Antioxidant and Antimicrobial Potential of Malva neglecta Wallr. Extracts Prepared by “Green” Solvents

The medicinal plant Malva neglecta Wallr. is known for its high concentration of beneficial bioactive compounds. This study investigated extracts prepared from the plant’s flowers, leaves, and roots. Different green solvents were used: 70% ethanol, and for the first time in relation to this plant species, natural deep eutectic solvents (NADES)—one based on choline chloride and citric acid (NADES1) and another using choline chloride and glycerol (NADES2). Key bioactive compounds were identified and quantified using spectrophotometric assays and HPLC-PDA-MS profiling to determine their role in the plant’s antioxidant activity. The analysis revealed that M. neglecta contains a wide range of flavonoid glycosides and phenolic acids, with the flowers and leaves exhibiting the highest diversity and concentrations of these compounds with a predominance of quercetin and kaempferol glycosides. Among the solvents tested, the ethanolic extracts showed the highest total contents of phenols, flavonoids, and condensed tannins. The flower extracts—regardless of the solvent used—exhibited the strongest antioxidant activity, as demonstrated by the DPPH, FRAP, and ABTS assays. Alkaloids were detected in all organs tested only in low quantities. The antibacterial (against Bacillus cereus, Staphylococcus aureus, Escherichia coli, and Pseudomonas aeruginosa) and antifungal activity (against Penicillium chrysogenum, Fusarium oxysporum, Aspergillus parasiticus, A. carbonarius, A. niger, A. flavus, and A. ochraceus) of the extracts was evaluated and compared. As a whole, the NADES1 extracts exhibited higher antibacterial potential than the ethanolic extracts. Such a clear trend regarding the antifungal activity was not observed. The highest antifungal activity was exhibited by NADES1 root extracts. NADES2 extracts showed a complete lack of antimicrobial effects.