Antioxidant Potential of Parsley Leaf (Petroselinum crispum) Essential Oil on Hypothyroidism and Testicular Injury in Mice Intoxicated by Carbon Tetrachloride

The aim of the present study was to investigate the ameliorative potential of parsley (Petroselinum crispum) leaf essential oil (PO) against the detrimental effects of carbon tetrachloride (CCl(4)) on the thyroid gland and testes of mice. Twenty-four adult male mice were divided into four groups and treated for 4 weeks. The 1(st) control group received 3 mL/kg olive oil intraperitoneally, twice a week followed by 0.5 mL/kg saline intragastrically daily. The 2(nd) CCl(4) group received CCl(4) (3 mL/kg intraperitoneally, twice a week). The 3(rd) PO group received PO (0.5 mL/kg intragastrically daily), while the 4(th) CCl(4)+PO group received CCl(4) coadministrated with PO at the aforementioned doses. CCl(4) group recorded significant (p < 0.05) reduction in the activities of antioxidant enzyme catalase (CAT) and superoxide dismutase (SOD) and significant (p < 0.05) increase in the lipid peroxidation end product's level malondialdehyde (MDA) in the testes and thyroid glands. Meanwhile, serum levels of testosterone, follicle-stimulating hormone (FSH), luteinizing hormone (LH), and thyroid hormones (thyroid-stimulating hormone (TSH), total triiodothyronine (T3), free triiodothyronine (fT3), total thyroxine (T4), and free thyroxine (fT4)) significantly decreased. Also, histopathologically, the testicular tissue showed hypospermatogenesis within irregular-shaped seminiferous tubules with prominent edema in the interstitial spaces confirming the aforementioned biochemical alterations. Treatment with PO significantly reduced the testicular and thyroid oxidative stress (p < 0.05) and elevated the testosterone (73.47%), FSH (92.11%), LH (33.33%), T3 (23.47%), fT3 (39.13%), T4 (27.91%), and fT4 (75%) as compared to that of CCl(4)-treated group corresponding values. The PO GC/MS analysis indicated bioactive monoterpenes (major component is 1,3,8-mentha triene 34.48%) and phenylpropenes (major component is myristicin 21.04%). Results suggested the ameliorative effect of PO against CCl(4)-induced hypogonadism in mice by suppressing oxidative stress and maintaining thyroid gland function.