Background: Ultraviolet radiation (UVR) is the major cause for hyperpigmentation, and to prevent this natural products are increasingly being explored as potential skin whitening agents. The aim of this study was to determine the total phenolic and flavonoid content, free radical scavenging activity, anti-tyrosinase activity and the inhibition of melanin content in α-melanocyte stimulating hormone-induced B16F10 melanoma cells of an aqueous extract of Garcinia atroviridis Griff. ex. T. Anderson fruit pericarps. Methods: The aqueous extract was prepared by extraction with distilled water at 105 o C for 60 min. Total phenolic and flavonoid content were determined using the Folin-Ciocalteau and aluminium chloride methods, respectively. Scavenging activity was assessed using 2,2-Diphennyl-1-picrylhydrazyl (DPPH) and 2,2′-Azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt (ABTS). Tyrosinase activity and melanin content were determined spectrophotometrically. Results: The results showed that the aqueous extract of Garcinia atroviridis fruit pericarps had a phenolic (26.33 ± 0.77 mg GAE/g plant extract) and flavonoid content (9.31 ± 0.40 mg QE/g plant extract). The aqueous extract of Garcinia atroviridis significantly inhibited mushroom tyrosinase activity (IC 50 of 40.72 ± 1.83 µg/mL) and cellular tyrosinase activity (at a concentration of 125 µg/mL) in α-melanocyte stimulating hormone-induced B16F10 melanoma cells. The Garcinia atroviridis extract also suppressed melanin content at concentrations of 31.25-125 µg/mL. Correlations of mushroom tyrosinase inhibition with DPPH and ABTS scavenging activities were 0.8673 and 0.9468, respectively. Conclusion: Our findings show that an aqueous extract of Garcinia atroviridis fruit pericarps is a source of natural compounds and antioxidant capacity which can inhibit tyrosinase activity and melanin content. Thus, aqueous extracts of Garcinia atroviridis may be a potential source of skin whitening agents for hyperpigmentation.

The permeability-based assay is commonly used to assess intestinal barrier function, and it relies on using a transwell insert as an essential compartment. The device consists of a semipermeable membrane that is attached at the bottom of the insert and splits the system into the apical and basolateral compartments. However, commercial inserts are standardized with different pore sizes based on the application and offer only a flat plane of two-dimensional cell culture. Herein, we present a simple, low-cost 3D-printed transwell device and a robust method to functionalize the inserts for paper-based 3D cell culture. This 3D-printed device was fabricated from a polylactic acid (PLA) filament, and a paper membrane used to support HT-29 cells for intestinal permeability assessment. A device showed good biocompatibility when culturing HT-29 cells for 48 and 72 h with 97 % and 98 % cell viability, respectively. Together with fluorescence images, cells were attached directly to the microfiber networks of a Matrigel-functionalized paper, indicating that the functionalized paper is biocompatible and bioactive. Furthermore, in a more appropriate culture microenvironment, SEM analyses revealed cellular features differentiating into mucus-secreting cells, evidenced by the formation of microvilli on the cell surface, which was further confirmed by immunofluorescence staining of villin-1. To demonstrate the usability of the 3D-printed transwell device, intestinal permeability was assessed using both chemical and biological stimulation treatments. The permeability results employing FITC-dextran validated the association between a different level of relative fluorescence intensity unit (RFU) and the orange color of live cells by CellTracker^TM. As a result, this 3D-printed transwell device provides a straightforward and cost-effective method for manufacturing a device for customization in many laboratory settings, making it a feasible alternative to marketed transwell devices that do not allow for customization.

Current in vitro methods for intestinal barrier assessment predominantly utilize two-dimensional (2D) membrane inserts in standard culture plates, which are widely recognized for their inability to replicate the microenvironment critical to intestinal barrier functionality. Our study focuses on creating an alternative method for intestinal barrier function by integrating a 3D-printed transwell device with a paper-based membrane. Caco-2 cells were grown on a Matrigel-modified paper membrane, in which the tight junction formation was evaluated using TEER measurements. Neutrophil-like dHL-60 cells were employed for neutrophil extracellular trap (NET) formation experiments. Furthermore, intestinal barrier dysfunction was demonstrated using NET-isolated and Staurosporine interventions. Intestinal barrier characteristics were investigated through immunofluorescence staining of specific proteins and scanning electron microscopy (SEM). Our paper-based intestinal barrier exhibited an increased resistance in a time-dependent manner, consistent with immunofluorescence images of Zonulin Occludens-1 (ZO-1) expression. Interestingly, immunofluorescence analysis revealed changes in the morphology of the intestinal barrier and the formation of surface villi. These disruptions were found to alter the localization of tight junctions, impacting epithelial polarization and surface functionality. Moreover, we successfully demonstrated the permeability of a paper-based intestinal barrier using FITC-dextran assay. Hence, the 3D-printed transwell device integrated with a paper membrane insert presents a straightforward, cost-effective, and sustainable platform for an in vitro cell model to evaluate intestinal barrier function.

Elevated high-density lipoprotein (HDL) levels do not correlate with reduced cardiovascular disease risk, suggesting that measuring HDL levels is an inadequate biomarker. Consequently, cholesterol efflux capacity (CEC), also referred to as HDL function, has emerged as a more relevant indicator of atherosclerosis risk. Most conventional assays utilize two-dimensional (2D) cell culture, which does not accurately represent the in vivo microenvironment. In this study, a paper membrane scaffold was developed to form foam cells by culturing THP-1 cells on Whatman No. 1 paper. Differentiation of monocytes into macrophages, which serve as cholesterol donors, was achieved by treating the cells with 100 nM phorbol 12-myristate 13-acetate (PMA). The macrophages were treated with 50 mM BODIPY-cholesterol to induce foam cell formation. Cell adhesion between the cells and the fibrous paper was examined using environmental scanning electron microscopy (ESEM). CD marker expression in monocytes and macrophages was analyzed using fluorescence imaging. CEC was calculated as the percentage of BODIPY-cholesterol released relative to total cholesterol, based on fluorescence intensity (Ex 482 nm, Em 522 nm). The CEC values from 38 volunteers did not differ significantly from those obtained with the commercial cell-based method (p < 0.0001). This paper-based THP-1-derived macrophage platform enables foam cell formation and CEC measurement.