The objectives of this study were to examine the physicochemical and structural properties of peptide derivatives of dermaseptin S4, investigate their detrimental effects on red blood and sperm cells and ascertain their antibacterial potency to control bacterial contaminants in fresh bovine semen. The dermaseptin S4 peptide derivatives used in this study were K4S4, S4(5–28), S4(5–28)a, K20S4(5–28), K4S4(1–16)a, K4S4(1–15)a and K4S4(1–15). Peptides K4S4, S4(5–28)a, K20S4(5–28), K4S4(1–15)a and K4S4(1–16)a, with a higher positive charge, were the most potent against the bacterial strains tested, with the lowest minimum inhibitory concentration (MIC), whereas S4(5–28) and K4S4(1–15), with a lower positive charge, showed the highest MIC (p < .01). Haemolysis percentage depended on peptide concentration (p < .01). The K4S4 was the most powerful haemolytic peptide, showing the highest haemolysis percentage at all peptide concentrations (p < .01). In contrast, S4(5–28), S4(5–28)a, K20S4(5–28) and K4S4(1–15) were not able to produce 50% cell lysis up to 100 µM (p < .01). All peptides reduced sperm motility in a dose‐dependent manner when used in concentrations from 16 to 64 μM (p < .01). The highest reduction was seen due to K4S4 activity, and the lowest reductions of sperm motility were observed due to K4S4(1–16)a and K4S4(1–15)a activity (p < .01). Hence, we can conclude that K4S4(1–16)a and K4S4(1–15)a at a concentration of approximately 15 µM are the most promising peptides as antibacterial agents in fresh bovine semen, because at this concentration, they showed the most potent antibacterial activity against evaluated strains without significant effects on haemolysis or a reduction in sperm motility.

中文翻译：

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用于控制细菌污染的新鲜牛精液中dermaseptin S4的肽衍生物：物理化学和结构表征，抗菌效力以及对红血和精细胞的影响。

这项研究的目的是检查皮肤抑素S4肽衍生物的理化和结构特性，研究其对红血球和精子细胞的有害作用，并确定其控制新鲜牛精液中细菌污染物的抗菌能力。本研究中使用的皮肤抑素S4肽衍生物为K4S4，S4（5–28），S4（5–28）a，K20S4（5–28），K4S4（1–16）a，K4S4（1–15）a和K4S4（1-15）。肽K4S4，S4（5–28）a，K20S4（5–28），K4S4（1-15）a和K4S4（1-16）a具有较高的正电荷，它们对测试的细菌菌株最有效，最低最低抑菌浓度（MIC）最低，而正电荷较低的S4（5–28）和K4S4（1–15）最高MIC（p  <.01）。溶血百分比取决于肽浓度（p  <.01）。K4S4是最强大的溶血肽，在所有肽浓度下均显示出最高的溶血百分比（p  <.01）。相比之下，S4（5–28），S4（5–28）a，K20S4（5–28）和K4S4（1–15）不能产生高达100 µM的50％细胞裂解（p  <.01） 。当使用浓度从16到64μM时，所有肽都以剂量依赖的方式降低精子活力（p  <.01）。K4S4活性最高，而K4S4（1-16）a和K4S4（1-15）a活动最低，精子活力降低最低（p <.01）。因此，我们可以得出结论，浓度约为15 µM的K4S4（1–16）a和K4S4（1–15）a是新鲜牛精液中最有希望的抗菌肽，因为在此浓度下，它们显示出最大的抗菌肽。对被评估菌株具有强大的抗菌活性，对溶血或精子活力没有明显影响。