Azelaic AcidvsGreen Tea Extract (EGCG)

Azelaic acid exhibits multi-modal activity: (1) Tyrosinase inhibition—competitively inhibits tyrosinase selectively in hyperactive melanocytes (melasma, PIH) while sparing normal ones; may involve mitochondrial enzyme interference in dysregulated melanocytes. (2) Antimicrobial—bacteriostatic against Cutibacterium acnes by inhibiting bacterial protein synthesis. (3) Comedolytic—normalizes follicular keratinization, reducing hyperkeratinization and corneocyte cohesion; may modulate keratinocyte differentiation. (4) Anti-inflammatory—scavenges ROS, inhibits neutrophil free radicals, reduces pro-inflammatory cytokines. Inhibits 5-alpha-reductase in sebocytes, potentially reducing sebum. Multi-pathway activity explains efficacy in acne, rosacea, and hyperpigmentation. Safe during pregnancy.

EGCG scavenges ROS (superoxide, hydroxyl radical, peroxynitrite) and chelates iron/copper that catalyze Fenton reactions. Inhibits MMP-2 (gelatinase A) and MMP-9 (gelatinase B) that degrade collagen types I, III, IV and elastin in photoaged skin — these enzymes are UV-upregulated via AP-1 and NF-kappa B. Reduces sebum by inhibiting 5-alpha reductase type 1 (testosterone to DHT conversion in sebaceous glands). Anti-inflammatory: NF-kappa B inhibition (I-kappa B degradation prevention), COX-2 suppression, TNF-alpha/IL-1beta reduction. Promotes keratinocyte differentiation via involucrin and filaggrin upregulation. Catechol structure enables dual antioxidant and metal-chelating activity. Topical EGCG reduces UV-induced erythema and prevents collagen degradation when used before sun exposure.