Active compounds on TRP ion channels from Waldheimia glabra: a medicinal plant of Himalaya

Waldheimia glabra (Decne.) Regel, commonly known as Smooth Ground Daisy, is a wild aromatic plant belonging to the Asteraceae family. It grows in the Alpine zones of the Himalaya up to 4000-5400 m above sea level (a.s.l.), in particular in the north of Pakistan, Kashmir, Tibet, Nepal and Bhutan. Local populations use this plant in religious rituals (incense) or in traditional herbal medicine to treat skin diseases, headache, and joint pain and fever. In literature few data are available on the investigation of this aromatic plant. Objectives: The present work focuses on the chemical composition of W. glabra extracts and incense, as well as its activity on TRP ion channels. Methods: Extracts and incense of W. glabra were analyzed by HS-SPME-GC/MS, GC/MS and NMR analysis. Tests on the activity of W. glabra extracts and isolated compounds (+)-ludartin 1 and B-ring-homo-tonghaosu 2 on TRP channels were also performed. Results: Some extracts and pure compounds from W. glabra showed an interesting activity in terms of efficacy and potency on rat TRPA1, an ion channel involved in several sensory mechanisms, including pungency, environmental irritation and pain perception. Activity is discussed and compared with that of other known TRPA1 natural agonists with different chemical structures. All compounds showed only a negligible inhibition activity on rat TRPM8 ion channel. Conclusions: Our findings demonstrate that W. glabra is involved in the receptor activation mechanism and therefore represents a new natural product potentially useful in pharmaceutical and agrifood research.