Synthesis and antibacterial evaluation of novel psoralen derivatives against methicillin-resistant Staphylococcus aureus (MRSA).

Today, the bacterial infections caused by multidrug-resistant pathogens seriously threaten human health. Thereby, there is an urgent need to discover antibacterial drugs with novel mechanism. Here, novel psoralen derivatives had been designed and synthesized by a scaffold hopping strategy. Among these targeted twenty-five compounds, compound ZM631 showed the best antibacterial activity against methicillin-resistant S. aureus (MRSA) with the low MIC of 1 µg/mL which is 2-fold more active than that of the positive drug gepotidacin. Molecular docking study revealed that compound ZM631 fitted well in the active pockets of bacterial S. aureus DNA gyrase and formed a key hydrogen bond binding with the residue ASP-1083. These findings demonstrated that the psoralen scaffold could serve as an antibacterial lead compound for further drug development against multidrug-resistant bacterial infections.

Praziquantel promotes protection against Schistosoma japonicum infection in mice.

Praziquantel (PZQ) is the first line drug for the treatment of schistosomiasis. Several studies have confirmed that PZQ regulates host immunity, and we have recently found that pretreatment with PZQ enhances resistance against Schistosoma japonicum infection in buffaloes. We speculate that PZQ induces physiological changes in mice that prevent S. japonicum infection. To test this hypothesis and provide a practical measure to prevent S. japonicum infection, we determined the effective dose (the minimum dose), protection period and onset time of protection by comparing the worm burden, female worm burden and egg burden in PZQ-pretreated mice and blank control mice. Morphological differences between parasites were observed by measuring the total worm length, oral sucker, ventral sucker and ovary. The levels of cytokines, nitrogen monoxide (NO), 5-hydroxytryptamine (5-HT) and specific antibodies were measured using kits or soluble worm antigens. Hematological indicators on day 0 were analyzed in mice that received PZQ on days -15, -18, -19, -20, -21 and -22. The PZQ concentrations in plasma and blood cells were monitored using high performance liquid chromatography (HPLC). The effective dose was found to be two oral administrations (interval of 24 h) at 300 mg/kg body weight (BW) or one injection at 200 mg/kg BW, and the protection period of PZQ injection was 18 days. The optimal preventive effect was observed at two days post-administration, with a >92% worm reduction rate and significant worm reduction until 21 days after administration. Adult worms from PZQ-pretreated mice were runtish showing a shorter length, smaller organs and fewer eggs in the uteri of females. Detection of cytokines, NO, 5-HT and hematological indicators showed that PZQ induced immune-physiological changes, including higher levels of NO, IFN-γ and IL-2, and a lower level of TGF-ß. No significant difference in the anti-S. japonicum specific antibody levels was observed. The PZQ concentrations in plasma and blood cells 8 and 15 days post-administration were lower than the detection limit. Our results confirmed that pretreatment with PZQ promotes the protection of mice against S. japonicum infection within 18 days. Although we observed some immune-physiological changes in the PZQ-pretreated mice, the exact mechanisms involved in the preventive effect require further study.

Discovery of Novel 3,11-Bispeptide Ester Arenobufagin Derivatives with Potential in Vivo Antitumor Activity and Reduced Cardiotoxicity.

Arenobufagin, one of the bufadienolides isolated from traditional Chinese medicine Chan'su, exhibits potent antitumor activity. However, serious toxicity and small therapeutic window limits its drug development. In the present study, to our knowledge, novel 3,11-bispeptide ester arenobufagin derivatives have been firstly designed and synthesized on the base of our previous discovery of active 3-monopeptide ester derivative. The in vitro antiproliferative activity evaluation revealed that the moiety at C3 and C11 hydroxy had an important influence on cytotoxic activity and selectivity. Compound ZM350 notably inhibited tumor growth by 58.8 % at a dose 10 mg/kg in an A549 nude mice xenograft model. Therefore, compound ZM350 also presented a concentration-dependent apoptosis induction and low inhibitory effect against both hERG potassium channel and Cav1.2 calcium channel. Our study suggests that novel 3,11-bispeptide ester derivatives will be a potential benefit to further antitumor agent development of arenobufagin.

From Inflammation to Fibrosis: Novel Insights into the Roles of High Mobility Group Protein Box 1 in Schistosome-Induced Liver Damage.

Schistosomiasis is a chronic helminthic disease of both humans and animals and the second most prevalent parasitic disease after malaria. Through a complex migration process, schistosome eggs trapped in the liver can lead to the formation of granulomas and subsequent schistosome-induced liver damage, which results in high mortality and morbidity. Although praziquantel can eliminate mature worms and prevent egg deposition, effective drugs to reverse schistosome-induced liver damage are scarce. High mobility group box 1 (HMGB1) is a multifunctional cytokine contributing to liver injury, inflammation, and immune responses in schistosomiasis by binding to cell-surface Toll-like receptors and receptors for advanced glycation end products. HMGB1 is increased in the serum of patients with schistosomiasis and enables hepatic stellate cells to adopt a proliferative myofibroblast-like phenotype, which is crucial to schistosome-induced granuloma formation. Inhibition of HMGB1 was found to generate protective responses against fibrotic diseases in animal models. Clinically, HMGB1 presents a potential target for treatment of the chronic sequelae of schistosomiasis. Here, the pivotal role of HMGB1 in granuloma formation and schistosome-induced liver damage, as well the potential of HMGB1 as a therapeutic target, are discussed.