Fluorescence studies of the interactions of ubiquinol-10 with liposomes.

Ubiquinone-10 plays a central role in energy production and its reduced form, ubiquinol-10 is also capable of acting as a potent radical scavenging antioxidant against membrane lipid peroxidation. Efficiency of this protection depends mostly on its localization in lipid bilayer. The intrinsic fluorescence of ubiquinol-10 and of the exogenous probe, Laurdan, has been used to determine the location of ubiquinol-10 in unilamellar liposomes of egg phosphatidylcholine (EggPC) and dimyristoyl phosphatidylcholine. Laurdan fluorescence moiety is positioned at the hydrophilic-hydrophobic interface of the phospholipid bilayer and its parameters reflect the membrane polarity and microheterogeneity, which we have used to explore the coexistence of microdomains with distinct physical properties. In liquid-crystalline bilayers ubiquinol has a short fluorescence lifetime (0.4 ns) and a high steady-state anisotropy. In a concentration-dependent manner, ubiquinol-10 influences the Laurdan excitation, emission and generalized polarization measurements. In EggPC liposomes ubiquinol-10 induces a decrease in membrane water mobility near the probe, while in dimyristoyl liposomes a decrease in the membrane water content was found. Moreover the presence of ubiquinol results in the formation of coexisting phospholipid domains of gel and liquid-crystalline phases. The results indicate that ubiquinol-10 molecules are mainly located at the polar-lipid interface, inducing changes in the physico-chemical properties of the bilayer microenvironment.

Effect of acylethanolamides on lipid peroxidation and paraoxonase activity.

N-acylethanolamides (NAEs) are hydrophobic molecules synthesized in many tissues. An increase in the plasma levels of NAEs has been observed in human diseases. Previous studies have suggested that NAEs could exert a protective effect against oxidative stress. Aim of the study was to investigate whether NAEs (oleoylethanolamide, palmitoylethanolamide and anandamide), differing for acyl chain length and unsaturation, exert a protective role against plasma lipid peroxidation triggered by incubation with Cu2+2 or AAPH (2,2'-azobis(2-amidinopropane) dihydrochloride). Moreover, we investigated the effect of NAEs on the activity of HDL-associated paraoxonase (PON1), an enzyme involved in the antioxidant end anti-inflammatory role of human high density lipoproteins (HDL). The results demonstrated that the NAEs protect plasma lipids and PON1 activity against AAPH and/or copper-induced oxidation.

Oleoylethanolamide protects human sperm cells from oxidation stress: studies on cases of idiopathic infertility.

N-acylethanolamides are naturally occurring hydrophobic molecules usually present in a very small amount in many mammalian tissues and cells. The presence of N-acylethanolamides has also been demonstrated in human reproductive tracts and fluids, although their biological effects and molecular mechanisms of action are not yet completely elucidated. It is known that some N-acylethanolamides, such as oleoylethanolamide, have antioxidative properties. The aim of this study was to test whether oleoylethanolamide could protect sperm cells from reactive oxygen species-induced oxidative damage in cases of idiopathic infertility, because the excessive generation of these radicals was associated with this pathology. Our results show that 2.5 nM oleoylethanolamide in vitro supplementation significantly reduces DNA strand breaks both in fertile and infertile subjects. Moreover, oleoylethanolamide increases kinematic parameters, such as curvilinear velocity and amplitude of lateral head displacement and hyperactivation, both in the presence and in the absence of oxidative stress. Results of this study support the hypothesis of a possible protective action of oleoylethanolamide against reactive oxygen species, which could explain its beneficial effects on in vitro capacitated spermatozoa.

Idiopathic infertility: effect of palmitoylethanolamide (a homologue of anandamide) on hyperactivated sperm cell motility and Ca2+ influx.

The goal of this study was to examine the effect of palmitoylethanolamide (PEA) on the capacitation process and hyperactivated motility (HA) in idiopathic infertile men. Our data show the effect of PEA on the kinematic parameters of sperm cells from idiopathic infertile men during the capacitation of spermatozoa in vitro, both in the presence and absence of 2.5 nM PEA, a molecule physiologically present in human reproductive tracts. Two groups of sperm cells were identified. In group I (36 +/- 14 x 10(6) cells/mL), PEA significantly increased some motility parameters and HA during capacitation. In group II (58 +/- 18 x 10(6) cells/mL), PEA did not significantly modify motility parameters and HA. Fura 2 AM (acetoxymethyl ester derivative of fura 2) measurements demonstrated that PEA increased external Ca2+ influx (which modulates HA) in group I, while no change was measured in group II. In conclusion, our data indicated that PEA modulated certain physiological sperm functions that are involved in fertilization; in particular, we showed that PEA modulated for HA in men with low sperm kinematic parameters.