Abstract
Background: Neuroinflammatory processes are critical in the development and progression of Alzheimer's disease (AD). The potent anti-neuroinflammatory inhibitors are expected as the candidates to treat AD. Cryptotanshinone (1), a major bioactive constituent in the traditional Chinese medicinal herb Dan-Shen Salvia miltiorrhiza Bunge, has been reported to possess remarkable pharmacological activities, especially anti-oxidation and anti-inflammation. Methods: Cryptotanshinone (1) was biotransformed with the fungus Cunninghamella elegans AS3.2028 to improve its bioactivities and physicochemical properties. The structures of transformed products were elucidated by comprehensive spectroscopic analysis including HRESIMS, NMR and ECD data. Their anti-neuroinflammatory activities were assessed by ELISA, transcriptome analysis, western blot, and immunofluorescence methods. Results: Three oxygenated products (2–4) at C-3 of cryptotanshinone (1) were obtained, among them 2 was a new compound. All of the biotransformed products (2–4) were found to inhibit significantly lipopolysaccharide-induced nitric oxide production in BV2 microglia cells with the IC50 values of 0.16‒1.16 μM, approximately 2‒20 folds stronger than the substrate (1). These biotransformed products also displayed remarkably improved inhibitory effects on the production of inflammatory cytokines (IL-1β, IL-6, TNF-α, COX-2 and iNOS) in BV-2 cells via targeting TLR4 compared to substrate (1). The underlying mechanism of 2 was elucidated by comparative transcriptome analysis, which suggested that it reduced neuroinflammatory mainly through mitogen-activated protein kinase (MAPK) signaling pathway. Western blotting results revealed that 2 downregulated LPS-induced phosphorylation of JNK, ERK, and p38 in MAPK signaling pathway. Conclusion: The biotransformed products of cryptotanshinone exhibit potent anti-neuroinflammatory activities. These findings provide a basal material for the discovery of candidates in treating AD.
Transcriptome Analysis and Microsatellite Markers Development of a Traditional Chinese Medicinal Herb Halenia elliptica D. Don (Gentianaceae)
