PON1 and Infertility: Reduced PON1 activity was observed in the seminal plasma of men presenting teratozoospermia, azoospermia, subfertility and infertility (Verit et al., 2009; Gulum et al., 2017; Ozer et al., 2019), whereas increased PON1 activity was positively associated with sperm concentration (Ozer et al., 2019).