Effect of different olive oil-derived antioxidants (hydroxytyrosol and 3,4-dihydroxyphenylglycol) on the quality of frozen-thawed ram sperm

Incubating frozen-thawed buffalo sperm with olive fruit extracts counteracts thawing-induced oxidative stress and improves semen quality

Freezing-thawing procedures and semen manipulation for in vitro fertilization induce oxidative stress, which in turn leads to impaired sperm quality. The aim of this study was to evaluate whether incubation of frozen-thawed buffalo semen with olive fruit extracts (OFE), known to contain a high concentration of phenolic antioxidants, would improve semen quality by reducing oxidative stress. Frozen sperm (4 ejaculates/4 bulls/3 replicates) were thawed and diluted to 30 × 106/mL in IVF medium with 0, 72, 143, and 214 μL/mL of OFE, corresponding to 0 (D0-control), 50 (D50), 100 (D100), and 150 (D150) μM hydroxytyrosol. Sperm viability, acrosome integrity, membrane functionality, motility, and sperm kinetics were evaluated immediately after thawing (T0) and after 1 (T1) and 2 h (T2) of incubation at 38.7 °C. Based on the results, sperm biological antioxidant potential (BAP) and ROS levels (ROMs) were assessed in D0 and D100 groups at T1 and T2. To assess the effect of OFE on fertilizing ability, heterologous penetration rates were also evaluated, using bovine abattoir-derived oocytes. The treatment with OFE at all concentrations tested increased (P < 0.05) the percentage of acrosome intact spermatozoa compared to the D0-control at T1, but the effect was more evident (P < 0.01) with D100 (54.5 ± 3.0, 60.5 ± 1.5, 65.2 ± 3.3, and 62.5 ± 1.7, with D0, D50, D100, and D150 OFE, respectively). Total motility, progressive motility, rapid velocity, and progressive velocity decreased (P < 0.05) at T2 only in the D0-control group. The percentage of rapidly progressive sperm and the progressive motility tended to increase (P < 0.10) at T1 and T2, respectively, in D100 compared to D0 (24.7 ± 4.1 vs 16.4 ± 1.6 and 22.8 ± 2.7 vs 17.0 ± 1.2, respectively). The treatment with D100 OFE of frozen-thawed sperm increased (P < 0.05) some kinetic parameters (VAP and WOB). Spermatozoa incubated with D100 OFE exhibited higher (P < 0.01) total and normospermic oocyte penetration rates compared to D0 (86.5 ± 1.4 vs 78.5 ± 0.7, and 70.6 ± 1.5 vs 63.8 ± 1.1, respectively). Additionally, D100 OFE increased sperm BAP concentrations at both T1 and T2, while ROS levels were unaffected. These results suggest that incubating frozen-thawed buffalo semen with OFE is an effective strategy for preserving semen quality and in vitro fertilization ability by enhancing sperm antioxidant capacity.

Effects of hydroxytyrosol on post-thaw quality of rooster sperm

Semen cryopreservation is one of the most important reproduction techniques in the livestock and poultry industry. Cryopreservation induces cold stress, generating reactive oxygen species (ROS) and oxidative stress causing structural and biochemical damages in sperm. In this study, we evaluated the effects of the hydroxytyrosol (HT), as an antioxidant, at the concentrations of 0, 25, 50, and 100 μg/mL on post-thaw semen quality metrics in rooster. Semen samples were collected twice a week from 10 roosters (29 weeks), processed and frozen according to experimental groups. Different quality parameters, including total motility, progressive motility, viability, morphology, membrane integrity, and malondialdehyde were measured after thawing. Results showed that 25 and 50 μg/mL of HT produced the highest percentage of total motility (51.01 ± 2.19 and 50.15 ± 2.19, respectively) and progressive motility (35.74 ± 1.34 and 35.15 ± 1.34, respectively), membrane integrity (48.00 ± 2.18 and 46.75 ± 2.18, respectively) as well as viability (53.00 ± 2.17 and 52.50 ± 2.17, respectively) compared with the other groups (p < .05). The group with 25 μg/mL of HT showed the lowest significant (p < .05) MDA concentration (1.81 ± 0.25). Our results showed that the effect of HT was not dose-dependent and optimum concentration of HT could improve functional parameters of rooster sperm after freezing-thawing. These findings suggest that HT may have protective effects on the rooster sperm during the freezing-thawing process.

Evaluation of the effect of the addition of an olive oil-derived antioxidant (Pectoliv-80A) in the extender for cryopreservation of rooster sperm through the use of a discriminant statistical tool

During the poultry sperm cryopreservation process, an excess of reactive oxygen species is generated resulting in oxidative stress which harms the quality of avian spermatozoa. To counteract this effect, the addition of exogenous antioxidants, such as Pectoliv-80A (a by-product of olive oil), to the cryopreservation diluent is interesting. For this purpose, 16 roosters belonging to the Utrerana avian breed were used. Six semen pools (from the 6 different replicates) were divided into 4 aliquots corresponding to different concentrations of Pectoliv-80A that were tested (0, 300, 400, and 500 μg/mL), and the cryopreservation process was carried out. To evaluate post-thawing semen quality, different parameters such as motility, membrane functionality, reactive oxygen species production, lipid peroxidation, and acrosome integrity were studied. A discriminant canonical analysis was used to determine both the differences between the Pectoliv-80A concentration groups and the discriminant power of the aforementioned parameter used for semen evaluation. Total motility and membrane functionality were reported to be the most discriminant variables for differentiating the different antioxidant enrichment groups and concluded that concentrations of 300 μg/mL showed the most desirable quality of post-thawing semen. The present study could lead to the optimization of both cryopreservation and quality evaluation techniques of the sperm of rooster species, that support the conservation program of endangered local breeds.

Evaluation of the effects of hydroxytyrosol on human sperm parameters during cryopreservation

Human sperm cryopreservation is a routine procedure in assisted reproductive technology, but it has detrimental effects on different sperm parameters due to oxidative stress. Our objective was to assess the impacts of hydroxytyrosol (HT), as an antioxidant, on human sperm parameters following cryopreservation. In the first phase, 20 normal human semen samples were cryopreserved using the rapid freezing method with different concentrations of HT including 0, 50, 100, 150, and 200 μg/mL. In the second phase, 20 normal semen samples were collected and cryopreserved with 50 and 100 μg/mL HT. The beneficial effects of HT were determined by evaluation of motility (computer-assisted sperm analysis; CASA), viability (Eosin-nigrosine stain), DNA integrity (sperm chromatic dispersion test, SCD), reactive oxygen species (DCF and DHE staining by flowcytometry) lipid peroxidation (malondialdehyde, MDA test) and mitochondrial membrane potential (JC1 staining by flowcytometry) of sperm after cryopreservation. After thawing, sperm motility had an increasing trend in 50 and 100 μg/mL HT groups in comparison with other groups, althought the difference was not significant. However, sperm viability was significantly increased at 50 and 100 μg/mL HT. Our data also showed that sperm DNA fragmentation was significantly decreased after thawing at 100 μg/mL in comparison with 0 and 50 μg/mL HT. However, the level of intracellular reactive oxygen species, lipid peroxidation and mitochondrial membrane potential were not significantly different between groups. Our results showed that HT may have protective effects on the viability and DNA integrity of human sperm during the freezing-thawing process.

Effect of olive, flaxseed, and grape seed nano-emulsion essential oils on semen buffalo freezability

The existing treatise targeted to compare the effects of adding different nano-emulsions essential oils (olive, flaxseed, and grapeseed oils) in freezing extender on semen quality and freezability in buffalo. Nano-emulsions were prepared from olive, flaxseed, and grapeseed oils and characterized for their sizes and shapes. Semen extended in four tubes were supplemented with 0 (control) and 3.5% nanoemulsion oils, including olive (NEO), flaxseed (NEFO) and grape seed oils (NEGSO) respectively. NEGSO resulted in the highest (p < 0.05) membrane integrity, vitality, progressive motility (P-motility) of sperm compared to the other groups in post-thawed buffalo bull semen (at 37 °C for 30 s). The addition of NEGSO had the best results for membrane integrity, progressive motility, and vitality of sperm after incubation (at 37 °C and 5% CO2 for 2 h). A superior (p < 0.05) value of total antioxidant capacity in frozen-thawed spermatozoa was monitored in all supplemented groups as relative to the control. The values of malondialdehyde (MDA) and nitric oxide (NO) were lower (p < 0.05) in NEGSO group compared with other groups. Both NEO and NEFO exhibited the same results for MDA, and NO levels (p > 0.05). All supplemented groups exhibited lower hydrogen peroxide levels (p < 0.05) as relative to the un-treated group. The lowest (p < 0.05) caspase 3 levels were verified in NEGSO treatment, followed by NEFO and NEO treatments. Post-thawed sperm showed ultrastructural damages in the control group, and theses damages were attenuated or resorted by the NEGSO, NEFO and NEO supplemented to freezing extender. In consequences with in vitro results regarding the sperm attribute, a greater pregnancy rate (92%) was observed in NEGSO group as compared with NEFO (88%), NEO (76%) and CON (68%) groups. Our findings demonstrate that NEGSO (3.5%) could be used as a new strategy in enhancing sperm functionality, potential fertility and reducing the oxidative damage and apoptosis markers. This could be significantly applicable for sperm physiology cryopreservation in the milieu of assisted reproduction systems.

Discriminant Analysis and Data Mining CHAID Decision Tree as Tools to Evaluate the Buffering Effect of Hydroxytyrosol on Reactive Oxygen Species in Rooster Sperm Cryopreservation

Sperm cryopreservation is effective in safeguarding genetic biodiversity in avian species. However, during this process, spermatozoa are very susceptible to plasma membrane peroxidation in the presence of high concentrations of reactive oxygen species (ROS). To mitigate this effect, the addition of exogenous antioxidants, such as hydroxytyrosol (3,4-dihydroxyphenylethanol; HT), an antioxidant derived from olive oil, to the cryopreservation sperm diluent, could be useful. To verify this, a cryopreservation diluent was supplemented with different concentrations (0 μg/mL, 50 μg/mL, 100 μg/mL, and 150 μg/mL) of HT. For this, semen was collected in 10 replicates from 16 roosters of the Utrerana avian breed, and a pool was prepared with the optimum quality ejaculates in each replicate. After cryopreservation, spermatozoa were thawed and different in vitro semen quality parameters were evaluated. A discriminant canonical analysis (DCA) was carried out and revealed that total motility (TM; Lambda = 0.301, F = 26,173), hypo-osmotic swelling test (HOST; Lambda = 0.338, F = 22,065), and amplitude of lateral head displacement (ALH, Lambda = 0.442; F = 14,180) were the variables with the highest discriminant power. Finally, a chi-squared automatic interaction detection (CHAID) decision tree (DT) was performed excluding fresh semen samples and ROS was found to be the most valuable variable to discriminate between the different established freezing groups. Samples in the absence of HT or with low concentrations of this antioxidant showed less desirable ROS values in cryopreserved rooster semen. The present study could lead to the improvement of cryopreservation techniques for the genetic material of local poultry breeds and optimize the conservation programs of endangered native avian breeds.

Hydroxytyrosol and resveratrol improves kinetic and flow cytometric parameters of cryopreserved bull semen with low cryotolerance

There is considerable interest in breeding programs to "rescue" semen with poor post-thaw fertility from bulls known as "bad freezers". We hypothesized that there may be an interaction between the post-thaw recovery of sperm and the efficacy of antioxidant addition to extenders. The current study assesses the effects of antioxidant additives hydroxytyrosol (HT) and resveratrol (RSV) on the post-thaw semen parameters in two groups of bulls classified as either high or low cryotolerant (i.e., "good" and "bad" freezers). Semen samples were collected from 40 bulls and processed in the extenders containing different concentrations of HT (experiment 1; 0, 25 and 50 µM) and RSV (experiment 2; 0.0, 0.01, 0.1 and 1 mM). In experiment 1, bulls in the low cryotolerance group had a significant improvement in post-thaw recovery at 25 µM and 50 µM (P < 0.05). These improvements were observed in motility and several cellular parameters. However, post-thaw semen quality in the high cryotolerance group was not significantly affected by the HT addition. In experiment 2, although RSV did not have any positive impact in high cryotolerance group, post-thaw recovery in the low cryotolerance bulls was significantly improved in 0.1 mM RSV. Oxidative stress markers in either high or low cryotolerance groups were not significantly changed by RSV addition (P > 0.05). It can be concluded that addition of optimized concentrations of HT and RSV to the extender could be a strategy for improving the post-thaw semen, especially in bulls with high genetic merit but low initial cryotolerance.

Hydroxytyrosol effectively improves the quality of pig sperm at 17 °C

Artificial insemination (AI) is a proven breeding technology which has been widely used in pig reproduction. Low temperature can cause very serious damage to pig sperm below 15 °C and the situation is even more serious at lower temperature. Besides, the preservation of pig sperm is mainly carried out at 17 °C because of its outstanding performance in pig reproduction. However, the accumulation of a large amount of reactive oxygen species (ROS) during the preservation process is the main reason for the deterioration of sperm quality. In our research, by adding different concentrations of hydroxytyrosol to the diluent during the storage of pig sperm at 17 °C, we compared them with the traditional diluent to study the sperm motility, the cumulative amount of ROS, the extent of sperm membrane damage, the sperm acrosome integrity, the sperm DNA damage and the activity of antioxidant enzymes (CAT, T-AOC, SOD, GSH-PX, MDA) to evaluate the effect of hydroxytyrosol on the sperm quality during storage. We used proteomics sequencing technology to monitor difference in sperm protein between the control samples and the addition of 120 μmol/L hydroxytyrosol samples (optimum concentration) after three days storage. Ultimately, we selected the control samples and the addition of 120 μmol/L hydroxytyrosol samples to test the effect of AI. The results of our research showed that during storage of pig sperm at 17 °C, the sperm quality and antioxidant capacity of the hydroxytyrosol-treated samples significantly improved (HT 120 μmol/L) (P < 0.05). Proteomics sequencing analysis proved that the addition of 120 μmol/L hydroxytyrosol treatment samples had potential value in improving sperm quality. The significant increase in sow pregnancy rate and piglet birth weight proved that hydroxytyrosol had important practical value in pig reproduction. Based on our results, we demonstrated that the addition of hydroxytyrosol to the diluent could improve the quality of pig sperm and the efficiency of AI.

Effects of Gossypium spp., Balanites aegyptiaca, and Sesamum indicum seeds oils on quality of chilled and frozen-thawed ram semen

Background and Aim:

Essential oils found frequently in plants are well known for their activities against bacteria, viruses, and fungi, and antioxidant properties. This study aimed to analyze egg yolk replacement by seed oils of Gossypium spp. (cotton), Balanites aegyptiaca (desert date), and Sesamum indicum (sesame) in semen extender, on ram sperm quality chilled at 4°C and frozen-thawed.

Materials and Methods:

Ejaculates were collected from adult rams and refrigerated at 4°C in a Tris-based extender containing 1.25%, 2.5%, 5%, and 10% of Gossypium spp., B. aegyptiaca, and S. indicum seed oils, to evaluate which were the two best extenders for comparison with BIOXcell, a commercial extender for deep freezing ram semen.

Results:

The data showed that sperm movements analyzed by the CASA system were faster in extenders supplemented with 2.5-5% of cottonseed oil and 1.25-10% of sesame oil, whereas in the extender containing B. aegyptiaca oil, all seminal parameters studied had the worst values. During the sperm-freezing process, 5% of cottonseed oil and 5% sesame seed oil were selected from the first study, with sesame oil reaching the best sperm quality. Thus, sperm motility and velocity were 44.14±13.99%, 24.44±12.6%, and 25.92±11.50%; and 20.26±9.56%, 8.76±6.38%, and 9.42±5.40%, respectively, for sesame oil, cottonseed oil, and BIOXcell.

Conclusion:

In summary, 2.5-10% of cottonseed oil and 1.25-10% of sesame seed oil can replace egg yolk in a Tris–egg yolk–based extender. Moreover, a Tris-based extender supplemented with 5% sesame seed oil could be an alternative for deep freezing ram semen, even though these results need to be confirmed with semen collected from rams with appropriate sexual rest.

Bayesian Analysis of the Effects of Olive Oil-Derived Antioxidants on Cryopreserved Buck Sperm Parameters

The present study evaluates the effect of olive oil-derived antioxidants, hydroxytyrosol (HT) and 3,4-dihydroxyphenylglycol (DHPG), on cryopreserved caprine sperm using Bayesian inference of ANOVA. For this proposal, sperm was collected, pooled and diluted in freezing media supplemented with different concentrations of HT, DHPG and the mixture (MIX) of both antioxidants. Sperm motility, viability, acrosome integrity, mitochondrial status, and lipid peroxidation (LPO) were assessed in fresh and frozen-thawed sperm samples. The results provided evidence that HT at low concentrations improves sperm motility and viability, and reduces the LPO. Contrastingly, DHPG and MIX exert a positive effect by reducing LPO values as concentration increases. Additionally, mitochondrial potential was reduced when samples were supplemented with HT at low concentrations and mixture of both antioxidants. Conclusively, the addition of olive oil-derived antioxidants (HT at 10 µg/mL and DHPG at 30 µg/mL) implements a protective effect in cryopreserved buck sperm. Bayesian analysis alternatives offer new possibilities to determine the repercussion of antioxidants on sperm, both quantitatively and qualitatively.

Overview on the Antioxidants, Egg Yolk Alternatives, and Mesenchymal Stem Cells and Derivatives Used in Canine Sperm Cryopreservation

Sperm cryopreservation is a widely used assisted reproductive technology for canine species. The long-term storage of dog sperm is effective for the breeding of dogs living far apart, scheduling the time of artificial insemination that suits the female, and preventing diseases of the reproductive tract. However, spermatozoa functions are impaired during the freeze-thaw processes, which may decrease reproductive performance. Numerous attempts have been made to restore such impairments, including the use of cryoprotectants to prevent the damage caused by ice crystal formation, and supplementation of antioxidants to reduce reactive oxygen species generation due to osmotic stress during the procedure. Egg yolk derivatives, antioxidants, and, more recently, mesenchymal stem cells (MSCs) and their derivatives have been proposed in this research field. This review article will summarize the current literature available on the topic.

Analytical Characterization of Water-Soluble Constituents in Olive-Derived By-Products

Olive trees constitute one of the largest agroindustries in the Mediterranean area, and their cultivation generates a diverse pool of biomass by-products such as olive tree pruning (OTP), olive leaves (OL), olive stone (OS), and extracted olive pomace (EOP). These lignocellulosic materials have varying compositions and potential utilization strategies within a biorefinery context. The aim of this work was to carry out an integral analysis of the aqueous extractives fraction of these biomasses. Several analytical methods were applied in order to fully characterize this fraction to varying extents: a mass closure of >80% was reached for EOP, >76% for OTP, >65% for OS, and >52% for OL. Among the compounds detected, xylooligosaccharides, mannitol, 3,4-dihydroxyphenylglycol, and hydroxytyrosol were noted as potential enhancers of the valorization of said by-products. The extraction of these compounds is expected to be more favorable for OTP, OL, and EOP, given their high extractives content, and is compatible with other utilization strategies such as the bioconversion of the lignocellulosic fraction into biofuels and bioproducts.

Antioxidant effects of supplementation of 3,4-dihydroxyphenyl glycol on sperm parameters and oxidative markers following cryopreservation in canine semen

Supplementing the extender with antioxidants with low molecular weight can enhance the quality of the post-thaw sperm during the freezing process. This study was aimed at determining the impacts of 3,4-dihydroxyphenyl glycol (DHPG) on the spermatozoa of the canine undergoing freeze-thawing process. In this study, 24 ejaculates were obtained from three mixed-breed dogs and were diluted in a Tris-based extender. The diluted semen was divided into aliquots for supplementation of 10, 30, 50 and 70 µg/ml of DHPG, control (without antioxidant) and control sham (DMSO). After being extended, the semen was equilibrated at a temperature of 4°C and then transferred to the straws and kept 4 cm above the liquid nitrogen for 20 min and was finally immersed in the liquid nitrogen. They were cryopreserved for seven days; then, sperm parameters including sperm motility evaluation, motility characteristics, viability, DNA and plasma membrane integrity, total antioxidant capacity (TAC), reduced glutathione content (GSH), antioxidant enzymes (superoxide dismutase [SOD], catalase [CAT] and glutathione peroxidase [GPx]) activity malondialdehyde (MDA) levels were evaluated. This study showed that spermatozoa cryopreservation with 50, 30 and 70 µg/ml of DHPG concentrations had better progressive motility, Curvilinear Velocity, Linearity, viability, intact plasma membrane and the levels of TAC, GPx and GSH were higher than the control group. The 50, 30 and 70 µg/ml of DHPG concentrations led to the significant decrease of DNA damage compared to the control group. Total motility, average path velocity, straight-line velocity and CAT activity were significantly improved in 30 and 50 µg/ml of DHPG concentrations, compared to the control group. Also, the 50 and 30 µg/ml of DHPG concentrations, decreased MDA levels compared to the other groups, significantly. In conclusion, our study showed that the addition 50 µg/ml of DHPG to the canine semen extender improved the semen characteristics and oxidative markers in the cryopreservation process.

Polyphenols in Farm Animals: Source of Reproductive Gain or Waste?

Reproduction is a complex process that is substantially affected by environmental cues, specifically feed/diet and its components. Farm animals as herbivorous animals are exposed to a large amount of polyphenols present in their natural feeding system, in alternative feed resources (shrubs, trees, and agro-industrial byproducts), and in polyphenol-enriched additives. Such exposure has increased because of the well-known antioxidant properties of polyphenols. However, to date, the argumentation around the impacts of polyphenols on reproductive events is debatable. Accordingly, the intensive inclusion of polyphenols in the diets of breeding animals and in media for assisted reproductive techniques needs further investigation, avoiding any source of reproductive waste and achieving maximum benefits. This review illustrates recent findings connecting dietary polyphenols consumption from different sources (conventional and unconventional feeds) with the reproductive performance of farm animals, underpinned by the findings of in vitro studies in this field. This update will help in formulating proper diets, optimizing the introduction of new plant species, and feed additives for improving reproductive function, avoiding possible reproductive wastes and maximizing possible benefits.

Effect of olive-derived antioxidants (3,4-dihydroxyphenylethanol and 3,4 dihydroxyphenylglycol) on sperm motility and fertility in liquid ram sperm stored at 15°C or 5°C

The aim of the present study was to evaluate the effect of the addition of two olive oil-derived antioxidants, hydroxytyrosol (3,4-dihydroxyphenylethanol, HT) and 3,4-dihydroxyphenylglycol (DHPG), on ovine semen during liquid storage at 5°C and 15°C. Semen was collected, pooled, diluted and then divided into aliquots supplemented with different concentrations (5 μg/ml, 10 μg/ml, 50 μg/ml and 100 μg/ml) of HT, DHPG and a mixture (MIX) of both antioxidants. Sperm motility characteristics were assessed in the different samples at 0, 6, 24, 48, 72 and 96 hr after cooling, and a fertility trial was also conducted. The results showed that the antioxidant addition did not significantly improve total and progressive motility in ovine cooled sperm maintained at 15° or 5°C. However, in samples stored at 5°C, LIN (48, 72, 96 hr), STR (0 hr) and WOB (0, 48, 72, 96 hr) values significantly decreased in comparison with control treatment when high antioxidant concentrations were added (MIX100 or HT100). When samples were maintained at 15°C, MIX50 showed significantly higher VCL values than the control treatment after 6 hr cooling, and MIX100 showed significantly lower VCL values at 96 hr after cooling. According to the artificial insemination trial, no significant differences were observed when antioxidants were added. In conclusion, the use of HT and DHPG showed small impact in sperm motility and fertility was not affected (nor detrimentally nor positively) when insemination was carried out using antioxidant-supplemented liquid sperm.