Nitric oxide radical scavenging activity of compounds isolated from Plantago major

Abstract

Plantago major, a perennial herbaceous plant found across various provinces in Vietnam, is known for its short stem, growing 15-45 cm tall, with fibrous roots forming clusters. A study investigating the nitric oxide (NO) radical scavenging activity of several Vietnamese medicinal plants revealed that the methanol extract of P. major exhibited significant inhibitory activity with an IC₅₀ value of 75,8 μg/mL. Utilizing column chromatography combined with preparative thin-layer chromatography on both normal and reverse phases, fractions PMA and PMC of this species led to the isolation of eight compounds. These include two iridoids: 3β-methoxyartselawnin C (1) and iridolactone (2); three alkaloids: uridine (3), caffeine (4), and paraxanthine (5); and three phenolics: 4-hydroxybenzoic acid (6), vanillin (7), and 3,5-dihydroxyfuran-2(5H)-one (8). Their structures were identified by analyzing nuclear magnetic resonance (1D- and 2D-NMR) data, high-resolution mass spectrometry (HRMS) data, and comparing them with literature references. Compounds 1-5 and 8 are reported for the first time in this species. NO radical scavenging activity assays indicated that compounds 2, 3, and 7 displayed IC₅₀ values of 99,6, 77,9, and 34,2 µM, respectively, while the remaining compounds exhibited weak biological activity.