Photoprotective bioactives from Olive mill wastewater: a sustainable approach

<b>ABSTRACT</b>Olive mill wastewater (OMW), a liquid byproduct of olive oil extraction, poses significant environmental challenges as an agricultural waste due to its high pollutant load. This study explores the bioactive potential of an ethyl acetate extract of OMW (EAE-OMW) and its silica gel chromatography-derived column fractions (CF_S). Total phenolic and flavonoid contents were quantified, revealing high values of 291.25 µg GAE/mg extract and 91.4 µg QE/mg extract, respectively. Antimicrobial activity was assessed against 12 pathogens, with minimum inhibitory concentrations (MIC) ranging from 1.56 to 6.25 mg/mL for the EAE and 3.13 to 25 mg/mL for the fractions. Antioxidant capacity, measured via DPPH radical scavenging, demonstrated significant activity for the EAE (IC₅₀ = 34.69 µg/mL) and prominent fractions Fr₅ (72.42 µg/mL) and Fr₄ (81.41 µg/mL). Photoprotective evaluation revealed effective sun protection factor (SPF) values for the EAE and fractions, with enhanced activity in binary and ternary combinations, suggesting synergistic effects. These findings highlight the potential of OMW-derived extracts and fractions as natural bioactive agents for antimicrobial interventions, antioxidant applications, and photoprotective solutions, offering a pathway for integrating waste valorization with biotechnological innovation.