OBJECTIVE: In this study, we aim to investigate the involvement of heme oxygenase-1 (HO-1) in the anti-inflammatory effects of ZnC in lipopolysaccharide (LPS)-induced RAW 264.7 murine macrophages.
MATERIALS AND METHODS: We used immunoblotting analysis to evaluate the involvement of HO-1 in the anti-inflammatory effects of ZnC and the signaling pathway involved was measured using Dual luciferase reporter assay.
RESULTS: Results from immunoblotting analysis demonstrated that pretreatment of cells with ZnC enhanced the expression of HO-1 in RAW 264.7 cells. Pretreatment of cells with HO-1 inhibitor (tin protoporphyrin IX dichloride) significantly attenuated the inhibitory effects of ZnC on nitric oxide (NO) production, inducible nitric oxide synthase (iNOS) expression and NF-κB activation in LPS-induced RAW 264.7 cells, suggesting that HO-1 play an important role in the suppression of inflammatory responses induced by ZnC. Furthermore, results from co-immunoprecipitation of Nrf2 and Keap1 and dual luciferase reporter assay showed that pretreatment of ZnC was able to activate the Nrf2 signaling pathway. Treatment of cells with p38 inhibitor (SB203580), c-Jun N-terminal kinase inhibitor (SP600125), and MEK 1/2 inhibitor (U0126) did not significantly suppress the induction of HO-1 by ZnC. Moreover, our present findings suggest that the effects of ZnC on NO production, HO-1 expression, and Nrf2 activation were attributed to its Zn subcomponent, but not l-carnosine.
CONCLUSION: Pretreatment with ZnC was able to activate Nrf2/HO-1 signaling pathway, thus suppressing the expression of inflammatory mediators, such as NO and iNOS in LPS-induced RAW 264.7 cells.
Objective: This study aims to fractionate water extract of Labisia pumila, identify the compound(s) involved and elucidate the possible mechanism(s) of its vasorelaxant effects.
Methods: Water extract of Labisia pumila was subjected to liquid-liquid extraction to obtain ethyl acetate, n-butanol and water fractions. In SHR aortic ring preparations, water fraction (WF-LPWE) was established as the most potent fraction for vasorelaxation. The pharmacological mechanisms of the vasorelaxant effect of WF-LPWE were investigated with and without the presence of various inhibitors. The cumulative dose-response curves of potassium chloride (KCl)-induced contractions were conducted to study the possible mechanisms of WF-LPWE in reducing vasoconstriction.
Results: WF-LPWE produced dose-dependent vasorelaxant effect in endothelium-denuded aortic ring and showed non-competitive inhibition of dose-response curves of PE-induced contraction, and at its higher concentrations reduced KCl-induced contraction. 1H-[1,2,4]oxadiazolo[4,3-a]quinoxalin-1-one (ODQ) significantly inhibited vasorelaxant effect of WF-LPWE. WF-LPWE significantly reduced the release of intracellular calcium ion (Ca2+) from the intracellular stores and suppressed the calcium chloride (CaCal2)-induced contraction. Nω-nitro-L-arginine methyl ester (L-NAME), methylene blue, indomethacin and atropine did not influence the vasorelaxant effects of WF-LPWE.
Conclusion: WF-LPWE exerts its vasorelaxant effect independently of endothelium and possibly by inhibiting the release of calcium from intracellular calcium stores, receptor-operated calcium channels and formation of inositol 1,4,5- triphosphate. WF-LPWE vasorelaxant effect may also mediated via nitric oxide-independent direct involvement of soluble guanylate cyclase (sGC)/ cyclic guanosine monophosphate (cGMP) pathways.
METHODS: Rats were devided into five groups consisting of three treatment groups and two control groups. Baseline blood investigations were done before and following commencement of treatment. Spontaneous hypertensive rats were treated for 28 consecutive days and the blood pressure was measured weekly.
RESULTS: Kadukmy™ administration showed a significant reduction in systolic blood pressure (SBP), diastolic blood pressure (DBP) and mean arterial pressure (MAP) (P