Mechanisms of the Liebermann-Burchard and Zak Color Reactions for Cholesterol

Burke, R. W.; Diamondstone, B. I.; Velapoldi, R. A.; Menis, Oscar

doi:10.1093/clinchem/20.7.794

Cited by 124 publications

(61 citation statements)

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“…For Liebermann-Burchard, the proposed mechanism by Burke et al starts with the protonation of the -OH group and a loss of water followed by successive protonation resulting in an exceedingly conjugated product via initial formation of the carbonium ion of 3,5-diene ( Fig. 3) [12].…”

Section: Test Of Terpenes and Triterpenoid Glycosidesmentioning

confidence: 99%

Surface‐Active Properties of Solvent‐Extracted Panax ginseng Saponin‐Based Surfactants

Mesgarzadeh

Akbarzadeh

Rahimi

2017

J Surfact & Detergents

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In this study, saponins were extracted from Panax ginseng root powder. The crude solvent-extracted saponins containing triterpenoid glycosides and terpenes that were identified by TLC techniques. The critical micelle concentrations (CMC) of the saponins were determined by measuring the change in (a) the UV-visible spectrum of iodine due to the micelle-iodine complexation, (b) the absorption intensity of aqueous alpha-lipoic acid due to the micellar solubilization of the drug, and (c) the surface tension due to the abrupt change in the air/liquid interface saturation by surfactants monomers. The development of new absorption peak due to the micelle-iodine complexation, enhancement in the absorbance due to the micelle-solubilized lipoic acid, and displacement of monomer-micelle equilibrium to micelle formation in higher monomer concentration region are some of the physicochemical properties in which CMC could be determined. We found a CMC of 0.009% w/v.

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Section: Test Of Terpenes and Triterpenoid Glycosidesmentioning

confidence: 99%

Surface‐Active Properties of Solvent‐Extracted Panax ginseng Saponin‐Based Surfactants

Mesgarzadeh

Akbarzadeh

Rahimi

2017

J Surfact & Detergents

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“…Total lipids were extracted from prostasomes by a mixture of chloroform ⁄ methanol (2 : 1, v : v) using the procedure by Folch et al (1957). Their cholesterol content was determined by the Liebermann-Burchard colorimetric reaction (Burke et al, 1974) using a mixture of chloroform, acetic anhydride and sulphuric acid (300 : 200 : 10, v : v : v). Prostasomal cholesterol content was calculated by intrapolation using a cholesterol standard value curve.…”

Section: Prostasomes Preparation and Quantificationmentioning

confidence: 99%

Prostasomes: inhibitors of capacitation and modulators of cellular signalling in human sperm

Pons-Rejraji

Artonne

Sion

et al. 2010

International Journal of Andrology

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Seminal fluid inhibits sperm capacitation mainly because of its high cholesterol content. Prostasomes are the main source of cholesterol in seminal fluid. They are known to have numerous protective properties and are able to transfer proteins and lipids to spermatozoa, but their impact on capacitation and acrosome reaction (AR) is not yet well understood. The aim of this study was to determine the effects of prostasomes on human sperm capacitation and AR. After 80% Percoll selection, freshly ejaculated human spermatozoa were incubated for 3 h under capacitating conditions with prostasomes, phosphodiesterase inhibitor 3-iso-butyl-methylxantine (IBMX), or a combination of prostasomes and IBMX. Physiological concentration of prostasomes significantly decreased tyrosine phosphorylation levels of human sperm capacitation markers P110 and P80 (p < 0.01), and the proportions of capacitated (p < 0.05) and acrosome-reacted spermatozoa (p < 0.05). Prostasomes significantly increased the proportion of spermatozoa that did not incorporate propidium iodide and significantly attenuated the effect of IBMX on P110 tyrosine phosphorylation. Prostasomes had no effect on the pH(i) increase associated with capacitation. They significantly increased intracellular cAMP concentration ([cAMP](i)) and, when prostasomes and IBMX were present together, [cAMP](i) was further increased. To our knowledge, this is the first study to show clearly that prostasomes inhibit capacitation and spontaneous AR.

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“…Total PL were determined by measuring the amount of inorganic phosphorus (Bartlett, 1959), using HNO 3 as oxidant instead of H 2 O 2 . Cholesterol was assayed using Lieberman±Burchard reagent (Burke et al, 1974). The crossreaction with desmosterol and cholesterol sulphate were 20 and 50%, respectively.…”

Section: Quanti®cation Of Total Pl and Cholesterolmentioning

confidence: 99%

Membrane fluidity and lipid content of human spermatozoa selected by swim-up method

Force¹,

Grizard²,

Giraud³

et al. 2001

Int J Androl

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In this work, we examined whether spermatozoa (spz) from normospermic fertile patients and selected by a swim-up (S-U) procedure had a particular membrane fluidity related to their maturity and their lipid content as compared with the sperm cells from the whole ejaculate (total sperm). Swim-up selected sperm had a reduced cytoplasmic space as revealed by a lower creatine kinase (CK) activity compared with total sperm (2 +/- 1 vs. 12 +/- 5 mUI/10(7) spz, p < 0.05). The cholesterol (Chol) and total phospholipid (PL) contents were significantly lower in S-U selected sperm than in total sperm (0.72 +/- 0.08 vs. 1.20 +/- 0.30 nmol/10(6) spz for Chol and 1.77 +/- 0.17 vs. 2.78 +/- 0.50 nmol/10(6) spz for PL, p < 0.05) and such a decrease was observed for the three major membrane PL: phosphatidylethanolamine (PE), phosphatidylcholine (PC) and sphingomyelin (SM). However, these decreases were not associated with a change in either Chol/PL or PC/(PC + PE) molar ratios. Membrane fluidity estimated by fluorescence polarization remained comparable between the S-U sperm fraction and total sperm (fluorescence polarization anisotropy, r, which is inversely proportional to the fluidity: 0.235 +/- 0.006 vs. 0.230 +/- 0.005). The sperm membrane fluidity obtained in normospermic patients was compared with abnormospermic ones (oligoasthenoteratospermia). In abnormospermic patients, the membrane fluidity was decreased in migrated spermatozoa compared with total sperm (anisotropy: 0.210 +/- 0.010 vs. 0.250 +/- 0.013, p < 0.01). Our data suggest that the S-U method selected a subpopulation of mature spermatozoa characterised by a low content of Chol and PL, likely related to a reduced membrane area. The fact that Chol/PL and PC/(PC + PE) molar ratios were unchanged shows a maintenance of the membrane quality. This was confirmed by the fluorescence anisotropy measurement showing no difference in plasma membrane fluidity between S-U selected sperm and total sperm. In abnormal semen the migrated spermatozoa had a lower fluidity compared with total sperm suggesting a defective sperm function. These results bring new elements characterizing the S-U selected spermatozoa.

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Mechanisms of the Liebermann-Burchard and Zak Color Reactions for Cholesterol

Cited by 124 publications

References 0 publications

Surface‐Active Properties of Solvent‐Extracted Panax ginseng Saponin‐Based Surfactants

Surface‐Active Properties of Solvent‐Extracted Panax ginseng Saponin‐Based Surfactants

Prostasomes: inhibitors of capacitation and modulators of cellular signalling in human sperm

Membrane fluidity and lipid content of human spermatozoa selected by swim-up method

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