Beneficial effects of Sambucus nigra L. (black elder) as a traditional medicine have been associated with the phytoconstituents including polyphenols, terpenes and lectins. Various antioxidant rich natural products have also been implicated with improvement of reproductive health and fertility, however, the effect of Sambucus nigra on the ovarian cell functions has not been investigated yet. The objectives of the present study were to screen the polyphenols in the elderflower and elderberry extracts, and to examine the secretion activity of steroid hormones 17β-estradiol and progesterone by human ovarian granulosa cells HGL5 after supplementation of the extracts at a concentration range of 12.5 to 100 µg.ml-1 . Qualitative as well as quantitative screening of polyphenols by high-performance liquid chromatography with diode-array detector (HPLC-DAD) analysis revealed rutin to be the most abundant polyphenol in both elderflower and elderberry extracts. In culture, neither elderflower nor elderberry extract caused any significant impact (p>0.05) in cell viability as studied by AlamarBlue assay in comparison to control. However, a dosedependent stimulation of 17β-estradiol release was detected by ELISA after supplementation of elderflower (at 50 µg.ml-1 ; p<0.01) and elderberry (at 100 µg.ml-1 ; p<0.05) extracts at higher doses used in the study. On the other hand, both elderflower and elderberry extracts stimulated the secretion of progesterone by HGL5 cells at a lower dose (12.5 µg.ml-1 ; p<0.05), as compared to control. Therefore, elderflower and elderberry extracts may have the potential to regulate steroidogenesis in ovarian cells., Simona Baldovska, Shubhadeep Roychoudhury, Marek Bandik, Michal Mihal, Erika Mnahoncakova, Julius Arvay, Ales Pavlik, Petr Slama, Adriana Kolesarova., and Obsahuje bibliografii