It has long been suggested that a Na⁺-dependent carrier-mediated transport system is involved in the absorption of nucleobases and analogs, including some drugs currently in therapeutic use, for their uptake at the brush border membrane of epithelial cells in the small intestine, mainly based on studies in non-primate experimental animals. The presence of this transport system was indeed proved by the recent identification of sodium-dependent nucleobase transporter 1 (SNBT1/Slc23a4) as its molecular entity in rats. However, this transporter has been found to be genetically deficient in humans and higher primates. Aware of this deficiency, we need to revisit the issue of the absorption of these compounds in the human small intestine so that we can understand the mechanisms and gain information to assure the more rational use and development of drugs analogous to nucleobases. Here, we review the current understanding of the intestinal absorption of nucleobases and analogs. This includes recent knowledge about the efflux transport of those compounds across the basolateral membrane when exiting epithelial cells, following brush border uptake, in order to complete the overall absorption process; the facilitative transporters of equilibrative nucleoside transporter 1 (ENT1/SLC29A1) and equilibrative nucleobase transporter 1 (ENBT1/SLC43A3) may be involved in that in many animal species, including human and rat, without any major species differences.

Vascular dementia (VD) is a common neurodegenerative disease, and the cognitive dysfunction is a major manifestation of VD. Lots of evidences showed that beta-amyloid (Aβ) deposition and neuroinflammation act as vital elements in the progress of VD. The previous studies showed that osthole (OST) can improve the cognitive function of VD and Alzheimer’s disease (AD). However, the effect of OST on Aβ in VD brain is still unclear. Chronic cerebral hypoperfusion (CCH) of rats were used to investigate the effect of OST on Aβ through nod-like receptor protein 3 (NLRP3) inflammasome in this study. Morris Water Maze and Y-maze were used to test the spatial learning, memory and working abilities. Hematoxylin–eosin (H&E) and Nissl staining were used to observe the morphology and number of hippocampal neurons. Immunofluorescence staining was used to observe the number of microglia activated. Western blot was used to detect the expression of proteins. The study results showed that OST obviously enhanced the spatial learning, memory and working abilities induced by modified bilateral common carotid artery occlusion (BCCAO) in rats, improved the pathological damage of hippocampal neurons induced by BCCAO in rats, inhibited the activation of microglia induced by BCCAO in rats. Furthermore, this study also discovered that OST reduced Aβ deposition in VD hippocampus via inhibition the NLRP3 inflammasome. Together, these results suggest that OST reduces Aβ deposition via inhibition NLRP3 inflammasome in microglial in VD.

Ochratoxin A (OTA) is a mycotoxin produced by Aspergillus and Penicillium, and it is found in many foods. Acrylamide (AA) can be produced in foods treated at high temperatures. In this study, we investigated the combined toxicity of OTA and AA against human renal and hepatic cells in vitro. The concentration at which the synergistic effect of OTA and AA occurs was determined using the combination index obtained from the cell viability results for OTA and AA individually or in combination. The synergistic toxicity of both substances was evaluated by cell viability and the production of reactive oxygen species. In addition, apoptosis-related markers were significantly upregulated by OTA and AA individually or in combination. To determine the combined toxic effects of OTA and AA on the cells, the levels of enzymes involved in the phase I reaction and apoptosis-related markers were determined using quantitative (q)PCR and Western blot. The expression levels of CYP enzymes CYP1A1 and CYP1A2 involved in the phase I reaction significantly increased when the cells were treated with OTA and AA in combination. The expression of apoptosis-related markers, Bcl2-associated X protein (Bax) and caspase 3, also increased when the cells were treated with OTA and AA in combination. Therefore, the synergistic toxicity of OTA and AA suggests that such effects may contribute to nephrotoxicity and hepatotoxicity.

Crocetin is a major bioactive ingredient in saffron (Crocus sativus L.) and has favorable cardiovascular effects. Here, the effects of crocetin on L-type Ca²⁺ current (I_Ca-L), contractility, and the Ca²⁺ transients of rat cardiomyocytes, were investigated via patch-clamp technique and the Ion Optix system. A 600 µg/mL dose of crocetin decreased I_Ca-L 31.50 ± 2.53% in normal myocytes and 35.56 ± 2.42% in ischemic myocytes, respectively. The current voltage nexus of the calcium current, the reversal of the calcium current, and the activation/deactivation of the calcium current was not changed. At 600 µg/mL, crocetin abated cell shortening by 28.6 ± 2.31%, with a decrease in the time to 50% of the peak and a decrease in the time to 50% of the baseline. At 600 µg/mL, crocetin abated the crest value of the ephemeral Ca²⁺ by 31.87 ± 2.57%. The time to half maximal of Ca²⁺ peak and the time constant of decay of Ca²⁺ transient were both reduced. Our results suggest that crocetin inhibits L-type Ca²⁺ channels, causing decreased intracellular Ca²⁺ concentration and contractility in adult rat ventricular myocytes. These findings reveal crocetin's potential use as a calcium channel antagonist for the treatment of cardiovascular disease.

Early diagnosis of Niemann–Pick diseases (NPDs) is important for better prognosis of such diseases. N-Palmitoyl-O-phosphocholine-serine (PPCS) is a new NPD biomarker possessing high sensitivity, and with its combination with sphingosylphosphocholine (SPC) it may be possible to distinguish NPD-C from NPD-A/B. In this study, a rapid liquid chromatography-tandem mass spectrometry (LC-MS/MS) method (method 1) and a validated LC-MS/MS analysis (method 2) of PPCS and SPC were developed, and we have proposed a diagnostic screening strategy for NPDs using a combination of serum PPCS and SPC concentrations. Nexera and API 5000 were used as LC-MS/MS systems. C18 columns with lengths of 10 and 50 mm were used for method 1 and 2, respectively. ²H₃-Labeled PPCS and nor-SPC were used as internal standards. Selective reaction monitoring in positive-ion mode was used for MS/MS. Run times of 1.2 and 8 min were set for methods 1 and 2, respectively. In both methods 1 and 2, two analytes showed high linearity in the range of 1–4000 ng/mL. Method 2 provided high accuracy and precision in method validation. Serum concentrations of both analytes were significantly higher in NPD-C patients than those of healthy subjects in both methods. Serum PPCS correlated between methods 1 and 2; however, it was different in the case of SPC. The serum PPCS/SPC ratio was different in healthy subjects, NPD-C, and NPD-A/B. These results suggest that using a combination of the two LC-MS/MS analytical methods for PPCS and SPC is useful for diagnostic screening of NPDs.