Abstract
Five new isopimarane diterpenes, robustaditerpene A-E (1–5), which include 19-nor-isopimarane skeleton and isopimarane skeleton, were isolated from the liquid fermentation of the endophytic fungus Ilyonectria robusta collected from Bletilla striata. The structure elucidation and relative configuration assignments of all compounds were accomplished by interpretation of NMR and HRESIMS spectrometric analyses and 13C NMR calculation. And the absolute configuration of 1-5 were identified by single-crystal X-ray diffraction and ECD calculation. Compound 3 inhibited lipopolysaccharide-induced B lymphocytes cell proliferation with an IC50 value at 17.42 ± 1.57 μM while compound 5 inhibited concanavalin A-induced T lymphocytes cell proliferation with an IC50 value at 75.22 ± 6.10 μM. These data suggested that compounds 3 and 5 may possess potential immunosuppressive prospect.
Highlights
Immunosuppressive agents are a significant class of clinical drugs for organic transplantation and treatment of autoimmune diseases, such as rheumatoid arthritis, systemic lupus, multiple sclerosis, myasthenia gravis, and pemphigus (Dangroo et al, 2016)
For searching the leading compounds with immunosuppressive activity, we studied an endophytic fungus Ilyonectria robusta, isolated from the medicinal plant Bletilla striata
Robustaditerpene A (1) was obtained as a colorless acicular crystal. It has a molecular formula of C19H30O4 as determined by (+)-High Resolution Electrospray Ionization Mass Spectra (HRESIMS) analysis, corresponding to five degrees of unsaturation
Summary
Immunosuppressive agents are a significant class of clinical drugs for organic transplantation and treatment of autoimmune diseases, such as rheumatoid arthritis, systemic lupus, multiple sclerosis, myasthenia gravis, and pemphigus (Dangroo et al, 2016). It is a significant requirement to develop new, efficient, and safe immunosuppressive agents. Natural products play a highly important role in the drug discovery and development process. Many clinically applied drugs derived from or were natural products (Newman and Cragg, 2016). Several immunosuppressive agents, such as mycophenolic acid, cyclosporin A, tacrolimus, sirolimus, corticosteroids and so on, were generated from natural products (Kahan, 2003; Wang et al, 2019)
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