Excessive production of reactive oxygen species (ROS) during semen cryopreservation can induce structural and functional changes in spermatozoa. It is well known that antioxidants can mitigate the effect of ROS. Moreover, the application of antioxidants in freezing media is an appropriate strategy for protecting spermatozoa against deleterious effects of ROS during the cryopreservation process. As an example, oregano is a medicinal plant with important activities, with antiseptic, antibacterial, antithrombotic, and antioxidant properties. This study aimed at evaluating the antioxidant effects of oregano extract on cryopreserved human spermatozoa. In the first phase, 13 semen samples with different concentrations of oregano extract (0.0, 50, 100, 150, 300, and 500 μg/mL) were cryopreserved to achieve an optimal dose of oregano extract. Then, motility, viability, and plasma membrane integrity were evaluated. In the second phase, 20 samples were cryopreserved in freezing media supplemented with or without the optimal concentration of oregano (100 μg/mL). After thawing, motility, the levels of ROS, lipid peroxidation, and translocation of phosphatidylserine (PS) were evaluated. The results showed that 100 μg/mL oregano extract significantly increased the total motility in frozen–thawed spermatozoa in comparison with the control group (28.2 ± 4.3 vs. 42.4 ± 1.6, p < 0.05). This concentration significantly decreased the percentage of 2′,7′-dichlorofluorescein-positive cells (25.53 ± 1.2 vs. 21.48 ± 1.2) and the malondialdehyde level (4.25 ± 0.7 vs. 0.82 ± 0.4 μM) (p < 0.05). In the oregano group, the percentage of vital spermatozoa without PS externalization was significantly higher than that in the control group (25.88 ± 1.6 vs. 16.8 ± 1.9, p < 0.001), while the percentage of dead spermatozoa with PS externalization spermatozoa was significantly lower than that in the control group (51.65 ± 1.4 vs. 60.36 ± 1.9, p < 0.05). In general, the addition of oregano extract to sperm freezing extender has protective effects against oxidative stress and apoptosis.

中文翻译：

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牛至的水提取物通过其抗氧化作用提高了冷冻保存的人类精子的质量。

精液冷冻保存过程中活性氧（ROS）的过量产生会导致精子的结构和功能发生变化。众所周知，抗氧化剂可以减轻ROS的影响。此外，在冷冻培养基中使用抗氧化剂是在冷冻保存过程中保护精子免受ROS有害影响的合适策略。例如，牛至是具有重要活性，具有防腐，抗菌，抗血栓形成和抗氧化特性的药用植物。这项研究旨在评估牛至提取物对冷冻保存的人类精子的抗氧化作用。在第一阶段，将13种精液样品与不同浓度的牛至提取物（0.0、50、100、150、300和500μg/ mL）冷冻保存，以获得最佳剂量的牛至提取物。然后，评估了运动能力，生存力和质膜完整性。在第二阶段中，将20个样品冷冻保存在补充有或没有最佳浓度牛至（100μg/ mL）的冷冻培养基中。解冻后，评估其运动性，ROS水平，脂质过氧化作用和磷脂酰丝氨酸（PS）的转运。结果显示，与对照组相比，牛至提取物100μg/ mL显着提高了冻融精子的总运动能力（28.2±4.3 vs. 42.4±1.6，p  ＜0.05）。该浓度显着降低了2'，7'-二氯荧光素阳性细胞的百分比（25.53±1.2对21.48±1.2）和丙二醛水平（4.25±0.7对0.82±0.4μM）（p  <0.05）。牛至组中没有PS外在化的活精子百分比显着高于对照组（25.88±1.6 vs. 16.8±1.9，p  <0.001），而死于PS外在化精子的精子百分比显着降低与对照组相比（51.65±1.4 vs. 60.36±1.9，p  <0.05）。通常，将牛至提取物添加到精子冷冻增量剂中对氧化应激和细胞凋亡具有保护作用。