Antioxidant potential of new sphingolipid, sphinganine, and metabolites from Lentinus sajor-caju (Fr.) Fr. 1838 (Polyporaceae)

Two novel lipids lentinoside A (6), [1-O-β-D-galactopyranosyl-(2S,3R,4E,8E)-2-[(2′R)-2-hydroxytricosanoylamino]-9-methyl-4,8-heptadecadiene-1,3-diol], and lentinamide A (5), [((2′R)-2-hydroxy-N-((2S,3S,4R)-1,3,4-trihydroxyheptatriacontan-2-yl)pentadecanamide)] were isolated from Lentinus sajor-caju (Fr.) Fr. 1838, alongside stearic acid (1), ergosterol (2), ergosterol endoperoxide (3), and asperglaucide (4). Antioxidant evaluation revealed that (3) (25.706%) and the extract (25.858%, IC50 = 0.188 mg/mL) exhibited DPPH• radical scavenging capacity, though lower than the reference ascorbic acid (21.26%, IC50 = 0.0621 mg/mL). In the ABTS•+ assay, (4) demonstrated the strongest activity (0.800 mg TE/g), followed by (6) (0.646 mg TE/g) and (5) (0.612 mg TE/g). FRAP assay revealed (5) had the highest ferric reducing capacity (0.982 ± 0.069 mg Fe(II)/g), followed by (4) (0.690 mg Fe(II)/g). In contrast, (2) (0.456 mg Fe(II)/g) and the extract (0.440 mg Fe(II)/g) displayed weak capacity. These findings highlight lipid and peptide contributions to the nutraceutical potential of L. sajor-caju and expands the chemical diversity of bioactive fungal metabolites.