Alkaloids from Waltheria spp. (Malvaceae): Chemosystematic Aspects, Biosynthesis, Total Synthesis, and Biological Activities

Abstract

Waltheria, a genus within the Malvaceae family, is abundantly distributed in tropical and subtropical areas worldwide. Many species of this genus are widely utilized in various ways, including chewing, in folk medicine, acting as an anti-inflammatory agent, and treating gastrointestinal disorders, rheumatism, and asthma, among other conditions. These applications are largely due to their secondary metabolites, primarily quinolone alkaloids and cyclopeptides. Several biological activities have been reported for Waltheria species, including antifungal, anticancer, trypanocidal, acetylcholinesterase inhibitory, potential anti-HIV, antinociceptive, analgesic, anti-inflammatory, antibacterial, antioxidant, and leishmanicidal activities. This review not only presents information on isolated alkaloids and their biological activities but also delves into biosynthetic, chemosystematic, medicinal chemistry, and total synthesis aspects. Additionally, the manuscript highlights other applications of alkaloids of the genus, such as a study on their herbicidal activity, which shows significant potential for agricultural use.