A comprehensive review of phytochemistry, pharmacology and quality control of plants from the genus Viola.

This article provides a comprehensive review of the genus *Viola* (family Violaceae), focusing on its phytochemistry, pharmacology, and quality control. Over 370 compounds have been identified from *Viola* species, including flavonoids, coumarins, alkaloids, lignans, sesquiterpenes, triterpenoids, sterols, fatty acids, phenolic acids, and notably cyclotides—cyclic peptides with diverse bioactivities. Pharmacological studies demonstrate that *Viola* plants exhibit antibacterial, antiviral, antioxidant, anti-inflammatory, antitumor, neuroprotective, hepatoprotective, and other effects, with some extracts and compounds showing activity against drug-resistant bacteria and viruses such as HIV and influenza. Quality control methods, primarily involving chromatographic and spectroscopic techniques, have been developed mainly for *Viola yedoensis* and *Viola tianshanica*, but are limited for other species. The review highlights the need for further research on toxicity, pharmacokinetics, polysaccharides, and quality control across more *Viola* species to support their safe and effective clinical use.