Detection, Isolation, and ¹H NMR Quantitation of the Nitrile Glycoside Sarmentosin from a Bryophyllum pinnatum Hydro-Ethanolic Extract

Abstract

Bryophyllum pinnatum (Lam) Pers. (Crassulaceae) is widely used in folk medicine as leaf juice, aqueous, or hydro-ethanolic extracts. It is also listed as a medicinal plant in several countries such as France and Brazil. The main reported constituents are flavone glycosides, especially those with the rare 3-O-α-l-arabinopyranosyl-(1 → 2)-α-l-rhamnopyranoside moiety. Despite several phytochemical screenings indicating the presence of cyanide derivatives or alkaloids, there are no reports of nitrogenous metabolite characterization from this plant species. Nevertheless, the occurrence and the type of such compounds are of particular interest, as they may account for some of the numerous biological activities and ethnomedicinal uses described for B. pinnatum and could be regarded as chemical/taxonomic markers. Consequently, a hydro-ethanolic extract of B. pinnatum was investigated by using UHPLC–HRMS/MS and the nitrile glucoside sarmentosin was detected for the first time within the genus Bryophyllum/Kalanchoe. Considering the wide use of B. pinnatum and its closely related species for health purposes, the target metabolite was isolated by a combination of centrifugal partition chromatography in elution/extrusion mode and MPLC in order to confirm its structure. A linear, selective, precise, fast, and reliable 1H NMR quantitation method was then developed and validated and may become a tool for easy quality assessment of the plant species. The amount of sarmentosin was determined as 2.07% of the examined sample. Sarmentosin was also detected in Kalanchoe laciniata, confirming the occurrence of this compound within the genus.

Natural Products Containing the Nitrile Functional Group and Their Biological Activities

“…(Crassulaceae) and Kalanchoe laciniata. 89 In a study of the chemical constituents of a traditional Tibetan medicine, Rhodiola kirilowii (Regel) Maxim, used as an adaptogen in China, an ethanol extract of the roots was evaluated. 90 In addition to known compounds, a new nitrile, 4-(β-Dglucopyranosyloxy)-3-hydroxy-2-(hydroxymethyl)-butanenitrile 154 (Figure 16), was isolated.…”