Background: Several Serratula species are used in folk medicine and showed interesting biological activities. The objective of this work was to continue the investigation of the chemical composition of the ethyl acetate extract of the flowers of Serratula cichoracea which in our previous study showed a significant antioxidant activity in 1,1-diphenyl-2-picrylhydrazyl radical (DPPH•) essay compared to quercetin used as control molecule and to evaluate the isolated compounds for their antioxidant and antimicrobial activities.
Methods: Ethyl acetate extract (15 g) was fractionated by column chromatography on silica gel. After purification on preparative plates, the isolated compounds were identified by spectral analyses mainly high resolution electrospray ionisation mass spectrometry (HR-ESIMS) and one- and two-dimensionnal nuclear magnetic resonance spectroscopy experiments, and were evaluated in vitro for antioxidant activity using 1,1-diphenyl-2-picrylhydrazyl radical and for antimicrobial properties.
Results: A new phytoecdysteroid named 22-epi-ajugasterone C (1) together with ajugasterone C (2), were isolated. Compounds 1 and 2 had weak scavenging effect compared with myricetin used as positive control, whereas the two compounds showed antimicrobial properties against multiresistant strains like Staphylococcus aureus, Escherichia coli, Serratia sp., Klebsiella pneumoniae and Candida albicans.
Conclusion: The new isolated phytoecdysteroid and its epimer ajugasterone C, responded to their effectiveness against different various antibiotic-resistant bacteria.