Boronate probes for the detection of hydrogen peroxide release from human spermatozoa

Human spermatozoa are compromised by production of reactive oxygen species (ROS), and detection of ROS in spermatozoa is important for the diagnosis of male infertility. The probes 2',7'-dichlorohydrofluorescein diacetate (DCFH), dihydroethidium (DHE), and MitoSOX red (MSR) are commonly used for detecting ROS by flow cytometry; however, these probes lack sensitivity to hydrogen peroxide (H2O2), which is particularly damaging to mammalian sperm cells. This study reports the synthesis and use of three aryl boronate probes, peroxyfluor-1 (PF1), carboxyperoxyfluor-1, and a novel probe, 2-(2-ethoxyethoxy)ethoxyperoxyfluor-1 (EEPF1), in human spermatozoa. PF1 and EEPF1 were effective at detecting H2O2 and peroxynitrite (ONOO(-)) produced by spermatozoa when stimulated with menadione or 4-hydroxynonenal. EEPF1 was more effective at detection of ROS in spermatozoa than DCFH, DHE, or MSR; furthermore it distinguished poorly motile sperm as shown by greater ROS production. EEPF1 should therefore have a significant role in the diagnosis of oxidative stress in male infertility, cryopreservation, age, lifestyle, and exposure to environmental toxicants.