Antioxidant Effects of Marigold (Calendula officinalis) Flower Extract on the Oxidative Balance of Bovine Spermatozoa

Abstract

Summary The aim of our study was evaluation of potential antioxidant effects of marigold (Calendula officinalis) extract and assessment of its in vitro impact on the selected quality parameters of bovine spermatozoa. Marigold is medicinal herb from the family Asteraceae native to southern Europe, and it commonly used in pharmacology and medicine. Its well-known positive properties include antioxidant, antibacterial, antiflammatory, antiviral, antifungal, antihelmintic and wound-healing activities. In this study, the flower extracts were subjected to high performance liquid chromatography (HPLC), which identified especially phenolic acids (rosmarinic and chlorogenic acids) and polyphenols (rutin, kaempferol, resveratrol, quercetin and apigenin). These substances are known for their antioxidant activity and protective effects against oxidative stress. For our experiments, 10 samples of semen from sexually mature Holstein bulls were collected on a single day by using an artificial vagina, diluted in physiological saline solution and exposed to solutions with different concentration of marigold flower extract (75, 150 and 300 µg/mL). Selected quality parameters (motility, mitochondrial activity, production of reactive oxygen species – ROS, protein oxidation and lipid peroxidation – LPO) were analyzed after 0, 2 and 24 hours of in vitro culture. The motility evaluation was performed by using the computer-assisted sperm analysis (CASA) method. This method revealed that 75 and 150 µg/mL extract had positive effects and increased the motility (P<0.01) and mitochondrial activity (P<0.0001) of bovine spermatozoa compared to the control group following 2 and 24 hours. This phenomenon was observed also in case of ROS production, protein oxidation and LPO. Marigold extract concentrations of 75 and 150 µg/mL decreased the levels of ROS, protein oxidation and damage to the membranes caused by LPO compared to the control group (P<0.05; P<0.01) at time 2 and 24 hours. At the same time, 300 µg/mL extract exhibited positive, although less significant, effects compared to 75 and 150 µg/mL extracts. The data acquired from our study confirm that 75 and 150 µg/mL of marigold flower extract have positive effects on the motility and mitochondrial activity of bovine spermatozoa, and decrease ROS generation, LPO and protein oxidation in spermatozoa. Based on our results, the flower extract from marigold could be used for protection against oxidative stress in in vitro cultures of male gametes.