Phytochemical study of Ulmus minor subsp. minor fruits, a rich source of antiinflammatory constituents

Ulmus minor Mill. subsp. minor is a deciduous medium-sized tree native to Europe, extending to Central Asia and North West Africa [1]. The plant is used in popular medicine for the treatment of many ailments: the bark decoction is taken as an astringent for intestinal disorders or in local applications against skin diseases, while bark ointment is topically applied against rheumatism; the leaves are used boiled in vinegar as a pesticide to treat scabies [2,3]. Moreover, plant immature samaras are eaten raw in the Italian phytoalimurgical tradition as snacks, to flavor salads and thicken soups [4] but till now no deep chemical study on their secondary metabolites have been provided so far. Therefore, in this work the phytochemical investigation of plant species samaras EtOAc and n-BuOH extracts is reported for the first time, resulting in the isolation and characterization of twenty compounds including a new flavan-3-ol and a new trihydroxy fatty acid. The extracts and some compounds, selected for their isolation amount and not common distribution in the plant kingdom, were tested for their inhibitory effect on some mediators of inflammation in J774A.1 cells stimulated with lipopolysaccharide of Escherichia coli (LPS). NO release and iNOS and COX-2 expression were evaluated and both the extracts and compounds significantly inhibited NO release as well as iNOS and COX-2 expression in macrophages. In particular, 8-(2-pyrrolidinone-5-yl)-catechin, oxylipin, and catechin 7-O-alfa-L-rhamnopyranoside (20–5 μM) seems to be the more promising in inhibiting the inflammatory response in macrophages (P < 0.001 vs. LPS control treated cells).