Optimization of enzymatic production of anti-skin aging biopeptides from white sorghum [Sorghum bicolor (L) Moench] grain.

Recently, kafirins from white sorghum [Sorghum bicolor (L) Moench] grain have shown promise as a source of biopeptides with anti-skin aging effects (anti-inflammatory, antioxidant, and inhibition of photoaging-associated enzymes). This study employed response surface methodology (RSM) to optimize the extraction and enzymatic hydrolysis of kafirins (KAF) for the production of peptides with anti-skin aging properties. The optimization of conditions (reaction time and enzyme/substrate ratio) for liquefaction with α-amylase and hydrolysis of KAF with alcalase was performed using 3² complete factorial designs. Subsequently, ultrafiltered peptide extracts were obtained with molecular weights of 1-3 kDa (KAF-UF₃) and lower than 1 kDa (KAF-UF₁), which mainly contain hydrophobic amino acids (proline, leucine, isoleucine, phenylalanine, and valine) and peptide fractions with molecular weights of 0.69, 1.14, and 1.87 kDa. Consequently, the peptide extracts protected immortalized human keratinocytes (HaCaT cells) from ultraviolet B radiation (UVB)-induced damage by preventing the decrease and/or restoring the activity of antioxidant enzymes [superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GSH-Px)]. Furthermore, KAF-UF₃ and KAF-UF₁ inhibited (20-29%) elastase and collagenase overactivity in UVB-exposed murine fibroblasts (3T3 cells). Thus, KAF-UF₃ and KAF-UF₁ exhibited behavior similar to that observed with glutathione (GSH), suggesting their potential as functional peptide ingredients in skincare products.