Discovery of novel fusidic acid derivatives in mitigating LPS-induced acute liver injury by modulating RIPK1

Abstract

Inflammation plays a crucial role in the onset and progression of sepsis, affecting the overall trajectory of the condition. Additionally, sepsis can result in acute liver injury, which in turn may cause damage to multiple organ systems. Fusidic acid (FA) is a natural product with a steroidal structure and has good anti-inflammatory activity without the hormonal side effects of steroidal anti-inflammatory drugs, so it has potential applications in the development of anti-inflammatory drugs. In the present study, a series of novel FA derivatives were designed and synthesized by structural modification of FA C-3, C-16 and C-21, among which, compound 12 exhibited the strongest anti-inflammatory activity. Compound 12 inhibited nitric oxide (NO) release with an IC₅₀ of 3.26 ± 0.12 μM. Assessments conducted in both in vivo and in vitro settings indicated that compound 12 can reduce the levels of inflammatory factors, inhibit the activation of inflammatory pathways and improve liver pathological damage. Cellular thermal shift assay showed that compound 12 had binding ability with receptor interaction protein kinase 1 (RIPK1). Furthermore, through the western blotting experiment, this study found that compound 12 inhibited proteins such as RIPK1, p-IκB, p-p65, p-p38, p-JNK and p-ERK within the RIPK1/nuclear factor-κB (NF-κB)/mitogen-activated protein kinases (MAPK) signaling pathway. Concurrently, ELISA experiments indicated that compound 12 could dose-dependently reduce the levels of IL-6 and TNF-α. These results imply that compound 12 can protect the liver from inflammatory invasion by suppressing RIPK1 expression, which subsequently results in decreased activation of the NF-κB and MAPK signaling pathways. In this study, we creatively modified the structure of fusidic acid and obtained a new type of fusidic acid derivative 12. Compared with the glucocorticoids currently used for glucocorticoid receptors, compound 12 is novel in terms of structure and mechanism of action in alleviating sepsis. Our research indicates that compound 12 represents a promising candidate for the design and development of anti-sepsis therapeutics.