Chemical constituents with free-radical-scavenging activity from the leaves of Lantana montevidensis (Spreng.) Briq.

Background: Seventy percent aqueous methanolic extract of the leaves of Lantana montevidensis exhibited antibacterial, anti-inflammatory, anti-pyretic, antioxidant and analgesic activities. Previous phytochemical study of the leaves led to the isolation of various flavones, pentacyclic triterpenoids, β-sitosterol and benzoic acid. Materials and Methods: The 70% aqueous methanolic extract of L. montevidensis (Spreng.) Briq. leaves was partitioned between water and n-hexane, CHCl₃, EtOAc, and n-BuOH, successively. By using a series of different chromatographic techniques, the CHCl₃ and EtOAc extracts afforded nine compounds. The isolated compounds were identified by spectroscopic techniques and by comparison with literature values and/or authentic samples. The free radical scavenging activity of some of the isolated compounds was evaluated. Results: Hispidulin-7-O-glucurnoide methyl ester (1), hispidulin-7-O-glucoside (2), cinaroside (3), nepetin-7-O-glucoside (4) pectolinarigenin (5), apigenin (6), luteolin (7) in addition to salicylic acid (8) and β-sitosterol-3-O-glucoside (9) have been isolated. Compounds 1-4 are first report from the genus Lantana while compounds 5, 8 and 9 are first report from this plant. The structures of these compounds were elucidated on the basis of spectral methods, including 2D NMR experiments, and confirmed by comparing with the literature data and/or authentic samples. Additionally, some of the isolated flavonoids exhibited free radical scavenging activity. Conclusion:Lantana montevidensis (Spreng.) Briq. cultivated in Egypt is rich in biologically active ingredients.

Key words:  Apigenin, cinaroside, free radical scavenging activity, hispidulin-7-O-glucurnoide methyl ester, hispidulin-7-O-glucoside, Lantana montevidensis, luteolin, nepetin-7-O-glucoside, pectolinarigenin.