Background: Rosmarinus officinalis essential oil (Rom) has been reported recently to be of interest for use in sperm cryopreservation. However, related to its lipophilic characteristics, encapsulation in cyclodextrin could enhance Rom positive effects by increasing its solubility in sperm extenders.
Objective: To compare the effect of Rom preloaded in hydroxypropyl-β-cyclodextrin (Rom-cd) to Rom alone (Rom) on ram sperm conserved at 4°C.
Materials and methods: Ram epididymal sperm was collected from six testes. Each collected sperm was split into four equal aliquots. The control aliquot was diluted with Tris extender (Tris + citric acid + fructose + penicillin), two aliquots were treated with Rom at 0.5µl ml-1 and 1µl ml-1 respectively, and one aliquot treated with Rom-cd at 1µl ml-1. All sperm aliquots were analyzed for motility after 0, 2, 4, 24 and 48 h of storage at 4°C using a Computer Aided Semen Analysis (CASA). Membrane integrity and oxidative stress status were measured after 48 h of storage.
Results: The results indicated that motility parameters were best preserved in the extender containing Rom-cd compared to the groups treated by Rom without cyclodextrin. Rom alone resulted to higher sperm motility than the control group. Lower oxidative stress and more cell membrane protection were observed in Rom treated samples, especially when using Rom-cd.
Conclusion: The ability of Rom to protect ram sperm against cryopreservation damages was improved after encapsulation in hydroxypropyl-β-cyclodextrin (HPβCD).