| In vitro: |
| J Agric Food Chem. 2001 Jun;49(6):3113-9. | | Antioxidative activities of phenylethanoid glycosides from Ligustrum purpurascens.[Pubmed: 11410017] |
Tea and kudingcha (bitter tea) are the two most popular beverages consumed in China. Tea derived from the leaves of Camellia sinensis has been well studied for its various health benefits, but there are very limited data on the biological activities of bitter tea derived from the leaves of Ligustrum purpurascens (LP).
METHODS AND RESULTS:
The present study was carried out to characterize the antioxidants present in the bitter tea brewed from the leaves of LP. It was found that the crude glycoside fraction possessed strong protection against oxidation of human low-density lipoprotein (LDL). The column chromatographic separation led to the isolatation of five phenylethanoid glycosides, namely, acteoside, Ligupurpuroside A, cis-ligupurpuroside B, trans-ligupurpuroside B, and osmanthuside B. When acteoside was heated in the boiling water, it was isomerized to form isoacteoside. Acteoside, isoacteoside, and Ligupurpuroside A purified from LP were protective, whereas cis-ligupurpuroside B, trans-ligupurpuroside B, and osmanthuside B exhibited no protection to human LDL from Cu(2+)-medicated oxidation. Acteoside, isoacteoside, and Ligupurpuroside A were also effective in preventing the peroxyl free radical-induced oxidation of alpha-tocopherol in human LDL. The antioxidant activities of acteoside, isoacteoside, and Ligupurpuroside A were comparable to that observed for a green tea antioxidant, (-)-epicatechin gallate. The inhibitory effect of these three phenylethanoid glycosides on oxidation of human LDL and alpha-tocopherol was dose-dependent at concentrations of 5-40 microM.
CONCLUSIONS:
The present results suggest that the bitter tea beverage derived from LP contains effective antioxidants that may have an equal benefit as a green tea beverage. |
|
| In vivo: |
| Phytother Res. 2018 Apr;32(4):715-722. | | Hypolipidemic activity and mechanisms of the total phenylpropanoid glycosides from Ligustrum robustum (Roxb.) Blume by AMPK-SREBP-1c pathway in hamsters fed a high-fat diet.[Pubmed: 29468762 ] | The aim of this study was to evaluate the hypolipidemic effect and mechanisms of total phenylpropanoid glycosides extracted from Ligustrum robustum (Roxb.) Blume (LRTPG) in hamsters fed a high-fat diet and to discover bioactive components in HepG2 cell model induced by oleic acid.
METHODS AND RESULTS:
LRTPG of high (1.2 g/kg), medium (0.6 g/kg), and low (0.3 g/kg) doses was administrated daily for 21 consecutive days in hamsters. We found that in hamsters fed a high-fat diet, LRTPG effectively reduced the concentrations of plasma triglycerides (TG), free fatty acid, total cholesterol, low-density lipoprotein cholesterol, and hepatic TG and total cholesterol. And the compounds acteoside, Ligupurpuroside A, ligupurpuroside C, and ligupurpuroside D significantly inhibited lipid accumulation in HepG2 cell at the concentration of 50 μmol/L. Mechanism research demonstrated that LRTPG increased the levels of phospho-AMP-activated protein kinase and phospho-sterol regulatory element binding protein-1c in liver, further to suppress the downstream lipogenic genes as stearoyl-CoA desaturase 1, glycerol-3-phosphate acyltransferase, 1-acylglycerol-3-phosphate O-acyltransferase 2, and diacylglycerol acyltransferase 2. In addition, LRTPG increased the hydrolysis of circulating TG by up-regulating lipoprotein lipase activities.
CONCLUSIONS:
These results indicate that LRTPG prevents hyperlipidemia via activation of hepatic AMP-activated protein kinase-sterol regulatory element binding protein-1c pathway. | | Spectrochim Acta A Mol Biomol Spectrosc. 2015 Jan 25;135:256-63. | | Investigation on interaction between Ligupurpuroside A and pepsin by spectroscopic and docking methods.[Pubmed: 25078459 ] | Ligupurpuroside A is one of the major glycoside in Ku-Din-Cha, a type of Chinese functional tea.
METHODS AND RESULTS:
In order to better understand its digestion and metabolism in humans, the interaction between Ligupurpuroside A and pepsin has been investigated by fluorescence spectra, UV-vis absorption spectra and synchronous fluorescence spectra along with molecular docking method. The fluorescence experiments indicate that Ligupurpuroside A can effectively quench the intrinsic fluorescence of pepsin through a combined quenching way at the low concentration of Ligupurpuroside A, and a static quenching procedure at the high concentration. The binding constant, binding sites of Ligupurpuroside A with pepsin have been calculated. The thermodynamic analysis suggests that non-covalent reactions, including electrostatic force, hydrophobic interaction and hydrogen bond are the main forces stabilizing the complex. According to the Förster's non-radiation energy transfer theory, the binding distance between pepsin and Ligupurpuroside A was calculated to be 3.15 nm, which implies that energy transfer occurs between pepsin and Ligupurpuroside A.
CONCLUSIONS:
Conformation change of pepsin was observed from UV-vis absorption spectra and synchronous fluorescence spectra under experimental conditions. In addition, all these experimental results have been validated by the protein-ligand docking studies which show that Ligupurpuroside A is located in the cleft between the domains of pepsin. |
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