菊苣（Cichorium mudulosum Boiss）。 et Huet（CGB）提取物具有α-葡萄糖苷酶抑制作用（IC ₅₀ = 59.34 ± 0.07 μg/mL，阳性对照药阿卡波糖 IC ₅₀ = 126.1 ± 0.02 μg/mL），但该过程中涉及的精确酶抑制剂尚不存在。已知。采用生物亲和超滤法对CGB提取物中的α-葡萄糖苷酶抑制剂进行筛选，筛选出六种潜在抑制剂（槲皮素、乳糖素、3-O-甲基槲皮素、金丝桃苷、乳三苦苷、异绿原酸B）作为精准抑制剂。结合率计算和酶抑制效果评价表明，乳酸菌素和乳酸苦素表现出最大的抑制活性。接下来，通过α-葡萄糖苷酶活性测定、酶动力学、多光谱分析和分子对接模拟，研究了CGB活性成分乳糖素和乳糖苦素对α-葡萄糖苷酶的抑制作用及其机制。研究结果表明，与阿卡波糖（阳性药物，IC _{50 = 195.2 ± 0.30 μM）相比，乳糖素（IC 50} = 52.76 ± 0.21 μM）和乳糖苦素（IC ₅₀ = 17.71 ± 0.64 μM）对α-葡萄糖苷酶表现出更强的抑制作用。酶动力学研究表明，乳酸菌素通过非竞争性抑制机制抑制α-葡萄糖苷酶，而乳酸苦素则通过竞争性抑制机制抑制α-葡萄糖苷酶。荧光结果表明，乳酸菌素和乳酸苦素通过静态猝灭产生乳酸菌素-α-葡萄糖苷酶和乳酸菌苦素-α-葡萄糖苷酶复合物，有效降低α-葡萄糖苷酶的荧光。此外，圆二色性（CD）和傅里叶变换红外光谱（FT-IR）分析表明，乳糖素或乳三苦素与α-葡萄糖苷酶之间的相互作用导致α-葡萄糖苷酶的构象发生改变。分子对接和分子动力学模拟的结果进一步证实乳三苦素对位于 α-葡萄糖苷酶活性腔内的某些残基具有强大的结合亲和力。此外，与乳糖素相比，它对 α-葡萄糖苷酶具有更大的亲和力。结果验证了乳糖素和乳糖苦素对 α-葡萄糖苷酶的抑制作用，并阐明了其潜在过程。此外，它们还作为 CGB 衍生倍半萜结构改变的基础，旨在将其用于治疗糖尿病。