Lungwort (Pulmonaria officinalis) and Inflammation (general): evidence and sources

Our work reveals that the aerial parts of Pulmonaria officinalis L. are a new source of yunnaneic acid B. We studied antioxidant activity and cytotoxicity of this compound (1-50 μg/mL) and its contents in various plant extracts. This is the first study confirming the presence of yunnaneic acid B in P. officinalis L. and Pulmonaria obscura Dumort and hence in the Boraginaceae family. Determination of 1,1-diphenyl-2-picrylhydrazyl radical reduction and peroxynitrite-scavenging efficacy in inorganic experimental systems provided EC 50 values of 7.14 and 50.45 μg/mL, respectively. Then we examined the antioxidant action of yunnaneic acid B in blood plasma under peroxynitrite-induced oxidative stress in vitro. Yunnaneic acid B effectively diminished oxidative damage to blood plasma proteins and lipids. Furthermore, it was able to prevent the peroxynitrite-induced decrease in nonenzymatic antioxidant capacity of blood plasma. Additionally, cytotoxicity of yunnaneic acid B (at concentrations ≤50 μg/mL) toward peripheral blood mononuclear cells was excluded.

The Pulmonaria species (lungwort) are edible plants and traditional remedies for different disorders of the respiratory system. Our work covers a comparative study on biological actions in human blood plasma and cyclooxygenase-2 (COX-2) -inhibitory properties of plant extracts (i.e., phenolic-rich fractions) originated from aerial parts of P. obscura Dumort. and P. officinalis L. Phytochemical profiling demonstrated the abundance of phenolic acids and their derivatives (over 80% of the isolated fractions). Danshensu conjugates with caffeic acid, i.e., rosmarinic, lithospermic, salvianolic, monardic, shimobashiric and yunnaneic acids were identified as predominant components. The examined extracts (1-100 µg/mL) partly prevented harmful effects of the peroxynitrite-induced oxidative stress in blood plasma (decreased oxidative damage to blood plasma components and improved its non-enzymatic antioxidant capacity). The cellular safety of the extracts was confirmed in experimental models of blood platelets and peripheral blood mononuclear cells. COX-2 inhibitor screening evidently suggested a stronger activity of P. officinalis (IC 50 of 13.28 and 7.24 µg/mL, in reaction with synthetic chromogen and physiological substrate (arachidonic acid), respectively). In silico studies on interactions of main components of the Pulmonaria extracts with the COX-2 demonstrated the abilities of ten compounds to bind with the enzyme, including rosmarinic acid, menisdaurin, globoidnan A and salvianolic acid H.