In vitro evaluation of the antioxidant, anti-Propioni bacterium acne and antityrosinase effects of Equisetum ramosissimum (Jordanian horsetail)

Purpose: The investigation of Equisetum ramosissimum Desf. (Equisetaceae) extracts for total phenolic content, potential antioxidant properties, and antibacterial activity against Propioni bacterium acne and antityrosinase effects.Methods: The aerial parts of the E. ramosissimum from Jordan were extracted by maceration and Soxhlet methods, using solvents of different polarities. The composition of the extracts were qualitatively screened using standard phytochemical tests. Quantitatively, total phenolic content (mg/mL, equivalent to gallic acid), ABTS free radical scavenging activity (IC50), anti-P. acne (MIC and MBC), and tyrosinase inhibitory effects (IC50) were also determined.Results: The aqueous-methanol Soxhlet extract contained the highest total phenolic content (0.675 mg/mL gallic acid equivalents). Besides, phytochemical screening tests revealed the presence of phenols, flavonoids, tannins, alkaloids and saponins in the aqueous methanol Soxhlet extract, contributing to the antioxidant (IC50 = 0.125) and antityrosinase (IC50 = 1.125) effects. This extract also showed potent antimicrobial effects against P. acne (MIC = 6.250 mg/mL; MBC = 12.500 mg/mL). Other extracts, including ethanol, water and ethyl acetate, showed lower total phenolic content with moderate and weak biological activity.Conclusion: E. ramosissimum is a promising plant species to be considered for antioxidant, antiacne, and antityrosinase effects. However, further testing (including invivo, histological examination, and highperformance liquid chromatography (HPLC) analysis) is necessary to understand more about its mechanisms of action. Keywords: Antioxidant, Anti-Propioni bacterium acne, Antityrosinase, Equisetum ramosissimum, Total phenolic content, Jordanian horsetail