Analysis of Phytochemical Composition, Antioxidant Capacity and Antimicrobial Activity of Retama Monosperma Extracts

Introduction: Retama monosperma is an endemic plant of the Mediterranean basin used in traditional medicine to treat various diseases. It contains different bioactive phytochemicals and possesses several biological activities. The present work aimed to assess the phytochemical screening, total phenolic, total flavonoid, and total tannin compounds, as well as the antioxidant and antimicrobial activities.Methods: The phytochemical screening was determined by color reactions, characteristic reagents, and precipitation. Total phenolic, total flavonoid, and total tannin compounds were quantified using colorimetric methods in four fractions (hexane, ethyl acetate, ethanol, and aqueous). The antioxidant capacity was assisted using DPPH, ferric reducing power assay FRAP, ABTS radical scavenging, and phosphomolebdenum assay (PMA). The disc diffusion method and the microdilution assay were used to evaluate the antimicrobial activity against six microbial strains Staphylococcus aureus, Bacillus cereus, Enterococcus faecalis, Escherichia coli, Pseudomonas aeruginosa, and Candida albicans.Results: Qualitative phytochemical tests revealed the presence of flavonoids, tannins, coumarins, quinones, terpenoids, alkaloids, and sterols. The quantification of the total phenolic, total flavonoid, and total tannin compounds, confirmed that all fractions were rich in polyphenolic compounds. Additionally, the antioxidant capacity measurement showed that the ethanol fractions had the highest antioxidant capacity than the other fractions for all three antioxidant assays. DPPH, FRAP, and PMA, with an IC50 of 121.55 ± 0.90 µg/mL, 247.1 ± 1.32 µg/mL, and 216.66 ± 0.87 mg AAE/g extract, respectively. On the other hand, the aqueous fraction was the highest scavenging activity for the ABTS.+ test with 208.58 ± 0.77 µg/mL. In addition, the antimicrobial activity demonstrated that the ethyl acetate fraction showed the best activity, compared to the other fractions, against Staphylococcus aureus, and Bacillus cereus with minimum inhibitory concentration of 0.52 mg/mL, and minimum bactericidal concentration values of 16.65 mg/mL and 0.52 mg/mL, respectively.Conclusion: Our results suggest that R.monosperma could be exploited as a source of antioxidant and anti-infective phytocompounds.