**4. Conclusions**

The results obtained for the brown fucoidal macroalgae *C. compressa* from the Adriatic Sea indicated that it was a good source of compounds. The TPC and TTC content reflected a variation over the growing season, with the highest values in June. The detected FRAP showed high correlation with TPC and TTC content. The DPPH values were >80% inhibition over the whole sampling period, while the highest antioxidant activity with regards to ORAC was in August when the sea temperature was the highest. No evident correlation existed between the temperature and salinity change and TPC, TTC or antioxidant activity. From June to August, higher antimicrobial activity against foodborne pathogens was observed, especially against *L. monocytogenes*, *S. aureus* and *S. enteritidis*. Further investigations are needed to gain insight into the effect of abiotic factors, growth and thallus development of the alga on its biological potential and to discover the compounds responsible for the different biological activities.

**Author Contributions:** Conceptualization, V.Š. and G.T.; methodology, M.C., D.S., V.V. and D.B.; ˇ validation, D.S. and D.B.; formal analysis M.C., D.S., R.F., I.G.M., D.B. and M.d.C.R.-D.; resources, ˇ V.Š., D.B. and V.V.; data curation, M.C., D.S., R.F., I.G.M., D.B. and M.d.C.R.-D.; writing—original ˇ draft preparation, M.C. and V.Š.; writing—review and editing, V.Š., G.T., I.G.M. and V.V.; supervision, ˇ V.Š. and D.S.; project administration, V.Š. and G.T.; funding acquisition, V.Š., D.B. and V.V. All authors have read and agreed to the published version of the manuscript.

**Funding:** This research is supported by the PRIMA program under project BioProMedFood (Project ID 1467). The PRIMA programme is supported by the European Union.

**Institutional Review Board Statement:** Not applicable.

**Informed Consent Statement:** Not applicable.

**Data Availability Statement:** Data available on request.

**Acknowledgments:** The authors would like to thank Ivan Šimat from Centaurus d.o.o., Solin for administrative support and technical help during the investigations and Matilda Šprung for technical help during antimicrobial analyses.

**Conflicts of Interest:** The authors declare no conflict of interest.
