Application of fluorescently labeled tracer technique for detection of natural active macromolecules in Chinese medicine

Intestinal lymphatic transport of Smilax china L. pectic polysaccharide via Peyer's patches and its uptake and transport mechanisms in mononuclear phagocytes

Recently, the intestinal lymphatic transport based on Peyer's patches (PPs) is emerging as a promising absorption pathway for natural polysaccharides. Herein, the aim of this study is to investigate the PP-based oral absorption of a pectic polysaccharide from Smilax china L. (SCLP), as well as its uptake and transport mechanisms in related immune cells. Taking advantages of the traceability of fluorescently labeled SCLP, we confirmed that SCLP could be absorbed into PPs and captured by their mononuclear phagocytes (dendritic cells and macrophages) following oral administration. Subsequently, the systematic in vitro study suggested that the endocytic mechanisms of SCLP by model mononuclear phagocytes (BMDCs and RAW264.7 cells) mainly involved caveolae-mediated endocytosis, macropinocytosis and phagocytosis. More importantly, SCLP directly binds and interacts with toll-like receptor 2 (TLR2) and galectin 3 (Gal-3) receptor, and was taken up by mononuclear phagocytes in receptor-mediated manner. After internalization, SCLP was intracellularly transported primarily through endolysosomal pathway and ultimately localized in lysosomes. In summary, this work reveals novel information and perspectives about the in vivo fate of SCLP, which will contribute to further research and utilization of SCLP and other pectic polysaccharides.

A novel pectin polysaccharide from vinegar-baked Radix Bupleuri absorbed by microfold cells in the form of nanoparticles

Polysaccharides of vinegar-baked Radix Bupleuri (VBCP) have been reported to exhibit liver-targeting and immunomodulatory activities through oral administration, but the absorption behavior and mechanism of VBCPs have not been extensively studied. In this study, a novel HG type pectin polysaccharide, VBCP1-4, with a high molecular weight of 2.94 × 106 Da, was separated from VBCP. VBCP1-4 backbone was contained 1,4-α-D-GalpA, 1,4-α-D-GalpA6OMe, 1,3,4-α-D-GalpA and 1,2,4-α-D-Rhap. The branches were mainly contained 1,5-α-L-Araf, 1,3,5-α-L-Araf, t-α-L-Araf and t-α-D-Galp, which linked to the 3 position of 1,3,4-α-D-GalpA and the 4 position of 1,2,4-α-D-Rhap. VBCP1-4 could self-assemble to nanoparticles in water, with CMC values of 106.41 μg/mL, particle sizes of 178.20 ± 2.82 nm and zeta potentials of -23.19 ± 1.44 mV. The pharmacokinetic study of VBCP1-4, which detected by marking with FITC, revealed that it could be partially absorbed into the body through Peyer's patches of the ileum. In vitro absorption study demonstrated that VBCP1-4 was difficult to be absorbed by Caco-2 cell monolayer, but could be absorbed by M cells in a time and concentration dependent manner. The absorption mechanism was elucidated that VBCP1-4 entered M cells through clathrin-mediated endocytosis in the form of nanoparticles. These findings provide valuable insights into the absorption behavior of VBCP and contribute to its further development.

Preclinical pharmacokinetics-related pharmacological effects of orally administered polysaccharides from traditional Chinese medicines: A review

Polysaccharides (TCMPs) derived from traditional Chinese medicines (TCMs), such as Ganoderma lucidum, Astragalus membranaceus, Lycium barbarum, and Panax ginseng, are considered to be the main active constituents in TCMs. However, the significant pharmacological effects of orally administered TCMPs do not align well with their poor pharmacokinetics. This article aims to review the literature published mainly from 2010 to 2022, focusing on the relationship between pharmacokinetics and pharmacological effects. It has been found that unabsorbed TCMPs can exert local pharmacological effects in the gut, including anti-inflammation, anti-oxidation, regulation of intestinal flora, modulation of intestinal immunity, and maintenance of intestinal barrier integrity. Unabsorbed TCMPs can also produce systemic pharmacological effects, such as anti-tumor activity and immune system modulation, by regulating intestinal flora and immunity. Conversely, some TCMPs can be absorbed and distributed to various tissues, especially the liver, where they exhibit tissue-protecting effects against inflammation and oxidative stress-induced damage and improve glucose and lipid metabolism. In future studies, it is important to improve quality control and experimental design. Furthermore, research on enhancing the oral bioavailability of TCMPs, exploring the activity of TCMP metabolites, investigating pharmacokinetic interactions between TCMPs and oral drugs, and developing oral drug delivery systems using TCMPs holds great significance.

Investigation of the internalization and transport mechanism of Codonopsis Radix polysaccharide both in mice and Caco-2 cells

For Codonopsis Radix polysaccharides (CRPs), oral administration is generally considered the most convenient route for patients. However, the details of its absorption and transport mechanisms remain unclear. In this study, we aimed to evaluate the oral absorption of CPA (an inulin-type fructan extracted from CRPs) in mice and Caco-2 cells. It was labeled with fluorescein isothiocyanate, and the fluorescence derivative (FCPA) was used to trace the behavior of CPA. The results showed that FCPA could be absorbed after oral administration and has a wide tissue distribution, including in the stomach, intestine, kidneys, and liver. FCPA was poorly absorbed, and its internalization was time- and energy-dependent, as well as dependent on cholesterol- and dynamin-mediated endocytosis. Confocal laser scanning microscopy showed successful cellular internalization of FCPA from the cytoplasm to the nucleus. In addition, we found that FCPA was trafficked to endosomes and lysosomes, and that tubulin was required for its intracellular transport. These findings add new details to our knowledge of the internalization and transport mechanisms of CPA, which may prove useful to the development and application of oral formulations of CRPs.

Pharmacokinetics, distribution and excretion of inulin-type fructan CPA after oral or intravenous administration to mice

The aim of this work has been to establish and validate a simple and efficient method to detect the concentration of inulin-type fructan CPA from the roots of Codonopsis pilosula (Franch.) Nannf. in biosamples, and then apply it to evaluate the pharmacokinetics behavior, distribution character in tissue and excretion in mice. In this work, fluorescein isothiocyanate (FITC) was used to label CPA. Then FCPA was intravenously and orally administered to mice at different doses. In both i.v and p.o administration, FCPA concentration slowly declined in the circulatory system with a much longer T_1/2 and MRT. After p.o administration, the area under the time curve (AUC0-∞) was dose-dependently increased. Taken together, FCPA showed poor absorption and wide tissue distribution. These pharmacokinetic results yield helpful insights into the pharmacological actions of FCPA.

Oral absorption mechanism of the polysaccharides from Gastrodia elata Blume base on fluorescence labeling

The mechanisms of action of polysaccharides in vivo have been widely elucidated. However, the systematic research of its absorption and transport mechanisms remains unclear. Herein, we extracted a polysaccharide fraction (GEP) from Gastrodia elata by water extraction and alcohol precipitation and aimed to reveal its oral absorption processes through animal models and Caco-2 cells monolayer models. Our research data showed that GEP-Cy5.5 could be absorbed through the small intestine and the main absorption intestinal segment was the ileum (the absorption rate constant [Ka]: (3.64 ± 0.70) × 10^-4 cm/s; the effective apparent permeability [Papp value]: (4.88 ± 1.02) × 10^-5 cm/s). The ligated intestinal loops also revealed that GEP-Cy5.5 could pass through the villi of the small intestine and the mucosal barrier into the submucosa. Furthermore, GEP-Cy5.5 was readily absorbed into the blood through the gastrointestinal tract, then distributed in the liver and the kidney. The Papp value of in vitro transport study was (1.29 ± 0.08) × 10^-6 cm/s, which was a time-dependent process. Notably, GEP-Cy5.5 was transported through the endocytosis process mediated by clathrin and macropinocytosis. The underlying absorptive mechanisms of GEP in vivo and in vitro were clarified, which provided the guidance for clinical medicine administration and could deepen the biological understanding of oral polysaccharides.