Validation of Madecassoside Synergy Significantly Enhanced Cryptotanshinone’s Therapeutic Efficacy Against Acne Vulgaris

Current acne therapies face major limitations, including antibiotic resistance and skin irritancy. In this study, a synergistic strategy combining cryptotanshinone and madecassoside was developed through functional complementarity. Antibacterial activity against <i>Cutibacterium acnes</i> was evaluated using minimum inhibitory concentration (MIC) and inhibition zone assays, while cytotoxicity was assessed using human keratinocytes (HaCaTs). Anti-inflammatory efficacy was quantified by measuring tumor necrosis factor-alpha (TNF-α), interleukin-1 beta (IL-1β), interleukin-6 (IL-6), and prostaglandin E₂ (PGE₂) in lipopolysaccharide-stimulated macrophages and a copper sulfate (CuSO₄)-induced zebrafish inflammatory model. Systemic safety was examined in zebrafish models (developmental toxicity and sodium dodecyl sulfate-induced irritation). Finally, macroscopic severity, histopathology, and serum cytokines were used to assess an oleic acid-induced rat acne model. Cryptotanshinone inhibited <i>Cutibacterium acnes</i> (minimum inhibitory concentration = 62.5 μg/mL) but exhibited cytotoxicity (>5 μg/mL) and irritancy (≥1000 μg/mL). Madecassoside eliminated cryptotanshinone-induced cytotoxicity and reduced irritation. Importantly, the combination maintained antibacterial efficacy while synergistically enhancing anti-inflammatory effects, achieving a 94% reduction in follicular hyperkeratosis compared with 39% for cryptotanshinone alone (<i>p</i> < 0.01), alongside normalization of histopathology and cytokine levels. In conclusion, madecassoside functionally complements cryptotanshinone by neutralizing its cytotoxicity and irritancy, enabling a safe, synergistic therapy that concurrently targets antibacterial and anti-inflammatory pathways in acne pathogenesis.