Purification of bioactive compounds from rosemary by-products for innovative solutions in food industry

Maximizing the value of agricultural by-products is critical for advancing sustainable development and minimizing waste. This study delves into the solid by-products of Rosmarinus tournefortii de Noé, focusing on their fractionation and purification to unveil valuable bioactive compounds. Using flash chromatography, nine distinct fractions (F1 to F9) were successfully isolated. Cutting-edge analytical techniques including FTIR, UHPLC-MS/MS, and 2 D NMR (HSQC, HMBC and COSY) confirmed the presence of novel labdane diterpenoids (PF1), 24-nor-ursane triterpenoids (PF5), and ent-kaurane diterpenoids (PF6). Furthermore, HPLC-DAD profiling revealed rosmadial (79.43 % in F4) and luteolin (70.14 % in F7) as the dominant phenolic compounds. Notably, the crude extract demonstrated remarkable antioxidant activity, with an IC50 of 0.04±0.23 mg/mL. Fractions F7 and F8 also exhibited strong antioxidant potential, with IC50 values of 0.35±0.07 mg/mL and 0.36±0.02 mg/mL, respectively. Purified fractions PF7 and F8, enriched with luteolin and 3-hydroxyflavone, proved highly effective for pigmentation control, with PF7 showing an IC50 of 0.045±0.007 mg/mL. In addition, antimicrobial assays revealed that the 24-nor-ursane triterpenoid and fraction F6, containing ent-kaurane and carnosol, displayed potent inhibitory effects against Rhodotorula glutinis (24.1 mm). Molecular docking studies further highlighted PF5 as a potent inhibitor of alpha-amylase (-5.856 kcal/mol) and tyrosinase (-4.385 kcal/mol), while PF1 surpassed acarbose in alpha-glucosidase inhibition with a binding energy of −5.898 kcal/mol. Collectively, these findings highlight the immense potential of R. tournefortii by-products as a rich source of bioactive compounds for health and skincare, offering promising, sustainable solutions for the pharmaceutical, cosmetic and food preservation industries. • FTIR, UHPLC-MS/MS, and 2 D NMR revealed novel diterpenoids and triterpenoids. • Nine distinct bioactive fractions were effectively isolated by flash chromatography. • Flavonoid and phenolic fractions showed strong antioxidant and tyrosinase inhibitors. • Triterpenoids and diterpenoids showed strong antimicrobial activity, up to 24.1 mm. • Docking confirmed triterpenoids as potent alpha-amylase and tyrosinase inhibitors.