Comparative Biochemistry of Wild and In Vitro-Propagated Melilotus officinalis: Phytochemical Composition,...

Melilotus officinalis (L.) Lam. (yellow sweet clover) is a medicinally valuable Fabaceae species with recognized antioxidant and antimicrobial properties, yet the impact of cultivation system on its secondary metabolism remains poorly characterized for Central Asian populations. This study compared wild and in vitro-grown Melilotus officinalis from northern Kazakhstan (Astana city), examining phenolic composition, organic acids, antioxidant capacity, and antimicrobial activity as functions of cultivation system. Hydroethanolic extracts were analyzed by HPLC-DAD-ESI-Orbitrap MS/MS and UFLC-PDA, while antioxidant activity was assessed by TBARS and ABTS assays and antimicrobial activity by broth microdilution against eight bacterial and two fungal strains. Thirteen phenolic compounds were tentatively identified, revealing higher total flavonoid content in in vitro plants, dominated by apigenin di-C-pentoside isomers and vicenin-3, whereas wild plants showed greater diversity of phenolic acids and flavonols, including kaempferol and quercetin glycosides. Despite lower total phenolics, wild extracts more effectively inhibited lipid peroxidation, while ABTS radical scavenging was comparable between sources, and antimicrobial effects were strain-specific. Oxalic acid was approximately three-fold higher in in vitro material, a biochemical feature relevant for downstream use. These findings indicate that cultivation system substantially shapes the secondary metabolite profile and bioactivity of this regionally important medicinal species.