Abstract
This study aims to comprehensively investigate the usability of white mulberry (Morus alba L.) leaf extract as a natural dye, including its fastness properties, antibacterial activity, and antioxidant activity. In the study, dyeing processes were carried out on cotton fabric, wool fabric, wool yarn, polyester, leather, and pine wood materials using different mordanting techniques (pre-, co-, and post-mordanting) and pH values (4 and 8). Copper-II-sulfate, iron-II-sulfate, alum, silver nitrate, Reşadiye clay, and Önal-1 [3% (v/v) NH3 + 3% (w/v) Urea + 3% (w/v) CaC2O4] were used as mordants. Washing, light, rubbing, and perspiration fastness of the dyed materials were evaluated according to international standards, and color properties were analyzed using the CIE-Lab* system and Kubelka–Munk (K/S) values. Structural characterization of the extract was carried out using 1H-NMR, 13C-NMR, LC-MS/MS, and TLC. Antibacterial activity of the dyed materials was assessed using the disk-diffusion method, with undyed, extract-only, and mordant-only controls used to distinguish the contributions of the extract and the mordants. Ferric reducing antioxidant power (FRAP) evaluation across six solvent fractions revealed marked solvent-dependent efficacy, with the apolar hexane fraction exhibiting the highest reducing capacity (436.3 ± 12.45 µmol TE/g fw), followed by the chloroform (423.83 ± 11.76 µmol TE/g fw) and hexane/ethyl acetate (406.98 ± 10.23 µmol TE/g fw) fractions, whereas the polar methanol fraction showed the lowest reducing capacity (100.76 ± 4.32 µmol TE/g fw). This reducing potential was statistically associated with the enriched flavonoid and phenolic core constituents identified via LC-MS/MS, primarily hesperidin (8.365 ± 0.432 mg/g) and isoquercetin (0.645 ± 0.054 mg/g). Because only the single-electron-transfer FRAP assay was performed, no radical-scavenging (IC50) metrics are reported. The reducing capacity is therefore interpreted cautiously as a collective property of the phenolic–flavonoid fraction, in which hesperidin and isoquercetin are the principal contributors rather than any single decisive compound. The results revealed that white mulberry leaf extract exhibited high K/S values (21.33 for cotton fabric and 27.91 for wool yarn) and excellent antibacterial activity, particularly when a silver nitrate mordant was used. LC-MS/MS analysis confirmed the presence of bioactive compounds, including hesperidin (8.365 mg/g), isoquercetin (0.645 mg/g), and vanillic acid (0.189 mg/g) in the extract. These findings indicate that white mulberry leaf extract is a plant-derived colorant with multifunctional potential for textile, leather, and wood substrates. The present work does not quantify the environmental footprint of the complete process; therefore, no overall sustainability advantage relative to conventional dyeing is claimed. Any future environmental assessment should include measured extraction energy, water consumption, mordant loading, residual-metal concentrations in spent baths, and wastewater-treatment requirements.
