Inhibitory Effects of Polyphenols from Equisetum ramosissimum and Moringa peregrina Extracts on Staphylococcus aureus, Collagenase, and Tyrosinase Enzymes: In vitro Studies

Background: Skin problems caused by oxidative stress lead to the activation of collagenase and tyrosinase enzymes, contributing to skin aging, discoloration, and infections. Equisetum ramosissimum and Moringa peregrina were assessed for their potential uses in treating various skin conditions.
Objective: The present research aimed to investigate the positive effects of polyphenols in Equisetum ramosissimum and Moringa peregrina extracts as potential cosmetic products for the treatment of different skin conditions.
Methods: Total phenolic and flavonoid contents, antioxidants, and anti-collagenase and anti-tyrosinase activities of plant extract mixtures (PEM) at different ratios of (M. peregrina: E. ramosissimum) were determined using standard procedures. Inhibitory effects of PEM against acne-causing Staphylococcus aureus (ATCC 29213) were evaluated using the diameter (cm) of the inhibition zone method. A cream formulation containing PEM was developed and characterized for stability and potential skin irritation in rats using standard procedures.
Results: The PEM at a ratio of (2:1) showed the highest total phenolic and flavonoid content (150.15 ± 2.8 mg/g, equivalent to gallic acid, and 41.5 ± 1.2 mg/g, equivalent to quercetin, respectively). Antioxidant activities for PEM (2:1) were also optimal, as determined by the DPPH and ABTS methods (IC50 = 7.06 ± 0.12 µg/mL and 53.29 ± 3.3 µg/mL, respectively). Furthermore, PEM (2:1) exhibited superior inhibitory activities against collagenase and tyrosinase enzymes (IC50 = 32.4 ± 1.19 µg/mL and 8.4 ± 1.19 µg/mL, respectively). Antimicrobial activity of PEM (2:1) tested on S. aureus showed the largest zone of growth inhibition (2.8 cm) at a concentration of 60 mg/mL. Studies on the PEM (2:1) cream formulation revealed that it remained stable under room conditions. Skin irritation tests on rats showed no signs of oedema or erythema after treatment.
Conclusion: The PEM with a ratio of (2:1) demonstrated optimal activity as an oxidative stress-neutralizing agent, inhibitor of enzymes responsible for skin aging and hyperpigmentation, and antibacterial agent. The cream formulation containing PEM exhibited physical stability and no detectable risk of skin irritation throughout the research procedures.