Chemical Class–Driven Polyphenolic Profiles Shape In Vitro Regenerative Activity of Four Medicinal Plants Relevant to Burn Wound Healing

Background: Burn wound repair is driven by oxidative balance and keratinocyte regeneration. Polyphenol-rich botanicals are considered promising due to combined antioxidant and pro-regenerative properties. This study compares four ethnopharmacologically relevant species—Boswellia serrata (BS), Sambucus nigra (SN), Ocimum basilicum (OB), and Galium verum (GV)—to determine how their polyphenolic class profiles relate to in vitro regenerative activity. Methods: Ethanolic (E—99.5%) and hydroalcoholic (H—70%) extracts were profiled by LC–MS, total polyphenol content (TPC), and DPPH assays. Biological effects were assessed in HaCaT keratinocytes using Alamar Blue (24/48 h) and scratch wound closure (24 h), and results were correlated with chemical profiles. Results: The H extract of OB (OB-H) and of GV (GV-H) had the highest TPC (62.6 and 63.9 mg GAE/g) and lowest DPPH IC50 (18.7 and 17.1 μg/mL), aligning with the strongest biological responses—HaCaT viability up to 169.1% and wound closure up to 414%. SN extracts, dominated by rutin, promoted moderate migration with preserved viability, whereas BS produced modest viability gains. Conclusions: Polyphenolic composition—particularly the dominance of phenolic acids—correlates strongly with in vitro regenerative responses in HaCaT keratinocytes. O. basilicum and G. verum hydroalcoholic extracts displayed the most favorable profiles.