Violaceae: chemical constituents, traditional use and pharmacology

Species of the Violaceae family, especially those of the genus Viola, are widely used in traditional medicine to treat various diseases. Their use is due to a large number of secondary metabolites present in plants of this family that present anticancer, antioxidant, antibacterial, anti-inflammatory, antiviral, insecticidal and cytotoxic activities, among other properties. This review describes the chemical constituents, traditional uses and biological activities reported for the Violaceae family to date. The literature reports seven hundred and sixty-two secondary metabolites in the Violaceae family, which were classified into seven specific organic functional classes (flavonoids, terpenoids, sterols, alkaloids, phenylpropanoids, essential oils, cyclotide peptides), and one nonspecific class (miscellaneous compounds). This review presents the chemical structures, names, and corresponding plant sources of these compounds along with their biological activities. The rich profile of biologically active compounds isolated from Violaceae species might be a valuable resource for inspiring the rational development of novel therapeutic drugs.