Phytochemical study of Stachys sylvatica (Lamiaceae) aerial parts

Abstract

In this article, the first complete phytochemical study of Stachys sylvatica (Lamiaceae) aerial parts, collected in Tuscan-Emilian Apennine, is reported. Twenty-three known compounds were isolated from the chloroform, chloroform-methanol 9:1 and methanol extracts; they were subsequently characterized by means of one- and two-dimensional nuclear magnetic resonance spectroscopy (1D- and 2D-NMR) and mass spectrometry as six simple phenolic derivatives (chlorogenic acid (1), caffeic acid (2), p-coumaric acid methyl ester (3), niduloic acid (4), hydroxytyrosol (5), tyrosol (6)), one glycosylated aliphatic alcohol (ebracteatoside B (7)), six glycosylated phenylpropanoids (decaffeoyl verbascoside (8), lavandulifolioside (9), betanyoside F (10), verbascoside (11), isoacteoside (12), cystanoside D (13)), four flavonoids (stachyspinoside (14), chrysoeriol 7-O-β-D-glucopyranoside (15), naringenin 7-O-(6’’-E + Z-p-coumaroyl)-β-D-glucopyranoside (16), apigenin 7-O-(6’’-E + Z-p-coumaroyl)-β-D-glucopyranoside (17)), three lignans (syringaresinol 4’-O-β-D-glucopyranoside (18), pinoresinol 4-O-β-D-glucopyranoside (19), 2-episesaminol 2-O-β-D-glucopyranoside (20)) and three ionones (loliolide (21), vomifoliol (22), (3S,5R,6R,7E,9R)-3,5,6,9-tetrahydroxy-7-megastigmene (23)). In addition, a further phenolic derivative (ethyl caffeate (b)) and four carboxylic acids (azelaic acid (a), trihydroxyoctadecadienoic acid (c), trihydroxyoctadecenoic acid (d) and dihydroxydodecadienoic acid (e)) have been tentatively identified by ultra-high performance liquid chromatography coupled to an electrospray ionization source high-resolution Orbitrap mass spectrometer (UHPLC-ESI-HR-Orbitrap/MS). Chemosystematic relationships between S. sylvatica and other related species were highlighted.