Identification of bioactive compounds that contribute to the α-glucosidase inhibitory activity of rosemary. Issue 2 (10th February 2020)

• Record Type: Journal Article
• Authors: Ma, Yan-Yan; Zhao, Deng-Gao; Zhang, Ruiqiang; He, Xuan; Li, Bao Qiong; Zhang, Xiang-Zhi; Wang, Zijian; Zhang, Kun
• Is Part Of: Food & function. Volume 11:Issue 2(2020)
• Page Start: 1692
• Page End: 1701
• Publication Date: 2020-02-10
• Subjects: Food -- Analysis -- Periodicals; Food -- Composition -- Periodicals; Nutrition -- Periodicals; 664.07
• DOI: 10.1039/c9fo02448d
• Languages: English
• ISSNs: 2042-6496

Abstract

Abstract : To investigate the bioactive compounds that contribute to the α-glucosidase inhibitory activity of rosemary, phenolics and triterpene acids were characterized and quantified using quadrupole-Orbitrap mass spectrometry and enzyme assay. Abstract : To investigate the bioactive compounds that contribute to the α-glucosidase inhibitory activity of rosemary, phenolics and triterpene acids were characterized and quantified using quadrupole-Orbitrap mass spectrometry and enzyme assay. Two phenolic diterpenes (carnosol and hydroxy p -quinone carnosic acid) and two triterpene acids (betulinic acid and ursolic acid) were identified as potent α-glucosidase inhibitors. Carnosol, a major diterpene in rosemary, showed significant α-glucosidase inhibitory activity with IC50 value of 12 μg mL −1, and its inhibition mode was competitive. The inhibition mechanism of carnosol on α-glucosidase was further investigated by a combination of surface plasmon resonance (SPR) spectroscopy, fluorescence quenching studies and molecular-modeling techniques. The SPR assay suggested that carnosol had a high affinity to α-glucosidase with equilibrium dissociation constant ( K D ) value of 72.6 M. Fluorescence quenching studies indicated that the binding between carnosol and α-glucosidase was spontaneous and mainly driven by hydrophobic forces. Molecular docking studies revealed that carnosol bound to the active site of α-glucosidase. Furthermore, the oral administration of carnosol at 30 mg kg −1 significantly reduced the postprandial blood glucose levels of normal mice. This is the first report on the α-glucosidase inhibition and hypoglycemic activity of phenolic diterpenes, and these results could facilitate the utilization of rosemary as a dietary supplement for the treatment of diabetes.