ABSTRACT
Objective:To study the protective effect of dihydroartemisinin (DHA) on adjuvant-induced arthritis (AIA) and collagen-induced arthritis (CIA) in rats, in order to explore its possible mechanism. Method:Wistar rats were randomly divided into eight groups, namely AIA control group, AIA model group, AIA DHA group and AIA methotrexate group, CIA control group, CIA model group, CIA DHA group and CIA methotrexate group. To establish adjuvant-induced arthritis (AIA) model, rheumatoid arthritis rats were induced through intradermal injection with 0.1 mL Freund's complete adjuvant (FCA) into right postpedes except for the control group. To establish the model of collagen-induced arthritis (CIA), except for control group, the caudal root of rats was immunized subcutaneously with 0.2 mL of emulsion containing 1 g·L-1 of Collagen type Ⅱ (CⅡ). One week later, CⅡ emulsion was injected for the second time. After the rheumatoid arthritis model was successfully established and the administration with DHA (30 mg·kg-1·d-1), the anti-inflammatory effect of DHA on AIA/CIA rats was observed, including the arthritis index (AI), paw swelling degree and effect of DHA on immune organ index of AIA/CIA rats. Interleukin (IL)-6 levels in serum was detected by enzyme-linked immunosorbent assay (ELISA) and pathological sections of ankle joints of AIA/CIA rats. RAW264.7 macrophage cells were cultured in vitro and treated with DHA at various doses (0.5, 1, 2, 4, 8, 16 μmol·L-1) for 24 h, and the cell viability was detected by methyl thiazolyl tetrazolium(MTT) assay. Lipopolysaccharides (LPS) group, LPS+DHA groups (0.5, 1, 2 μmol·L-1) and control group were established. The level of IL-6 was detected by enzyme-linked immunosorbent assay(ELISA). The protein expression levels of nuclear transcription factor-κB p65 (NF-κB p65) was tested by Western blot. Result:Compared with control group, the paw swelling, AI, spleen index and IL-6 levels of model group were significantly increased (PPPPPPPP-1) groups had a remarkable effect on the cell viability (PP-1. The level of IL-6 and the protein expression of NF-κB p65 in LPS group were higher than those of control group. Compared with LPS group, DHA (0.5 μmol·L-1) groups could significantly reduce the secretion of IL-6 (PκB p65. Conclusion:DHA can alleviate the ankle joint lesion on rheumatoid arthritis rats. Its mechanism may be related to NF-κB signal pathway.
ABSTRACT
In this study,in order to detect the antimicrobial activity of artemisinin and its derivatives artesunate and dihydroartemisinin,two methods including broth dilution and plate punching method were used to detect the antibacterial activity against gram-negative bacteria(Escherichia coli)and gram-positive bacteria(Staphylococcus aureus)of artemisinin,dihydroartemisinin and artesunate at various concentrations within 5 mmol·L~(-1)and at four time points(8,16,24,32 h).Two antibacterial positive drugs,streptomycin against E.coli and penicillin against S.aureus,were used as positive controls.Plate punching method showed that,unlike the results of 5 mmol·L~(-1)dihydroartemisinin or artesunate,no inhibition zone was detected at the same concentration of artemisinin after 24 h-treatment against E.coli.Broth dilution method showed that,the antibacterial activity of dihydroartemisinin against E.coli.was stronger than those of both artesunate and artemisinin;IC_(50)at24 h-treatment was 155.9μmol·L~(-1)for dihydroartemisinin,370.0μmol·L~(-1)for artesunate and none for artemisinin.Interestingly,dihydroartemisinin and artesunate showed the strongest antibacterial activity between 16-24 h,while artemisinin showed relatively stronger antibacterial activity between 8-16 h.Dihydroartermisinin showed no antibacterial activity against S.aureus.Above all,the antibacterial activity of artemisinins against E.coli is dihydroartemisinin>artesunate>artemisinin.Artemisinin and its derivatives have showed different antibacterial kinetics,and no antibacterial activity against S.aureus.has been detected with dihydroartemisinin.
Subject(s)
Anti-Bacterial Agents , Pharmacology , Artemisinins , Pharmacology , Artesunate , Pharmacology , Escherichia coli , Microbial Sensitivity Tests , Staphylococcus aureusABSTRACT
Toll-like receptors 4(TLR4),an important member of the TLR family,is considered as gene encoding LPS recep?tors,and major receptors for identifying lipopolysaccharide(LPS).LPS-induced TLR4 signaling pathway plays a key role in endotox?emia.After TLR4 activated by LPS,the mitogen-activated protein kinase(MAPK)signaling pathway and nuclear transcription factor κB(NF-κB)are activated and large amounts of inflammatory factors are released,triggering inflammatory cascade reaction.This arti?cle reviews the mechanisms of endotoxemia in treatment based on TLR4 signal pathway in three perspectives:the effects of LPS-TLR4 signaling pathway on the upstream target proteins,LPS-induced TLR4 signal transduction,and the downstream target proteins regulat?ed by LPS-TLR4 signaling pathway.