Design, characterization, and in vitro antiproliferative efficacy of gemcitabine conjugates based on carboxymethyl glucan

Chaenomeles sinensis polysaccharide and its carboxymethylated derivative alleviate dextran sulfate sodium-induced ulcerative colitis via suppression of inflammation and oxidative stress

Chaenomeles sinensis fruit polysaccharide (CSP) and carboxymethylated CSP (CSP-M) were prepared using ultrasound extraction and the sodium hydroxide-chloroacetic acid method. Structural analysis revealed that both CSP and CSP-M mainly consisted of glucose, arabinose, rhamnose, glucuronic acid, galactose, and xylose, and the introduction of carboxymethyl did not damage the polymer chain of CSP. In vivo studies verified that both CSP and CSP-M could remarkably alleviate the symptoms of ulcerative colitis (UC) mice and reduce intestinal epithelial cell depletion, along with the infiltration of inflammatory cells in colon tissue, by mediating the expression of myeloperoxidase (MPO), inflammatory factors [tumour necrosis factor-α (TNF-α), interleukin-1β (IL-1β), and IL-6], and oxidative stress factors [malondialdehyde (MDA), superoxide dismutase (SOD), glutathione (GSH), and nitric oxide (NO)]. Most importantly, the introduction of carboxymethyl significantly enhanced the anti-UC activity of CSP, confirming the efficacy of carboxymethylation as a method to enhance the biological activities of CSP, thereby suggesting the potential of CSP-M as a therapeutic option for UC.

Carboxymethylation of polysaccharides: Synthesis and bioactivities

Polysaccharides are a structurally diverse class of biomolecules with a wide variety of bioactivities. Natural polysaccharides isolated from plants and fungi are used as raw materials in food and pharmaceutical industries due to their therapeutic properties, non-toxicity, and negligible side effects, but many natural polysaccharides possess low bioactivities when compared to synthetic medicines due to their structure and physicochemical properties. Literature studies revealed that carboxymethylation of polysaccharides enhances the bioactivities and water solubility of native polysaccharides significantly, and provide structural diversity and even the addition of new bioactivities. This review article mainly focuses on the recent research on carboxymethylation of polysaccharides including preparation, characterization, and bioactivities. This article also throws light on future directions and scope to develop new carboxymethylated polysaccharide derivatives for many industries such as food processing, cosmetics, nutraceuticals, and pharmaceutical industry.

Development of potent CPP6-gemcitabine conjugates against human prostate cancer cell line (PC-3)

Gemcitabine (dFdC) is a nucleoside analogue used in the treatment of various cancers, being a standard treatment for advanced pancreatic cancer. The effect of gemcitabine is severely compromised due to its rapid plasma degradation, systemic toxicity and drug resistance, which restricts its therapeutic efficacy. Our main goal was to develop new active conjugates of dFdC with novel cell-penetrating hexapeptides (CPP6) to facilitate intracellular delivery of this drug. All new peptides were prepared by solid phase peptide synthesis (SPPS), purified and characterized by HPLC and LC-MS. Cell-penetrating peptides (CPP) contain a considerably high ratio of positively charged amino acids, imparting them with cationic character. Tumor cells are characterized by an increased anionic nature of their membrane surface, a property that could be used by CPP to target these cells. The BxPC-3, MCF-7 and PC-3 cancer cell lines were used to evaluate the in vitro cytotoxicity of conjugates and the results showed that conjugating dFdC with CPP6 significantly enhanced cell growth inhibitory activity on PC-3 cells, with IC₅₀ between 14 and 15 nM. These new conjugates have potential to become new therapeutic tools for cancer therapy.

RGDV-modified gemcitabine: a nano-medicine capable of prolonging half-life, overcoming resistance and eliminating bone marrow toxicity of gemcitabine

BACKGROUND

Gemcitabine has been widely used as a chemotherapeutic drug. However, drug resistance, short half-life and side effects seriously decrease its chemotherapeutic efficacy.

PURPOSE

The object of preparing RGDV-gemcitabine was to prolong the half-life, to overcome drug resistance and to eliminate bone marrow toxicity of gemcitabine.

METHODS

Arg-Gly-Asp-Val was coupled with gemcitabine, forming 4-(Arg-Gly-Asp-Val-amino)-1-[3,3-difluoro-4-hydroxy-5-(hydroxylmethyl)oxo-lan-2-yl]pyrimidin-2-one (RGDV-gemcitabine) involving 9-step reactions. The advantages of RGDV-gemcitabine to gemcitabine were demonstrated by a series of assays, such as in vitro half-life assay, in vitro drug resistance assay, in vivo anti-tumor assay, in vivo kidney toxicity assay, in vivo liver toxicity assay and in vivo marrow toxicity assay. The nano-features of RGDV-gemcitabine were visualized by TEM, SEM and AFM images. The tumor-targeting action and release of RGDV-gemcitabine were evidenced by FT-MS spectra.

RESULTS

Half-life and anti-tumor activity of RGDV-gemcitabine were 17-fold longer and 10-fold higher than that of gemcitabine, respectively. RGDV-gemcitabine, but not gemcitabine, showed no kidney toxicity, no liver toxicity, no marrow toxicity and no drug resistance. The advantages attributed to the nanofeatures of RGDV-gemcitabine were targeting tumor tissue and releasing gemcitabine in tumor tissue.

CONCLUSION

RGDV-gemcitabine successively overcame the defects of gemcitabine and provided a practical strategy of nano-medicine.

Synthesis of amino acid derivatives of 5-alkoxy-3,4-dihalo-2(5H)-furanones and their preliminary bioactivity investigation as linkers

A series of amino acid derivatives are successfully synthesized via a metal-free C-N coupling reaction of 5-alkoxy-3,4-dihalo-2(5H)-furanones and amino acids. Their structures are well characterized with ¹H NMR, ¹³C NMR, ESI-MS and elemental analysis. As potential linkers of the 2(5H)-furanone unit with other drug moieties containing a hydroxyl or amino group, the effect of amino acids is investigated by comparison with other 2(5H)-furanone compounds by constructing C-O/C-S bonds. The preliminary results of the biological activity assay by the MTT method on a series of cancer cell lines in vitro reveal that the introduction of amino acids basically has no toxic effect. This can lead to these 2(5H)-furanone derivatives being further well-linked with other bioactive moieties with amino or hydroxy groups as expected. Thus, the biological activity assay gives a direction for the design of bioactive 2(5H)-furanones based on these amino acid linkers.