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The antioxidative effects of the isoflavan glabridin on endogenous constituents of LDL during its oxidation.
Atherosclerosis. 1998 Mar; 137(1):49-61.A

Abstract

The effect of the consumption of glabridin, an isoflavan isolated from Glycyrrhiza glabra (licorice) root, on the susceptibility of low density lipoprotein (LDL) to oxidation was studied in atherosclerotic apolipoprotein E deficient (E[o] mice) and was compared with that of the known flavonoids, quercetin and catechin. Glabridin inhibitory activity on in vitro oxidation of human LDL was also investigated by determining the formation of lipid peroxides and oxysterols and the consumption of LDL-associated lipophilic antioxidants. Determination of the extent of LDL oxidation by measuring the formation of thiobabituric acid reactive substances (TBARS) after 2 h of LDL incubation with CuSO4 (10 microM) or 2,2'-azobis (2-amidino-propane) dihydrochloride (AAPH) (5 mM), revealed that glabridin or quercetin consumption resulted in a 53 and 54% reduction in copper ion induced oxidation, respectively, and a 95 and 83% reduction in AAPH induced LDL oxidation, respectively. No inhibition was obtained with consumption of catechin. About 80% of glabridin was found to bind to the LDL human particle. In the in vitro oxidation of LDL induced by AAPH (5 mM), glabridin inhibited the formation of TBARS, lipid peroxides and cholesteryl linoleate hydroperoxide (CLOOH) at all the concentrations tested (5-60 microM), while in oxidation induced by copper ions (10 microM), glabridin exhibited a pro-oxidant activity at concentrations lower than 20 microM, and a clear antioxidant activity at concentrations greater than 20 microM. Glabridin (30 microM) inhibited the formation of cholest-5-ene-3,7-diol (7-hydroxycholesterol), cholest-5-ene-3-ol-7-one (7-ketocholesterol) and cholestan-5,6-epoxy-3-ol (5,6-epoxycholesterol) after 6 h of AAPH induced LDL oxidation, by 55, 80 and 40%, respectively, and after 6 h of copper ion induced LDL oxidation, by 73, 94 and 52%, respectively. Glabridin also inhibited the consumption of beta-carotene and lycopene by 38 and 52%, respectively, after 0.5 h of LDL oxidation with AAPH, but failed to protect vitamin E. The in vivo and in vitro reduction of the susceptibility of LDL to oxidation obtained with glabridin, may be related to the absorption or binding of glabridin to the LDL particle and subsequent protection of LDL from oxidation by inhibiting the formation of lipid peroxides and oxysterols, and by protecting LDL associated carotenoids.

Authors+Show Affiliations

Laboratory of Natural Compounds for Medical Use, Migal, Galilee Technological Center, Kiryat Shmona, Israel.No affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info available

Pub Type(s)

Journal Article

Language

eng

PubMed ID

9568736

Citation

Belinky, P A., et al. "The Antioxidative Effects of the Isoflavan Glabridin On Endogenous Constituents of LDL During Its Oxidation." Atherosclerosis, vol. 137, no. 1, 1998, pp. 49-61.
Belinky PA, Aviram M, Fuhrman B, et al. The antioxidative effects of the isoflavan glabridin on endogenous constituents of LDL during its oxidation. Atherosclerosis. 1998;137(1):49-61.
Belinky, P. A., Aviram, M., Fuhrman, B., Rosenblat, M., & Vaya, J. (1998). The antioxidative effects of the isoflavan glabridin on endogenous constituents of LDL during its oxidation. Atherosclerosis, 137(1), 49-61.
Belinky PA, et al. The Antioxidative Effects of the Isoflavan Glabridin On Endogenous Constituents of LDL During Its Oxidation. Atherosclerosis. 1998;137(1):49-61. PubMed PMID: 9568736.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - The antioxidative effects of the isoflavan glabridin on endogenous constituents of LDL during its oxidation. AU - Belinky,P A, AU - Aviram,M, AU - Fuhrman,B, AU - Rosenblat,M, AU - Vaya,J, PY - 1998/5/6/pubmed PY - 1998/5/6/medline PY - 1998/5/6/entrez SP - 49 EP - 61 JF - Atherosclerosis JO - Atherosclerosis VL - 137 IS - 1 N2 - The effect of the consumption of glabridin, an isoflavan isolated from Glycyrrhiza glabra (licorice) root, on the susceptibility of low density lipoprotein (LDL) to oxidation was studied in atherosclerotic apolipoprotein E deficient (E[o] mice) and was compared with that of the known flavonoids, quercetin and catechin. Glabridin inhibitory activity on in vitro oxidation of human LDL was also investigated by determining the formation of lipid peroxides and oxysterols and the consumption of LDL-associated lipophilic antioxidants. Determination of the extent of LDL oxidation by measuring the formation of thiobabituric acid reactive substances (TBARS) after 2 h of LDL incubation with CuSO4 (10 microM) or 2,2'-azobis (2-amidino-propane) dihydrochloride (AAPH) (5 mM), revealed that glabridin or quercetin consumption resulted in a 53 and 54% reduction in copper ion induced oxidation, respectively, and a 95 and 83% reduction in AAPH induced LDL oxidation, respectively. No inhibition was obtained with consumption of catechin. About 80% of glabridin was found to bind to the LDL human particle. In the in vitro oxidation of LDL induced by AAPH (5 mM), glabridin inhibited the formation of TBARS, lipid peroxides and cholesteryl linoleate hydroperoxide (CLOOH) at all the concentrations tested (5-60 microM), while in oxidation induced by copper ions (10 microM), glabridin exhibited a pro-oxidant activity at concentrations lower than 20 microM, and a clear antioxidant activity at concentrations greater than 20 microM. Glabridin (30 microM) inhibited the formation of cholest-5-ene-3,7-diol (7-hydroxycholesterol), cholest-5-ene-3-ol-7-one (7-ketocholesterol) and cholestan-5,6-epoxy-3-ol (5,6-epoxycholesterol) after 6 h of AAPH induced LDL oxidation, by 55, 80 and 40%, respectively, and after 6 h of copper ion induced LDL oxidation, by 73, 94 and 52%, respectively. Glabridin also inhibited the consumption of beta-carotene and lycopene by 38 and 52%, respectively, after 0.5 h of LDL oxidation with AAPH, but failed to protect vitamin E. The in vivo and in vitro reduction of the susceptibility of LDL to oxidation obtained with glabridin, may be related to the absorption or binding of glabridin to the LDL particle and subsequent protection of LDL from oxidation by inhibiting the formation of lipid peroxides and oxysterols, and by protecting LDL associated carotenoids. SN - 0021-9150 UR - https://www.unboundmedicine.com/medline/citation/9568736/The_antioxidative_effects_of_the_isoflavan_glabridin_on_endogenous_constituents_of_LDL_during_its_oxidation_ L2 - https://linkinghub.elsevier.com/retrieve/pii/S0021-9150(97)00251-7 DB - PRIME DP - Unbound Medicine ER -