Secondary metabolites from the stem bark of Strychnos aff. dariensis

Abstract

The genus Strychnos (Loganiaceae) is well-known as a rich source of various bioactive indole alkaloids. In continuation of our phytochemical studies on plants from Amazonia [1], we examined Strychnos aff. dariensis, collected in Peru. This species has been traditionally used in South America [2] as an arrow poison and is applied till nowadays as a drug from Yanesha tribe in Peru [3]. Extraction with EtOAc and MeOH and then treatment in different pH values, resulted to a first fractionation of the plant material. Further phytochemical investigation of this plant led to the isolation and structure elucidation by NMR and HRMS of 14 compounds that belong to the categories of phenolic acids (p-hydroxybenzoic acid and vanillic acid), flavonoids (luteolin, 3',4',7-trihydroxyflavone, 3-methoxy quercetin, strychnobiflavone and minaxin), lignans (syringaresinol-β-D-glucoside, balanophonin and ficusal) and alkaloids (venoterpine, condensamine, diaboline and 11-methoxy diaboline). The presence of the indole alkaloid 11-methoxy-diaboline as a major constituent was in accordance with the literature [4] that reports that in species of Strychnos with a relatively low percentage of alkaloids it constitutes the main component.