Boosting the Sustainable Transformation of Cornus mas L. Stones Using a Hybrid Strategy Involving Microwave-Assisted Extraction

A hybrid two-route strategy for converting <i>Cornus mas</i> L. stones into bioactive and other high-value compounds was developed and thoroughly evaluated. In Route 1, microwave-assisted extraction (MAE) is applied directly to the stones biomass following an experimental design created with Design Expert 11. Route 2 involves Soxhlet <i>n</i>-hexane extraction of the raw biomass, followed by MAE of the resulting defatted residue. The efficiency of the two routes was evaluated by comparing total polyphenol, flavonoid, and saponin content (TPC, TFC, TSC) and antioxidant activity (AA) of all obtained extracts, the fatty acid composition of MAE (route 1) and Soxhlet <i>n</i>-hexane extracts, and the metabolite composition of MAE extracts recovered in Route 1 and Route 2. The series of analyses performed involved GC-FID fatty acid profiling and composition determination using HPLC-HRMS/MS. These analyses showed that Soxhlet oil yield was 4.00 ± 0.18% with low AA, whereas subsequent MAE extracts had higher TPC, TFC, and TSC and 1.7-fold higher ABTS values than those of MAE Route 1. The increased AA is likely a result of the higher overall phenolic content, especially the presence of the potent antioxidant methyl gallate, which was not detected in MAE Route 1 extract, and not identified in C. cherry stones until now. Our results show that the CCD-optimized hybrid strategy effectively maximizes the recovery of bioactive compounds, demonstrates the superior potential of Route 2 for obtaining antioxidant-rich extracts, and widens the extent of applications of the underused C. cherry stone biomass.