The oxygenated products of cryptotanshinone by biotransformation with Cunninghamella elegans exerting anti-neuroinflammatory effects by inhibiting TLR 4-mediated MAPK signaling pathway

Jing-Shuai Wu,Qin-Yu Meng,Xiao-Hui Shi,Lu-Xin Liu,Zhen-Kun Zhang,Hua-Shi Guan,Chang-Lun Shao,Chang-Yun Wang

doi:10.1016/j.bioorg.2020.104246

Abstract

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. To improve its bioactivities and physicochemical properties, in the present study, cryptotanshinone (1) was biotransformed with the fungus Cunninghamella elegans AS3.2028. Three oxygenated products (2–4) at C-3 of cryptotanshinone (1) were obtained, among them 2 was a new compound. Their structures were elucidated by comprehensive spectroscopic analysis including HRESIMS, NMR and ECD data. All of the biotransformation 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 biotransformation 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. These findings provide a basal material for the discovery of candidates in treating Alzheimer's disease.

Highlights

Alzheimer's disease (AD) is a progressive and irreversible neurodegenerative disorder and the most common form of dementia among the elderly[1]
Primary antibodies against COX-2 (#12282), iNOS (#13120), TLR4 (#14358), p38 (#8690), extracellular regulated protein kinases (ERK) (#4695), Jun NH2-terminal protein kinase (JNK) (#9252), phosphor-ERK1/2 (Thr202/Tyr204, #4370), phosphor-p38 (Thr180/Tyr182, #4511), phosphor-JNK (Thr183/Tyr185, #4668) and NF-κB p65 (#8242) were purchased from Cell Signaling Technology (Beverly, MA, USA)
The EtOAc extract of the broth was subjected to the silica gel column chromatography and semi-preparative HPLC, resulting in the isolation of three biotransformed products (2 − 4), of which 2 was a new metabolite

Summary

Introduction

Alzheimer's disease (AD) is a progressive and irreversible neurodegenerative disorder and the most common form of dementia among the elderly[1]. In 2019, one sodium oligomannate derived from a traditional Chinese medicine seaweed, GV-971, was approved as a drug in China to relieve AD by inhibiting β-amyloid protein aggregation, remodeling gut microbiota and suppressing gut bacterial amino acids-shaped neuroinflammation[4]. It should be noted that neuroinflammatory processes are critical in the development and progression of AD5–8. The potent anti-neuroinflammatory inhibitors derived from natural products are expected as the candidates to treat AD9. 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

Results

Discussion

Conclusion