Tanshinone IIA prevents LPS-induced inflammatory responses in mice via inactivation of succinate dehydrogenase in macrophages

Metabolic reprogramming is associated with NLRP3 inflammasome activation in activated macrophages, contributing to inflammatory responses. Tanshinone IIA (Tan-IIA) is a major constituent from Salvia miltiorrhiza Bunge, which exhibits anti-inflammatory activity. In this study, we investigated the effects of Tan-IIA on inflammation in macrophages in focus on its regulation of metabolism and redox state. In lipopolysaccharides (LPS)-stimulated mouse bone marrow-derived macrophages (BMDMs), Tan-IIA (10 μM) significantly decreased succinate-boosted IL-1β and IL-6 production, accompanied by upregulation of IL-1RA and IL-10 release via inhibiting succinate dehydrogenase (SDH). Tan-IIA concentration dependently inhibited SDH activity with an estimated IC50 of 4.47 μM in LPS-activated BMDMs. Tan-IIA decreased succinate accumulation, suppressed mitochondrial reactive oxygen species production, thus preventing hypoxia-inducible factor-1α (HIF-1α) induction. Consequently, Tan-IIA reduced glycolysis and protected the activity of Sirtuin2 (Sirt2), an NAD+-dependent protein deacetylase, by raising the ratio of NAD+/NADH in activated macrophages. The acetylation of α-tubulin was required for the assembly of NLRP3 inflammasome; Tan-IIA increased the binding of Sirt2 to α-tubulin, and thus reduced the acetylation of α-tubulin, thus impairing this process. Sirt2 knockdown or application of Sirt2 inhibitor AGK-2 (10 μM) neutralized the effects of Tan-IIA, suggesting that Tan-IIA inactivated NLRP3 inflammasome in a manner dependent on Sirt2 regulation. The anti-inflammatory effects of Tan-IIA were observed in mice subjected to LPS challenge: pre-administration of Tan-IIA (20 mg/kg, ip) significantly attenuated LPS-induced acute inflammatory responses, characterized by elevated IL-1β but reduced IL-10 levels in serum. The peritoneal macrophages isolated from the mice displayed similar metabolic regulation. In conclusion, Tan-IIA reduces HIF-1α induction via SDH inactivation, and preserves Sirt2 activity via downregulation of glycolysis, contributing to suppression of NLRP3 inflammasome activation. This study provides a new insight into the anti-inflammatory action of Tan-IIA from the respect of metabolic and redox regulation.

[Systematic evaluation of neuromuscular blocking agents on prognosis of patients with moderate to severe acute respiratory distress syndrome]

Objective: To evaluate the prognostic impact of neuromuscular blocking agents (NMBA) on patients with acute respiratory distress syndrome (ARDS). Method: Online search of MEDLINE, Embase, Web of Science, CNKI, CBM and other Chinese databases for randomized controlled trials (RCTs) of NMBA in patients with ARDS from January 1994 to June 2019 was done, and literature was selected according to inclusion and exclusion criteria. The patients were divided into NMBA group and non-NMBA group according to whether NMBA was adopted or not. The prognostic indicators (ICU mortality, 28 d mortality, 90 d mortality) and NMBA-related complications (ICU acquired muscle weakness, barometric injury, pneumothorax) of the patients in the two groups were mainly analyzed. Meta-analysis of the data was performed using RevMan 5.0 software. Results: A total of 6 RCTs were included, and 1 502 patients were enrolled, including 761 in the NMBA group and 741 in the no-NMBA group. The 90-day mortality in the NMBA group and no-NMBA group were 38.8% and 42.6%, OR=0.87 (95%CI: 0.70-1.07, P=0.190); the 28-day mortality rates were 32.5% and 36.5%, OR=0.71 (95%CI: 0.45-1.11, P=0.130); ICU mortality rates were 31.8% and 43.8%, OR=0.60 (95%CI: 0.41-0.88, P=0.009). Conclusion: NMBA can reduce the ICU mortality of moderate to severe ARDS patients, but not reduce 28-day and 90-day mortality.

Design, synthesis and molecular docking of amide and urea derivatives as Escherichia coli PDHc-E1 inhibitors

By targeting the ThDP binding site of Escherichia coli PDHc-E1, two new 'open-chain' classes of E. coli PDHc-E1 inhibitors, amide and urea derivatives, were designed, synthesized, and evaluated. The amide derivatives of compound 6d, with 4-NO2 in the benzene ring, showed the most potent inhibition of E. coli PDHc-E1. The urea derivatives displayed more potent inhibitory activity than the corresponding amide derivatives with the same substituent. Molecular docking studies confirmed that the urea derivatives have more potency due to the two hydrogen bonds formed by two NH of urea with Glu522. The docking results also indicate it might help us to design more efficient PDHc-E1 inhibitors that could interact with Glu522.

[Studies on constituents of the leaves of Lindera aggregata (Sims) Kosterm]

OBJECTIVE

To study the antibacterial and anti-inflammatory constituents of the leaves of Lindera aggrega.

METHOD

Compounds were isolated by colum chromatography, and the structures were identified by spectroscopic methods.

RESULT

Six compounds were isolated and identified as mixture of 6-Acetyllindenanolide B-1 and B-2(I), dehydrolindestrenolide (II), hydroxylinderstrenolide (III), linderalactone (IV), kameofero (V), beta-sitosterol (VI).

CONCLUSION

These compounds were obtained from the leaves of Lindera aggregata for the first time.