Targeting Skin Aging at Multiple Fronts: Integrated In Silico and In Vitro Evidence of Antioxidant, Anti-Protease, and UVB-Protective Effects of Vitex trifolia

Skin aging is driven by oxidative stress, extracellular matrix degradation, and ultraviolet-B (UVB)-induced cellular injury. Plant-derived bioactives with multi-targeted protective actions offer promising avenues for cosmeceutical development. This study assessed ethanolic leaf extracts of Vitex trifolia, an Indonesian medicinal plant traditionally used for skin disorders. Phytochemical analysis showed a total phenolic content of 78.52 ± 0.01 mg GAE/g and total flavonoid content of 1.99 ± 0.02 mg QE/g. LC–HRMS profiling identified major flavonoid and phenolic acid derivatives. Antioxidant assays demonstrated strong radical-scavenging and reducing activities, with IC50 values of 63.47 ± 0.24 (DPPH) and 70.13 ± 1.28 μg/mL (ABTS) and a Ferric Reducing Antioxidant Power (FRAP) value of 36.3 ± 0.18 FeSO4 eq/100 g. Enzymatic studies confirmed potent collagenase inhibition (IC50 = 27.94 ± 3.20 μg/mL) and moderate elastase inhibition, supported by molecular docking analysis. In HaCaT keratinocytes, the extract remained non-cytotoxic up to 100 μg/mL and exerted cytoprotective activity against UVB-induced damage at 12.5–50 μg/mL. The extract also downregulated UVB-induced matrix metalloproteinase-1 (MMP-1) and matrix metalloproteinase-9 (MMP-9) expression up to 42% and 69%, respectively, outperforming ascorbic acid. These findings highlight V. trifolia as a multifunctional natural candidate for anti-photoaging cosmeceutical applications over single-compound antioxidants, as demonstrated by its combined antioxidant, enzyme-inhibitory, cytoprotective, and MMP-modulating activities, as well as a wider cell safety profile.