Synergistic anti-photoaging and anti-inflammatory effects of Eucommia ulmoides, Styphnolobium japonicum, and Portulaca oleracea extracts via TGF-β/Smad/IL-17 pathway

Eucommia ulmoides Oliv. (PE), Styphnolobium japonicum (L.) Schott (PS) and Portulaca oleracea L. (PP) are well-characterized medicinal botanicals with established therapeutic profiles. PE exhibits anti-psoriatic and anti-aging properties through bioactive constituents, as demonstrated in vitro and in vivo research. PS flowers contain sophoricoside, a validated modulator of atopic dermatitis pathways, while PP displays broad-spectrum anti-inflammatory and antioxidant activities. Given their complementary mechanisms and the limited efficacy of single-agent approaches against UVB-driven oxidative stress/inflammation, we hypothesized that a tripartite extract (ESP: PE/PS/PP) would demonstrate synergistic photoprotection. This study evaluated the efficacy of ESP through integrated experimental cell models, a murine model of acute UVB-induced photoaging, and transcriptome analysis. ESP extracts demonstrated synergistic antioxidant and photoprotective activities through multi-target mechanisms, effectively attenuating UVB-induced photoaging in vitro and in vivo. LC-QTOF-MS analysis identified major bioactive components comprising organic acids, polysaccharides, iridoids, and flavonoids. In a paracrine signaling model using conditioned medium from UVB-exposed HaCaT cells to stimulate HFF cells, ESP significantly inhibited UVB-induced secretion of inflammatory mediators (PGE2, TNF-α, IL-1α, IL-6). Transcriptome sequencing coupled with RT-qPCR validation revealed that ESP attenuated photoaging via the IL-17 signaling pathway, downregulating key mediators including matrix metalloproteinases (MMP1/3/13), chemokines (CXCL3/8, CCL7), and colony-stimulating factors (CSF2/3). Furthermore, ESP reduced mitochondrial ROS generation, stabilized membrane potential, activated the TGF-β/Smad pathway, and upregulated COL1A1 and COL3A1 expression. Significantly, in a murine model of acute UVB-induced photoaging, ESP treatment produced dose-dependent restoration of UVB-damaged skin. It markedly attenuated epidermal hyperplasia, and increased collagen density. Concurrently, it improved skin elasticity and barrier function (TEWL), while suppressing pro-inflammatory cytokines (TNF-α, IL-6, IL-17) and MMP3 expression, and upregulating collagen genes (COL1A1, COL3A1). These findings demonstrated that ESP inhibits photoaging through four integrated pathways: (1) attenuating inflammatory cytokines, (2) scavenging ROS, (3) enhancing collagen synthesis, and (4) restoring structural and functional integrity to the skin. Our data established ESP as a potent anti-photoaging agent that protects against UVB-induced damage via coordinated modulation of the TGF-β/Smad pathway and IL-17 signaling. Its dose-dependent efficacy, demonstrated through effective ROS scavenging, enhanced collagen synthesis, and significant anti-inflammatory activity, validates ESP as a novel, multi-target strategy against skin aging.