Variability on the Phytochemical Composition, Antioxidant and Antimicrobial Activities of Ruppia cirrhosa Extract Using Two Different Methods of Extraction

Background: Nowadays, there is increasing attention to the discovery of new bioactive substances from marine sources. This research aimed to characterize the phytochemical composition as well as antioxidant and antimicrobial activities of Tunisian Ruppia cirrhosa extracts (RCEs) using two different extraction methods. Methods: RCEs were obtained by two different extraction methods: maceration and successive extraction. The determination of polyphenolic contents and antioxidant activity was made by calorimetric assay, and the effect of RCE was observed against pathogenic bacteria and fungi using the solid diffusion method. Results: The successive extraction of R. cirrhosa extract relatively showed higher total phenol (38.1 mg GAE/g) and condensed tannin (18.07 mg CE/g) contents than the maceration extraction (35.43 mg EAG/g and 12.99 mg CE/g, respectively). However, the total flavonoid amount of RCE was higher in the maceration extraction (33.09 mg CE/g) than in the successive extraction (21.27 mg CE/g). The total antioxidant capacity of RCE indicated a decrease in this activity after fractionation. Indeed, the activity of RCE decreased from 47.8 to 37.83 mg GAE/g, and RCE obtained by the two extraction methods showed moderate antioxidant activity using reducing power (IC50=380-490 µg/mL) and β-carotene bleaching (IC50=110-310 μg/mL) assays. Furthermore, RCEs obtained by maceration had the greatest antibacterial activity against all tested strains (IZ=3.33-9.33 mm) except Salmonella typhimurium (IZ=2 mm), Enterococcus faecalis (IZ=6 mm), and Streptococcus aureus (3.67 mm) as compared to those obtained by successive extraction. The strains of Candida had a sensitivity for R. cirrhosa extracts obtained by maceration. Indeed, R. cirrhosa extracts obtained by successive extraction had higher inhibitory activity against Candida krusei deduced through an inhibition diameter of 6 mm. Conclusion: It can be concluded that R. cirrhosa extract is rich in bioactive molecules, and it has an extremely promising biological potential.