Structures and Properties of Phenylethanoid Glycosides from Barleria prionitis Linn.: Insights from Theoretical and Experimental Investigations

From the whole plant of Barleria prionitis Linn. collected in Laos, six phenylethanoid glycosides, acetylmartynoside A (1), martynoside (2), 3-O-methylpoliumoside (3), isoaceteoside (4), leucosceptoside A (5), 2-(3-hydroxy-4-methoxyphenyl)-ethyl-O-(α-l-rhamnosyl)-(1-3)-O-(α-l-rhamnos-yl)-(1-6)-4-O-E-feruloyl-β-d-glucopyranoside (6) were isolated. Their structures were elucidated by 1D and 2D NMR and mass spectra. In addition, the antioxidant activity of compounds 1-6 was investigated. All of the compounds showed Keap1 protein inhibitory effect with binding affinity in the range of -9.639 - -9.084 kcal/mol and moderate DPPH free radical scavenging activity with their IC50 values in the range of 110-389 μM. Furthermore, the predicted toxicity results of all of them indicated a level of 5 and a high LD50 value (LD50 = 5000 mg/kg), which showed low toxicity and high safety for oral consumption in humans.