Abstract
The poor bioavailability and rapid metabolism of curcumin (CUR) restrict its clinical application. Piperine (PIP), which was extracted from natural compounds, can increase the plasma concentration of curcumin in humanidad. As an artificial synthetic piperine analog, silepcimide (ILE) has significant advantages because of the low price and simple synthesis process. In this study, a simple and rapid HPLC-UV method was developed for determination of the plasma concentration of CUR, PIP,ILE and dihydrocurcumin (DHC, a metabolite of CUR) simultaneously. Meanwhile, the effects of PIP and ILE on the plasma concentration and pharmacokinetics of DHC in SD rats was studied to explore whether ILE could serve as a CUR bioavailability enhancer. The metabolic pathway of CUR was studied by comparing the differences of CUR plasma concentration between intravenous injection and oral administration over the same time period, and reacting with small intestine homogenate without microbes of SD rats. The results of drug-time curve showed that combined administration of ILE and CUR had significant effect on plasma concentrations of DHC. Repeated administration of PIP or ILE could significantly increase the plasma concentration of DHC. Plasma CUR could be detected in the samples of from intravenous injection of CUR rats, whereas, it couldn’t be detected in the plasma sample form oral administration rats. CUR incubated with intestinal homogenate without intestinal bacteria could not be transformed into DHC. In conclusion, our results show that ILE can improve the bioavailability of CUR. Additionally, it was inferred that most of the CUR was reduced to DHC by NADPH when it was absorbed from gastrointestinal tract, and our results demonstrated that this pathway might be mediated by gastrointestinal microorganisms.
Highlights
Curcumin (CUR) is a natural diketone compounds which is extracted from curcuma rhizome (Aggarwal et al, 2007)
Establishment of an efficient and convenient method for the determination of curcumin in biological samples would be helpful for the study of curcumin pharmacokinetics
The results showed that the mixture of 80% dimethyl sulfoxide (DMSO) and 20% EtOH was used as gavage agent with CUR at dose of 200 mg kg−1, the concentration of curcumin metabolites in rat plasma could be greatly improved
Summary
Curcumin (CUR) is a natural diketone compounds which is extracted from curcuma rhizome (Aggarwal et al, 2007). Stimulant and colouring properties in diet (Eigner and Scholz, 1999), curcumin can inhibit the activity of oxidative stress and the activity of nuclear factor kappa-B(NF-κB), Cyclooxygenase-2(COX-2), lipoxygenase(LOX), inducible NOS)iNOS) and other inflammatory mediators, thereby plays an anti-inflammatory and anti-oxidant role (Bengmark, 2006; Li J. et al, 2019). Research on Pharmacokinetics of Curcumin et al, 2011; Darvesh et al, 2012; Ullah et al, 2017) and malaria (Reddy et al, 2005; Nandakumar et al, 2006). Clarification of the pharmacokinetics of curcumin and its related factors would improve its clinical application, which is of great important in the research and development of natural products. Establishment of an efficient and convenient method for the determination of curcumin in biological samples would be helpful for the study of curcumin pharmacokinetics
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