Towards understanding the role of unexpected bis-5-alkylresorcinols and prominent acetophenones as rhizome constituents of the European alpine Primula auricula

Rhizomes of the alpine Primula auricula (Primulaceae) were analyzed comprehensively for phytochemical composition. Separation of the lipophilic fraction obtained from the methanolic extract yielded three acetophenones, two benzoic acids, two cinnamic acid derivatives and four bis-5-alkylresorcinols. The compounds were identified using NMR and MS data, as well as by co-chromatography via HPLC-DAD. The bis-5-alkylresorcinols striatol, bis-norstriatol, mono-norstriatol were identified for the first time in a Primula species, and among them, a derivative with a C-12 aliphatic chain named primulastriatol was structurally identified for the first time from a plant source. The major rhizome constituent paeonol showed no activities against the fungus Trichoderma reesei , weak seed germination inhibition properties of Lactuca sativa seeds, notable anti-feedant activities against Spodoptera littoralis caterpillars and strong activities against the nematode species Panagrellus redivivus at 2 mg/mL indicating an important role as defense chemical for the rhizome. The results are discussed in the context of their possible chemophenetic and ecological significance.