Hedwigia ciliata (Hedw.) P. Beauv. moss extracts - Chemical characterization and in vitro testing of immunomodulatory potential

Owing to structural diversity and potental pharmacological activity, bioactive compounds derived from natural sources are in the focus of intensive exploration. In this study, the chemical composition of different moss extracts of Hedwigia ciliata P. Beauv. was examined, and further tested for antioxidant, antineurodegenerative/anti-neuroinflammatory, antidiabetic, and antiproliferative activity in vitro. The extracts were prepared by Soxhlet extractor using solvents of different polarity. Chemical analysis revealed the presence of phenolics, flavonoids, and triterpenoids as secondary metabolites of high biological activity. Antioxidant activity of extracts was assessed using three different methods, DPPH (2,2-diphenyl-1-picrylhydrazyl), total reducing power assay, and β-carotene/linoleic acid assay. To evaluate the enzyme-inhibitory activity, extracts were screened for α-amylase, α-glucosidase, acetylcholinesterase, and tyrosinase inhibitory effects. The biocompatibility of moss extracts was confirmed using normal human fibroblast cell line, MRC-5. The H. ciliata extracts displayed significant antiproliferative activity (~ 50% inhibition) against the MDA-MB-231 (human breast adenocarcinoma) cells, which had not previously been reported elsewhere. The potential anti-neuroinflammatory activity was observed due to significant reduction of the NO production by LPS-stimulated BV2 (normal murine microglia cell line), being in line with previously recognized antineurodegenerative potential, as measured by the inhibition of acetylcholinesterase and tyrosinase activity. Furthermore, the H. ciliata extracts displayed significant antidiabetic effect via α-glucosidase inhibition. In general, the obtained results suggest the potential immunomodulatory activity of the moss H. ciliata extracts, remaining to be characterized in more detail in search for mechanisms underlying the immunomodulation processes.