###### Abstract  
Cell-culture-based drug tests are usually performed in an instantaneous delivery manner. However, in vivo pharmacokinetic studies have shown a steady increase in the concentration of bioactive compounds in the plasma following oral administration, with the maximum concentration observed after several hours. Here, a novel palm-sized syringe pump powered by the manual winding of a spring was utilized for sustained delivery of chlorogenic acid (CHA) to lipopolysaccharide-acrylamide (LPS)-challenged RAW 264.7 macrophages over 2 h. When delivered in a sustained manner and simulating the in vivo pharmacokinetics following oral administration, CHA showed a stronger inhibitory effect on LPS-induced expression of inducible nitric oxide synthase and the transcription and secretion of pro-inflammatory cytokines, such as tumor necrosis factor-\(\alpha\). It also enhanced the mRNA expression of the gene encoding heme oxygenase 1. The suppression of phosphorylation of p38 but not the nuclear translocation of nuclear factor-xB was affected by the sustained delivery of CHA. High-performance liquid chromatography analysis indicated that the sustained delivery model showed a higher concentration of CHA in the conditioned medium two hours after starting the delivery. A stronger anti-inflammatory effect of CHA was observed upon sustained delivery to the cell medium, simulating an in vivo pharmacokinetic release profile following oral administration. pharmacokinetics; ingestion; oral administration; chlorogenic acid; anti-inflammation; antioxidant; windup precision syringe pump +
Footnote †: journal: Medical Imaging  
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Footnote 1: email: _Applied_  
protein kinase (MAPK) and nuclear factor (NF)-\(\kappa\)B signaling pathways and decreases the production of pro-inflammatory cytokines [10; 11; 12]. In vivo studies have shown that different administration approaches, such as injection and ingestion of nutraceuticals, exhibit very different pharmacokinetics. While the concentration of nutraceuticals, such as CHA, in plasma reaches maximum levels immediately after injection and then starts to reduce, a sustained increase in its concentration in plasma is observed over a couple of hours after ingestion [13; 14]. In cell studies, an instantaneous delivery method is typically employed without considering pharmacokinetic differences. Although the release of nutraceuticals, including polyphenols, can be tailored via microencapsulation, accurate control of their release profile is difficult [15]. Microencapsulation is a technology used for packing active substances, such as polyphenols, in small-sealed capsules. Packaged materials are called core materials, and packing materials are called wall materials. For instance, CHA is encapsulated in chitosan via ionic gelation [16]. The in vitro release profile of the core material is affected by various factors, including the use of the microencapsulation method, choice of the wall material, and particle size. The in vitro anti-inflammatory activity of bioactive compounds is strongly affected by different encapsulation approaches [17; 18; 19]. Variable encapsulation efficiency and incomplete release of the core material from these encapsulation particles also limits the direct comparison of different delivery profiles. For instance, in vitro release kinetics have shown incomplete release of CHA from chitosan nanoparticles in various buffers [16]. A syringe pump is a motor-driven precision pump that involves the use of a syringe to deliver precise and accurate amounts of fluid into subjects [20]. The bulky size and electrical outlet requirements of a common syringe pump limit its application in cell studies. A palm-sized windup syringe pump was previously devised in our lab [21]. Its compact size and cord-free design render it suitable for cell studies. In this study, it was used to actualize the controllable sustained delivery of CHA into the culture medium.