Surface decoration by Spirulina polysaccharide enhances the cellular uptake and anticancer efficacy of selenium nanoparticles

A simple and solution-phase method for functionalization of selenium nanoparticles (SeNPs) with Spirulina polysaccharides (SPS) has been developed in the present study. The cellular uptake and anticancer activity of SPS-SeNPs were also evaluated. Monodisperse and homogeneous spherical SPS-SeNPs with diameters ranging from 20 nm to 50 nm were achieved under optimized conditions, which were stable in the solution phase for at least 3 months. SPS surface decoration significantly enhanced the cellular uptake and cytotoxicity of SeNPs toward several human cancer cell lines. A375 human melanoma cells were found extremely susceptible to SPS-SeNPs with half maximal (50%) inhibitory concentration value of 7.94 μM. Investigation of the underlying mechanisms revealed that SPS-SeNPs inhibited cancer cell growth through induction of apoptosis, as evidenced by an increase in sub-G(1) cell population, deoxyribonucleic acid fragmentation, chromatin condensation, and phosphatidylserine translocation. Results suggest that the strategy to use SPS as a surface decorator could be an effective way to enhance the cellular uptake and anticancer efficacy of nanomaterials. SPS-SeNPs may be a potential candidate for further evaluation as a chemopreventive and chemotherapeutic agent against human cancers.

Effects of the polysaccharide SPS-3-1 purified from Spirulina on barrier integrity and proliferation of Caco-2 cells

Following ultrasonication combined with a hot water extraction, a new type of bioactive polysaccharide, SPS-3-1, was purified from Spirulina using ultrafiltration centrifugation and gel filtration chromatography. The structure of SPS-3-1 was determined with high performance gel permeation chromatography, gas chromatography, periodate oxidation, fourier transform infrared spectroscopy, nuclear magnetic resonance, and atomic force microscopy performance. SPS-3-1 is a homogeneous β-pyran polysaccharide with 1 → 2, 1 → 3, and 1 → 4 glycosyl bonds, mainly composed of d-ribose, l-rhamnose, l-arabinose, l-foucose, and d-glucose. The molar ratio of these components is 1:0.70:1.03:2.1:6.59. The molecular weight of SPS-3-1 is 623.02 kDa. SPS-3-1 has a linear filament structure with a width of 34.132 nm and a height of 819.169 pm. We found that SPS-3-1 significantly enhanced transepithelial electrical resistance, a tight junction integrity marker, in a Caco-2 intestinal cell monolayer model. Analysis of the effect of SPS-3-1 on cell proliferation showed that SPS-3-1 inhibited the in vitro growth of Caco-2 and HepG2 cells with an IC₅₀ of 566.67 μg/mL and 1078.95 μg/mL, respectively.

Anti-colon cancer effects of Spirulina polysaccharide and its mechanism based on 3D models

Spirulina polysaccharides (PSP) possess significant biological properties. However, it is still a lack of investigation on the anti-colorectal cancer effect and mechanism. In this study, PSP showed significant effects on LoVo cell spheroids with an IC₅₀ value of 0.1943 mg/mL. The analysis of transcriptomics and metabolomics indicated the impact of PSP on LoVo spheroid cells through involvement in the two pathways of "glycine, serine, and threonine metabolism" and "ABC transporters". And, the q-PCR data further verified the pointed mechanism of PSP on colon cancer (CC) by regulating the expression levels of relevant genes in the synthesis pathways of serine and glycine in tumor cells. Furthermore, the anti-colon cancer effects of PSP were verified via other human colon cancer cell lines HCT116 and HT29 spheroids (IC₅₀ = 0.0646 mg/mL and 0.2213 mg/mL, respectively), and three patient-derived organoids (PDOs) with IC₅₀ values ranging from 3.807 to 7.788 mg/mL. In addition, this study found that a mild concentration of PSP cannot enhance the anti-tumor effect of 5-Fu. And a significant inhibition was found of PSP in 5-Fu resistance organoids. These results illustrated that PSP could be a treatment or supplement for 5-Fu resistant colorectal cancer (CRC).

Design and development of spirulina polysaccharide-loaded nanoemulsions with improved the antitumor effects of paclitaxel

Aims: In this study, we prepared spirulina polysaccharides into spirulina polysaccharide-loaded nanoemulsions (SPS-NEs), and determined the antitumor effect of SPS-NEs, when combined with paclitaxel (PTX).Methods: SPS-NEs were prepared by a phase transformation method. The Characterisation and stability of SPS-NEs was measured. The antitumor effect of SPS-NEs combined with PTX was determined by S180 cells or RAW 264.7 macrophages and S180 tumour-bearing mice.Results: SPS-NEs were spherical and stable, the particle size of SPS-NEs was 84.6 ± 3.31 nm, PDI = 0.235 ± 0.02. PTX + SPS-NEs exhibited a much greater toxicity against RAW 264.7 cells than PTX. PTX + SPS-NEs increased the release of NO, IL-6 and TNF-α, and the expression of p-p65 NF-κB, p-I-κB, TLR4. In addition, PTX + SPS-NEs significantly inhibited tumour growth by 72.82% and increased the secretion of serum IL-2, TNF-α and IFN-γ.Conclusions: SPS-NEs can regulate immunity through TLR4/NF-κB signalling pathways, which enhances the anti-tumour effect of PTX.

Spirulina polysaccharides improve postthaw sperm quality in bulls by inhibiting the activation of pathways related to protein kinase A

Sperm cryopreservation is widely used in assisted reproductive technology (ART) and livestock breeding. Although sperm cryopreservation accelerates breeding, the quality of cryopreserved sperm tends to be decreased. Improving the quality of frozen sperm is a hot topic, and spirulina polysaccharide, known for its immunomodulatory and antioxidant properties, is considered a promising natural extract for extensive studies. In this study, a pectic polysaccharide was extracted from spirulina (PSP), and its effects on postthaw bovine sperm viability were evaluated. Phosphoproteomic analysis based on TMT labelling and LC-MS/MS was employed. The results revealed that 10 mg/L PSP had significant protective effects on postthaw sperm viability, plasma membrane integrity, acrosomal integrity, and mitochondrial membrane integrity. Moreover, PSP increased the antioxidant capacity by activating antioxidant enzymes such as SOD, CAT, and GSH-PX and reduced apoptosis, ROS release and MDA levels. In addition, PSP resulted in decreased phosphorylation levels of proteins related to the acrosome, flagellum, metabolism, energy acquisition, and apoptosis. This protective effect of PSP on frozen sperm was achieved by inhibiting the activation of protein kinase A(PKA) protein-related pathways.