Alkaloids from Lime Flower (Tiliae flos) Exert Spasmodic Activity on Murine Airway Smooth Muscle Involving Acetylcholinesterase

Planta Med DOI: 10.1055/a-1534-3766Lime flower (Tiliae flos) is traditionally used either for treatment of the common cold or to relieve symptoms of mental stress. Recently, the presence of a new class of piperidine and dihydro-pyrrole alkaloids from lime flower has been described. The present study aimed to investigate the pharmacological activity of hydroacetonic lime flower extracts, alkaloid-enriched lime flower fractions, and isolated alkaloids on the murine airway smooth muscle and the cholinergic system. While a hydroacetonic lime flower extract did not show any pharmacological activity, enriched Tilia alkaloid fractions potentiated acetylcholine-induced contractions of the trachea by ~ 30%, showing characteristics comparable to galanthamine. Effects were abrogated by atropine, indicating an involvement of muscarinic receptors. The dihydro-pyrrole alkaloid tiliine A, the piperidine alkaloid tiliamine B, and the acetylated piperidine alkaloid tilacetine A were characterized as acetylcholinesterase inhibitors. The positive control galanthamine (IC50 = 2.0 µM, 95% CI 1.7 to 2.2 µM) was approximately 100 times more potent compared to tiliine A (IC50 = 237 µM, 95% CI 207 to 258 µM) and tiliamine B (IC50 = 172 µM, 95% CI 158 to 187 µM). Neither DNA synthesis of HepG2 liver cells, HaCaT keratinocytes, and Caco-2 intestinal epithelial cells nor cell viability of primary human fibroblasts was reduced by the alkaloids. The indirect cholinergi...
Source: Planta Medica - Category: Drugs & Pharmacology Authors: Tags: Original Papers Source Type: research