Structural Characterization and Anti-Ultraviolet Radiation Damage Activity of Polysaccharides from Helianthus annuus (Sunflower) Receptacles

Helianthus annuus L. (H. annuus) receptacles, a major agricultural by-product generated during seed processing, are currently underutilized. This study aimed to explore the valorization potential of this by-product by extracting H. annuus receptacles total polysaccharides (HRTP) and characterizing their potential as natural ingredients in ultraviolet (UV)-protective cosmetics. A new purified polysaccharide named H. annuus receptacles polysaccharide-1 (HRP-1) was isolated, likely exhibiting a backbone of alternating →4)-α-D-GalA-(1→ and →4)-α-D-GalA(6-OCH3)-(1→ units, with a weight-average molecular weight (Mw) of 163 kDa. HRTP demonstrated significant protective effects against UV-induced damage in human immortalized keratinocyte (HaCaT) cells by suppressing intracellular reactive oxygen species (ROS) levels and downregulating MAPK-p38/ERK/JNK pathways, thereby inhibiting inflammatory cytokines (IL-1β, IL-6, IL-8, and TNF-α) and matrix metalloproteinases (MMP-1, MMP-3, and MMP-9). Additionally, HRTP exhibited moisturizing properties. These findings highlight H. annuus receptacle polysaccharides as sustainable, bioactive ingredients for eco-friendly sunscreen formulations, providing a practical approach to converting agricultural by-products into high-value industrial biomaterials.