Development of Cosmetic Emulsions Enriched with Pinus nigra Extracts Prepared by Different Extraction Approaches: Physicochemical Stability, Biological Activity and Taxifolin Permeability

The growing demand for natural cosmetic ingredients has increased interest in plant-derived extracts with multifunctional biological properties. In this study, oil-in-water (O/W) cosmetic emulsions containing Pinus nigra needle extracts obtained by different extraction methods (Soxhlet, reflux, hot oil maceration, and cold oil maceration) and a commercially available essential oil were developed and comprehensively characterized. The formulations were evaluated for physicochemical stability (pH, viscosity, and color), total phenolic content (TPC), taxifolin content, antioxidant, anti-inflammatory, and anti-tyrosinase activities, as well as taxifolin permeability using the Skin-PAMPA model. Water-based extracts, particularly the reflux extract, exhibited the highest TPC (8.02 ± 0.63 mg GAE/mL cream), while formulations containing water extracts demonstrated the greatest antioxidant activity (79.72 ± 5.38% (reflux) and 76.78 ± 4.36% (soxhlet) DPPH inhibition). In contrast, oil-based extracts showed higher anti-inflammatory activity, with hyaluronidase inhibition reaching 85.25 ± 0.89%, and enhanced taxifolin permeability (50.56 ± 2.82 × 10−6 cm/s). Principal component analysis indicated a positive correlation between TPC and antioxidant activity (r = 0.806), whereas permeability was negatively correlated with TPC and antioxidant activity but positively associated with oil-based formulations. All emulsions exhibited satisfactory physicochemical stability during storage. Different extraction approaches were associated with distinct chemical and functional profiles of the resulting P. nigra-based cosmetic emulsions.